Color and grayscale display

avenues at avenues at
Mon Dec 21 10:45:33 EST 1998

At 05:32 AM 12/21/98 -0500, you wrote:
>avenues at wrote:
>> I am trying to register some 256-color aerial photos to grayscale
>> orthophotos using the routines. Registration is difficult
>> because of the poor color and grayscale representation of the images in
>> GRASS-Linux. I have tried using the float colormode. This improves the
>> greyscale image but not the color image. I have also tried using the 24-bit
>> x-driver, but that does not result in any better color or greyscale
>> representation. Are there any other techniques which might give better
>> resuilts? Thank you for your help.
>> Note: I can export the images from GRASS using r.out.ppm and display them
>> with xv in Linux, and the color is improved. Is there some internal limit
>> in GRASS that does not allow display of all 256 colors?
>> Jim Schmidt
>> USDA Forest Service
>> Sonora, California
>perhaps you are running X in 8 bit color and running out of colors to
>allocate. Have you tried 16 or 24 bit mode (startx -- -bpp 16  (or 24) 
>) to see if the display looks better?

I did use startx -- -bpp 24, but it did not seem to result in a better
color or grey scale representation. I will check on that again, however.
Thanks for the advice.

Jim Schmidt 

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