Working with blend modes is almost always an experimental process. Because it’s nearly impossible to predict the results, you always seem to end up experimenting with different modes and Fill Opacities until you get the results you’re looking for.
In this article I’m going to give you a high-level view of what the various blend modes do, and then I’ll dig deeper into the nuts and bolts of the blend modes by explaining some of the math involved, and their interrelationships with each other. I’m not going to “show” you how the blend modes work—I’m going to “explain” how they work. By the time you finish reading this article, you should have a better idea of how to use blend modes and where to begin your “experimentation,” which in turn should reduce the time it takes to achieve the results you’re looking for.
Great run down on one of the most important parts of a lot of post work. This all applies to many other FX programs as well. These modes exist in After Effects and Modo as well. I Highly suggest anyone interested in geting the most out of their imagery to study up on them.