I made this image with gimp as a test image. The image is 100% #ff0000 no matter what I convert the image to I don't get a pixel count.

$ identify -verbose red1.tiff
Image: red1.tiff
  Format: TIFF (Tagged Image File Format)
  Geometry: 256x256
  Class: DirectClass
  Colorspace: RGB
  Type: Palette
  Depth: 1 bits
  Endianess: MSB
  Channel depth:
    Red: 1-bits
    Green: 1-bits
    Blue: 1-bits
  Channel statistics:
    Red:
      Min: 1
      Max: 1
      Mean: 1
      Standard deviation: 0
    Green:
      Min: 0
      Max: 0
      Mean: 0
      Standard deviation: 0
    Blue:
      Min: 0
      Max: 0
      Mean: 0
      Standard deviation: 0
  Colors: 1
  Histogram:
  Rendering-intent: Undefined
  Resolution: 72x72
  Units: PixelsPerInch
  Filesize: 192kb
  Interlace: None
  Background Color: white
  Border Color: #DFDFDF
  Matte Color: grey74
  Dispose: Undefined
  Iterations: 0
  Compression: None
  Orientation: TopLeft
  document: /home/blata/red1.tiff
  comment: Created with The GIMP
signature: d764b5e26d0f9155ebf131dcbf35ecaae5b3508c4b7d240173f5fe85b406ae64
  Tainted: False
  User Time: 0.000u
  Elapsed Time: 0:01

This image is the same with three white ovals cut out of the red. Again no pixel count. If I could get a simple pixel count per color then I can do the math and all is good.

identify -verbose red2.tiff
Image: red2.tiff
  Format: TIFF (Tagged Image File Format)
  Geometry: 256x256
  Class: DirectClass
  Colorspace: RGB
  Type: Palette
  Depth: 8 bits
  Endianess: MSB
  Channel depth:
    Red: 1-bits
    Green: 8-bits
    Blue: 8-bits
  Channel statistics:
    Red:
      Min: 255
      Max: 255
      Mean: 255
      Standard deviation: 0
    Green:
      Min: 0
      Max: 255
      Mean: 32.4795
      Standard deviation: 84.5242
    Blue:
      Min: 0
      Max: 255
      Mean: 32.4795
      Standard deviation: 84.5242
  Colors: 105
  Histogram:
  Rendering-intent: Undefined
  Resolution: 72x72
  Units: PixelsPerInch
  Filesize: 192kb
  Interlace: None
  Background Color: white
  Border Color: #DFDFDF
  Matte Color: grey74
  Dispose: Undefined
  Iterations: 0
  Compression: None
  Orientation: TopLeft
  document: /home/blata/red2.tiff
  comment: Created with The GIMP
signature: 1e69860505dfe98ecbede60074549452546deb485ce49723f2feb62ab73b40c9
  Tainted: False
  User Time: 0.000u
  Elapsed Time: 0:01



Troy Arnold wrote:
On Wed, Feb 21, 2007 at 07:27:20PM -0800, Wade Pinkston wrote:
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

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.

If the image is in an indexed format, you can use identify from the
imagemagick suite:

$ identify -verbose some.gif
[...]
       155: (238,238,238,  0)   #EEEEEE00
       244: (245,245,242,  0)   #F5F5F200
       264: (249,249,249,  0)   #F9F9F900
       139: (252,252,252,  0)   grey99
      3885: (255,255,255,  0)   white
      3197: (235,235,217,255)   #EBEBD9FF

[...]
This shows that this image has 3,885 white pixels.


-troy



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Wade Pinkston

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Windows,a
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16 bit patch to an
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