Good progress.
Reshot the bottle, optimizing for geometry. The farther you are, the less difference between middle and corners. So I shot the bottle from 3 meters away, using my 400mm lens. Also made sure that I was level (spoiler alert: the label on the bottle is slightly canted...).
Reshot the bottle, optimizing for geometry. The farther you are, the less difference between middle and corners. So I shot the bottle from 3 meters away, using my 400mm lens. Also made sure that I was level (spoiler alert: the label on the bottle is slightly canted...).
Further testing showed that I was victim of some Gimp cleverness. When you do a grayscale gradient, the pixels aren't pure gray, there is some randomness in the hue and this isn't good for the displace map. Once I managed to turn this off, results are pretty good. This is the raw result (no need for median filtering this time).
The last two letters of Roses look off because they are actually layers with copies the first e and s in Pamplemousses and there is a difference in lighting. But the (slightly) corrected shape of these letters near perfectly matches the (very) corrected shapes of the last two, which is proof that the technique works. "SOURCE DE VITAMINE C` also becomes a near-perfect circle.
Now to create an even more precise gradient on the fly...