Checked into source GIT, the tone mapping SYSLIB blend program plugin addition from Andrea. Checked into manual GIT, the attached tex file changes for HDR/clipping stuff exactly as provided by Andrea. Appended Examples.txt to add Example 6 tone mapping description exactly as provided by Andrea. (Andrea, please verify correctness in case I made a mistake). Thank you.
On Wed, Apr 2, 2025 at 2:32 AM Andrea paz <[email protected]> wrote: > I have included some small adds in the manual that deal with HDR. See > if they fit. There would also be to change the Blend Algebra examples > file written by Georgy. > > [Part to append to the file > https://cinelerra-gg.org/download/testing/BlendPluginExamples/Examples.txt > ]: > > > Example 6. > ---------- > > To tonemapping an HDR media and report its values within the range (0, > 1.0): > > BLEND_PROGRAM_INIT > > COLORSPACE_RGB > PARALLEL_SAFE > > BLEND_PROGRAM_PROC > > float mult; > > mult = KEY_A-0.5; > if (mult >= 0) mult = 1+mult*10; > else mult = 1/(1-mult*10); > > R(0) = R(0)*mult; > G(0) = G(0)*mult; > B(0) = B(0)*mult; > > BLEND_PROGRAM_END > > > First attach this blend program to your track above the other plugin > which you want to make not to clip. Switch clipping off in the blend > program dialog. This blend program will use the alpha slider (which > can have the value between 0.0 and 1.0) in the following manner: > > 0.5 (exactly in the middle): no RGB change > 0.6: R,G,B are multiplied by 2 > 0.7: multiplied by 3 > ... > 1.0: multiplied by 6 > 0.4: multiplied by 1/2 (i.e. divided by 2) > 0.3: multiplied by 1/3 > ... > 0.0: multiplied by 1/6 (divided by 6) > > If you set it, for example, to 0.4 here, your R,G,B values will be > divided by 2, so that the color values up to 2.0 will be scaled down > into the clip range. If you can have values up to, let's say, 5.0, > then set the alpha slider to 0.1 to scale down by 5, etc. > > Then attach the plugin you need to work unclipped, your histogram or > whatever. Pay attention that all the color values your plugin gets > now, are scaled down uniformly. > > Then attach the same blend program once more, under your needed > plugin. This time set the alpha slider to 0.6 (if it is 0.4 in the > upper one), or to 0.9 (if the upper one is 0.1), i.e. displace it from > the middle in the opposite direction. The unclipped values coming from > your working plugin will be scaled back by the same amount. >
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