Hi Gyan,

Contrast can go from -1000 to 1000. The range was expanded a few years ago; the doc wasn't updated.

Do note that what contrast does is scale the distance of a pixel's value from the median value i.e. 128 for a 8-bit input. So, if a pixel channel has a value of 100, then a contrast of 3 results in a value of   128 + 3*(100-128) = 44.

The order is contrast -> brightness -> gamma.


thank you very much for this information. Some time ago I tested the eq filter with high contrast values and had some problems, and then I thought that's because the allowed range is [-2..+2]. Now I tested it again and couldn't reproduce these problems. I just verified that two cascaded eq=contrast=2 filters give exactly the same result as one eq=contrast=4 filter. That's very good news!

I have one more question. Can you please explain the unit of the brightness value? What does brightness=1 mean? Does it mean add 256 to a 8-bit video, or add 1024 to a 10-bit video?

Thanks,
Michael

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