CMYK -> SRGB conversion results in color change

[diz000]

Questions, enhancements, tips, etc.

I have a JPEG image with CMYK colour space. When I try to convert to srgb I get an image with slightly changed colors.
Not sure if it's a bug. Probably similar to #3159 . Didn't find a solution there. Would be great if someone could help solving this issue.

To Reproduce
Use command
vips colourspace input.jpg output.jpg srgb

Screenshots
Input:

Output:

Environment

• OS: Ubuntu 20.04
• Vips: 8.15.1

[lovell]

Given the use of ICC profiles, you able to try vips icc_transform input.jpg output.jpg srgb (as discussed in the #3159 issue you linked to)?

[110111011]

Similar issue, but probably unrelated. Generates the same result (as expected).

[jcupitt]

I think I found it -- the input.jpg image has no colour profile (it's a raw cmyk image), so whatever image display or conversion program you use will pick a fallback for you. Different programs will have different fallback profiles, so you'll get varying results.

You can check for a profile with eg.:

$ vipsheader -a cmyk7.jpg  | grep icc
$ 

[diz000]

Thank you for your answers. Seems like @jcupitt is right. Many thanks!