Lab space -- some interesting reading
Plasmodium
Registered Users Posts: 65 Big grins
I've discovered a few hard to read but interesting articles about how the Lab colorspace manages saturation.
http://tech-slop.serveit.org/wiki/index.php?title=Equating_HSL_and_Lab
http://tech-slop.serveit.org/wiki/index.php?title=Lightness_Limits_Saturation
http://tech-slop.serveit.org/wiki/index.php?title=Offsetting_ab
The author of these articles gave this pointer for managing color adjustments in Lab. This technique is not intuitive at all, but I've given it a shot and it seems to be a phenomenal way of using sliders to make color adjustments in lab space:
- take a photograph that needs some general balancing
- Image > Mode > Lab
- New Layer and fill with L=50%, a=30, and b=30 (your colour palette is in Lab mode, right?)
- set Blending mode to Linear Light
- Advanced Blending
-- turn off L channel
Right about now you should be looking at a mess. Now for the fun part.
- Adjustment Layer > Hue/Sat and clip it to the Linear Light layer
- Open up the Hue/Sat dialog and get crazy with the Cheez Whiz
What you are basically doing is offsetting a and b in a particular direction. You use the Hue slider to set the direction, and use the Sat slider to set the amount. Seems to do decent enough with a little practice.
Should get you thinking about different ways of manipulating ab. Again, not without irony of some sort. Using a polar system to offset a Cartesian system. Man, that cracks me up.
I found this info here: http://www.photoshoptechniques.com/forum/showthread.php?t=15825
http://tech-slop.serveit.org/wiki/index.php?title=Equating_HSL_and_Lab
http://tech-slop.serveit.org/wiki/index.php?title=Lightness_Limits_Saturation
http://tech-slop.serveit.org/wiki/index.php?title=Offsetting_ab
The author of these articles gave this pointer for managing color adjustments in Lab. This technique is not intuitive at all, but I've given it a shot and it seems to be a phenomenal way of using sliders to make color adjustments in lab space:
- take a photograph that needs some general balancing
- Image > Mode > Lab
- New Layer and fill with L=50%, a=30, and b=30 (your colour palette is in Lab mode, right?)
- set Blending mode to Linear Light
- Advanced Blending
-- turn off L channel
Right about now you should be looking at a mess. Now for the fun part.
- Adjustment Layer > Hue/Sat and clip it to the Linear Light layer
- Open up the Hue/Sat dialog and get crazy with the Cheez Whiz
What you are basically doing is offsetting a and b in a particular direction. You use the Hue slider to set the direction, and use the Sat slider to set the amount. Seems to do decent enough with a little practice.
Should get you thinking about different ways of manipulating ab. Again, not without irony of some sort. Using a polar system to offset a Cartesian system. Man, that cracks me up.
I found this info here: http://www.photoshoptechniques.com/forum/showthread.php?t=15825
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