Can a tweaked texture be made for SketchUp using PhotoShop?

[Joe52]

I'm wanting to tweak a texture by extracting maps out of a texture then merge the original texture with the maps in a photo editor and import the final texture in SketchUp. The books I found for PhotoShop or PS Essentials don't cover using it for this purpose. Are there any online guides that cover the steps and suggested settings after the maps and the original textures are first brought in the editor up to the point just before the layers are merged into a single layer?

One program doesn't generates an ambient occlusion map but does generate normal, diffuse, specular, and normal maps. Is there a simple way to make a "fake" ambient occlusion map using PhotoShop or PS Essentials with the original texture and the maps, or to compensate for the lack of an ambient occlusion map?

[numbthumb]

At least some answers could be find in this nomeradona´s tutorial: http://www.sketchupartists.org/tutorials/sketchup-and-photoshop/texture-workflow-with-sketchup-photoshop-and-podium/

[Joe52]

That answers it partly, the normal map goes in the layer above the diffuse map and blend is set to multiply. But for multiple maps, how are the layers supposed to be organized (with the diffuse map always the bottom layer)?

Is the layer order supposed to be as follows from top down or does it matter with the exception that the diffuse map is always the bottom layer?:

1. ambient occlusion
2. displacement
3. specular
4. normal
5. diffuse

Is blend mode for maps 1-4 except normal map set to multiply, or is normal set to multiply and maps 1-3 (ambient occlusion, displacement, and specular) set to overlay?

Do normal and ambient occlusion maps need to be desaturated first or does it matter that these are not greyscale?