пт, 1 дек. 2023 г., 18:59 Andrea paz via Cin <[email protected]>:
> I tried to make other changes to the plugins for Color Correction to > be able to make it also see out-of-range (HDR) values and be able to > change them. All of this involves floating point calculation. I tried > changing the range of the following plugins: > Alpha; Color3Way; ColorBalance; Gradient; Histogram Bezier e Overlay. > If interested, I can report attempts to modify the code, but I got > good results only with Color3Way. > More in detail: > Alpha: My modifications ruin the plugin. Probably widening the range 0 > - 1.0 leads the algorithms to wrong results. However, I think the > original plugin works in floating point. > ColorBalance: From my tests I did not notice any difference with the > unmodified plugin (I used an appimage). I am under the impression that > this plugin already works in floating point and does not need > modification. > Gradient: Here again I find no difference with the original plugin. > Again, I have the impression that the plugin already works in floating > point. > Overlay (shared effect): I don't notice any difference with the original > plugin. > Histogram Bezier: I tried extending the range similarly to Histogram > (which works well in HDR, after modification). In this case I see no > change. The code is much more complex and it is probably not enough to > delete the CLAMP. > The change I made is to the file "bistogram.C" > line 361 I changed the value of 1.0 to 10.0. > I also tried editing the file bistogramconfig.C > line 110 e 111 I changed the value of 1.0 to 10.0. > line 229 I changed the value of 1 to 10. > I put these details because the plugin is very important for CC and I > would love it if someone more experienced than me could make it work > on out-of-range data as well. Besides, the plugin is not only a > histogram but also uses the very important "Curves". > For the Videoscope plugin I could not make changes because the code is > too complicated for my skills; similarly to Histogram Bezier. > > Finally I describe Color3Way, in which the modification worked. In the > original plugin the color wheels already seems to work in floating > point, but not the V bar of brightness values (which are clipped). > With the modification the V bar also works on out-of-range data. > The modification is as follows: > File "color3way.C": > line 281 I changed the value of 1.0 to 100.0. > line 284 I changed the value of 1.0 to 100.0 > (I have also tried other values, e.g., 10.0, and the clamp always > works up to those values). > The floating point calculation works for both the saturation bar and the V > bar. > With the tests done so far, I have had no problems or errors/warnings > on the terminal. > > I did the tests with exr images and then enabled the internal CinGG > engine (but in the tests it also works with "ffmpeg first"). I set the > color model to RGBA-FLOAT (inescapable: with integer 8-bit models you > cannot have HDR) and the color range to 2020 NCL (but it works with > all possible settings, not relevant). The graphics driver is X11 > because with X11-OpenGL it does not work. > Used patches: > 0001-TEST-Simpler-unlimited-float-overlay.patch > 0002-Allow-negative-numbers-in-overlayer.patch > noclamp_in_histogram.diff > Manual changes in color3way.C > > I am happy with the success with Color3Way (as with Histogram) because > I believe it will become increasingly important to work on HDR video > in the future. On the other hand, I regret not having success with > Curves (Histogram Bezier) because it is an essential plugin for CC. > Thanks for experiments! I wonder if anyone who worked on colour correction plugins in cinelerra still can be contacted? I do not feel very comfortable in this area, because some advanced usage of plugins/modes/rerouting already bite us earlier .... -- > Cin mailing list > [email protected] > https://lists.cinelerra-gg.org/mailman/listinfo/cin >
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