Comment by networked

I didn't realize WebP was limited-RGB in addition to 4:2:0. According to RFC 9649, this is accurate. While the ITU-R Recommendation 601 on color is only a "SHOULD" in the RFC, you'd need a custom decoder to break out of limited RGB:

> The VP8 specification describes how to decode the image into Y'CbCr format. To convert to RGB, Recommendation 601 [REC601] SHOULD be used. Applications MAY use another conversion method, but visual results may differ among decoders.