I have a quickie. In most 3d applications there’s a feature known as a “dirt map” which allows the blending of two images depending on greyscale of the dirtmap. Is there any such feature in blender?
-uli
The ‘stencil’ texture option will do something like that. For this to work, you have to use at least three texture channels. First and third containing the images to blend, second the stencil texture (disable all ‘mapto’ buttons and enable ‘stencil’ mode), which if it is an image must have an alpha channel (or use calc.alpha button in texture section). One thing to remember is that a disadvantage of Blender’s current stencil implementation is that all stencil textures influence each other.
Hey, thx eeshlo 
. It definitely works, I just need to fine tune it and decide whether its worth using for certain textures.
-uli
Could someone do a sample blend of this technique or exapnd on it a bit? It would be a big help, thanks.
An image texture doesn’t really need an alpha channel to be a stencil texture, when you click the stencil button it affects the alpha value of all textures on top of that layer depending on the RGB value.
If the stencil texture doesn’t have an alpha value, it will be calculated from the greyscale. So yes, it implicitly needs one.
Martin
LOD: are you sure this site is still active, I just get time out errors trying to connect to it?
Yes