I have a design. Some parts of it are white, I want to extrude everything except the white. The white, will be holes. This cannot be done manually, it must be done by color white. What tool is the easiest way to get this done?
I don't think there is anything in standard graphics applications (i.e., the Adobe Creative Suite) that is going to help here.
The quickest way I can think of would be to use a 3D application like Bryce to get what you by using the terrain editor. The caveat is that most terrain editors extrude on gray scale with white being the highest elevation and black being the lowest, but that's a simple inversion of the image to get what you need.
3D applications are off-topic here, but pretty much all of them have some kind of a terrain editor that does exactly what you describe. The reason why I suggest Bryce is because they have a free version for you to play with.
This can be done in Photoshop CS 6 Extended, but the one thing that you'll need to do is invert your layer, as Photoshop uses white to be the highest point and black to be the lowest point. Heres a quick example.
Create your height/depth/grayscale image (remember to use 32-bit for best results). You'll want to have one layer (selected) when you do the next step. In the 3D panel select Mesh from Depth Mask > Plane... Done.
In the example above I make a separate layer with the gradient, difference clouds with gaussian blur, and text along with the black background and converted it.
I hope this helps. Cheers!
I would vectorize the image in order to get a vector line around the white part. Then import this vector into your 3D tool and extrude it.
Incidentally, by "vectorize" I am referring to the automated process most vector illustration tools have to generate vectors from a raster image: http://en.wikipedia.org/wiki/Vectorization_%28computer_graphics%29