PS: Catching Up to 1998

[fhaber]

Amazon jogged my memory yesterday by cancelling my (!October) order for "Photoshop Channel Chops" by Monroy. I'd ordered it on an impulse buy, since two friends had suggested it as the best answer to an idle question.

What idle question? Something like, "You know, I'd give my eye teeth to understand what an alpha channel really is/was, and what the Photoshop designers were thinking of when they invented Overlay, Multiply, and the other stuff from, what was it, the PS4 era? Know anything that would give me some background?"

Should I bother reordering it somewhere else? Blasted Amazon US still has it for sale NEW, at the price I (didn't) pay. What is this, flypaper for new suckers (g).

To expand a bit, I'd like to know how Adobe got from the basic CG math of this stuff

http://en.wikipedia.org/wiki/Alpha_compositing

to the tools we have now for layering and masking - from both the RGB and paper sides of things. I just missed rubylith, but have some early experience with video masking. I sometimes have a hard time guessing what tool at what opacity and polarity will give what effect, but I assume I'm not alone in that.