[CentOS] Changing Color Mappings

Kwan Lowe kwan.lowe at gmail.com
Wed Mar 18 19:14:37 UTC 2009


2009/3/18 Brian Becker <bbecker at jaeb.org>:
> 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.

Sounds like you're approaching it incorrectly.  I had to do a similar
thing for a class I took some years ago. The goal was to make a viewer
for a fax TIFF image. The approach I used was to break the b/w image
into 4x4 or 8x8 blocks, then count the number of dark pixels and based
on that, assign that to a grayscale level. It worked, but was quite
slow.

ImageMagick has some utilities that do similar things.


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