[CentOS] Changing Color Mappings

Wed Mar 18 19:39:26 UTC 2009
John R Pierce <pierce at hogranch.com>

Brian Becker wrote:
> I have been tasked with finding a way to change the color mappings on 
> a CentOS 5.2 system.  Basically I want to make an image that is black 
> and white appear in different shades of gray by adjusting the color 
> mappings.  I need to know the starting point for the color maps 
> however so I can make the appropriate adjustments.  I have been told 
> this should be some kind of look up table array of 256x3 elements.   I 
> have searched through the frame buffer in the kernel and the driver 
> area for the intel frame buffer but haven't found anything that looks 
> appropriate.  Does this table exist or is the problem being tackled 
> completely wrong.

just translate your gray scale image on the way to the frame buffer.   
messing with the hardware RAMDAC will be extremely hardware specific, 
and will affect the entire display, not just your image.   modern 
computers can completely redraw the screen dozens of times/second, 
plenty fast enough for this.