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Re: [vox-tech] count pixels
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Re: [vox-tech] count pixels



Wade Pinkston wrote:
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Hello, I need to process some images and count the number of pixes of a
given color.

A little background. I want to take pix of leaves against a mat
background. The leaves are then subjected to damage. I'll then take a
duplicate photo. Now what I want to do is subtract out the colors of the
leaf leaving only a two tone image.

I was hoping to find a way to then use ImageMagick or Gimp to count the
pixels of color so I can then get a percent change between the two images.

Does anybody know how to get ether of these two programs to give this type
of information. Actually any software would be help full.



- --
Wade Pinkston

Ipsa scientia potestas est

Windows,a
32 bit graphical interface for a
16 bit patch to an
8 bit operating system internally coded for a
4 bit processor written by a
2 bit company that can't stand
1 bit of competition

This might not be the method you were thinking but here's an example using ImageMagick
http://ecocam.evsc.virginia.edu/change_detection_description/change_detection_description.htm

What you're doing is called Change Detection and is pretty common in GIS applications.
It's probably overkill to suggest doing it in GRASS but if you did it would be a simple subtraction of the two photos and then you could summarize the table of pixels. But this would involve some method of importing the images to a RASTER data set.

Alex
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