Posterize Reset and Refine Palette

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davidh
Posts: 835
Joined: June 9th, 2009, 2:16 am

Posterize Reset and Refine Palette

Post by davidh »

Reset does not close all open Color pickers. If you leave them open, re-add the color patches and run Auto Palette some of the patches are black.

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Refine palette now works differently. Sometimes it seems not to work at all, or any adjustments are practically invisible. Previously the changes made mostlu clearly visible.

1. Add a few color patches and run Auto Palette. Then run Refine Palette and the colors are just reordered. Sometimes there does seem to be a very sligt adjustment to one of the colors.
2. Run Refine Palette repeatedly and the output looks the same.

3. Change the colors patches by probing the input image and run Refine Palette. There might be some visible adjustment, sometimes a color is not adjusted but completely changed or replaced by anothe color.
4. Again run Refine Palette repeatedly and there do not seem to be any visible adjustments

5. Change the colors patches by clicking respective Color Pickers picking colors not existing in the input image. When you run Refine Palette, you might get almost completly different colors, not just adjusted.
The Helps says "...PWP makes an incremental adjustment to the existing palette colors...".
Does the "existing palette colors" mean the colors existing in the input image or in the color patches?

It is difficult to say which or whether a color was adjusted or replaced because as I noted in 1. Refine Palette seems to reorder the color patches as well.
jsachs
Posts: 4210
Joined: January 22nd, 2009, 11:03 pm

Re: Posterize Reset and Refine Palette

Post by jsachs »

I fixed the color picker problem.

Posterize definitely was not working correctly before, although the results may have seemed more pleasing in some cases. Refine palette now converges much faster than before so incremental changes each time you do it are much smaller.

K-means clustering essentially replaces each of the palette colors with the average of the image pixels that map to the palette color (in other words the average of all pixels that more closely match the palette color than any of the other palette colors). If a palette color is more different from all the image pixels than all the other palette colors, it does not get adjusted. If only a few random colors map to a palette color, it can be changed a lot.
Jonathan Sachs
Digital Light & Color
davidh
Posts: 835
Joined: June 9th, 2009, 2:16 am

Re: Posterize Reset and Refine Palette

Post by davidh »

Thanks for clarifying it to me. Now I think I understand.

It is true that previously the adjustments were much better visible and sometimes quite nice. But as often then not they were quite striking and occasionally even over the top. It looked as if after several rounds the colors were rotating around the whole image, thus creating various impressive results depending on the number of color patches.
In a way it worked like a kind of a spectacularity generator.
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