I was looking at this GOG.ico in ffmeg, and was surprised to see all the streams for it...indicating it was holding multiple images in the .ico container or .ico has some kind of self-creation function where it generates the resolutions from a singular image based on condition? Or Maybe I'm overthinking it and its just a container with 7 different image variants stored inside?
Regardless I was curious on what the method of creation was for this many .ico in one hybrid, and how to replicate it. I'm already familiar with how to create a singular .ico image using gimp and/or ffmpeg....gimp is probably using ffmpeg itself. If its 7 images, those can be mapped to various streams of the .ico container using a tool like ffmpeg.
What's a more automated workflow people use to create these kinds of elaborate .iso though?