Image Processing. Processing Digital Images digital images are often processed using “digital...
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Transcript of Image Processing. Processing Digital Images digital images are often processed using “digital...
![Page 1: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/1.jpg)
Image ProcessingImage Processing
![Page 2: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/2.jpg)
Processing Digital Images
• digital images are often processed using “digital filters”
• digital filters are based on mathematical functions that operate on the pixels of the image
MotionMotionFilterFilter
![Page 3: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/3.jpg)
2 Classes of Digital Filters
• Global filters transform each pixel uniformly according to the function regardless of its location in the image
• Local filters transform a pixel depending upon its relation to surrounding ones
![Page 4: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/4.jpg)
Global Filters
Brightness and Contrast control
• Histogram thresholding
• Histogram stretching or equalization
• Color corrections
• Inversions
![Page 5: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/5.jpg)
Contrast and Brightness functions
• like the knobs on your TV set
Input Image Scale
Out
put I
mag
e S
cale
Input Image ScaleO
utpu
t Im
age
Sca
le
Contrast
Knob
Brightnesss
Knob
![Page 6: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/6.jpg)
Contrast and Brightness functions
• like the knobs on your TV set
Input Image Scale
Out
put I
mag
e S
cale
Increase Increase
Slope Contrast
Input Image ScaleO
utpu
t Im
age
Sca
le
Contrast
Knob
Brightnesss
Knob
![Page 7: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/7.jpg)
Contrast and Brightness functions
• like the knobs on your TV set
Input Image Scale
Out
put I
mag
e S
cale
Increase Increase
Slope Contrast
Input Image ScaleO
utpu
t Im
age
Sca
le
Increase Increase
Offset Brightness
Contrast
Knob
Brightnesss
Knob
![Page 8: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/8.jpg)
Increasing Contrast
![Page 9: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/9.jpg)
How Contrast Functions Work
• Index into the Input Array
of brightness (index = brightness)
• Get the corresponding
brightness value from
the Output Array
• What does this function do?
Brightness
Input Output0 01 12 23 34 45 56 6. .. .
255 255
![Page 10: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/10.jpg)
What would this function do?Brightness
Input Output0 01 02 13 14 35 36 4. .. .
255 255
![Page 11: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/11.jpg)
Increasing Brightness
![Page 12: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/12.jpg)
What would this function do?Brightness
Input Output0 81 92 103 114 125 136 14. .. .
255 255
![Page 13: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/13.jpg)
Contrast & Brightness Demo
• Photoshop– Image->Adjust->Brightness/Contrast– Image->Adjust->Curves (more advanced)
![Page 14: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/14.jpg)
Global Filters
• Brightness and Contrast controlHistogram thresholding
• Histogram stretching or equalization
• Color corrections
• Inversions
![Page 15: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/15.jpg)
Histogram Thresholding
• thresholding creates a binary image by converting pixels according to a threshold value
![Page 16: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/16.jpg)
Thresholding Demo
• Photoshop– Image->Adjust->Threshold
![Page 17: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/17.jpg)
Global Filters
• Brightness and Contrast control
• Histogram thresholdingHistogram stretching or equalization
• Color corrections
• Inversions
![Page 18: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/18.jpg)
Histogram Stretching
![Page 19: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/19.jpg)
The Algorithmfor Histogram Stretching
Find darkest pixel = D
Find lightest pixel = L
Let max possible pixel value = M
Then the new value for every pixel in the image
is:
New pixel value = x M(Old pixel value – D) (L – D)
![Page 20: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/20.jpg)
Histogram Equalization
Can you read this?
![Page 21: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/21.jpg)
Histogram Equalization
Now can you read this?
![Page 22: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/22.jpg)
Histogram Equalization Demo
• Photoshop– Image->Adjust->Equalize– Image->Adjust->Levels (more advanced)
![Page 23: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/23.jpg)
Global Filters
• Brightness and Contrast control
• Histogram thresholding
• Histogram stretching or equalizationColor corrections
• Inversions
![Page 24: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/24.jpg)
Color Corrections
• Making changes to the colors in an image
- Hue shifting
- Pseudo coloring
• Performed by manipulation of re-mapping functions
![Page 25: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/25.jpg)
Hue-shifting
• Hue-shifting is used to modify the color makeup of an image
![Page 26: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/26.jpg)
Hue-shifting Demo
• Photoshop– Image->Adjust->Hue/Saturation
![Page 27: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/27.jpg)
Pseudo-coloring
• Pseudo-coloring can be used to add color to grayscale images
• Different colors are assigned to each level of gray
![Page 28: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/28.jpg)
Pseudo-coloring Demo
• Photoshop– Image->Adjust->Gradient Map
![Page 29: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/29.jpg)
Global Filters
• Brightness and Contrast control
• Histogram thresholding
• Histogram stretching or equalization
• Color correctionsInversions
![Page 30: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/30.jpg)
Inversions
![Page 31: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/31.jpg)
Inversion Demo
• Photoshop– Image->Adjust->Invert
![Page 32: Image Processing. Processing Digital Images digital images are often processed using “digital filters” digital filters are based on mathematical functions.](https://reader038.fdocuments.in/reader038/viewer/2022103004/56649cf35503460f949c118f/html5/thumbnails/32.jpg)
Review
• Global Filters- Contrast & Brightness Control
- Thresholding- Histogram stretching & equalization
- Color corrections- Inversion