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Old 29th May 2009, 04:01   #1  |  Link
Chengbin
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What is the deal of grain retention

I should have asked this question a long time ago. Lurking around the forum, and I often hear goals of retaining grain.

Why in the world would you want to retain grain?!?

I thought grain was an unwanted artifact from video cameras. Why would you want that?

In real life the world isn't filled with grain, so it is not for realism.

For me MVDegrain 3 is one of the best feature of encoding.

If it is an artifact, and it is not for realism, why would you want to waste huge amount bits on grain??
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Old 29th May 2009, 05:06   #2  |  Link
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Grain is also an "Ambiance" factor. A mark of "classic" film is that of natural film grain. Film grain has been in movies for ever, and some (lots actually) like the affect that it provides. Reminds them of old times or something. In addition it prevents banding by providing dither, and gives the illusion of detail as well.

I filter my film grain heavily, but just so that there is only a sprinkling left. I don't eliminate it entirely. But that's me.
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Old 29th May 2009, 05:22   #3  |  Link
*.mp4 guy
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... there is also the small problem that separating grain from detail perfectly is impossible.
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Old 29th May 2009, 06:06   #4  |  Link
Blue_MiSfit
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Quote:
... there is also the small problem that separating grain from detail perfectly is impossible.
Exactly. Removing "only" the film grain is almost impossible in all cases.

If we're talking about CCD / CMOS sensor noise (aka "grain") then yes, this is highly objectionable and can be removed in many cases - particularly chroma noise. That ugly blue and red noise you see on high ISO digital camera images is what I'm referencing here

Grain is a part of all true film. Sometimes I find it best to just keep as-is, and sometimes I filter it. Very rarely do I try to remove "all" grain, because this usually results in an ugly, over-filtered image. It also often creates banding in the unfortunate 8 bit YV12 color-space we get to work with In fact, in most cases I add artificial grain after processing images for this very reason.

Still, to each his own. MDegrain/2/3 are all amazing filters, and there's some seriously good hardware out there in the pro sector as well.

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Old 29th May 2009, 17:02   #5  |  Link
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I personally like the look of grain myself, but too much is still too much, though. And even if I didn't like it, I'd still prefer it over (over)smooth video with ugly banding.
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Old 29th May 2009, 18:40   #6  |  Link
zn
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Digital cameras like RED is way to go, hope they will trash their old cassete cameras soon.

And I hate when they digitally add grain, unless it is needed for effects like in "300" movie.

They can add "grain" or "black & white" features to disc players, for customers who need it.

Last edited by zn; 29th May 2009 at 18:42.
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Old 29th May 2009, 22:30   #7  |  Link
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I love grain
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Old 29th May 2009, 22:35   #8  |  Link
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Grain was invented for HD to hide the problems of imperfect/immature Plasma/LCD and HD encodings.
I hate too much grain. I hate grain.

enjoy,
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Old 30th May 2009, 07:56   #9  |  Link
*.mp4 guy
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Quote:
Originally Posted by Blue_MiSfit View Post
Exactly. Removing "only" the film grain is almost impossible in all cases.

If we're talking about CCD / CMOS sensor noise (aka "grain") then yes, this is highly objectionable and can be removed in many cases - particularly chroma noise. That ugly blue and red noise you see on high ISO digital camera images is what I'm referencing here
High ISO digital often looks horrid, but you still have to be careful about how you handle it, or you will get a really washed out look. Also, even at low 100-400 ISO's, you will have noise, and removing it would be just as destructive as removing grain from film.

Quote:
Originally Posted by Mtz View Post
Grain was invented for HD to hide the problems of imperfect/immature Plasma/LCD and HD encodings.
no

Quote:
Originally Posted by zn View Post
Digital cameras like RED is way to go, hope they will trash their old cassete cameras soon.
Digital cameras have "grain" too, often to a far larger extent then large format low grain film.
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Old 30th May 2009, 10:22   #10  |  Link
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Originally Posted by *.mp4 guy View Post
Digital cameras have "grain" too, often to a far larger extent then large format low grain film.
Non spatially correlated noise is easier to remove though.

Last edited by MfA; 30th May 2009 at 10:26.
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Old 30th May 2009, 20:12   #11  |  Link
*.mp4 guy
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In practice, it is spatially correlated by the complex debayer filters (all high resolution digital cameras use bayer AFAIK). Also, theoretically, the fact that the ccd is partitioned into squares and not points will introduce frequency correlation aswell. Also, film grain should have a simple gaussian correlation, which is not exactly difficult to deal with. Furthermore, none of the denoising methods I would consider actually using would be significantly negatively affected by a simple positive spatial correlation.
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Old 30th May 2009, 22:52   #12  |  Link
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The sample footprint is determined more by the anti-aliasing filter than the sensor shape.

There is nothing simple about spatial correlation, it's the only real distuingishing feature of signal compared to noise you have to work with in spatial denoising ... the only methods which wouldn't be negatively affected are purely temporal.
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Old 30th May 2009, 23:31   #13  |  Link
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I think the primary reason why we need "grain retention" is because of this: If a decoder cannot retain the grain in a movie, then the result will not be a perfectly degrained video, but an ugly blurred mess! So if you want a good quality encode, you must either use high quality pre-processing that removes most of the grain without generating additional artifacts (e.g. MVDegrain) before encoding -or- you must use an encoder that retains the grain in a decent way. But high quality pre-processing is slow, really slow. Plus there are far too many thing that can go wrong with bad noise reduction, as seen in many releases! And as mentioned before, not everybody likes degrained video. The grain gives the film a "natural" and more detailed look. Strong denoising creates an "artificial" look. That's why I'm usually not a big fan of denoising...
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Last edited by LoRd_MuldeR; 30th May 2009 at 23:35.
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Old 31st May 2009, 02:02   #14  |  Link
Chengbin
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Originally Posted by LoRd_MuldeR View Post
The grain gives the film a "natural" and more detailed look. Strong denoising creates an "artificial" look. That's why I'm usually not a big fan of denoising...
I'm not sure if I agree with grain give a video a more natural look. People don't have grain on their faces. That's why I love MVDegrain 3. It restores the natural look of the video.
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Old 31st May 2009, 02:11   #15  |  Link
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I'm not sure if I agree with grain give a video a more natural look. People don't have grain on their faces. That's why I love MVDegrain 3. It restores the natural look of the video.
Different people, different preferences

IMO quite often you see faces that have been degrained much too strong and thus look unnatural. More like dolls than humans

(That maybe doesn't happen with a good degrain tool, such as the one from MVTools)
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Last edited by LoRd_MuldeR; 31st May 2009 at 02:38.
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Old 31st May 2009, 02:17   #16  |  Link
Sharktooth
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Quote:
Originally Posted by Mtz View Post
Grain was invented for HD to hide the problems of imperfect/immature Plasma/LCD and HD encodings.
I hate too much grain. I hate grain.

enjoy,
Mtz
complete nonsense. grain exists since the first life form with a visual system called "eye" appeared on earth.
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Old 31st May 2009, 11:46   #17  |  Link
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Originally Posted by Sharktooth View Post
complete nonsense. grain exists since the first life form with a visual system called "eye" appeared on earth.
True, I can clearly see noise in front of my eyes, especially when its dark! ^^;
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Old 31st May 2009, 11:59   #18  |  Link
scharfis_brain
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And since there is grain being produced by the eye our neural network called 'brain' is able to filter it out temporally if you stare for long enough on a object
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Old 31st May 2009, 13:58   #19  |  Link
Sharktooth
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*** BUT ***
guess what? videos are not a stable objects (images)...
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Old 31st May 2009, 14:04   #20  |  Link
scharfis_brain
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That's where your brain's object tracking starts to work
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