Couple weeks ago I was working on some Lower Thirds in After Effects and I accidentally came into a very cool transfer mode. I meant to set the Track Matte to Alpha but instead I set it to Lumma and it looked very good, I switched through transfer modes with no comparable results. My question is how do you do something like that in Photoshop. Clipping layer puts in to Alpha Matte, how do you get something comparable to a Lumma Matte. On a side note (I used to know this) how do you set up an arbitrary map in photoshop and how do you control what colors you want to emphasize(never knew how to do that)? I wanna use it as input for a Glow in After Effects.
Thanks in advance