![• The negative of the image with intensity level in the range [0,L-1]
is given by the expression: S=L-1-r
• Power-law (gamma) transformation
s= 𝑐 ∗ 𝑟𝑦](https://image.slidesharecdn.com/imageprocessinglab3-250427223418-3856ae2f/85/Image-processinglab-image-processing-image-processing-9-320.jpg)
![Contrast stretching matlab code
• Imadjust(I,[oldmin oldmax],[newmin newmax])
• Task3
Contrast stretching mfile that take gray or RGB image
Min(min(I))
Max(max(I))](https://image.slidesharecdn.com/imageprocessinglab3-250427223418-3856ae2f/85/Image-processinglab-image-processing-image-processing-15-320.jpg)
Image processinglab image processing image processing
- 1. Image processing Lab 3 By: Eng Noha Abd-Elkareem
- 2. Histogram processing • Histogram: gray level against number of pixel for gray level • provide distribution of pixel values. • Illustrate brightness and contrast of image
- 3. MATLAB code • For gray &binary image imhist(image) display histogram of 2d image • For RGB image imhist(RGB(:,:,1)) imhist(RGB(:,:,2)) imhist(RGB(:,:,3)) • Task1 • Create function that get gray or RGB image and return histogram •
- 4. NI=I-127
- 6. Basic intensity transformation functions • There are three basic Types of functions: Linear(negative and Identity transformation). Logarithmic (Log and invers-log transformation). Power-low(nth-power and nth-root transformation).
- 8. Logarithmic transformation • General form: s = c * log𝟐(𝟏 + 𝒓) The log transformation maps a narrow range of low input grey level values into a wider range of output values .(brights images). • The inverse log transformation performs the opposite transformation . S=exp(r)
- 9. • The negative of the image with intensity level in the range [0,L-1] is given by the expression: S=L-1-r • Power-law (gamma) transformation s= 𝑐 ∗ 𝑟𝑦
- 10. Task2(Practical) Log, inverse log . power, root and negative(imcomplement(I)) (im2double&im2uint8)
- 11. Q)A 4x4 , 4bits/pixel image passes through appoint-wise intensity transformation given by S=T(r) = αlog2 1 + 𝑟 + 𝛽 Where α and 𝛽 are unknown parameters. Only a few pixels are available in the input and output images , as shown below (a) Find α and 𝛽 (b)what is the value of the pixel with the “?” mark in the output image. (c)what is the value of the pixel with the “?” mark in the input image. 3 15 ? 1 3 5 11 8 ? 5 T(r)
- 12. Q) A4x4,4bits/pixel image (shown below) passes through one point-wise intensity transformations given by S=T(r)= round(5 𝑟 ) 7 3 4 1 1 2 0 3 4 2 2 1 0 3 5 1 T(r)
- 13. Piecewise Linear Transformation Functions • Contrast stretching. • Equation • New value= 𝑣𝑎𝑙𝑢𝑒−𝑜𝑙𝑑𝑚𝑖𝑛 𝑜𝑙𝑑𝑚𝑎𝑥−𝑜𝑙𝑑𝑚𝑖𝑛 ∗ 𝑛𝑒𝑤 𝑚𝑎𝑥 − 𝑛𝑒𝑤 𝑚𝑖𝑛 + 𝑛𝑒𝑤 𝑚𝑖𝑛
- 14. Contrast stretching example • Q) A4*4, 4bits/pixel original image is given by Apply full-scale contrast stretch to the image . show your work and sketch the resulting image • old min=6 old max=14 • new min=0 new max=15 • New value= 6−6 14−6 ∗ 15 − 0 + 0 = 0 • New value= 13−6 14−6 ∗ 15 − 0 + 0 =13
- 15. Contrast stretching matlab code • Imadjust(I,[oldmin oldmax],[newmin newmax]) • Task3 Contrast stretching mfile that take gray or RGB image Min(min(I)) Max(max(I))
- 16. Intensity level slicing • Highlights a specific range of grey levels.
- 17. Bit Plane Slicing • Often by isolating particular bits of the pixel values in an image we can highlight interesting aspects of that image • 10110011 most • most least • significant significant
- 18. Bit Plane Slicing example 255 13 127 7 55 40 150 255 160 20 200 14 170 90 255 9 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1 0 1 1 1 0 1 1 1 0 1 1 Plane 4 Plane 5 Plane 3 Plane 1 Plane 0 Plane 2 Plane 7 Plane 6 13=0000 1101
- 19. Thank You