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Beep6581 / RawTherapee

A powerful cross-platform raw photo processing program
https://rawtherapee.com
GNU General Public License v3.0
2.76k stars 313 forks source link

Add an indicator for imaginary colors #5760

Open teplit opened 4 years ago

teplit commented 4 years ago

It makes sense to see visually which colors are within the gamut of human vision and which are not especially for working color spaces with large proportion of imaginary colors like ACESp0. Such technical view can be used to assess more objectively the conversion of camera colors via the input profile into the working color space as well as the color handling of RawTherapee tools. It can be employed to inspect a photograph for unprintable colors (or more precisely said colors outside human vision - I guess that very few people will be interested to print infrared or ultraviolet colors even if they can).

Thanatomanic commented 4 years ago

Is it not enough to have gamut indicators? I know that gamuts can contain imaginary colors, but those big color spaces are rarely used as output profiles, and certainly not for web or print.

teplit commented 4 years ago

Well, 500px.com welcomes wide gamut photos. I use almost exclusively ProPhoto as output profile for my photographs destined for web or print. I see rarely problems with 8 bit ProPhoto JPEGs on Flickr or 500px. For professional print I use 16 bit ProPhoto PNGs.

Thanatomanic commented 4 years ago

That's a nice move from 500px.com, and luckily the color management of most browsers has come a long way since the dark ages!

Still, even the widest practically used color spaces (Rec.2020, DCI-P3) stay within the realm of real colors. And only the highest end monitors support these color spaces to a significant extent: 99% of DCI-P3 and still only roughly 80% of Rec.2020. Exporting in ProPhoto seems overkill to me, but I won't challenge you on your preference 😄

My conclusion atm is that, while not a bad feature request in itself (don't get me wrong!), this is a rather low priority thing with a limited practical use. Edit: we may need this in <5 years though if display tech continues as it currently does...

teplit commented 4 years ago

I’m proposing this feature mainly for diagnostic purposes, not because I’m hoping that in near future the computer displays will be able to show colors outside human vision…

If the starting point for RAW development is an image with a lot of imaginary colors then probably it is better to change that starting point. Also if a RawTherapee tool misbehave, then you can check the input of that tool: is it real or imaginary color, or maybe unclipped data (out of gamut color)?

I agree that this is a low priority request – few people probably use or will use ACESp0 as working color space. However ProPhoto, the default working space of RawTherapee, also contains imaginary colors albeit in smaller proportion.

teplit commented 4 years ago

Bruce Lindbloom gives here coding efficiency (percentage of real colors) for several RGB working spaces some of them included in RawTherapee: