Color Palette Quantization in Photoshop

ReadMe.md

Here's an example regarding the image color quantization I've been talking about.

This is an original subtitle bitmap having a palette of 4 or 5 colors:

Rainbow Ring

Original (from 32bpp PNG)

fate-suite\apng\o_sample.png

Original

400%

All following images are zoomed to 400% and taken as screenshots from Photoshop

Photoshop (to 8-bit alpha palette)

PngQuant (to 8-bit alpha palette)

Paletteuse/gen Regular (to 8-bit non-alpha palette; only single transparent color)

ffmpeg -y -loglevel verbose -i "fate-suite\apng\o_sample.png" -filter_complex "split[split1][split2];[split1]palettegen=max_colors=255:use_alpha=1[pal1];[split2][pal1]paletteuse=use_alpha=1" -frames:v 1 out.png

Paletteuse/gen New Alpha-Patch (to 8-bit alpha palette)

ffmpeg -y -loglevel verbose -i "fate-suite\apng\o_sample.png" -filter_complex "split[split1][split2];[split1]palettegen=max_colors=255[pal1];[split2][pal1]paletteuse" -frames:v 1 out.png

ELBG Filter (to 8-bit alpha palette)

ffmpeg -y -loglevel verbose -i "..\fate-suite\apng\o_sample.png" -filter_complex "elbg=pal8=1" -frames:v 1 out.png

ELBG with new Alpha-Patch (to 8-bit alpha palette)

ffmpeg -y -loglevel verbose -i "..\fate-suite\apng\o_sample.png" -filter_complex "elbg=pal8=1:use_alpha=1" -frames:v 1 out.png