hackerb9
commented
6 months ago Good question. I don't think I tested it with animation. My guess is it won't work and you'd have to explode the GIF to individual files. [Update: I have tested it and it definitely does not work.]
One reason I didn't test it with animated images is because the GIF format (from 1989) has only a 1-bit alpha channel, which looks grotty because each pixel is either transparent or opaque with no in-between. For such images, often just picking a single color to turn transparent works better and is super fast and easy. (convert input.gif -fuzz 50% -transparent blue output.gif). My script outputs PNG format because it has 8-bit alpha (256 levels of transparency), but PNG can only show static images, not animation.
However, nowadays people often call any animated video without sound a "GIF" and modern formats (WEBP, WEBM) support the same color depth as PNG (24-bit color, 8-bit alpha) and can play animations. So, maybe I should consider outputting to a lossless WEBP instead of PNG so that animated files have a chance to work.
On the other hand... this is a very simple script and I don't want to complicate it with features that perhaps people don't even want. And, there's the question of whether the simplifying presumptions that work well-enough for a static image hold for the kinds of animations that people want. Is the "fuzz" factor going to be the same on each frame? Does choosing the top-left pixel as the background work for all frames?
If it starts getting complicated, I think people may want to just go for an industrial strength solution, like ffmpeg:
ffmpeg -i input.mp4 -vf "colorkey=0x000000:0.06:0.06" -c:v libwebp_anim -lossless 0 -compression_level 6 -q:v 50 -loop 0 -an -preset picture -metadata:s:v:0 alpha_mode="1" output.webp
I want to remove the background of my gifs with this script, any additional configurations have to be made or the usage is same for gifs as mentioned in the readme?