At what resolution?
One approach is to threshold and then compute the mean intensity over a known area surrounding the stain. That will give you a count of the number of pixels above the threshold.
The other way is to sketch an outline around the perimeter and measure the area.
Which approach you choose depends on what you really mean by “area occupied by black stains”.
Consider - suppose your stain looked like a checkerboard (stained pixels and unstained pixels in a checkerboard pattern). If the checkerboard filled a square region 8 pixels across, do you consider the area to be 32 (just the black squares) or 64 (the size of the square containing all the black squares)?
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Kenneth Sloan
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Vision is the art of seeing what is invisible to others.
> On Apr 3, 2015, at 10:44 , Ion C. Andronache <
[hidden email]> wrote:
>
> <image1.tif><image2.tif>
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image1.tif (1M)