test build 180 released
http://madshi.net/madVRhdrMeasure180.zip
Changes:
1) "map" is now available in 10% steps, to give you more control.
2) The ACES "repair hue & lum" options were removed (always on now).
3) Added ACES "split" option to give you more control over the compression curve.
4) Modified the ACES compression formulas to give us more control.
5) Added ACES "process in BT.2020" option, to allow you to apply ACES compression in BT.2020 instead of the output gamut.
The default option for the "split" parameter is 0.2, which should be roughly similar to how the original ACES compression parameters worked. The "split" parameter defines how much of a curve we have. The bigger this value is, the less clipping we have, and more of a curve. The "split" parameter is important if we increase the "threshold" parameter, because in the previous builds, when using a threshold near to 1.0, the "split" internally went down to near zero (it was calculated like "1.0 - threshold"), which basically turned the ACES "curve" into a clipping graph. Now if you keep "split" set to 0.2, you can increase the threshold up to 1.0, or even beyond 1.0, and there will still be a compression curve applied. The compression does start at the threshold, and it will then compress above that. A split value of around 0.2 look fine to me, but you can experiment with different values, if you like.
In order to find good threshold + limit + split values, I'd recommend to use the same values for Red, Green and Blue as a starting point. Once you're happy, you can still tune the values some more, by maybe trying different values for Red, Green and Blue. In theory, I could also allow the "split" value to be set differently per RGB channel. But I wonder if all of this is even needed. Using the same threshold, split and limit for all 3 channels might be fully sufficient?
I don't recommend using the "process in BT.2020" checkbox. However, if you like it, we can discuss it. It should do roughly what build 178 did - if you set all the other ACES parameters to their default and "split" to around 0.2. |