how to find the median of histogram?
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i am trying to implement "Dualistic Sub-Image Histogram Equalisation". where the input image needs to be subdivided into two , based on the median of the image. any suggestion would help me.
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Answers (2)
Adam
on 21 Aug 2015
Just sort all the image values and take the central one if you want the median value of an image.
If you want the median value of a histogram then just choose an odd number of bins and take the central one.
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Image Analyst
on 21 Aug 2015
Of course not. The median of the bin counts is not the same as the median of the image gray levels. See my answer.
Image Analyst
on 21 Aug 2015
What's wrong with simply using the median() function?
theMedian = median(grayImage(:))
belowMask = grayImage <= theMedian;
aboveMask = grayImage > theMedian;
belowGray = grayImage .* uint8(belowMask);
aboveGray = grayImage .* uint8(aboveMask);
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Image Analyst
on 21 Aug 2015
You can use mat2gray() to scale them each to 0-1.
aboveGray = mat2gray(double(aboveGray));
Multiply by 255 if you need a uint8 image in the range 0-255
aboveGray = uint8(255 * mat2gray(double(aboveGray)));
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