Digital Imaging Systems –I/ODigital Imaging Systems –I/O

Workflow of digital imaging

Two Competing imaging format for motion pictures Film vs Digital Video( TV) Presentation of the final medium is the last battle. Hybrid process

Image capture format Film Digital capture using silicon sensors Which one is better????

Image capture format – Film 3 layers of RGB color sensitive silver halide crystals Latent image Process of developing, stopping, fixing.

Image capture format – Film Film capture showing silver halide formation on dye

sensitive layers

Image capture format – Film Advantage :

best resolution ever possible Inexpensive providing authenticity on the final production universally compatible

Disadvantage : Noise or artifacts non-realtime Hard to manipulate

Image capture format – Digital Capture Digital camera functions:

traditional camera : lens, aperture, shutter uses silicon sensors composed of an array light sensitive area (or

pixel) in a grid to capture the light intensity

Image capture format – Digital Capture Image Sensor

Converts light energy in to electronic charge The electronic charge is amplified, measured and converted into

binary code Two types of sensors for digital imaging devices( camcorder,

scanner, digital cam.) CCD( expensive, dominating ) CMOS ( new, cheaper, more noise)

Image capture format – Digital Capture Sensor Types based on # of chips

1chip sensor, 3 chip sensor

1 Chip Sensor Characteristics The pixels within them are regular in size and shape. The pixels are laid out in a grid pattern. The pixels exist only in one, single, layer. Three pixels are required to produce a unique colour, therefore

the number of pixels must be divided by three, when determining the actual pixel resolution of a sensor.

Sensor types based on the mechanism of filtering sensor pixels. Linear array, Multi Shot Matrix, Single Shot Matrix sensors.

Image capture format – Digital Capture 3 Chip sensor

Image capture format – Digital Capture Advantage

Potentially better at sensing light Easy to duplicate and store without chemical/scanning process Provides realtime feedback

Disadvantage Formats change too rapidly-> constant reinvestment Not yet caught up to Film’s resolution

A Solution :Digital Intermediate- A process that a production is captured on film then transferred

into digital for editing/efx/coloring and output to film again.

- Why : Taking advantage of both film resolution and easiness of digital image processing

- Facilities : Telecine, Laser negative film printer, and high-end computer

Digital Imaging System

Input – scanner, digital (video) camera Processor Output – monitor , printer

Digital Imaging Systems - Scanner Drum Scanner

Traditional high-end scanner used by pre-press houses and printers for the production of colour separations.

PhotoMultiplier Tube to achieve the greatest possible dynamic range and sharpness.

Very high in cost & quality

Digital Imaging Systems – Scanner Flatbed Scanner

Most commonly available type of scanner Scans both reflectives and film Various price per various quality

Digital Imaging Systems – Scanner Film Scanner

Dedicated to scanning film formats from 35mm to 5*4 ‘s

Digital Imaging Systems – Scanner Telecine machines

To convert film reels into digital form by using high-end film scanner Process of bringing film frame rate (24 fps) to come up with video

frame rate (29.97 fps)

Digital Imaging Systems – Display CRT(Cathod Ray Tube) monitor

- Electron beam moves back and forth across the back of the screen.

- Each time the beam makes a pass across the screen, it lights up phosphor dots on the inside of the glass tube, thereby illuminating the active portions of the screen.

- By drawing many such lines from the top to the bottom of the screen, it creates an entire screenful of images. ( Progressive )

- Refresh rate

LCD(Liguid Crystal Display) monitor- Utilizes two sheets of polarizing material with a liquid crystal

solution to block/pass light to represent colors.

Digital Imaging Systems – Printer Dye-sublimation printers Thermal wax printers Color laser printers Digital photographic printers Inkjet Printers Film Recorders – exposes light from digital file onto film which

can be developed in a normal manner

Reference Digital Imaging by Mark Galer and Les Horvat, Focal

Press © 2001 http://www.webopedia.com http://www.audiovideo101.com http://www.cinebyte.com/video.htm Tritiny Grayer’s Lecture Note( 2003)