Am 22.01.2019 um 00:13 schrieb Kenneth:

> Anyway, I'm still a bit perplexed about the normals difference between the
> following two constructs (using a continuous-tone color photo of your choice):
> 
> 1)
> box {<0, 0, 0>, <1, 1, 0.1>
> pigment {rgb .5}
> normal {bump_map {jpeg "my color photo.jpg" interpolate 2} bump_size 10}  }
> .....
> 
> and 2)
> #declare NORM_FUNCTION =
> function {pigment {image_map {jpeg "my color photo.jpg" interpolate 2} }}
> 
> box {<0, 0, 0>, <1, 1, 0.1>
> pigment {rgb .5}
> normal {function { NORM_FUNCTION (x, y, z).gray} bump_size 1.0}
> .....

In this case, the difference is due to another reason, namely that 
`bump_map` has a special implementation: Rather than sampling somewhat 
arbitrary points in the pattern, it adapts to the resolution of the 
image, and also samples in the image plane. It can't do the same trick 
in the function-based variant because it can't even tell that the 
function is based on an image.

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