L*a*b Color Space

Submitted by Mile23 on Sun, 10/16/2005 - 10:04

I've recently been learning a lot about the L*a*b (or Lab) color space, for image manipulation.

To see why, here's a simple experiment you can do: Open up an image in Photoshop and convert it from RGB mode to Lab Color mode. Add a Curves effect layer (or just edit the curve) and tweak the a and b channels. Choke them down so that a 90% input equals a 100% output, and a 10% input equals a 0% output.

Now compare the original image to the tweak. You can't do this by simply turning up the saturation, either...

So here's some stuff dealing with L*a*b color. More to come on this topic, for sure.

Starting with a few useful definitions and a few tips.

I got started with all this because I saw a book at the bookstore, called Photoshop Lab Color: The Canyon Conundrum And Other Adventures In The Most Powerful Color Space. Someone buy me this book. :-)

One thing I've found myself doing with just about every RAW camera file I'm importing is to turn off sharpening, and do the sharpening manually to the Luminance channel only, sometimes using the Luminance channel as a mask. Much, much better. And the other thing I've been able to do is remove purple fringing (which was a major problem with my Olympus, and a more minor one with the Pentax). This is possible because the fringe doesn't affect the Luminance channel, which can, again, be used as the basis for a good selection.

Now I find myself wishing I could import RAW files directly to L*a*b rather than having to convert through an RGB colorspace first.

What fun. :-)