[vox-tech] count pixels

[Jim Angstadt]

--- Wade Pinkston <blata at bugs.osu.edu> 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.

Here is an example of using IM to compare 2 images, in
this case, images from a webcam:

 http://www.notbig.org/bin/webcam.sh.txt

Note the command that begins with 

  differ=$(composite 

which first compares 2 images, then ignores minor
color variations, converts the pixel comparison to
text, and then manipulates the text as needed.

I don't really understand what you are trying to do,
but this sample of IM make be helpful for image
comparisons.

Jim






 
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