We had a half-baked idea that RGB could mean generic RGB space and sRGB
would mean strict sRGB interpretation.
Unfortunately, this did not work well in practice. For example,
`icc_transform("srgb")` would tag the result as RGB rather than sRGB
(the converter didn't know it was writing sRGB pixels, it just saw
conversion to RGB with an ICC profile), and then later stages would do
unnecessary icc_imports, or worse, fail.
This patch makes RGB and sRGB strict synonyms. If you want to treat an
RGB image as something other than sRGB, you'll need to do it by hand
with the icc_ functions.
See
https://github.com/libvips/pyvips/issues/14446212e92b1 (r34904985)https://github.com/libvips/libvips/issues/1494
e48f45187b