Simon,
Thanks for the correction. I have a wide gamut monitor (NEC PA2411 calibrated with Spectraview). With both Chrome and Firefox, I see a clear difference between your two images. With Edge, the sRGB displays with the same saturation as does the ProPhoto image. I presume that is the expected behavior with Edge: the sRGB numbers will be closer to 255 because of the smaller gamut and if these numbers are sent directly to the wide gamut monitor, the saturation will increase. Right?
Regards,
Bill
Right.
Each blob has RGB values of either 0 or 255, depending on the colour. For exmaple the red blob has RGB values of 255,0,0 in both files. The only differerence between the two files is the colour space, and the corresponding profile that's embedded. The red value 255,0,0 is a much more intense red in ProPhoto RGB than in sRGB. A colour managed browser should map that to the equivalent colour in the monitor's colour space, or the nearest equivalent if the red is outside the monitor's gamut (which it almost certainly will be with ProPhoto RGB colours).
As all the colour blobs in the ProPhoto RGB image are outside the gamut of sRGB, then a normal gamut monitor (roughly sRGB normally) will show the colours as the nearest within sRGB, which will be almost the same as for the sRGB image colour blobs, which are within sRGB. So the images will look the same on a normal (narrow) gamut monitor, but the ProPhoto RGB image should look more saturated on a wide-gamut monitor.
Edge and IE appear not to use the monitor profile, but convert everything to sRGB,
and send the sRGB image data to the monitor, ignoring the monitor's profile. That means that both sets of colour blobs will look the same (as they're converted to sRGB) on any monitor. But as Edge and IE don't use the monitor profile, the colours will look much more saturated on a wide-gamut monitor.
I can sort of see a reason why Microsoft might do that. For users that don't use colour management (monitors aren't profiled) and have normal gamut monitors with a gamut very close to sRGB, then Edge and IE will display colours roughly correctly, whatever the colour space of the image. But that behaviour means that colours are absolutely 100% guaranteed to be wrong on any monitor whose colour space is not identical to sRGB. On wide-gamut monitors, Edge and IE are completely hopeless.
Given that colour management is built-in to Edge and IE, why not have an option to use the monitor profile, instead of converting to sRGB? It would be a tiny amount of code to do this.