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histeq


about
The histeq algorithm maximizes the contrast in the image by equalizing it's histogram.

pro's
- some hidden regions will become visible
- better contrast means that the image will look better on paper when it's printed
con's
- the thermal image will lose all the temperature information after this process

algorithm

histogram function:
(1)

where:

M horizontal image size (pixels)
N vertical image size (pixels)
d Dirac function (d(k)=1 for k=0, d(k)=0 else)
i takes values in {0,1,.. , L-1} interval
L the number of gray levels

the cummulative histogram function:

where:

h(j) histogram function (1)

The processed image (g(m,n)) is obtained by replacing the gray levels from the original image using the histeq function:

examples:

original image processed image
'scaffolding' image
view histogram view histogram
'reservoir' image
view histogram view histogram

associated histograms:

original 'scaffolding' image
processed 'scaffolding' image
original 'reservoir' image
processed 'reservoir' image
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