Cannot choose ProPhotoRGB as output profile

[Morgan_Hardwood]

@Andi

I wonder that RT uses ProPhoto as working space but by default does not support it as output by default?

It does support it, it just doesn’t use it by default.

@Andi

Wouldn’t it be better to provide ProPhoto as default output for 16 bit TIFFs

Why would it?

@Andi

since no additional conversion is needed from working space?

Wrong assumption. The image at the end of the pipeline is apparently in L*a*b*.
https://github.com/Beep6581/RawTherapee/blob/dev/tools/color_management.svg