bump map from color map (RGB) generation?

Question

Is there a library like PIL (Python Imaging Library) which takes a RGB image (pixel data) and generates a bump map image? If not, how can I do that? I know the results might not be very good.

I know it will probably be slow to do in Python, it can be ported to C and called from Python later, after prototyping and seeing the results.

Answer 1

There's no 'proper' way to generate a bump map from a regular image because the 3D information simply isn't there. But if you know your textures are all from a similar source where directional lighting has been baked into the texture to some degree, you may be able to fake some usable bump maps via some standard image processing approaches.

PIL already offers this capability. You want one of the functions in the ImageFilter module, probably EMBOSS, eg.

import ImageFilter
import ImageOps
color_bump_map = diffuse_map.filter(ImageFilter.EMBOSS)
grey_bump_map = ImageOps.grayscale(color_bump_map)

That should allow you to take an image like one on the left below, and generate one like one that on the right:

(This example was done in Photoshop, but using the same type of filters.)

Answer 2

There are plenty of tools that will create a normal map given a heightmap / bumpmap. Creating a normal map from any old photo requires a lot more guesswork (to reconstruct the height by looking at the light and shadows) and will usually not give very good results.

One tool which can do it is Njob:

http://charles.hollemeersch.net/njob