Again this isn't really a bit depth issue, bump maps introduce banding because they represent height, and normal maps represent direction, so on a slope, every pixel in your bump map would need to represent a step of the gradient, however in a normals map it can simply represent a direction. Tangent space normal maps…
When talking about accuracy in normal maps we basically have 2 separate issues to consider. 1. Accuracy as it pertains to bit depth, comparing a 8bit image to a 24bit image, sure you would instantly say the full color image has more accuracy. However, we fail to consider that a tangent space normal map, being the…