Re: how to count % color coverage?

[Igor Khavkine <igor.kh@gmail.com>]

On 8/26/05, Paolo Pedaletti <paolo.pedaletti@unimib.it> wrote:

> My best wish would be:
> 
> Color 0: 1.4%
> Color 2: 4.5%
> Color 10: 50.1%
> ....
> ...
> 
> (% of surface, image extension)

You need the netpbm package.

$ giftopnm image.gif > image.ppm
$ pamfile image.ppm   # get the dimension
image.ppm:       PPM raw, 50 by 48  maxval 255
$ ppmhist image.ppm   # create histogram
   r     g     b         lum     count
 ----- ----- -----      -----   -------
     0     0     0          0      1631
    51    51    51         51         9
   166   166   166        166         9
   136   136   136        136         9
   161   161   161        161         8
[...]

The colors are given by RGB values and count is the number of pixels
of given color. Divide by the total number of pixels for percentages.

Hope this helps.

Igor