First mentioned by Nickesm (viewtopic.php?p=94656#p94656) Gifski looked interesting for its purpose, as it also advertised a Windows GUI version -- which sadly I couldn't make work; it executed alright with no patent error and then just stayed in memory without any visible UI...
Anyway here it is as a CLI utility for anyone interested (see below for version details). And please beware that "By default Gifski maximizes quality at cost of file size, so it is expected that the GIF files will be massive". If you need smaller files, several solutions are proposed near the bottom of Gifski's homepage.
Gifski makes smooth GIF animations using advanced techniques that work around the GIF format's limitations.
gifski 1.32.0
https://gif.ski by Kornel Lesiński
Usage: gifski.exe [OPTIONS] --output <a.gif> <FILES>...
Arguments:
<FILES>... PNG image files for the animation frames, or a .y4m file
Options:
-o, --output <a.gif> Destination file to write to; "-" means stdout
-r, --fps <num> Frame rate of animation. If using PNG files
as input, this means the speed, as all frames
are kept. If video is used, it will be
resampled to this constant rate by dropping
and/or duplicating frames [default: 20]
--fast-forward <x> Multiply speed of video by factor [default: 1]
--fast 50% faster encoding, but 10% worse quality
and larger file size
--extra 50% slower encoding, but 1% better quality
-Q, --quality <1-100> Lower quality may give smaller file
[default: 90]
--motion-quality <1-100> Lower values reduce motion
--lossy-quality <1-100> Lower values introduce noise and streaks
-W, --width <px> Maximum width.
By default anims are limited to about 800x600
-H, --height <px> Maximum height (stretches if the width is
also set)
-q, --quiet Do not display anything on standard
output/console
--repeat <num> Number of times the animation is repeated
(-1 none, 0 forever or <value> repetitions
--matte <RGBHEX> Background color for semitransparent pixels
-h, --help Print help (see more with '--help')
-V, --version Print version
