Question about creating custom textures

[mohonay]

Since of how easy dsfix makes it to retexture stuff, I have been spending a lot of time working on all sorts of custom armor and weapons. I've got a good grasp on how to recolor and clean up the existing textures. But I dont understand the more advanced texturing, like when someone creates a texture that seems to completely change the surfaces of armor and weapons. For example the balder shield has the tree-like crest/emblem on the front of it. In-game it appears raised up off the shields surface. Looking at some retextures on the nexus, people have iven it a flat surface or designed their own emblems that seem to pop off the shield's surface. I understand each model has a texture consisting of three parts: the image with all the fine details and color, the same image in greyscale, and then a bright purple image mapping out the topography of the texture, giving the fine details more dimension on the models surfaces in-game. It's that last part I don't understand. Can anyone educate me a bit on what exactly this type of texture is and how they're created, or at least point me in the direction of where I can learn? I apologize for my noobness.