Advanced Image Processing Techniques
Explore various digital image types, transformations, and corrections such as brightness adjustment, linear and non-linear transformations, gamma correction, and probability functions like PMF and CDF to enhance image quality and analysis in image processing.
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Presentation Transcript
Feladat: olvasson be egy tetszleges tesztkpet s ksztsen kr 5 pixel vastagsg keretet
Digitlis kpek tpusai Raszter Pikszelekb l ll Vektor Egyenletekb l ll
Brightness Brightness can be easily increased or decreased by simple addition or subtraction to the image matrix
Lineris transzformcik, s=c*r+b a) s = 2*r+32 b) s = r-56 c) s = 0.3*r Melyik melyik?
Lineris transzformcik, s=c*r+b Original a) b) c) a) b) c) a) b) c) a) s = 2*r+32 b) s = r-56 c) s = 0.3*r Melyik melyik?
Gamma korrekci (c=1)
Introduction to probability PMF and CDF are both related to probability. They will be used in Histogram Equalization. PMF Probability Mass Function. It gives the probability of each number in the data set (frequency of each element).
Probability PMF Calculating PMF from image matrix PMF Image matrix 0 1 2 3 4 5 6 7 2 4 3 3 2 4 3 4 2/25 4/25 3/25 3/25 2/25 4/25 3/25 4/25 1 2 7 5 6 7 2 3 4 5 0 1 5 7 3 1 2 5 6 7 6 1 0 3 4
Probability PMF Calculating PMF from histogram Frequency of gray level values for an 8 bits per pixel image. Not monotonically increasing function
Probability CDF CDF Cumulative Distributed Function Cumulative sum of values calculated by PMF
Probability CDF CDF will be calculated using the histogram CDF makes the PDF grow monotonically Monotonical growth is necessary for histogram equalization.
Histogram equalization Histogram equalization is used for enhancing the contrast of the images. The first two steps are calculating the PDF and CDF. All pixel values of the image will be equalized.
Histogram equalization Image with its histogram
Histogram equalization Small image (values) Small image (values)
Histogram equalization Image detail Frequency of pixel values
Histogram equalization min = 52 max = 154 cdfmin is the minimum non-zero value of the cumulative distribution function (in this case 1), M N gives the image's number of pixels (for the example above 64, where M is width and N the height) and L is the number of grey levels used (in most cases, like this one, 256).
Histogram equalization New min. value = 0, old min. value 52 New max. value = 255, old max. value 154 Original Equalized
Histogram equalization Corresponding histogram (red) and cumulative histogram (black) An unequalized image The same image after histogram equalization Corresponding histogram (red) and cumulative histogram (black)
Hisztogram ekvalizci Komanda histeq
