(03-05-2024, 04:51 PM)Fabien Wrote: When I load a JPG into GIMP and use it, GIMP writes a profile to the EXIFs.
What's the point of this, given that a profile is only used to adjust the colourimetry errors of a device (screen, printer, etc.)?
Wrong assumption. The profile maps an encoding to real world values. So the encoding in the image, together with the image color profile, tells what the real word values should be, and these real world values, together with the display/printer color profile are used to compute inputs to the display/printer so that it outputs the originally intended real world values.
It happens that in many Images the color profile is sRGB and that if not specified SRGB is used by default, but this is not mandatory and can be something else (AdobeRGB is another frequent one, that supports a wider range of colors (aka "gamut")).