Re: Regarding pixel values

Dear Fred / Wolfgang:
Thanks a lot.

I was looking for -contrast-stretch  option.
That worked perfectly for me.

Thanks,
Shameer

On Sat, May 21, 2011 at 11:42 AM, Fred Weinhaus <[email protected]> wrote:

> The function you want is called -contrast-stretch.  You can provide
> percentile values to clip either end of the histogram and then it
> stretches the histogram and image linearly between those values
> converted to graylevels. You can stretch the image channels together
> or separately. The latter is done by using -channels rgb prior to
> -contrast-stretch.
>
> To stretch the image linearly and all channels together by 1% on the
> low side and 1% (at the 99% percent) on the high side, it would be
>
> convert image -contrast-stretch 1,1% resultimage
>
> see
> http://www.imagemagick.org/Usage/color_mods/#contrast-stretch
>
>
> http://www.imagemagick.org/script/command-line-options.php?ImageMagick=4dk567trius4djjoe7fimpst40#contrast-stretch
>
> Fred
>
>
>
>
>
> >Thanks a lot Fred. I will check the options you have suggested.
> >
> >I want to calculate 99th percentile value of the image and the 1st
> >percentile of the image using the pixels and use these percentiles to
> level
> >the image using black, white, and gamma. I will use 99th percentile as
> >black, 1st percentile as white and gamma =1.
> >
> >Do you know about any alternative method which can do this ?
> >
> >Please let me know,
> >Thanks,
> >Shameer
> >
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