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Contrast Stretch and Normalization

version (2.2 KB) by Sergei Koptenko
Stretches contrast on the image and normalize image from 0 to 1


Updated 16 Jun 2006

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Stretches contrast on the image and normalize image from 0 to 1. The main difference of this function to the standard stretching functions is that standard function finds global minimum and maximum on the image, then uses some low and high threshold values to normalize image (values below LowTHR are equated to LowTHR and values above HighTHR are equated to HighTHR). This function uses threshold values that are NEXT to miminum and maximum. Thus, we can exclude image background (which is normally zero) and find minimum value on the image itself. Same consideration goes to high thr. We exclude first global maximum because, if its a spike, we have better chance with the next value, and if it is not a spike, normally, next value is quite close to max (assuming smooth image), so our error is small. If image is uniform, (all pixels have the same value), for instance zero, function returns the input array

Comments and Ratings (2)

Liu tiger

marr = abs_max*(array_in == 0)+ array_in; % Temporary Move ABS MIN to ABS MAX

The above is the wrong place.

Worked well for me.

MATLAB Release Compatibility
Created with R2006a
Compatible with any release
Platform Compatibility
Windows macOS Linux