Alpha Layers

[Chris Northcross]

Hey gang! Got a few hours yesterday to experiment with SA yesterday and decided to try using layers with alpha in one of my paintings. Ran into a problem I couldn't figure out. First the set up: In photoshop, I took a photo of someone standing in front of a flag, extracted the person from the background, cloned in the background so it was a solid flag, and saved both the person (with transparent background and alpha channel) and the flag as separate .tiff files (and later as .psd files) I then brought them into SA on different layers. I set the flag layer as the background and the extracted person as the foreground, turned on "all layers" and initially left the alpha set to off (though I later switched it on). I expected to see the layers appear as the original picture looked--the person in the foreground standing in front of a flag. What I got instead was the person in foreground standing over a black background. When I turn the Alpha to "on" the background shows through, but only within the alpha channel of the background. What do I need to change to have only the foreground's alpha channel show up over the full background?

[Synthetik]

You can use the view current layer alpha only option to aid in debugging what is going on. I'd suggest taking a look at the alpha channels associated with both layers.

Studio Artist uses a fixed color background you specify in the layer preferences. Photoshop uses an actual image as the background. So neither of your layers is the background, they are both stacked on top of a fixed color background. The layers are applied from top to bottom in the list to build the final composite image when in view all mode.