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AV1@Scale: Film Grain Synthesis, The Awakening

(netflixtechblog.com)
252 points CharlesW | 1 comments | 03 Jul 25 16:34 UTC | HN request time: 0.21s | source
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fidotron ◴[03 Jul 25 17:02 UTC] No.44457084[source]▶
There are definite philosophical questions over the merits of adding noise, but the problem with their example here is their denoising process appears to excessively blur everything, so both it and the synthesized grain image look noticeably less sharp than the source. The grain itself also looks too much like basic noise, and not really grain like.
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1. aidenn0 ◴[03 Jul 25 19:35 UTC] No.44458449[source]▶
AV1 has tunable FGS levels, and to my eye they went very slightly higher than they should have (though there are tradeoffs; at some bitrates the blurring+renoising is so much better than the other visual artifacts you will otherwise get, that you do want it that high).

A few things to note:

- still-frames are also a mediocre way to evaluate video quality.

- a theoretically perfect[1] noise-removal filter will always look less detailed than the original source, since your brain/eye system will invent more detail for a noisy image than for a blurry image.

1: By which I mean a filter that preserves 100% of the non-grain detail present, not one that magically recovers detail lost due to noise.