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2007 Feb 21 21:29

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



På 2007-02-21, skrev Wade Pinkston:
> 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.

I don't know how to do this with Gimp or ImageMagick, but what about
using ppmhist from the pnmtools? To quite the manual:

NAME
       ppmhist - print a histogram of a portable pixmap


SYNOPSIS
       ppmhist [-hexcolor] [-noheader] [-map] [-nomap] [-sort={frequency,rgb}] [ppmfile]


DESCRIPTION
       Reads  a  PPM image as input.  Generates a histogram of the
       colors in the image, i.e. a list of all the colors and how many
       pixels of each color are in the image.

That seems like what you asked for.

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