Excuse my bad english
The recently released ‘dev’ version ‘69c1caa’ of March 19, 2023, contains changes that concern the colorimetry of RT, and in particular the « white balance ».
Two new features appear on the screen, in ‘White balance’:
- the “multipliers” of white balance channels. These are displayed, but you cannot modify them, they are given for information.
- a " checkbox “Observer 10° instead of Observer 2°” - (Observer 10° by default), acts on all the colorimetry:
** either for the automatic white balance calculations,
** or for the " Custom " white balance,
** or for the " Camera " mode, in this case, the temperatures and ‘tint’ are changed, but not the channel multipliers.
All the colorimetry is affected. I reproduce here the tooltip that concerns “Observer”:
« The color management in Rawtherapee (White balance, channel multipliers, highlight recovery,…) uses the spectral data of the illuminants and colors.
Observer is an important parameter of this management which takes into account the angle of perception of the eye. In 1931 it was fixed at 2° (privileges the use of the cones). In 1964 it was fixed at 10° (privileges the use of the cones, but partially takes into account the rods).
To avoid a (rare) drift of the colors due to the choice Observer 10° - probably due to the conversion matrix - Observer 2° must be selected.
In a majority of cases Observer 10° (default) will be a more relevant choice ».
Thanks to the excellent work of @Lawrence37 , the access to this essential parameter of the colorimetry is now possible directly from the GUI. Thanks to him.
Automatically the system will determine according to the versions of RT 5.8 or earlier, 5.9, which version of Observer to use.
Another improvement concerns the Automatic white balance “Temperature correlation” (Itcwb). This method based on the correlation of several colors of the image with spectral reference data has been improved to :
- on the one hand to make it compatible with the different versions of RT that contain Itcwb, 5.9, and versions that allow the use of “Inpaint opposed” (Highlight Reconstruction)
- on the other hand potential improvements have been deliberately hidden. An average default setting is selected.
What I propose to you, is to make you an actor, if you want, of the improvement of this automatic white balance (temperature correlation - Itcwb).
A Pull Request is open:
Recall, you can easily access the PR executables
Several tuning parameters are available. To do this in the PR concerned - branch “whitebalanceopt” go to Preferences > Color Management > White Balance automatic temperature correlation > check the corresponding box:
- directly via the GUI interface: 6 parameters are accessible,
- or by other means (pp3, compilation): 4 parameters.
Rawpedia has been updated, in good english. Thanks to @Wayne_Sutton and @Morgan_Hardwood for their contribution.
The goal is to find a better default setting than the current one. Obviously this is a compromise, because we cannot make these 10 settings continuously accessible. Maybe 1 or 2 settings should be made accessible.
If you agree to participate, please fill in your opinion directly in the PR
Thanks in advance