Re: L*a*b* image manipulation (was: Change PCS of CLUT input profile)
Re: L*a*b* image manipulation (was: Change PCS of CLUT input profile)
- Subject: Re: L*a*b* image manipulation (was: Change PCS of CLUT input profile)
- From: Mark <email@hidden>
- Date: Thu, 11 Oct 2007 22:49:04 +0200
Hello Steve, Marco,
I was hoping that changing saturation in LAB was just a matter of
applying a multiplication to a*b and that tone mapping could be
easily done with L* without affecting color.
L* is pretty good actually, it's a/b that'll get you. If you want
to do these kinds of manipulation then you should either look at
Bruce Lindbloom's correction profiles that unwarp Lab to some
extent OR go the more popular route and look into color appearance
models such as CIECAM02. Ref: Mark Fairchild's "Color Appearance
Models"
Is LAB particularly bad or does it just have it's flaws (as
probably every color space has). What is it good for?
for what you are looking for, think of it as bad.
thanks for the pointers - I'll definitely take a look at the book.
Just one question so I can get a picture of what CIECAM really is:
how should I imagine it, is it a Color Space, a linear or non linear
transformation of XYZ or CIELAB. Can I think of it as just another
Color Space with 3 components I can manipulate? Just give me
something I can dream about...
So a*b* are not good for changing saturation as I will have hue
changes, L*c*h* won't help either I guess, but how does a*b* compare
to the so commonly found adjustments HUE SATURATION BRIGHTNESS -
derived from R'G'B'. Compared to HSB, will a*b* perform worse?
Regards
MArk
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