Not necessarily AgentS. A bump map is basically a grayscale map which adds detailed bumps and grooves to an object or Height and depth. In general, whiter areas represent bumps or raised areas, and darker areas represent grooves, or depressed areas. So if you had say a tile image of Dark blue tile with white grout and you turned this image into a grayscale you would get the opposite of how the tile should appear. Meaning you would have lowered tiles (black because it is dark) and raised grout (white). Sometimes it is best to create a custom bump map to emphasize the texture you want.