You cannot tell if a color should be treated as linear or gamma-encoded until you perform some operation on it. If you are using linear workflow, and If you sample an image from a gamma-corrected image, you should get a linear color value,
which is the actual value but then gamma-corrected for some gamma curve value. but if you sample a pixel from a linear image, such as an already-corrected (linearlized) photo, or sample an pixel from a linear pallete for like a texture brush color, you should get a linear (the actual) value. the problem is that the sampler has no way of knowing if you;re sampling a linear-space color swatch like if you were picking a brush color, and return the actual pixel value, or sampling a pixel from a photo and should therefore gamma-correct (gamma .45 if your using 2.2 (.45=1/2.2)) the value --Roger Check out my website at www.rogerwickes.com for a good deal on my book and training course, as well as information about my latest activities. Use coupon Papasmurf for $15 off! ----- Original Message ---- From: Kent Mein <[email protected]> To: [email protected] Sent: Fri, November 12, 2010 10:34:28 AM Subject: [Bf-committers] color space changes Hi all, I was talking to Rant, Author of bug #24559 which was rejected. He asked me to explain the reason it was rejected. After looking at it a bit, I'm not so sure we should be rejecting this one. This has to deal with converting to linear color space. I think the current solution is odd to say the least. Try this little experiment. Load up the gimp, use the color picker to pick a color. Something like RGB 113 196 201 paint the entire picture that color and save the file. Load up blender, and open your image in the image editor. and use the color sampler to sample the color. Now in Hex I have color 71C4CA in both programs. In RGB though in blender I have .165 .552 .591 Now I get that it's a different color space but if I had chosen a different work flow, example: I had used 113 196 201 and converted them to 0.0-1.0 range I would get totally different numbers, something like: .441 .765 .785 It might make this simpler if we had a check box in the color picker for gamma corrected or not. Default on. If you unselect it, then you get linear color space, and all values are converted, (Hex = N/A for uncorrected?) Anyway what does everyone else think? The color correction is suppose to make our lives easier, right now though I'm more confused when looking at colors between multiple programs. Links for people that want more info: http://www.blender.org/development/release-logs/blender-254-beta/color-management/ https://projects.blender.org/tracker/index.php?func=detail&aid=24559&group_id=9&atid=498 Kent -- [email protected] http://www.cs.umn.edu/~mein _______________________________________________ Bf-committers mailing list [email protected] http://lists.blender.org/mailman/listinfo/bf-committers _______________________________________________ Bf-committers mailing list [email protected] http://lists.blender.org/mailman/listinfo/bf-committers
