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[Chicken-users] color egg


From: John J Foerch
Subject: [Chicken-users] color egg
Date: Mon, 29 Aug 2016 23:21:14 -0400
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux)

Hello,

Has anybody used the color egg to do colorspace conversions?  I'm
getting some unexpected results, and wonder whether there are bugs in
the egg, or whether I just misunderstand something about the colorspaces
involved.

Here are the relevant links:

  http://wiki.call-cc.org/eggref/4/color

  http://people.csail.mit.edu/jaffer/slib/Color.html

This call gives the result I expect:

 (color->sRGB (color:RGB709 1 0 0))
 => (255 0 0)

This one does not:

 (color->e-sRGB 16 (color:RGB709 1 0 0))
 => (57216 24576 24576)

I would expect a result of (65535 0 0)

This result also puzzles me:

 (color->L*C*h (color:RGB709 1 0 0))
 => (53.2405879437449 104.552006845446 39.997712561153)

I haven't worked with the L*C*h colorspace before, but from my reading,
since I gave pure red to convert, I would have expected a hue angle of
0, a chroma of 100% and a luminosity of something like 50%.

Unfortunately the egg has no unit tests, and I think that if some could
be written, that would be very helpful.

Is there anybody familiar with the color egg who can show me where
either it or I am going wrong?

Thank you,

--
John Foerch




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