Intensity Transformation Functions of digital image processing are described and implemented by using matlab syntax .

1. INTENSITY TRANSFORMATION FUNCTIONS USING
MATLAB
MD. SHAFI UD DOULA
PRESENTED BY
ID. 1009022 REG. NO. 000001481
PRESENTATION ON

2. OUTLINE
 INTENSITY TRANSFORMATION FUNCTIONS
 FUNCTION IMADJUST
 FUNCTION IMCOMPLIMENT
 LOGARITHMIC TRANSFORMATIONS FUNCTION IM2UINT8
 CONTRAST-STRETCHING TRANSFORMATION
 HISTOGRAM PROCESSING & FUNCTION PLOTTING
 SPATIAL FILTER

3. INTENSITY TRANSFORMATION FUNCTIONS
Image Negative
Log Transformation
Power Law(Gamma) Transformation
EXAMPLES

4. FUNCTION imadjust
g = imadjust(f, [low_in high_in] [low_out high_out], gamma)
SYNTAX
low_in low_out
high_in high_out
MAPPING
Input Image (f) Output Image (g)
BRIGHTER
OUTPUT
DARKER
OUTPUT
LINEAR
MAPPING
DEFAULT VALUE OF GAMMA IS 1

5. FUNCTION imadjust
Adjust Contrast of Grayscale Image
Adjust the contrast of the image so that 1% of the data is saturated at low and high intensities, and display it.

6. FUNCTION imadjust
Adjust Contrast of Grayscale Image Specifying Contrast Limits
Adjust the contrast of the image, specifying contrast limits.

7. FUNCTION imadjust
Adjust Contrast of Color Image
Adjust the contrast of the image, specifying contrast limits.

8. FUNCTION imadjust
Adjust Contrast of Image when Gamma >1
when Gamma >1 , Then Darker Contrast

9. FUNCTION imadjust
Adjust Contrast of Image when Gamma <1
When Gamma <1 , then Brighter Contrast .

10. FUNCTION imadjust
Adjust Contrast of Color Image when Gamma =1
When Gamma =1 , then Linear mapping low to low and high to high.

11. FUNCTION imadjust
Obtaining Negative Image
Mapping low to high and high to low.

12. FUNCTION imcompliment
g = imcomplement (f);
SYNTAX
Input Image (f)
Output Negative
Image (g)
IMCOMPLEMENT
In the complement of a binary image, zeros become ones and ones become zeros;
black and white are reversed.

13. FUNCTION imcompliment
Reverse Black and White in a Binary Image
Black and white are reversed

14. FUNCTION imcompliment
Obtaining Negative Image
Mapping low to high and high to low.

15. LOGARITHMIC TRANSFORMATIONS FUNCTION

16. LOGARITHMIC TRANSFORMATIONS FUNCTION im2uint8
gs = im2uint8 (mat2gray(g));
SYNTAX
 mat2gray brings the values to
the range [0 1]
 im2uint8 brings them to the
range [0 255]
Convert Image To 8-bit Unsigned Integers.

17. FUNCTION im2uint8
Im2uint8 matlab function for double to unsigned integer 8 image
Visual improvement of image outImg .

18. CONTRAST-STRETCHING TRANSFORMATION

19. CONTRAST-STRETCHING TRANSFORMATION FUNCTION
g = 1 ./ (1+ (m./(double(f) + eps)) .^ E)
SYNTAX
 Expands a narrow range of input levels
into a wide (stretched) range of output
levels.
 The result is an image of higher contrast.
Convert Image To 8-bit Unsigned Integers.

20. CONTRAST-STRETCHING TRANSFORMATION
Contrast-Stretching Transformation
Visual improvement of image g.

21. HISTOGRAM PROCESSING & FUNCTION PLOTTING
The histogram function is defined
over all possible intensity levels.
Normalize:

22. FUNCTION imhist
J = imhist(I,b);
SYNTAX
 I input image
 J output histogram
 The b =number of bins (default 256)

23. FUNCTION imhist
Since img is grayscale, by default the histogram will have 256 bins.

24. FUNCTION imhist and bar
Display a histogram of the image with bar diagram

25. FUNCTION imhist and stem
Display a histogram of the image with stem diagram

26. FUNCTION imhist and plot
Display a histogram of the image with plot diagram

27. FUNCTION histeq
J = histeq(I,hgram)
SYNTAX
 I input image
 J output histogram
 Hgram(number of intensity level) is
the specified histogram

28. FUNCTION histeq
Enhance Contrast Using Histogram Equalization

29. FUNCTION histeq
CDF Using Histogram Equalization

30. SPATIAL FILTERING
Spatial filtering is a technique that uses a pixel and its
neighbors to select a new value for the pixel.
Linear Spatial FilterEXAMPLES

31. FUNCTION imfilter
SYNTAX
g=imfilter(f, w, filtering_mode, boundary_options, size_options)
 f is the input image
 w is the filter mask
 filtering_mode -- correlation(‘corr’) or convolution (‘conv’)
 boundary_options -- border-padding issue
 size_options -- ‘same’ or ‘full’
 ‘full’: The output is of the same size as the extended (padded) image.
 ‘same’: The output is the same size as the input. This is the default.

32. Apply the filter to the original image to create an image with
motion blur
originalRGB = imread('peppers.png');
imshow(originalRGB)
h = fspecial('motion', 50, 45);
filteredRGB = imfilter(originalRGB, h);
The output is an array of uint8.
FUNCTION imfilter