Digital BW, The Print

> From: Steve Kale [mailto:stevekale@...]
>
> In other words, the difference between any two greyscale
> workspaces is just
> their gamma....LAB simply has a gamma that leads to nice equal
> increments in luminance.  Gray Gamma 2.2 doesn't.

Technically, LAB doesn't have a gamma. Neither does sRGB. A gamma is an
exponent that defines a simple curve. Both Lab and sRGB have a more complex
shape that is linear at the dark end. The eye/brain doesn't respond either
linearly or exponentially throughout its range, so it's necessary to use the
more complex shape in order to provide something resembling uniform steps.

However, "gamma" is starting to come to mean nothing more than the midscale
gray level. Gamma 2.2 means that a midscale gray is 0.5 to the 2.2 power in
luminance. The higher the gamma, the darker the gray. I wish these terms
wouldn't wander in meaning, but unless someone has a better term, I guess
we'll loosely refer to it as "gamma".

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...