What does "Ignore Film Grain"/Grain Rejection do exactly for Nvidia's new Sharpen Feature?

Discussion in 'Videocards - NVIDIA GeForce Drivers Section' started by EerieEgg, Nov 3, 2019.

  1. EerieEgg

    EerieEgg Member Guru

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    Hi there guys,

    I've recently been experimenting with Nvidia's new Sharpen feature and noticed this value defaulted to 15%.

    My question is, does this do more than just "Ignore Film Grain"? If not, then this setting shouldn't do anything at all in games with Film Grain disabled, but so far it appears to have an effect in each game I've tested where games look more "grainy" or "sandy" with this setting lower it seems (though perhaps this simply means in the games I've tested thus far, they force some form of film grain in their post pipeline).

    I would expect that one would want to exclude Film Grain from being sharpened by the filter (a value of 100% I would think for Ignore Film Grain provided I'm understanding all this correctly -- I may not be), but if this is so, then why would Nvidia Default it to a value of 15%?

    I noticed in techspot's article here: https://www.techspot.com/review/1903-dlss-vs-freestyle-vs-ris/ that they refer to this setting as "Grain Rejection". Does this imply the setting is more complex than simply bypassing sharpening the film grain?

    I really don't understand why one would want to sharpen the film grain effect so I expect I am seriously missing something in all this.

    Anyway, I haven't been able to find more information regarding this setting so does anyone know exactly what it does? Thank you for your time, I appreciate it.
     
  2. RealNC

    RealNC Ancient Guru

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    If the game has film grain, then without this, the grain is going to also be sharpened. If you don't like that, then use that option. "Ignore" and "reject" mean the same thing here.

    That's about it, really.
     
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  3. EerieEgg

    EerieEgg Member Guru

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    Alright, great -- thanks mate.
     
  4. EerieEgg

    EerieEgg Member Guru

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    Posting an update on this thread since I've done some more testing in other games with this setting:

    I could be missing something of course, but this setting does appear to do more than simply ignore any post process film grain a game may have as I've tested it in games that you can turn the film grain OFF in where this slider still seems to effect the image quality in a discernible way.

    For example, even with Film Grain unchecked in the graphics settings, this setting still appears to affect the amount of inner detail that gets sharpened in each game I've tested so far. After messing around with this slider a good bit, I think the default Nvidia's gone with (1/6 or 17% in the control panel) seems like a pretty decent value overall so I'll just leave it at the default setting.

    Usually I find 50% sharpening to be a bit too much -- Crysis 3 for example is already doing 25% sharpening and in my experience a mild amount of sharpening paired with TAA or any post AA that blurs the image seems to do a nice job of recovering some sharpness without the noticeable artifacts that can come along with oversharpening an image (but it is pretty subjective of course which looks preferable).
     

  5. RealNC

    RealNC Ancient Guru

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    Of course. The algorithm can't actually know with absolute certainty what is film grain and what is not. Other stuff is going to be affected as well.

    Also, if you lie and enable "ignore grain" but then disable film grain in the game, the algorithm still thinks there is film grain because you told it so. So, uh, don't do that? :p
     
  6. Cyberdyne

    Cyberdyne Ancient Guru

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    It just ignores noisy detail in general. A more accurate name would have been "Ignore High Frequency Detail". But i guess film grain is more commonly understood.
     

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