A bump is used in 3-D programs to give some relief or texture to a picture or image (which itself may already have a lot of texture). The image is wrapped around a 3-D object, and so is the bump, at the same time. And the result is the combination of the two. If it's a small bump, like bacteria here, it can be scaled up to fit the size of the image, which can lead to some unexpected effects (Corundum). A large bump may be scaled down, or both image and bump may be shrunk or enlarged to yield very unexpected and pleasing effects. But it will depend, at any rate, on the software program being used.

The method of making a bump may well mean using something like the hot wax filter in PSP, and then converting to gray scale. Once an image looks interesting, you take a shot with hot wax, maybe sharpen it up a bit, and if it looks like something, then it's a go. At any rate, using them in the 3-D program should be simple enough. You load both an image and bump for a particular 3-d object, like a sphere. You set reflection and stuff for the image, and set fuzziness, height, reflection and stuff for the bump, and wrap both simultaneously around the object on the screen, and see what you get. The Globes background is an example of this; each globe separately, at any rate, which were all then cut and pasted to get the final collection of globes. You could take a picture of a field of flowers and use something like the chicken bump, say, just to see what it looks like. A high 'fuzz' or blur factor for a bump should result more and more in the 'plastic effect' seen in certain backgrounds, here (e.g. Alien or Monk), but even just also suggested by some of these bumps, themselves.

And, ultimately, of course, having said all this, it's just about relaxing, being curious, having some fun with it and trying stuff that maybe shouldn't even work - just to see what happens. Try all kinds of settings. Use different sorts of images. Try all kinds of different bumps, like these. You may discover something that hadn't occurred to anyone else.

On the other hand, one might prefer the bump to reflect the terrain or topography of the image. Shadows do not necessarily imply a black area at the bottom of the 'terrain'. If you have one of the 'tooth' textures, here, or even bumps, applying it as a bump to an image won't necessarily produce the same tooth texture, though the result might still be interesting. But the 'teeth' won't protrude where they should. For that to work, you would need a height map of that little tile. And to produce a height map from an existing photo, or image, is not necessarily easy. Again, one has to correct for shadows, and then create the depths and heights as if the tile were three-dimensional and you could view it on the side from various angles. It might mean using a program where you shade over areas at a certain height, then continue with those at another range, or percentile, and so on, so that the application might eventually blend them together for a 'terrain map'. It would all depend on the application. Needlesstosay, if it were one, single computer generated scene, it might be easy to just insert a 'glass pane', a cutting plane and have the program create a height map up/down from that. But used in the way suggested above, these bumps can still provide very interesting effects.