dopus viewer not rendering ProPhoto RGB colorspace correctly. see ss:
Having played around with the ProPhoto RGB colour space, I soon came to the conclusion that the wider gamut was not worth the hassle.
If you use the tried and tested sRGB colour space in the ICC schema you will get much more reliable results, especially if you are shipping images to the web. The results of displaying an image in any ICC compliant app (Opus, Firefox, Edge, Photoshop Lightroom etc) will result in identical colour images being displayed on screen.
You will need to calibrate your monitor on a regular basis of course