Choosing colors and pallettes

[Helm]

http://en.wikipedia.org/wiki/L%2Aa%2Ab

fun to work with colors that don't exist.

[AlexHW]

L is lightness/luminance
a is a value between green and magenta
b is a value between yellow and blue
Lab is an absolute color space, where as cmyk and rgb are not, so Lab can describe more colors for the human eye.

[Conzeit]

I did read up some of the wiki data (although it's very dense so I didnt get much) but I couldnt imagine the inmediate practical implications of using this. in fact, I had put the LAB sliders on photopshop whitout knowing what they are, but I dismissed them...they are just wildly unpredictable every time I change a slider the function of ALL OTHER silders changes I cant even imagine getting used to that.

Kon, it just feels a lot more complicated; what exactly do you find more efficient about the LAB method, is it just the range of colors an absolute color space implies?

[AlexHW]

with rgb, you have to adjust all r, g, and b, to decrease or increase the luminance. that means you have three values each controlling the amount of brightness. With Lab, you are only useing one value to control luminance, and the other two are strictly for amount of color.

I much prefer only two values to choose a color than three, and those two dont affect the luminance either.
rgb just makes things difficult.

[Helm]

...which is why most people use HSL?

[AlexHW]

...which is why most people use HSL?

the hue slider in HSB doesnt only change the hue, it also adjusts the luminance.
in HSB, you still have threee values adjusting the brightness, so thats just as complicated as rgb.

[Lawrence]

the hue slider in HSB doesnt only change the hue, it also adjusts the luminance.

Which programs have Lab? I'd love to see this, I hate hue changes messing up my luminance.

[Ai]

Here's a rough view of LAB colorspace. It's a naive conversion to RGB; as wikipedia notes, A proper color profile for your monitor and picture is needed to reproduce LAB colors accurately. (for example, looking at this animation on my monitor, green recedes faster than blue which recedes faster than red.)


In this animation,
+TIME = -L
+X = +B
+Y = +A

Photoshop is the only app I've heard of supporting LAB color selection.
I'm trying to make an LAB colorselector for GIMP myself, as the color management support of GIMP is greatly increasing recently.

EDIT:
LAB in common terms:
(Consider LAB as three floating point values in the range (0.0 .. 1.0))

Darken/lighten a color : -L or +L
Make a color greyer : move A and B towards 0.5 (absolute grey is at A = 0.5 B = 0.5)
Traverse the color spectrum : Travel in a square around the A*B square in such a way that your distance from the centre is constant. This is overrated -- exact traversal of the spectrum I've rarely found useful.

[Frychiko]

I've been using LAB in photoshop for years... I prefer it over RGB and HSB.

[Conzeit]

 I'm pretty sure green is just supposed to disappear at the darkest level, since there is no other way to create black from what I see in photoshop, if I tried to make green as bright in 0 luminance as red or blue are, I'd end up with a green tinted screen......
I dont understand, in that animation the brighter the space is, the more yellow dominates the picture, how is it that it just disappears in the last few frames? is it supposed to be a fake color created by luminance or something?

......AAAAAAAAAH confusing, Kon...can u give us some examples of HSL's luminance fault?