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DIGITAL PHOTOGRAPHY

UNIT

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“Pixels & Images” Jefferson Senior High School ART DEPARTMENT – Alexandria, MN 56308

Bob Hatlestad, Instructor – rhatlest@alexandria.k12.mn.us Updated July 2008

UNIT OUTCOME: 1. The student will gain an understanding of pixels, images, resolution, and graphic formats.

ASSIGNMENTS: 1. Read Packet No. 2 on the “Pixels & Images” and complete Worksheet #2 by__________________. 2. Assignment Notebook: make sure you have and use daily for Assignments in Digital Photography. 3. Presentation on Pixels and Resolution: Choose “Pixels and Resolution” as your topic and create a 15-slide Power Point presentation. You can use information AND graphics to explain what these 2 concepts are and how they are used. You will not present this project, but turn it in for credit. Title this assignment “Pixels and Resolution”. Read and follow these steps for this Power Point project.

A. Search Engine: choose a search engine and type in the phrase “Pixels” or “Resolution”. You should find dozens of web sites with information and graphics.

B. Open Powerpoint: on your computer, go to Programs-308/408 Shortcuts-Microsoft Office 2007-Powerpoint to open the program. Select a slide and you can get started. To add more slides, you can go to Insert-New Slide, or use Ctrl+M. Choose a background that is suitable for your person.

C. Introduction: on your 1st slide, type in the name of your project (Pixels & Resolution) as a title slide. You should also type YOUR NAME on the 1st slide.

D. Information: on the next few slides, explain what pixels and resolution means to digital photography, and how they work together. You may “copy’n’paste” information from the Web to your Powerpoint if you wish. If you do this, please change the font style and color to match the other text in your presentation. (do NOT use more than 2 different fonts in this presentation) You will also have to “CITE” your sources – do this by copying the web address and pasting it on the slide where you are copying the information. Keep your source in a smaller font size (8-10 is recommended).

E. Graphics: Make sure you can find at least five (5) graphics explaining these 2 terms in your Powerpoint. Go to Google-Images (type in the name, hit the ENTER key) and find a graphic. Right-click on the photo and choose Copy. Then go back to your presentation and right-click and Paste (Ctrl+V) on the slide you want. You can move and/or resize the photograph to fit the slide.

F. Ending: On the last slide, wrap up your presentation with something you have learned by doing this project.

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G. Grading Folder: When you are completely finished, go to Save As, navigate to your “Grading Folder” on the X-Drive, add YOUR NAME to the title “Pixels & Resolution”.

BONUS PROJECTS: 1. Web Search: “Digital Photography” or “Digital Cameras”. Go on the Internet and find a good Search Engine. Type in “Digital Photography” or “Digital Cameras” – and look for 10-20 web sites that have good Digital Photography/Camera information and/or links. Copy the web addresses of five (5) of the BEST websites, paste it on an e-mail message, and send to the following e-mail address. Title the e-mail “Web Search” and include your NAME and Period Number in that message. rhatlest@alexandria.k12.mn.us NOTE: If you do not have an e-mail account, paste those 5 web addresses onto a Word document, type your NAME and Period Number on it, print it out, and hand it into the basket.

WEBSITES TO VISIT: www.webshots.com/ www.altavista.com/images www.digitalblasphemy.com/ www.visualparadox.com/ http://www.3dwallpaperworld.com/ (wide variety of wallpapers – some real cool) www.northernimages.com (great color landscapes) www.ditto.com/ (search engine for various graphics) www.snap-shot.com/ (great collection of color photos) http://graphicssoft.about.com/compute/graphicssoft/cs/digitalphotogentip/index.htm?rnk=r3&terms=powerpoint+terminology http://www.computerschool.net/dphoto/formats.html http://www.eyetec.net/group5/M21S1.htm#The%20Eye-Camera%20Analogy

KEY TERMS & DEFINITIONS: Anti-aliasing, the placing of semitransparent pixels around the jagged edges of a design detail. Bit: a binary digit, the smallest unit of computer information, a 1 or 0. Bitmap: a stored image that is mapped onto a rectangular grid of pixels, each pixel having a particular gray or color value which is defined as a specific number of bits. Bitmap images are typically created within image-editing programs and with a scanner. Because it has a physical dimension, “stretching” a bitmap results in image degradation, commonly known to as “pixellation”. BMP was developed by Microsoft and is the native graphics format for Windows users. The images you see when Windows starts up and closes, and the wallpaper that adorns your desktop, are all in BMP format. BMP tends to store graphical data inefficiently, so the files it creates are larger than they need to be. Brightness: refers to the lightness or darkness of an image. Another term related is “Luminance” which means how bright or dull an object is, or how intensely you perceive the energy of light to be. Compression: methods of reducing the bit information of a graphic file, typically resulting in a substantial decrease in file size. Compression techniques can best be described as “Lossy” the discarding of data (JPG), and “Lossless” (TIF and GIF). DPI—Dots Per Inch. Number of dots a printer or device (like a monitor) can display per linear inch. For example, most laser printers have a resolution of 300 dpi, most monitors 72 dpi, most PostScript imagesetters 1200 to 2450 dpi. Photo quality inkjet printers now range from 1200 to 2400 dpi. Digitize—To convert analog information into digital format for use by a computer. File extension In filenames, the group of letters after the period is called the file extension. Gamma is a measurement of contrast - how much different pixels vary in their brightness. GIF (graphics interchange format) The GIF file format was developed as a cross-platform graphic standard, which means that it is supported by all graphical Internet browsers. GIF supports up to 8-bit color (256 colors) and lets you create custom palettes for your image. GIF offers several advanced graphic

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options, including transparent backgrounds, interlaced images, and animation. The GIF file format uses lossless compression, which means that when you convert an image to the GIF file format, all of the file information is stored within the image so that the GIF file looks exactly like the original image. Graphic: Images, illustrations, graphics and clip art, in specific or various formats, used to create and enhance web pages and 2-dimensional materials. A term commonly used on the WWW to indicate clip art, illustrations, images, backgrounds, icons, animation, etc. for use in designs. Handles: the little black squares or boxes that appear in the 4 corners of an imported graphic or text box. Hue: 100-percent saturated color. Icon: A small picture or image that represents an object, a folder, or a program. Clicking or double-clicking icons launches programs, opens windows, and executes commands. Image: (see “graphic” above). JPEG (Joint Photographic Experts Group) The JPEG file format was developed as a compression scheme designed specifically for computer images. JPEG supports up to 32-bit color (4.2 billion colors) and is, therefore, an excellent option for photographs, image maps, and scanned color images. JPEG files use lossy compression, which means that the image loses information while continuing to provide high-quality images with a high level of compression. You can choose the image quality: the higher the image quality, the larger the file size. Some Web browsers support progressive JPEG images. Progressive images appear on screen gradually so that you can see portions of an image before it finishes loading. Light is a form of electromagnetic energy. Electromagnetic energy is radiated in waves along a straight-line path. Visible light is electromagnetic energy between wavelengths about 400nm and 700nm. Within this visible spectrum individual wavelength bands produce sensation of colors; mixed together they appear white. LCD—Liquid Crystal Display. A full-color display screen on cameras used to preview and review pictures and view information, such as menu options and camera settings. Lossless A type of compression algorithm that reduces file size without losing any data. Typically this is done by finding and eliminating redundant information. GIF and PNG file formats use lossless compression. Lossy Graphics files are big, and most file formats (such as BMP, TIFF, PICT, and PSD) are inefficiently coded, so they are larger than they need to be. Lossy techniques, such as JPEG, crunch files down smaller, but they throw out image quality in the process. Most of the time, however, you can't see the difference in image quality unless you try to print the graphics on a professional image setter. Mask: a 256-color gray scale bitmap similar to a stencil that allows some “open” and “closed” areas of the image. This allows some special effects affect certain open parts of the image, while the covered areas of the image are not affected because they are hidden by the mask. Megapixel: A unit equal to one million pixels. The higher the resolution, the more pixels in an image and therefore the greater the image quality. An image file that is 1 megapixel (MP) can make a photo realistic print of 5 x 7 inches; a 2 MP file can make an 8 x 10-inch print; a 3 MP file can make an 11 x 14-inch print. Megabyte—An amount of computer memory consisting of about one million bytes. The actual value is 1,048,576 bytes. Memory card—A storage device used to store data, such as picture and movie files. Available in a range of sizes, such as 8 MB, 32 MB, and 256 MB. Opacity: refers to the ability of an image/graphic to be “seen through” (high opacity), or NOT being able to see through, it blocks the view (low opacity). Pixel: the picture element, the individual data used to display a picture on a computer monitor. The smallest unit of a computer screen. It can range from black and white to millions of colors (see "bit depth"). The more colors available for a pixel to display, the more bytes requires. Screens are formatted in pixels per inch, such as 72 pixels/inch. The image displayed on monitors or in a graphic produced by a scanner or paint program is made up lots of dots called pixels. Collectively, the number of pixels displayed is referred to as the image's resolution. A pixel on a monitor is a number of red, green, and blue phosphor dots. These dots are "excited" to varying degrees by the monitor's three electron guns, and the results mix additively to generate a specific color.

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PPI—Pixels Per Inch. The number of pixels per linear inch is used to describe image resolution. A higher ppi means more image detail and correlates to higher image quality. Monitors display images at 72 ppi, inkjet printers require at least 150 ppi to produce photo realistic prints. PNG Portable Network Graphics A lossless graphics file format that combines many benefits of GIF and JPEG. PNG also allows for many features that the GIF format doesn’t, including 254 levels of transparency (GIF supports only 1), more control over image brightness, and support for more than 256 colors. PNG also supports progressive rendering and tends to compress better than a GIF. PSD PhotoShop's native format – Photo Shop Document. This puppy is the format you'll use for all of your graphics work. It has all the editing information (Layers, Channels, etc.) in it and is usually a pretty big file. Several graphics Programs can read and write this format, but it is not a universally accepted format. You'll need to keep an original of most of your work in this format so you can go back and edit it again if you need. You'll usually need to Save a Copy in another format (JPG) for presentation. Resample: a technique that smoothes out rough spots in a graphic by “estimating” how many missing pixels should appear, and then fills them it with the appropriate color. Resize: a technique where you change the height and width of a graphic with the handles, or with a graphic converter that changes size, shape, and file format. RGB RGB refers to the so-called scientific hues, the additive primary colors red, green, and blue, that, when mixed together in equal amounts, create white light. Television sets and computer monitors display their pixels based on values of red, green, and blue Resolution Resolution is a measure of graphics that’s used to describe what a printer can print, a scanner can scan, and a monitor can display. In printers and scanners, resolution is measured in dots per inch (dpi), the number of pixels a device can fit in an inch of space. A monitor's resolution refers to the number of pixels in the whole image, because the number of dots per inch varies depending on the screen's dimensions. For example, a resolution of 1,280 by 1,024 means that 1,024 lines are drawn from the top to the bottom of the screen, and each of these lines is made up of 1,280 separate pixels, and in turn, each dot may have any number of combinations of red, green, and blue intensities. Saturation is the purity of a color Shade: when black is added to a pure hue. TIFF tagged image graphics file format was designed to be the universal translator of the graphics world back in the 1980s when sharing graphics across computing platforms was a great headache. TIFF can handle color depths ranging from one-bit (black and white) to 24-bit photographic images with equal ease. Like any standards, however, the TIFF developed a few inconsistencies along the way: some graphical software companies estimate that there are more than 50 variations on the TIFF format. Tint: when white is added to a pure hue. Transparent GIF A feature of the GIF89a graphics standard, a transparent GIF lets the background show through selected parts of an image. When creating the GIF, the designer can designate one color in the image's palette as transparent. When the GIF is displayed, areas using that color reveal whatever is underneath. Transparency is most often applied to a GIF's background color to let the page's own background show through, so that images appear to float on the page. Vector: Also known as object-oriented graphics and Postscript type. An image file containing a series of mathematical instructions describing lines ellipses, rectangles and polygons. Vector files are typically created by programs like Adobe Illustrator.

Image Resolution: Refers to the spacing of pixels in the image and is measured in pixels per inch (ppi) or dots per inch (dpi). Output Resolution: Refers to the number of dots per inch (dpi) that an output device, such

as an imagesetter or laser printer, produces.

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Digital Photography – Unit 2

“Pixels & Images”

Digital Revolution 5-7

Digital Process 7-11

• Taking the Picture 8

• Downloading the Picture 8

• Editing the Image 8-9

• Displaying the Image 9-11

Pixels 11-14

Image Size 14-15

Resolution 15-17

Image Sensors 18-22

Bitmaps and Vector Graphics 23-26

Digital Formats 26-29

Psychology of Color 29-31

Works Cited 31

The Digital Revolution In the past couple of years a revolution has taken place. Digital cameras have become the fastest selling consumer electronics product in history. In 2002 over ten million digital cameras were sold in the United States (Infotrends). But the revolution is about more than just switching from film to pixels. It’s about a whole new way of seeing and documenting the world. Photography can be used for personal and creative expression. It is a powerful tool for professional and business communication. You can even make photo crafts. Digital imaging can be used throughout the curriculum. And now with the power of the Internet, you can instantly share your photos with people all over the world (instead of having them hidden away in a shoe box in a closet). One of digital photography's Biggest Advantages is that you can easily transfer images between all kinds of programs. For example, you can easily insert digital images into word processing or PowerPoint documents, send them via e-mail to friends, or post them on a Web site. With digital photography there’s no waiting to get your pictures back from the processor. Being able to see your images immediately means you know if you’ve got the picture or if you need to keep shooting. Best of all, you can transfer your pictures to your computer for all kinds of fun. You can use an image editing program to manipulate your images to improve or alter them. You can crop them, remove red-eye, change colors or contrast, and even add and delete elements. You can apply special effects and create fantastical montages. It’s like having your own darkroom. Before you start clicking away (with your camera or mouse), let's lay a little groundwork by offering a few definitions. These are the most exciting times in photography since George Eastman introduced the first Kodak cameras. Photography, in the hands of thousands of passionate amateurs and a few professionals, began to change the world. Today, that change continues.

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The Digital Darkroom Professionals know that many of the greatest benefits of digital photography stem from being able to quickly correct, enhance, and manipulate a photograph using image-editing software in the computer - usually called the "Digital Darkroom" or the "electronic darkroom." In the computer environment, it's possible to make dramatic changes to a photograph in minutes that would have taken hours, even days, in the traditional wet darkroom. Adobe Photoshop overwhelmingly dominates the professional image-editing software category. While there are many other image-editing software programs on the market, Photoshop has been the dominant one for nearly twenty years because photographers, graphic artists, and printers use it. Other programs, including Adobe's Photoshop Elements, don't have the features those professionals in these different industries demand. Digital Photography -- Digital photography is the process of bringing photographs into the computer. It doesn't necessarily require a digital camera- you can use scanners or have them digitized onto disk for you at a processing lab. Sometimes people abbreviate digital photography as DP.

Digital Imaging- Digital imaging can be thought of as the process of manipulating pictures on the computer. Once you get your photographs into the computer, you can touch them up or alter them using digital imaging techniques. It's a lot faster and less messy than spending all night in the darkroom using enlargers and chemicals.

Photo Editing or Image Editing Software -- This is the software that allows you to manipulate your digital images. Until recently this was synonymous with Adobe Photoshop, but as you'll see in Chapter 6, a number of other programs are now on the market, most of them cheaper and easier to use, though none quite as powerful.

Pixels -- All digital images are made up of pixels (short for "Picture Elements") -- millions of dots on the screen. Understanding resolution and pixels is an essential element in selecting a digital camera and working with images on the computer and the printer. Whether you already have a digital camera or you are in the process of shopping for one, getting started with digital photography is easy. Today's digital cameras are simple to use, with one-touch features that make snapping and printing photos incredibly intuitive. To get started, you will need some basic equipment: a digital camera, a computer with a CD/DVD burner and editing software, a printer, and CDs or DVDs to store and share your photos.

Why Go Digital?

Digital cameras are becoming more than just cameras. Some digital cameras are capable of capturing not only still photographs, but also sound and even video-they are becoming more like multimedia recorders than cameras. Once captured, digital photographs are already in a format that makes them incredibly easy to distribute and use. In addition to displaying and distributing photographs, you can also use a photo-editing program to improve or alter them. For example, you can crop them, remove red-eye, change colors or contrast, and even add and delete elements. It's like having a darkroom with the lights on and without the chemicals You can insert digital photographs into word processing documents, send them by e-mail to friends, or post them on a Web site where anyone in the world can see them. With many cameras you can immediately see your images on a small LCD screen on the back of most cameras, or you can connect the camera to a TV and show them much like a slide show. Some cameras can even be connected to a microscope to display dramatically enlarged images on a large-screen TV. Digital photography is instant photography without the film costs!

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If you're considering going digital, here are a few more Reasons to get Serious.

• Saves Money: Going digital saves you money in the long run by not buying rolls and rolls of film and paying for development.

• Saves Time: It saves you time because you don't have to make two trips to the store to drop off and then pick up your pictures.

• E-mail and Print photos Instantly: Share digital pictures seconds after taking them. E-mail them anywhere; print them at home or online. Or place them in an online album, so friends and family can view your pictures and order prints.

• Instant Results: Digital cameras instantly show you how your pictures look so you'll no longer have those disappointments a day or two later when your film is developed.

• View Images: You can view images before they are printed and if you don't like what you see, edit them to perfection or delete them. Digital photography doesn't use the toxic chemicals that often end up flowing down the drain and into our streams, rivers, and lakes.

• Unleash your Creativity: Fulfill those creative urges. Turn your digital pictures into photo greeting cards, high quality prints, CD album covers, photo T-shirts, online slide shows. You can do all this and more—once your pictures are digital.

• Enjoy pictures, enjoy life: Invigorating. Exciting. Delighting. Digital photography is all these things and more. Escape into a realm where you can do almost anything you want with your pictures.

The Digital Process

Your digital camera is just one link in the chain of digital imagery. There are 4 Main Parts of the Process – taking the picture, transferring it to your computer, editing it and printing, displaying or sharing it.

To make the most of your digital camera, you need a reasonably powerful computer with plenty of memory, editing software, a good monitor, a nice printer, and a CD/DVD burner. You can also purchase a cradle or dock to make uploading images to your computer even easier. Just place the camera into the dock, press a button, and the acquisition software launches, transferring the pictures to your computer with no further work on your part. There are many applications out there that will help you manage and edit your pictures effectively once they are in your computer.

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Step 1 = Taking the Picture:

Of course, the process begins with recording the image. Unlike traditional cameras that use film to store an image, digital cameras use a solid-state device called an image sensor. These fingernail-sized silicon chips contain hundreds of thousands or millions of photosensitive diodes called Photosites. Each of these photosites records the intensity or brightness of the light that falls on it. Each photosite reacts to the light that falls on it by accumulating a charge; the more light, the higher the charge. The brightness recorded by each photosite is then stored as a set of numbers that can then be used to set the color and brightness of dots on the screen or ink on the printed page to reconstruct the image.

Step 2 = Downloading the Picture

Digital photography gives you unprecedented power in later adjusting and modifying images once you get transfer them to the computer. But, how will you get your pictures into the computer? There are three basic methods:

1. Use a digital camera and download them to your computer. You can also transfer stills from a digital video camera.

2. Digitize traditional photographic prints, negatives, or slides using a flatbed or film scanner. 3. Get them from a Memory Card or the Internet via a photo-processing lab.

Digitizing your pictures involves converting your images from a series of color and light values into a series of hundreds of thousands of pixels - fortunately, the computer does this conversion for you. Once your image is digitized you will probably want to alter those pixels. This gets us to step three…

Transfer and Viewing Software. Digital cameras store hidden information about each photo in each image file. With the right software, you can view the date, time, aperture, shutter speed, flash setting, etc. of the image. Some will automatically name the photo based on the hidden information. These programs are inexpensive (under $30) and helpful in transferring and managing your photo library. Digital cameras offer a world of possibilities. You can view your pictures right away, and in moments e-mail them to friends and family. If you don't like a picture, simply delete it and take a new one.

• Convenient docking systems and picture card readers make it easy to get photos onto your computer. • Multiple ways to share: print at home, online, photo kiosk; share with e-mail or an online album. • Display screens and simple controls make cameras user-friendly. • No negatives to worry about; store photos on CD or hard drive. • Airport x-ray scanners won't damage digital pictures.

Step 3 = Editing the Images

One of the great advantages of digital photography is the ability to edit pictures on screen. Basic photo editing software comes bundled with most cameras and guides you every step of the way. If you want to do more serious 'darkroom' work, there are other applications out there (ImageExpert, PhotoSuite, Abode PhotoDeluxe and PhotoShop are just a few) that allow you to do much more. Image editing can be the most fun part of the process. This is where you get to mess around with your pictures on the computer. Editing your images can range from making simple tweaks (adjustments) to applying wild effects (filters). The things you can do with an image are almost endless. To do this, you'll need an image editing program, such as Photoshop, and some skill in using the software. Fortunately, the software can be quite inexpensive (often included free with your digicam, computer or printer).

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Basic Image Processing Procedures

Original Image

Adjust brightness & contrast

Crop, resize, resample

Recolor

Combine pictures into a montage

Filters-special artistic effects

Add titles, "paint" on your pictures

Step 4 = Displaying the Images

You could call everyone over to your computer's monitor to view your pictures, but you might want to have a bit more flexibility in your presentation. This is where a printer comes in handy. Printing your pictures on paper is in many ways more complex than getting the images into your computer. Making really good prints is something of a science and a craft. At least you don't need to use processing chemicals in a darkroom. One reason digital pictures are so popular is because they are so simple to share. One minute the picture is in your camera, the next it's gone around the world to a friend. People hundreds and thousands of miles away can see your pictures minutes after you take them.

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Sharing Pictures by E-Mail: No longer do you have to type a long e-mail message to describe an event. Now, you just attach a digital picture—and then write a long e-mail message about how easy it was to take and send the picture. One small catch is the file size of the picture. Normally you don't want to send a large picture file, because it could take a long time for your recipient to download it. Advantages of e-mailing pictures:

• It's simple, it's fast, and it's inexpensive.

Disadvantages of e-mail pictures:

• You can send only a few pictures at a time depending on the size of file (large is not good).

Sharing Pictures with an Online Album: An online album is the digital equivalent of a photo album. Well, almost. Its big advantage is that your pictures are on the Internet (that's online) and that anybody anywhere that you give permission to can see them—for free. Most commercial album sites, such as Ofoto, also let people order prints of your pictures. Advantages of an online album:

• Anybody you select can see the pictures and it’s FREE. • Good for showing and ordering lots of pictures at a time • You can transfer pictures, then adjust and edit those photos.

Disadvantages of an online album:

• Uploading lots of pictures to an album is slow without a high-speed connection • Some sites limit the length of storage based on how much business you do with them

But not just anybody can see them. The commercial album sites are password protected, so only the people you select can see your pictures. But don't use only an online site to store your pictures. An online site is ultimately a commercial business under somebody else's control. For long-term storage, your photos should be under your control. An online album is a great way to share pictures, but it's not a great way to back them up for permanent storage.

Share Pictures on a CD: Most people share digital pictures electronically using e-mail or an online

album. That's fast and easy, but it somehow lacks the personal touch. You can add that personal touch by giving a CD with photos on it as a gift. You can even create a special CD cover with the person's name or their photo. You can do this at home or hire a photo service to create a special gift for you. Advantages of a CD album:

• Puts a personal "gift" touch to your pictures • Holds hundreds of pictures, some big enough so they are suitable for printing • Provides durable, long-lasting storage

Disadvantages of a CD album:

• Requires special equipment or an extra cost if using an online photo service.

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Getting Prints of Digital Pictures Within seconds of reading this, you can start creating beautiful photographic prints from your digital pictures. You can do it at home, at a store, or have somebody else do it for you. Whichever way you choose, prints from digital pictures can have the Kodak quality you've come to expect. Not only can you make superb prints, you can do much more. Album pages, scrapbook designs, and framed enlargements all await your digital pictures. Here are three ways to create prints from your digital pictures.

1. Order Prints from an Online Photo Service: Without ever leaving your home, you can get beautiful traditional photo prints of your digital pictures from an online photo service. You simply transfer (upload) pictures from your computer to the online photo service. This typically takes about a minute per picture. They will be displayed in an online album that shows the pictures at thumbnail size. Using an online order form, you indicate the pictures to print and the print size. Many services even provide online editing software should you want to make a few last minute improvements to your pictures. Your prints will then be sent to your home. What could be easier?

2. Make Prints Yourself using a Photo Kiosk: You can make your own exquisite photo prints by using a Kodak picture maker. It's a walk-up kiosk about the size of an ATM. The kiosks are in thousands of stores. How do you use one? You insert your camera's picture card, a CD, or a diskette holding your pictures. It can even scan your negative or print if you don't have a digital file. Using the touch screen monitor, you select the pictures you want to print. You can add fancy borders and text messages, zoom, crop or enlarge your pictures, remove red eye, and more. Choose the print size. In just minutes, a superb print, created by you, will be in your hands.

3. Print your Photos on your home Inkjet Printer: Are you eager to turn your pictures into beautiful prints minutes after taking them? You can. Print them at home or on your inkjet printer. Just put Kodak ultima or premium picture paper into your printer, and in a few minutes an amazing quality photo print will be in your hands. Your print will look just like a traditional photograph. Both ultima and premium picture papers have been tested and proven to work with nearly every inkjet printer sold. So you can be sure they'll create great prints with your inkjet printer. You can choose glossy and satin surfaces. Use glossy as your primary paper. It shows every last freckle and detail. Use satin for a softer feel. It's wonderful for portraits, flowers, or simply for those who like a softer touch.

Pixels Short for Picture Element, a pixel is a single point in a graphic image. Graphics monitors display pictures by dividing the display screen into thousands (or millions) of pixels, arranged in rows and columns. The pixels are so close together that they appear connected. The number of bits used to represent each pixel determines how many colors or shades of gray can be displayed. A pixel is basically a dot, one single element, that when grouped with many more of these elements will make up the image. 1 megapixel is one million pixels. That means that a 1 megapixel sensor captures an image made up of one million pixels. The more pixels you have making up an image, the sharper the image will be. In digital cameras, the image sensor, which captures image information, consists of a geometric grid of pixels. The computer divides the screen or printed page into a grid of pixels. It then uses the values stored in the digital photograph to specify the brightness and color of each pixel by number. Controlling, or addressing a grid of individual pixels in this way is called bit mapping and digital images are called Bitmaps.

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On color monitors, each pixel is actually composed of three dots -- a red, a blue, and a green one. Ideally, the three dots should all converge at the same point, but all monitors have some convergence error that can make color pixels appear fuzzy. The quality of a display system largely depends on its resolution, how many pixels it can display, and how many bits are used to represent each pixel. VGA systems display 640 by 480, or about 300,000 pixels. In contrast, SVGA systems display 800 by 600, or 480,000 pixels. True Color systems use 24 bits per pixel, allowing them to display more than 16 million different colors.

Let’s start with one surprising fact: A Pixel has no size or shape. At the time it’s born, it’s simply an electrical charge much like the static electricity that builds up on your body as you shuffle across a carpet on a dry day. A pixel is only given size and shape by the device you use to display or print it. Understanding how pixels and image sizes relate to one another takes a little effort but you need to bring nothing more to the process than your curiosity and elementary school arithmetic skills. A pixel begins its life on the camera’s image sensor during that flickering moment when the shutter is open. The size of each photosite on the image sensor can be measured, but the pixels themselves are just electrical charges converted into digital numbers. These numbers, just like any other numbers that run through your head, have no physical size. Although the captured pixels have no physical dimensions, a sensor's size is specified like those in a digital photo, except the count is the number of photosites that it has on its surface. This size is usually specified in one of two ways—by the sensor's dimension in pixels, or by its total number of pixels. For example, the same image can be said to have 1800 x 1600 pixels (where "x" is pronounced "by" as in "1800 by 1600"), or t o contain 2.88-million pixels (1800 multiplied by 1600). Since pixels stored in an image file have no physical size or shape, it’s not surprising that the number of photosites doesn't by itself indicate a captured image’s sharpness or size. This is because the size of each captured pixel, and the image of which it’s a part, is determined by the output device. The device can spread the available pixels over a small or large area on the screen. The “General Rule” of Perceived Sharpness has two parts and goes as follows:

• If the pixels in an image are squeezed into a smaller area, perceived sharpness increases (from the same viewing distance). Images on high-resolution screens and printouts look sharper only because the available pixels are grouped into a small area—not because there are more pixels.

• As pixels are enlarged so the image is spread over a larger area, the image’s perceived sharpness falls (from the same viewing distance). If enlarged past a certain point, the square pixels will begin to show—the image becomes pixilated.

To visualize this concept, imagine two tile mosaics, one with small tiles and one with large. The one with small tiles will have sharper curves and more detail. However, if you have the same number of large and small tiles, the area covered by the small tiles will be much less. Sharpness and detail is also related to viewing distance. If you stand close to the small mosaic it will appear almost identical to the larger one viewed from farther away. To make an image larger or smaller for a given output device, it must be resized (resampled) in the camera, in a photo-editing program, or by the application you're printing it with. Resizing is performed by interpolation, and sometimes this is done without your even being aware of it. When an image is made larger, extra pixels are added and the color of each new pixel is determined by the colors of its neighbors. When an image is made smaller, some pixels are deleted.

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Direct pixel editing vs. On-Demand pixel editing

• In Direct pixel editing, an entire raster file must be loaded into the computer's memory. One pixel on-screen refers to one pixel in the source file. This is resource-intensive; it takes up a lot of memory, and it often slows down response time from the program.

• On-Demand pixel editing displays and loads only the pixels you need for the current magnification level. For example, if you zoom out to a 1:4 ratio, one pixel on-screen represents four pixels in the source file. As a result, the editing you are doing requires only a quarter of the resources. This speeds up response time.

General Information: Images that may be used by PC computers are saved in various

formats. Different image file formats are capable of holding different quantities of colors. Each file format will have a reference to the number of "bits per pixel" that the format is capable of supporting.

• 1 bit per pixel refers to an image with 2 colors. • 4 bits per pixel refers to an image with up to 16 colors. • 8 bits per pixel refers to an image with up to 256 colors. • 16 bits per pixel refers to an image with up to 32,768 colors. • 24 bits per pixel refers to an image with up to 16,777,216 colors.

How Many Megapixels Should Your Digital Camera Have? Every digital camera you see will be rated with a number, and the word megapixel after it. Megapixel is not a everyday word, at least not for most people, but to the camera industry, it is very important. In fact, the price of the camera will be primarily based on this feature. More information on cameras is included in Chapter 3.

CCD and CMOS Sensors Another label you will often see relating to the sensor is what type it is. The are two types of sensors, the CCD (Charged-Coupled Device) and the CMOS (Complementary Metal Oxide Semiconductor). Confused Yet? I only mention the sensor names because you will see them next to the megapixel rating. The fact is that most digital cameras use the CCD sensor. The CMOS is very similar, but uses less energy. It is more commonly found in professional cameras. Digital camera sensors range in sizes from 0.3 megapixels to 14 megapixels. The most common however, range from 1 megapixels to 6 megapixels. To determine which resolution would best suit your needs, you will need to ask your question, “How will I be using this camera?”

How Much Resolution Do You Need? If you plan to use this camera for internet use only, a 1 megapixel camera will be fine. Internet images are generally low resolution for a very important reason. A high resolution image takes a long time to download. Waiting for these images can be very boring, often causing people to click away and never view your image. Keep in mind though that a low resolution camera is not good for printing images. If you will be printing images, you will want to consider a higher resolution camera. On a high resolution image, you can always take the resolution down to low resolution for internet sharing, but you cannot increase the resolution of a low resolution image for printing. Whether you will be printing standard sized prints or enlargements, you will want the camera with the appropriate resolution. The list below shows the resolutions needed to print images in photographic quality:

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2 megapixels = 5” x 7”

3 megapixels = 8” x 10”

4 megapixels = 11” x 14”

5 megapixels = 12” x 16”

6 megapixels = 16” x 20” Please keep in mind that the quality of the printed images will also depend on the printer, paper, and ink being used, in addition to the resolution setting you have the camera set at.

Image Size The quality of a digital image, whether printed or displayed on a screen, depends in part on the number of pixels used to create the image (sometimes referred to as resolution). The maximum number that you can capture depends on how many photo sites there are on the image sensor used to capture the image. (However, some cameras add additional pixels to artificially inflate the size of the image. You can do the same thing in an image-editing program. In most cases this upsizing only makes the image larger without making it better.)

Image Sizes—Optical and Interpolated

Beware of claims about image sizes (often referred to as resolution) for cameras and scanners because there are two kinds; optical and interpolated. The Optical Resolution of a camera or scanner is an absolute number because an image sensor's photosites are physical devices that can be counted. To improve resolution in certain limited respects, the resolution can be increased using software. This process, called Interpolated Resolution, adds pixels to the image. To do so, software evaluates those pixels surrounding each new pixel to determine what its colors should be. For example, if all of the pixels around a newly inserted pixel are red, the new pixel will be made red. What's important to keep in mind is that interpolated resolution doesn't add any new information to the image—it just adds pixels and makes the file larger. This same thing can be done in a photo editing program such as Photoshop by resizing the image. Always check for the device's optical resolution. If this isn't provided, dump it—you're dealing with marketing people who don't have your best interests at heart.

Element Resolution Total Pixels

Color TV (NTSC) 320 x 525 168,000

Human eye 11,000 x 11,000 120 million

35-mm slide 20 million

1982 Kodak Disc camera film 3 million pixels—each about 0.0003 inch in diameter

The photo of the face (right) looks normal, but when the eye is enlarged too much (left) the pixels begin to

show. Each pixel is a small square made up of a single color.

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More pixels add detail and sharpen edges. If you enlarge any digital image enough, the pixels will begin to show-an effect called Pixelization. This is not unlike traditional silver-based prints where grain begins to show when prints are enlarged past a certain point. The more pixels there are in an image, the more it can be enlarged before pixelization occurs. This table shown above lists some standards of comparison. The numbers from various sources differ: The size of a photograph is specified in one of two ways-by its dimensions in pixels or by the total number of pixels it contains. For example, the same image can be said to have 1800 x 1600 pixels (where "x" is pronounced "by" as in "1800 by 1600"), or to contain 2.88-million pixels (1800 multiplied by 1600).

Camera Resolutions

As you have seen, image sensors contain a grid of photosites—each representing one pixel in the final image. The sensor's resolution is determined by how many photosites there are on its surface. This resolution is usually specified in one of two ways—by the sensor's dimension in pixels or by its total number of pixels. For example, the same camera may specify its resolution as 1200 x 800 pixels (where "x" is pronounced "by" as in "1200 by 800"), or 960-thousand pixels (1200 multiplied by 800). Very high end cameras often refer to file sizes instead of resolution. For example, someone may say a camera creates 30-Megabyte files. This is just a form of shorthand. Low-End Cameras currently have resolutions around 640 x 480 pixels, although this number constantly improves. Better cameras, those with 1 million or more pixels are called Megapixel Cameras and those with over 2-million are called Multi-Megapixel Cameras. Even the most expensive professional digital cameras give you only about 6-million pixels. As you might expect, all other things being equal, costs rise with the camera's resolution. The larger an image's size in pixels, the larger the image file needed to store it. For this reason, some cameras allow you to specify more than one size when you take a picture. Although you are likely to get better results with a larger image, it isn't always needed—especially when the image is going to be displayed on the Web or printed very small. In these cases smaller images will suffice and because they have smaller file sizes, you'll be able to squeeze more into the camera's memory.

Resolution

How many megapixels should your digital camera have? Know what it is or not, two facts are clear: Every camera will have a megapixel rating, and it will be one of the key factors in the price of the camera. A Pixel is a Dot. Grouped with other dots, they make up an image. A megapixel is one million of these dots. A two megapixel sensor will capture an image made up of two million dots. The more dots you have in your image, the clearer your image will be. Because the number of dots, or megapixels, in each image affects your quality, you should carefully evaluate what use you intend for your camera. Web sites and e-mail, various printed uses, and even invitations, brochures, and leaflets may be among the uses for your pictures.

This digital image of a Monarch butterfly chrysalis is 1800 pixels wide and 1600 pixels tall. It's said to be 1800x1600.

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• If you're after quick snapshots to share in e-mail or on Web pages only, a camera with one megapixel or less is probably enough for your needs — Web images are usually low resolution. This speeds up the time it takes an e-mail program or Web browser to load the data (each dot is a piece of data, after all). You cannot increase the resolution of low-resolution images and expect high-quality print results.

• If you intend to print pictures, whether with your printer or at a photo processor, you'll want a greater number of megapixels. The total megapixel count of your images will impact how big you can print them with good quality. Here are some basic guidelines for printing images ranging from 1-6 megapixels: (see diagram to the right)(Of course, the quality of your images when printed will also depend on your printer, paper, and ink!)

• For print applications such as brochures, catalogs, or leaflets, assume your best printable size to be about half the maximum size available for the image (example: print a 2 megapixel image no larger than 2.5" x 3.5"). Assume that for these applications, get as many megapixels as you can afford. If you intend to regularly use your camera for print, such as for a home-based business, view the camera as an investment.

• Keep in mind that if you edit or crop your images, this may reduce the size at which you can print your images, as cropping 'removes' some of the dots used. Image processing programs also offer a variety of ways to 'shrink' high resolution images, so if you're creating cover art for your band's CD, you can print it at a higher resolution, then save a copy at a lower resolution for your Web site and fan-club e-mail.

A confusing aspects of desktop publishing is Resolution and the Measurement of Resolution: SPI, PPI, DPI, and LPI. Often DPI is used in place of SPI and PPI although they aren't really the same. That only makes it more confusing. But it need not be. Here are the short definitions for each term.

• SPI (samples per inch) is scanner and digital image resolution. To scan an image the scanner takes a sampling of portions of the image. The more samples it takes per inch, the closer the scan is to the original image. The higher the resolution, the higher the SPI.

• PPI (pixels per inch) is the number of pixels displayed in an image. A digital image is composed of samples that your screen displays in pixels. The PPI is the display resolution not the image resolution. (Adobe Photoshop uses PPI and Corel Photo-Paint uses DPI for image resolution so it's no wonder everyone is confused.)

• DPI (dots per inch) is a measure of the resolution of a printer. It properly refers to the dots of ink or toner used by an imagesetter, laser printer, or other printing device to print your text and graphics. In general, the more dots, the better and sharper the image. DPI is printer resolution.

• LPI (lines per inch) refers to the way printers reproduce images, simulating continuous tone images by printing lines of halftone spots. The number of lines per inch is the LPI, sometimes also called line frequency. You can think of LPI as the halftone resolution.

- 1 megapixel = 4" x 6"

- 2 megapixels = 5" x 7"

- 3 megapixels = 8" x 10"

- 4 megapixels = 11" x 14"

- 5 megapixels = 12" x 16"

- 6 megapixels = 16" x 20

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Screen Resolution The size of each pixel on the screen is determined by the resolution of the screen. The resolution is almost always given as a pair of numbers that indicate the screen's width and height in pixels. For example, a monitor may be specified as being:

• Low resolution 640 x 480.

• Medium resolution of 800 x 600.

• High resolution of 1024 x 768 or more. (The first number in the pair is the number of pixels across the screen. The second number is the number of rows of pixels down the screen. ) Another way to think about the size of each pixel is in terms of how many pixels are displayed per inch on the screen. The larger the pixels, the fewer fit per inch. As you can see from the illustration below, the actual number of pixels per inch (the numbers in red) depends on both the resolution and the size of the monitor. (Screen measurements are based on a diagonal, and these measurements are horizontal measurements across the screen so they don't relate exactly to screen sizes.)

Screen Resolution and Image Size On any given monitor, changing screen resolution changes the size of displayed objects such as icons, text, buttons, and images. As the resolution increases, object sizes decrease but they do appear sharper. Take a look here at the same image displayed at three different resolutions: 640 x 480, 600 x 800, and 1024 x 768. When displaying images on the screen, it’s important that the viewer be able to see the entire image without having to scroll it. To ensure this, Web designers often assume that the lowest common denominator display is a 640 x 480 screen. For this reason, most images to be sent by e-mail or posted on a screen are sized so they are no larger than 600 pixels wide (for landscape images) or 400 pixels high (for portrait images). Just as the screen’s resolution can affect the size of an image, so can the size of the display. If you have a 14" monitor and 21" both set to 800 x 600 pixels, the pixels per inch are different. The same 800 pixels are spread across a larger screen on the larger monitor so the pixels per inch falls. Imagine the image printed on a balloon. As you inflate it, the image gets larger.

TIP: Checking Your System To see what resolution your Windows system is set to, display Window's Start Menu, point to Settings to cascade the menu, and then click Control Panel. When the Control panel opens, double-click the Display icon or command to display the Display Properties dialog box, then click the Settings tab on the dialog box and check the Screen Area setting.

This is a 640 x 480 display. That means there are 640 pixels on

each row and there are 480 rows.

640 x 480. At this resolution, an image in Photoshop fills the

screen.

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Image Sensors Just as in a traditional camera, light enters a digital camera through a lens controlled by a shutter. Digital cameras have one of three types of electronic shutters that control the exposure:

• Electronically Shuttered Sensors use the image sensor itself to set the exposure time. A timing circuit tells it when to start and stop the exposure

• Electromechanical Shutters are mechanical devices that are controlled electronically. • Electro-Optical Shutters are electronically driven devices in front of the image sensor which

change the optical path transmittence.

When the shutter opens, rather than exposing film, the digital camera collects light on an image sensor—a solid state electronic device. As you've seen, the image sensor contains a grid of tiny Photosites. As the lens focuses the scene on the sensor, some photosites record highlights, some shadows, and others record all of the levels of brightness in between.

Each site converts the light falling on it into an electrical charge. The brighter the light, the higher the charge. When the shutter closes and the exposure is complete, the sensor "remembers" the pattern it recorded. The various levels of charge are then converted to digital numbers that can be used to recreate the image. These two illustrations show how image sensors capture images. Unlike traditional cameras that use film to capture and store an image, digital cameras use a solid-state device called an Image Sensor. These fingernail-sized silicon chips contain millions of photosensitive diodes called Photosites. In the brief flickering instant that the shutter is open, each photosite records the intensity or brightness of the light that falls on it by accumulating a charge; the more light, the higher the charge. The brightness recorded by each photosite is then stored as a set of numbers that can then be used to set the color and brightness of dots on the screen or ink on the printed page to reconstruct the image. In this chapter, we’ll look closely at this process because it’s the foundation of everything that follows.

Image sensors are often tiny devices. Here you can see how much smaller the common 1/2" and

2/3" sensors are compared to a 35mm slide or negative.

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Image Sensors and Pixels Like the impressionists who painted wonderful scenes with small dabs of paint, your computer and printer can use these tiny pixels to display or print photographs. To do so, the computer divides the screen or printed page into a grid of pixels, much like the image sensor is divided. It then uses the values stored in the digital photograph to specify the brightness and color of each pixel in this grid—a form of painting by number. Controlling, or addressing a grid of individual pixels in this way is called bit mapping and digital images are called “Bit-Maps”. (Bitmaps) The makeup of a pixel varies depending on whether it's in the camera, on the screen, or on a printout. On an image sensor, each Photosite captures the brightness of a single pixel. The layout of the photosites can take the form of a grid or honeycomb depending on who designed it.

Area Array Sensors Hand a group of camera or scanner designers a theory and a box of components and you'll see fireworks. They will explore every possible combination to see which works best. The market determines the eventual winners in this "throw them against the wall and see what sticks" approach. At the moment, designers have two types of components to play with: area array and linear sensors. Most cameras use Area-Array Sensors with photosites arranged in a grid because they can cover the entire image area and capture an entire image all at once. These area array sensors can be incorporated into a camera in a variety of ways.

Linear Sensors

Scanners, and a few professional cameras, use image sensors with photosites arranged in either one row or three. Because these sensors don't cover the entire image area, the image must be scanned across the sensor as it builds up the image from the captured rows of pixels. Cameras with these sensors are useful only for motionless subjects and studio photography. However, these sensors are widely used in scanners.

Here you see a reproduction of the famous painting "The Spirit of ‘76" done in jelly beans. Think of each jelly bean as a pixel and it's easy to

see how dots can form images.

A typical image sensor has square photosites arranged in

rows and columns.

The Super CCD from Fuji uses octagonal pixels arranged in a

honeycomb pattern.

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• Linear Image Sensors put a different color filter over the device for three separate exposures—one each to capture red, blue or green.

• Tri-Linear Sensors use three rows of photosites—each with a red, green, or blue filter. Since each pixel has it's own sensor, colors are captured very accurately in a single exposure.

Image Sensors and Colors When photography was first invented, it could only record black & white images. The search for color was a long and arduous process, and a lot of hand coloring went on in the interim (causing one author to comment "so you have to know how to paint after all!"). One major breakthrough was James Clerk Maxwell's 1860 discovery that color photographs could be formed using red, blue, and green filters. He had the photographer, Thomas Sutton, photograph a tartan ribbon three times, each time with a different one of the color filters over the lens. The three images were developed and then projected onto a screen with three different projectors, each equipped with the same color filter used to take its image. When brought into register, the three images formed a full color image. Over a century later, image sensors work much the same way.

Additive Colors

Colors in a photographic image are usually based on the three primary colors red, green, and blue (RGB). This is called the Additive Color System because when the three colors are combined in equal quantities, they form white. This system is used whenever light is projected to form colors as it is on the display monitor (or in your eye). The first commercially successful use of this system to capture color images was invented by the Lumerie brothers in 1903 and became know as the Autochrome process. They dyed grains of starch red, green, and blue and used them to create color images on glass plates. On the monitor, each pixel is formed from a group of three dots, one each for red, green, and blue.

Subtractive Colors

Although most cameras use the additive RGB color system, a few high-end cameras and all printers use the CMYK system. This system, called Subtractive Colors, uses the three primary colors Cyan, Magenta, and Yellow (hence the CMY in the name—the K stands for an extra black). When these three colors are combined in equal quantities, the result is a reflected black because all of the colors are subtracted. The CMYK system is widely used in the printing industry, but if you plan on displaying CMYK images on the screen, they have to be converted to RGB and you lose some color accuracy in the conversion.

RGB uses additive colors. When all three are mixed in equal amounts they form white. When red and green overlap they

form yellow, and so on.

When you combine cyan, magenta, and yellow inks or pigments, you create

subtractive colors.

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From Black and White to Color

Image sensors record only the Gray Scale—a series of 256 increasingly darker tones ranging from pure white to pure black. Basically, they only capture brightness. How then, do sensors capture colors when all they can do is record grays? The trick is to use red, green, and blue filters to separate out the red, green and blue components of the light reflected by an object. (Likewise, the filters in a CMYK sensor will be either cyan, magenta, or yellow.) There are a number of ways to do this, including the following:

• Three separate image sensors can be used, each with its own filter. This way each image sensor captures the image in a single color.

• Three separate exposures can be made, changing the filter for each one. In this way, the three colors are "painted" onto the sensor, one at a time.

• Filters can be placed over individual photosites so each can capture only one of the three colors. In this way, one-third of the photo is captured in red light, one-third in blue, and one-third in green.

When three separate exposures are made through different filters, each pixel on the sensor records each color in the image and the three files are merged to form the full-color image. However, when three separate sensors are used, or when small filters are placed directly over individual photosites on the sensor, the optical resolution of the sensor is reduced by one-third. This is because each of the available photosites records only one of the three colors. For example, on some sensors with 1.2 million photosites, 300-thousand have red filters, 300-thousand have blue, and 600-thousand have green. Does this mean the resolution is still 1.2 million, or is it now 300-thousand? Or 600-thousand? Let's see. Each site stores its captured color (as seen through the filter) as an 8-, 10-, or 12-bit value. To create a 24-, 30-, or 36-bit full-color image, interpolation is used. This form of interpolation uses the colors of neighboring pixels to calculate the two colors a photosite didn't record. By combining these two interpolated colors with the color measured by the site directly, the original color of every pixel is calculated. ("I'm bright red and the green and blue pixels around me are also bright so that must mean I'm really a white pixel.") This step is computer intensive since comparisons with as many as eight neighboring pixels is required to perform this process properly; it also results in increased data per image so files get larger.

The gray scale contains a range of tones from pure white to pure black.

Here the full-color of the center green pixel is about to be interpolated from the colors of the eight

surrounding pixels.

When an image is open in Photoshop, a dialog box shows the red, green, and blue channels so you can select the one you want to work on. The top image in the dialog box is the combined

24-bit RGB.

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Color Channels Each of the colors in an image can be controlled independently and is called a Color Channel. If a channel of 8-bit color is used for each color in a pixel—red, green, and blue—the three channels can be combined to give 24-bit color. When interpolation is used, there has to be enough information in surrounding pixels to contribute color information. This isn't always the case. Low-resolution image sensors have a problem called Color Aliasing that occurs when a spot of light in the original scene is only big enough to be read by one or two pixels. Surrounding pixels don't contain any accurate color information about the pixel so the color of that spot may show up as a dot of color disconnected from the surrounding image. Another form of color aliasing shows up as out of place color fringes surrounding otherwise sharply defined objects.

CCD And CMOS Image Sensors Until recently, CCDs were the only image sensors used in digital cameras. They have been well developed through their use in astronomical telescopes, scanners, and video camcorders. However, there is a new challenger on the horizon, the CMOS image sensor that promises to become the image sensor of choice in a large segment of the market.

CCD Image Sensors: Charge-coupled devices (CCDs) capture light on the small photosites on their surface and get their name from the way that charge is read after an exposure. To begin, the charges on the first row are transferred to a Read Out Register. From there, the signals are then fed to an amplifier and then on to an analog-to-digital converter. Once the row has been read, its charges on the read-out register row are deleted, the next row enter the read-out register, and all of the rows above march down one row. The charges on each row are "coupled" to those on the row above so when one moves down, the next moves down to fill its old space. In this way, each row can be read—one row at a time. It is technically feasible but not economic to use the CCD manufacturing process to integrate other camera functions on the same chip as the photosites.

CMOS Image Sensors: Image sensors are manufactured in wafer foundries or fabs. Here the tiny circuits and devices are etched onto silicon chips. The biggest problem with CCDs is that there isn't enough economy of scale. They are created in foundries using specialized and expensive processes that can only be used to make CCDs. Meanwhile, more and larger foundries across the street are using a different process called Complementary Metal Oxide Semiconductor (CMOS) to make millions of chips for computer processors and memory. This is by far the most common and highest yielding process in the world. The latest CMOS processors, such as the Pentium III, contain almost 10 million active elements. Using this same process and the same equipment to manufacturer CMOS image sensors cuts costs dramatically because the fixed costs of the plant are spread over a much larger number of devices. (CMOS refers to how a sensor is manufactured, and not to a specific sensor technology.)

Image sensors are formed on

silicon wafers and then cut apart.

The CCD imaging elements used in most digital cameras are costly and consume high levels of energy. Increasing the size of these imaging elements to include more pixels would require much larger power supplies as well as make them

even more expensive.

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Bitmap and Vector Graphics

There are two kinds of computer graphics – Bitmap, or Raster (composed of pixels), and Vector (composed of paths). A bitmap image uses a grid of individual pixels where each pixel can be a different color or shade. Bitmaps are composed of pixels. Vector graphics use mathematical relationships between points and the paths connecting them to describe an image. Vector graphics are composed of paths.

The image to the left is representative of a bitmap and the image to the right is representative of a vector graphic. They are shown at four times actual size to exaggerate the fact that the edges of a bitmap become jagged as it is scaled up:

The jagged appearance of bitmap images can be partially overcome with the use of "Anti-Aliasing". Anti-aliasing is the application of subtle transitions in the pixels along the edges of images to minimize the jagged effect (left). A scalable vector image will always appear smooth (right). Bitmap images require higher resolutions and anti-aliasing for a smooth appearance. Vector-based graphics on the other hand are mathematically described and appear smooth at any size or resolution. Bitmaps are best used for photographs and images with subtle shading. Graphics best suited for the vector format are page layout, type, line art or illustrations. Wherever possible use the vector format for all your type, line art and illustrations and only use bitmaps for photos or images with complex or non-uniform shading.

Bitmap Image: Vector Graphic:

Diagram 2.1 – Bitmap vs. Vector image.

Anti-Aliased Bitmap Image:

Smooth Vector Image:

Diagram 2.2 – Anti-Aliasing

There are 2 types of Computer Graphics:

VECTOR BITMAP (raster)

Exist as a mathematical equation. Mathematically defined lines and curves.

They are rectangular grids made of little squares (like checkerboards).

Is resolution independent - scaling want effect image quality.

When a bitmap picture is resized, it often distorts the image.

Vector art consists of fills and outlines applied to a geometric description of a wireframe design.

The grid of pixels. Has four basic characteristics dimension, revolution, bit depth, and color model.

Characterized by geometric precision and a perfect focus.

Bitmapped image can simulate photographs and paintings because qualities of lighting transparency and depth of field.

Because computer screens are made up of a grid of pixels,

both vector and pixel images are displayed as pixels.

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BITMAP Most images produced by fax machines, scanners, digital cameras and other optical input devices are bitmapped, or called “Bitmaps” (or Raster Graphics). They are comprised of a rectangular grid or "map" of colored squares or "Pixels”. In a general sense, the total number of pixels and their characteristic bit-depth (number of displayable colors) determines the file storage size. The number of pixels plays a major role in the ultimate clarity of the final image. The number of displayable colors determines the photographic nature or quality of the final image. The drawback of bitmapped images is that they have a finite number of pixels. "Stretching" and rotating an image can severely affect the overall quality. Bitmapped images are resolution-dependent. This means that when you create a file, you must specify a resolution. When you change the resolution, the image becomes degraded. The advantage of bitmapped (or raster) images is simple: They are ideally suited to representing realistic images such as photographs. They also can be transformed using image-editing filters to create a range of special effects and natural looks.

VECTOR Vector images are graphics comprised of mathematically-described lines and curves called "Paths". These paths can be colored and filled with colors, gradients and patterns. Vectors are created in drawing-type programs like Adobe Illustrator. Appearing quite simplistic at times, vectors can be quite complex. Because they are mathematically described, the images can be resized and rotated in infinite possibilities and retain their original quality! The drawback is that vectors are limited in the number of defined colors and typically appear cartoonish or non photographic in nature.

Vector illustrations, by contrast, store each image as a series of instructions on how to draw the object. Because drawing instructions are usually much simpler and can be highly compressed, vector files are usually much smaller than their bitmapped counterparts. Furthermore, vector files are resolution-independent, because they are always rendered at the highest resolution the output device can produce. The biggest advantage of vector illustrations is that they can be resized without degradation. Vector illustration programs also facilitate reformatting objects. This means you can take a blue square and quickly make it red, orange, or purple by changing its fill attributes. In general, image-editing programs are designed for manipulating bitmapped images, and illustration packages are used to create vector graphics.

Vector vs. Raster - Who's the Master?

The great thing with Prodigy was that even though I had a 9600 bps modem, I could still see colorful graphics without much wait. Why? Because they were using something called "vector" graphics. The important thing to remember is that since the days of online services and the Internet boom, vector graphics took a hiatus from online design... until recently. See, when the Internet boom happened, the graphics standards were GIF and JPEG (which happen to be raster graphics) and vector graphics were non-existent as far as the Web was concerned. It wasn't until 1997 when Macromedia acquired a company known as FutureWave Software, who had a neat little program called Flash. Flash brought a whole new world of graphics to the Web - vector graphics.

So what's the difference between Vector and Raster?

There is a huge difference between vector and raster images. Raster is defined by a grid of pixels, each pixel is a different color to make an entire image. This is a great type of image format for photographs, but most graphics for the Web are flat colored. Vector graphics, on the other hand, are not defined by pixels and are not constricted to a grid format. Vector graphics are given instructions by the computer about how the objects should be shaped and their relative size. Still confused? Check out the example to the right:

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The image to the right is dramatization of how vector and raster graphics differ. The green dot on the left is supposed to be a vector graphic, while the image on the right is an exaggeration of a raster graphic. The vector dot would be created by a series of instructions that tell the computer that a perfect green circle with a specific size relative to the viewing area, will be displayed. The raster green dot, on the other hand, is defined by a series of pixels arranged in columns and rows with a specific color, nothing else! The computer has no idea that the raster dot is actually a dot, it only knows pixels and colors. The whole great thing is that since it takes less instructions for the computer to define a vector graphic than a raster graphic, vector graphics are generally smaller in file size. Some vector formats (such as Flash) also have the ability to imbed a raster file within themselves, so you can get the best of both worlds! 1 -Much like the GIF and JPEG formats you are used to seeing and working with, vectors have their own advantages and disadvantages as a way of delivering images on Web pages. The advantages, however, are getting more and more enticing.

2 -To understand why vectors are a good thing, let's look at how images work on a computer screen. Most of the graphics you see on the Web today are bitmaps; that is, they are made up of a set of pixels, each one a different color, combining into the patterns that make up the image. When you create a bitmap, you use a graphics application to essentially decide which pixels will be which color and what the dimensions of the image should be. Simple enough. But what happens if you want to change the size of the image? Well, you either start over and make a new graphic, or you stretch it - with generally unpleasant results.

3 - Enter the vectors. Rather than assigning colors to pixels, a vector graphic application lets you draw with lines and shapes. Essentially, a vector graphic is a series of commands that might dictate a line's direction, thickness, and color, which gets rendered on the screen later. The benefits are obvious: The files are very small (each pixel need not be accounted for), they can be resized to any proportion, and they are eminently flexible because they can simply be re-rendered at any point. If you're thinking that vectors sound like the perfect format for the Web, you're not alone. People have been trying to figure out how to get these lightweight graphics to the Web, and it's not hard to see why. Vector graphics shift the burden of file size to the rendering computer's processor, rather than tying it to the physical height and width of the image.

4 - Vector graphics are wonderful for the Web. They're way more efficient than transmitting bitmaps and they scale perfectly to the wide variety of display sizes browsing the Web. They're a great tool in communicating clearly and elegantly through the Web, while still adapting to the viewer's browser window.

Vector images can be converted to bitmaps. This process is called Rasterizing. When you convert a vector image to a bitmap, you can output the final bitmap image to any size. It's always important to save a copy of your original vector artwork in its native format before converting it to a bitmap; once it has been converted to a bitmap, the image looses all the wonderful qualities it had in its vector state. ector images can, quite easily, be converted to bitmaps. This process is called Rasterizing. When you convert a vector image to a bitmap, you can output the final bitmap image to any size.

No technology comes without at least a few drawbacks; so too with vectors. You can't approach the realism of a photograph with a line-drawn image. JPEGs still reign supreme for representing the real world - vectors can only come as close as cartoon-style drawings of people and things. And, as with too many other things on the Web, there seem to be as many vector formats as there are platforms and browsers - each as incompatible with one another.

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Metafiles: Metafiles are graphics that contain both raster and vector data. For example, a vector image that contains an object which has a bitmap pattern applied as a fill, would be a metafile. The object is still a vector, but the fill attribute consists of bitmap data.

Digital Formats

You have just bought your first digital camera or you have finally decided to explore the capabilities of that digital camera sitting in the back of your closet. You look in the manual (always a good read!) and discover that your camera can capture images in the JPEG, TIFF or RAW file formats. A big question mark pops up over your head and a perplexed look slowly creeps across your face. “Which one of these file format should I use?” you ponder, “and why?” “What are the differences between these formats and is one better than the others?” Before we look at the different file formats, let’s explore how your camera stores information. This will help in understanding which format will be the best for your purposes. Like traditional cameras, digital cameras capture light, but, instead of film, the light strikes a CCD (Charged Couple Device) or a CMOS (Complimentary Metal Oxide Semi-conductor) chip, either, of which has millions of pixel sites on them. For those of you who are wondering what a pixel is, the word “pixel,” coined by computer geeks is a contraction of picture element, and represents tiny squares of color used to construct a digital image. Multiple pixels when combined form the image. The pixel’s color represents the average hue, saturation and brightness of the area on the original image that the pixel covers. It is helpful to think of a digital image made of pixels as being similar to a mosaic of many multi-colored tiles. Digital image quality depends on the following three things: 1. the number of pixels in the image; 2. the size of the pixels; and 3. the range of colors available (bit depth.)

Each pixel site is covered with a single color filter, and depending upon your camera’s design the filter will be either a red, green, or blue filter, or a cyan, magenta, or yellow filter. Since each pixel site can only capture a single color, an on-board computer, using a complex interpolation scheme, calculates the correct color for each pixel. This same computer then makes further adjustments to the image using the white-balance settings you have chosen, as well as applying any other exposure, sharpening, or color-correction features you may have activated. The data is then stored as your image. In 1997, Foveon created a new design in sensor technology. Instead of using three color filters the way that other CMOS and CCD chips do, the Foveon chip embeds three layers of pixel sensors in silicon to take advantage of the fact that red, green and blue light penetrate silicon to different depths. This means that each sensor captures red, green and blue light at each and every pixel. All other image sensors record just one color per pixel. What this means is that the Foveon CMOS chip can potentially deliver increased sharpness, better color detail and resistance to unpredictable color artifacts.

Filename Extension - the portion of a filename, following the final point,

which indicates the kind of data stored in the file.

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GRAPHIC FILE FORMATS PCX,

BMP

PCX and BMP are bit-mapped file formats created by paint programs, like PC Paintbrush or some screen-capture programs. PCX is one of the oldest and most common bitmap formats available.

PDF

(PDF - Portable Document Format). The native file format for Adobe Systems' Acrobat. PDF is the file format

for representing documents in a manner that is independent of the original application software, hardware,

and operating system used to create those documents. A PDF file can describe documents containing any combination of text, graphics, and images in a device-independent and resolution independent format. These documents can be one page or thousands of pages, very simple or extremely complex with a rich use of fonts, graphics, color and images.

DRW DRW files are vector graphics created by Micrografx Designer.

GIF GIF (Graphics Interchange format) is a file format established by CompuServe. A GIF file (Usually 256-color) is a bitmapped file. The GIF89a lets you specify the appearance of transparent areas in the image. In Photoshop choose File > Export, and select an export format or method from the submenu.

JPEG A JPG file (Joint Photographic Experts Group) is a specially compressed file in bitmapped format. The file size of a JPG file is much smaller than similar pictures in other formats.

PCD PCD is a Kodak Photo CD file in bitmapped format. A PCD file actually contains five different resolution (ranging from low to high) of a slide or film negative.

EPS EPS stands for Encapsulated PostScript. This is a postscript description of an image for printing purposes. A TIFF header is added to an EPS file so that it can be viewed.

TIFF TIF stands for Tagged Image File Format. Files with the .TIF extension are usually created by scanners or image processing programs. These bitmapped files come in a number of different classes. There are many different varieties of TIFF.

TGA

(targa)

(TGA - The Truevision Targa Graphics Adaptor file format). The TGA format is a common bitmap file format for storage of 24-bit images. It supports colourmaps, alpha channels, compression and comments.

WMF WMF stands for Windows MetaFile. This native Windows vector format is used by the Windows Clipboard.

FLM The Filmstrip format is used for animation or movie files created by Adobe Premiere. When editing a Filmstrip file in Adobe Photoshop, you must not resize or crop if you plan to export the image back into Adobe Premiere.

FlashPix

Live Picture Inc., Eastman Kodak Company, Microsoft Corporation, and Hewlett-Packard Company joined in unveiling a new imaging architecture and image file format, "FlashPix." Targeted primarily for the consumer market, FlashPix is designed to simplify and expedite image processing on computers and networks. For example, the user will no longer have to calculate the necessary image resolution to achieve the best output from a digital file. FlashPix will make a determination based on communications between the scanner, imaging software, and printer. These functions will take place in the background without the user realizing they're taking place. Kodak provided advanced filtering algorithms and color space transformation technology. FlashPix supports two different color space options - a calibrated RGB color space definition and Photo YCC, the color format used with Kodak Photo CD. FlashPix also includes Microsoft's OLE Structured Storage and highly optimized JPEG encoding software from Hewlett-Packard.

PNG

(ping)

Like GIF, PNG (portable network graphic) offers lossless compression (it doesn't actually discard image data) and indexed color. Unlike GIF, it also supports full 24-bit color just as JPEG does. And these features make PNG a standout: built-in gamma, alpha-channel transparency, and two-dimensional interlacing.

Depending upon which file format you choose to use, your camera will process this information in various ways and store it on whichever digital storage media your camera uses. Different camera manufacturers use different media to store the information on, in the camera. Some of the different types available include, Compact Flash, Smart Media, Memory Sticks and IBM’s Micro-Drive (a 1-gigabyte hard drive the same

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size as a Compact Flash Card.) Media storage devices range in sizes from 16 megabytes up to 4 gigabytes in capacity and are growing every day. Remember, the larger the capacity of your digital film, the more images you can capture before you have to download or delete images to make room on the media so you can continue to shoot. This concept will be important in deciding which file format you choose.

Now that you have an inkling of how your digital camera captures information for your images, let’s look at what each file format is, its advantages, disadvantages and why you would choose one format over another. The 3 major players in the file format arena are: JPEG, which is captured in 8-bit color; TIFF, weighing in at 8.5 times larger than the file size of JPEG, is also captured in 8-bit color, and RAW, captured in 16-bit color, is 5 times larger than JPEG. There is one additional concept we should broach before moving on to our discussion of file formats, and that is the concept of compression. Compression is the art of taking an elephant, shrinking it to fit into a Volkswagen Beetle and then getting it out again at full size with all its parts intact. In the world of digital imaging, Compression is the ability of a program, like Photoshop, to take a large image file, and by using a series of steps called an algorithm, convert the information into a short hand form that greatly reduces the size of the file. Depending on the method used by a program, the compression scheme may actually throw away data that is duplicative or unnecessary. This kind of scheme, known as lossy compression, is the type of compression used to create JPEG files. The problem with lossy compression is that the greater the rate of compression, the more degraded the image becomes. However, if little compression is used, images can be obtained for all purposes that are of excellent quality.

Common Format Comparisons

Graphics Interchange Format

(.GIF files)

Joint Photographic Experts Group

(.JPEG files)

Portable Network Graphic

(.PNG files)

Compression: Compresses by scanning horizontally across a row of pixels and finding solid areas of color. Indexes the pixels based on the 256 color palette in the file. No image information is lost.

Compression: Some image data is discarded when it is compressed, reducing the quality of the final file. In general, a JPEG will compress a photographic image 2-3 times smaller than GIF. You can choose how much to compress a JPEG file, but since it is a lossy format, the smaller you compress the file, the more color information will be lost.

Compression: Compresses across rows and columns of pixels, often yielding better compression than GIF, which only scans rows. The compression is 'lossless', you do not lose color information as you compress the file smaller. Typically compresses images 5-25% better than GIF.

Best for: Images with repetitive areas of solid color, line drawings, screenshots, sharp images. Ideal for cartoon-like graphics, logos, graphics with transparent areas, and animations.

Best for: Scanned photographs, images using textures, images with gradient color transitions or any images that require more than 256 colors. It is generally best to let JPEGs handle photographic material and to leave the graphics to GIF.

Best for: Creating complex live transparency, high-color graphics, and better compressed low-color graphics.

Colors Supported: Contains only 256 colors (8-bit). Can contain a transparent area and multiple frames for animation.

Colors Supported: Supports millions of colors (24-bit).

Colors Supported: Can support up to 8-bit palette indexed color, 16-bit grayscale images, 48-bit truecolor. Can contain transparency or an alpha channel, and can be progressive.

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Downloads using: Interlacing, which uses the same technique for downloading as JPEG's progressive encoding. An interlaced GIF displays images in two passes of alternating lines instead of loading them one line at a time. The viewer begins to see the outline of the image sooner with interlacing.

Downloads using: Can download using progressive encoding: This technique downloads a rough whole image and gradually increases the image's clarity, instead of downloading from the top of the image and moving downward as is done normally. Requires more processing power to display.

Downloads using: A more sophisticated interlacing technique than GIF and starts displaying the image in 1/8th the time.

Browser Support: First graphic file type to be displayed by the early web browsers. The only graphic file formate that is universally supported by all graphical browsers, regardless of version. Most popular and versatile format for distributing color image on the Web.

Browser Support: Fully supported for use as inline images in version 2.0 and higher of Netscape Navigator and Internet Explorer, as well as in most other current browsers.

Browser Support: The most versatile of the Web graphic formats, however not all Web browsers can currently take full advantage of PNG characteristics without using plug-ins.

Other Issues: Any image can be saved as a GIF and the files are completely platform independent. The company holding the patent on the LZW compression model used in GIFS, has started to enforce the patent and charge software companies fees for including GIF support.

Other Issues: Need to be decompressed before they can be displayed; therefore, it takes a browser longer to decode and assemble a JPEG than a GIF of the same file size.

Other Issues: Designed to be network-friendly, so it is recognized and supported on all platforms. For Web purposes where every byte counts, photographic and continuous tone images are still best saved as JPEGs.

Psychology of COLOR

Color plays a vitally important role in the world in which we live. Color can sway thinking, change actions, and cause reactions. It can irritate or soothe your eyes, raise your blood pressure or suppress your appetite. As a powerful form of communication, color is irreplaceable. Red means "stop" and green means "go." Traffic lights send this universal message. Likewise, the colors used for a product, web site, business card, or logo cause powerful reactions.

Color Theory

Color theory encompasses a multitude of definitions, concepts and design applications. As an introduction, here are a few basic concepts. A color circle, based on red, yellow and blue, is traditional in the field of art. Sir Isaac Newton developed the first Color Wheel in 1666. Since then scientists and artists have studied and designed numerous variations of this concept. Differences of opinion about the validity of one format over another continue to provoke debate. In reality, any color circle or color wheel which presents a logically arranged sequence of pure hues has merit.

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Color Groups Groups of Colors Colors Definition

Primary

Red, Yellow, Blue

There are the 3 pigment colors that can not be mixed or formed by any combination of other colors. All other colors are derived from these 3 hues

Secondary Green, Orange, Purple These are the colors formed by mixing the primary colors.

Tertiary Yellow-Orange, Red-Orange, Red-Purple, Purple-Blue, Blue-Green, Green-Yellow

These are the colors formed by mixing the secondary colors.

Color Harmony

Harmony can be defined as a pleasing arrangement of parts, whether it be music, poetry, color, or even an ice cream sundae. In visual experiences, harmony is something that is pleasing to the eye. It engages the viewer and it creates an inner sense of order, a balance in the visual experience. When something is not harmonious, it's either boring or chaotic. At one extreme is a visual experience that is so bland that the viewer is not engaged. The human brain will reject under-stimulating information. At the other extreme is a visual experience that is so overdone, so chaotic that the viewer can't stand to look at it. The human brain rejects what it can not organize, what it can not understand. The visual task requires that we present a logical structure. Color harmony delivers visual interest and a sense of order. In summary, extreme unity leads to under-stimulation, extreme complexity leads to over-stimulation. Harmony is a dynamic equilibrium. There are many theories for harmony. The following illustrations and descriptions present some basic formulas.

1. A Color Scheme based on Analogous Colors

Analogous colors are any three colors which are side by side on a 12 part color wheel, such as yellow-green, yellow, and yellow-orange. Usually one of the three colors predominates.

2. A Color Scheme based on Complementary Colors

Complementary colors are any two colors which are directly opposite each other, such as red and green and red-purple and yellow-green. In the illustration above, there are several variations of yellow-green in the leaves and several variations of red-purple in the orchid. These opposing colors create maximum contrast and maximum stability.

3. A Color Scheme based on Nature

Nature provides a perfect departure point for color harmony. In the illustration above, red yellow and green create a harmonious design, regardless of whether this combination fits into a technical formula for color harmony.

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Color Context

How color behaves in relation to other colors and shapes is a complex area of color theory. Compare the contrast effects of different color backgrounds for the same red square. Red appears more brilliant against a black background and somewhat duller against the white background. In contrast with orange, the red appears lifeless; in contrast with blue-green, it exhibits brilliance. Notice that the red square appears larger on black than on other background colors.

Different readings of the same color. If your computer has sufficient color stability and gamma correction (link to Color Blind Computers) you will see that the small purple rectangle on the left appears to have a red-purple tinge when compared to the small purple rectangle on the right. They are both the same color as seen in the illustration below. This demonstrates how three colors can be perceived as four colors. Observing the effects colors have on each other is the starting point for understanding the relativity of color. The relationship of values, saturations and the warmth or coolness of respective hues can cause noticeable differences in our perception of color.

What is “Color Quantization” Most people don't have full-color (24 bit per pixel) display hardware. Typical display hardware stores 8 or fewer bits per pixel, so it can display 256 or fewer distinct colors at a time. To display a full-color image, the computer must choose an appropriate set of representative colors and map the image into these colors. This process is called "Color Quantization". ("color selection" or "color reduction" would be a better term.) Clearly, color quantization is a lossy process. It turns out that for most images, the details of the color quantization algorithm have *much* more impact on the final image quality than do any errors introduced by JPEG itself (except at the very lowest JPEG quality settings). Making a good color quantization method is a black art, and no single algorithm is best for all images.

Works Cited http://www.computerschool.net/dphoto/formats.html

http://www.eyetec.net/group5/M21S1.htm#The%20Eye-Camera%20Analogy