Understanding the background color

I thought it would be helpful to explain the significance of the background…color to After Effects.…This composition has a black background color.…The background color indicates which areas are transparent.…You can also see which areas of the comp are transparent by selecting the alpha…channel from the RGB channels pop-up.…Any areas that are solid white are fully opaque.…Any areas that are black indicate full transparency.…Wherever you see shades of gray, you are looking at shades of transparency.…

I will toggle off the alpha channel and turn off the transparency grid.…Now sometimes the black background color is not that useful.…You can change it in CS5 under Composition settings;…in CS4, Background Color is a menu item under Composition.…So if I change the background color to white, I can clearly see the drop shadow…effects on the video layers and the title.…Just to make it clear that the background color is transparency, let me create a new solid layer.…

I will make this white, and any size will do.…