Originally Posted by seedomo
Edgework certain gave the best example but I would add a very important step. You will want to blur the A and B with surface blur or use dust and scratches to preserve the color detail of objects that have sharp edges. To visualize the technique, since a and b are usually hard to see, you can add a crazy adjustment curve layer set to color blending mode over the BG layer to increase the contrast of the two channels while you play with the blur filters. Another way, often overlooked in photoshop, is to first select the two channels using shift-click. THEN, press the ~ key which will show you the whole image while you are only working on the two color channels you have selected. I was just working on a painting that had subtle details of color and it was the first image I couldn't successfully work on in Neat Image (IMHO, the very best of all the noise programs) LAB is certainly the ONLY way you should approach this since color blending in RGB is VERY bad. This is a very difficult thing to explain, but better shown by a test.
great test! thanks so much. a visual definately helps when trying to figure out the best methods.
I see that the top right is gaussian of A B.
Is bottom right the surface blur?