# distribution of excess pixels

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Navdeep Sony el 27 de En. de 2016
Comentada: Image Analyst el 27 de En. de 2016
I am trying to manually equalize the image using standard histogram equalization algorithm in which I am mapping the pixels to 4 bins but when I compare my histogram to the one obtained from histeq(image,4) both are bit different. You can see them here
Here as we can see in the histogram obtained using histeq (first one) all the four red dots are nearly at the same level but not in the second case. When I found the count of pixels at each bin I got following. For the histogram generated as a result of histeq( we can see uniform distribution of pixels here) following is the distribution
Bin number No. of pixels
1 4207
86 4146
171 4314
256 3965
For the histogram generated as a result of manual equalization( we can see non-uniform distribution of pixels here) following is the distribution
Bin number No. of pixels
1 2678
86 5583
171 5061
256 3310
Now we can see that in my case there is no uniform distribution of pixels because of which my histogram is different from the one obtained using histeq. Now I want to clip the histogram and distribute the excess pixels to other bins but the question is which pixels should be considered as excess pixels that can be moved to other bins? and to which bin should these pixels be moved? Please explain how this done. Thank you.
Btw I got this link but here i am not able to understand the term priority i.e what is priority of a pixel and how is it calculated?
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Image Analyst el 27 de En. de 2016
That is quantization, NOT equalization. You can use histeq() to do a histogram equalization using the standard crude method.
If you want a truly flat histogram, you can adapt my method: http://www.mathworks.com/matlabcentral/fileexchange/28972-custom-shaped-histogram
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Navdeep Sony el 27 de En. de 2016
Editada: Navdeep Sony el 27 de En. de 2016
@Image Analyst, thanks for replying. Why do we use quantization? Is it used to increase contrast? and do histeq also used quantization apart from equalization?
Image Analyst el 27 de En. de 2016
I don't know what that application would be. Maybe to achieve a certain artistic look perhaps? Or to save space because they can be compressed more. It might increase contrast around the image right around where the image has those quantization levels, but I don't think in a good way.

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