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



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

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

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