What is the deal of grain retention

[Chengbin]

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??

[Adub]

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.

[*.mp4 guy]

... there is also the small problem that separating grain from detail perfectly is impossible.

[Blue_MiSfit]

... 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.

~MiSfit

[Daiz]

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.

[zn]

Digital cameras like RED (http://www.red.com/) is way to go (http://www.reduser.net/), 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.

[Tagert]

I love grain :)

[Mtz]

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

[*.mp4 guy]

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.

Grain was invented for HD to hide the problems of imperfect/immature Plasma/LCD and HD encodings.

no

Digital cameras like RED (http://www.red.com/) is way to go (http://www.reduser.net/), 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.

[MfA]

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.

[*.mp4 guy]

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.

[MfA]

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.

[LoRd_MuldeR]

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...

[Chengbin]

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.

[LoRd_MuldeR]

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 :D

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)

[Sharktooth]

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.

[Soulhunter]

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! ^^;

[scharfis_brain]

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 ;)

[Sharktooth]

*** BUT ***
guess what? videos are not a stable objects (images)...

[scharfis_brain]

That's where your brain's object tracking starts to work ;)

[Chengbin]

True, I can clearly see noise in front of my eyes, especially when its dark! ^^;

That's right! I can see grain/noise when it is dark. What's up with that?

[Sharktooth]

that's due to "rods and cones" aka the photoreceptors cells... we see "pixels" too and we have different receptors for luma and chroma...
human eyes are not much different from a high quality digital camera... so they also "see" grain...
post processing is done by our brain though, but still we see grain...

[Soulhunter]

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 ;)
Btw, funny random fact: It seems I perceive blue color with a delay when its dark. For example, when I slowly move a cigarette in front of my eyes in complete darknes, I clearly see a blue "ghost (http://img5.imageshack.us/img5/6687/212a.png)" of the fervor following (1-3 cm distance) the actual one! Does the eye also change its exposure time for blue light in darkness or so? O.o

[scharfis_brain]

If I look at the green lit number of my radio clock in the darkness, I see the bright number w/o delay and the rest of the room with delay.

for sure the eye or brain integrates the low light areas slower than bright areas that's where the delay comes from.

[Midzuki]

human eyes are not much different from a high quality digital camera...

Which one was invented first? :)

[Lyris]

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?
No: Grain is part of the FILM process. NOISE is a usually unwanted artefact from video cameras.

Grain also increases the perceived detail.

Whoever said realism was the intention anyway?

[*.mp4 guy]

If you pay attention to your visions characteristics, it becomes clear that the brain does a lot of processing before we actually "see" anything.

Extrapolating from rod/cone density, inherent noise constraints, and the dynamic range and resolution of the HVS, its clear that some fairly impressive voodoo happens at some point.

[Gokumon]

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?!?

Because in most cases when people try to degrain movies you end up with people with waxy looking faces and smearing in motion. Just look at the degrained Blu-Ray movies that have come out to see this.

[Mug Funky]

OMG, i laughed several times in this thread.

What is the deal of grain filtering?

if a codec can preserve grain, imagine what details it can keep.

when the grain's gone, the encoding/prefiltering process is no longer transparent (which it should always strive to be, assuming you're working with a source that has had some form of direction, where we can assume it looks the way it's supposed to).

digital "grain" is dark current from CCD or CMOS sensors this comes in the dark areas obviously because it's an artefact of the sensor's natural noise floor. heat increases it, as well as interference from any number of things.

film grain is usually most apparent in the dark areas too, because when the negative hasn't got sufficient exposure, only a few silver grains will be chemically processed, and they'll show up as big grains (the actual silver is bleached out, the "grain" left behind is a spot of dye attached to where the silver was). you'll find the current state of the art in film is almost completely grainless even at high sensitivities, and if you're looking at a standard def transfer of a 35mm film, there'll be almost no grain at all.

"300" didn't have grain added to it - it was shot with very flat light (so hardly any contrast), and had the contrast cranked up to 11 in the colour grade. this pushed out the grain that was inherent in the film.

i'll only filter grain at all if (a) a client requests it because they have a few shots that are sticking out among the rest, or (b) my target bandwidth is so low that filtering noise is the lesser of two evils (the other evil is blocks/smears/bands/compression artefacts). with that said, i tend to work with pretty good sources - there'll be no added noise from compression or transmission, as it's all off a camera tape, master, or roll of neg.

[onesloth]

What is the deal of grain filtering?
...
i'll only filter grain at all if ... my target bandwidth is so low that filtering noise is the lesser of two evils
^the deal. (for personal backups)

[Mtz]

grain exists since the first life form with a visual system called "eye" appeared on earth.
When my eye is looking to the sky, I see "pure sky", no grain. Also when I'm looking to my car or at the faces of the people. No grain, no red faces, just eveything natural.
This is what I hope from a movie.
When a director wants some thing in his movie, OK, is his choice, but I don't want to see grain in ALL movies. Also I see no grain in TV broadcasting. But as I wrote in other post, they neeed to hide some problems of HD.
Now I'm waiting Pixar movie with grain.

enjoy,
Mtz

[Sharktooth]

no one said that. but an encoder should be able to "keep" the grain if it's in the source.

[R3Z]

Grain is beautiful, i like to think of it as the perfection of imperfection.

Heavilly filtered moving pictures just look devoid of all life and character. Cant imagine movies without it to be honest.

[Ghitulescu]

Grain is beautiful, i like to think of it as the perfection of imperfection.

Heavilly filtered moving pictures just look devoid of all life and character. Cant imagine movies without it to be honest.

I've seen yesteday "Funny Face" in 720p on ARTE HD. No grain at all, perfect image (great restoration). I own some DVDs with film grain, I don't like them from the image point of view. The grain issue it's a matter of taste. Just because one is used to something, it doesn't mean it should be like this.

On the other hand, trying to remove the noise grain that yield detail loss, that's a completely different story. It's bad!

[Lyris]

Even if the grain reduction doesn't destroy actual detail, it will lower the perceived detail, which is nearly as bad.

[kolak]

Film grain is nothing more than inperfection in recording process. Film grain became a digital nosie now and both are unwanted side effects of recording process. People get use to grain so much, that they think it's smething wanted. It's not! There are new digital cameras coming (like RED) and soon picture will be perfectly clean as it's in the reality seen by eye. Is anyone seeing any grain in the real life?
Because it was immposible to avoid it directors started using it as a effect and that's why people get use to it so much and think that it's something "real", which can't be avoided. It can- all we need is much bigger sensor and better technology, which is coming.
Film grain is the same side effect (inperfection in recording process/device) as digital noise with modern cameras or even home webcams- it doesn't exists in real life :) (at least is no seen by eye, so we don't need to "create" it during recording- or we can, but only to add artistic value).

Andrew

[Ghitulescu]

Film grain is nothing more than inperfection in recording process. Film grain became a digital nosie now and both are unwanted side effects of recording process. People get use to grain so much, that they think it's smething wanted. It's not! There are new digital cameras coming (like RED) and soon picture will be perfectly clean as it's in the reality seen by eye. Is anyone seeing any grain in the real life?
Because it was immposible to avoid it directors started using it as a effect and that's why people get use to it so much and think that it's something "real", which can't be avoided. It can- all we need is much bigger sensor and better technology, which is coming.
Film grain is the same side effect (inperfection in recording process/device) as digital noise with modern cameras or even home webcams- it doesn't exists in real life :) (at least is no seen by eye, so we don;t need to "create" it during recording- or we can, but only to add artistic value).

Andrew

My words :)

[Soulhunter]

Is anyone seeing any grain in the real life?
Yes, we do... Noise...

See some posts above!

[Ghitulescu]

Yes, we do... Noise...

See some posts above!

I don't see noise in real life. I see noise on TV and DVDs, but again not in real life. If one see grains while looking at a tree, a lake, a meadow, it should go to a doctor - has a visual problem.

[*.mp4 guy]

There is noise in human vision, it doesn't look much like film grain, but if you don't see it you aren't paying attention.

Anyway, most people here aren't arguing for grain being positive in general, its just that keeping it is the lesser of two evils. On the other hand, arguing for DNR is like arguing that we should remove the highly visible brush strokes from Van Gogh's paintings, it completely misses the point.

[Ghitulescu]

There is noise in human vision, it doesn't look much like film grain, but if you don't see it you aren't paying attention.

Anyway, most people here aren't arguing for grain being positive in general, its just that keeping it is the lesser of two evils. On the other hand, arguing for DNR is like arguing that we should remove the highly visible brush strokes from Van Gogh's paintings, it completely misses the point.

Then you should know that there are movies wherein the grains are added, just to keep the kino feeling. BluRay specifications allows the addition of artificial noise.

About the removal of noise that also kills the details (I've seen a Bollywood movie, the action was in a desert, the tiny sand waves were completely removed in the noise removal process, so it looked like a 3D anime). I fully agree with all that say that grain should be kept if its removal adversely affects the image quality. But it is possible (just expensive) to remove it without too much impact. What I do not like is that grain is artificially added, or that the studios (that charge a lot for their movies and managed to get yet again a prolongation of their rights) fool the people that grain is good. More money and rights for less work.

[Mug Funky]

i've never heard a director, while on a press junket promoting his film, say "yeah, we think you'll all really like this because we added a bunch of grain". studios don't care what the director requests or doesn't request in post, and there's certainly no International Grain Conspiracy by the big 3.

name 1 movie where you know for a fact grain has been deliberately added. i dare you. i know of 1 short film, and that was only to hide the fact they were cutting from 500T to 50D (the higher the number, the grainier. 50D is almost perfect, and therefore the cut between the film stocks became quite jarring).

now, that said, i don't agree with some clients adding grain to RED footage. it already has enough (that's right, i said it. it's grainy. deal with it).

human vision most certainly has grain. your brain's probably filtering it out... a clear blue sky will be made up of infinitesimal noisy bits when you look up at it. what's more, human vision has a significant "afterglow" effect that makes things even more weird looking. photodiodes have been able to outperform human vision for years now. the human eye can detect a flash of about 6 individual photons IIRC, which is insanely sensitive. but a PEC in the right mode can detect single photons quite reliably. there's the occasional misfire from shot noise, but it wont miss a photon. CCDs are able to do this as well in some cases, but with dark-current and shot noise problems.

one thing the human eye does NOT do is remove details willy-nilly in order to present the brain with a "cleaner" image. so philosophically i don't think our encodes should do this either... unless bandwidth or artistic intent say otherwise (obviously you don't want noisy footage in a cosmetics commercial...)

[*.mp4 guy]

Its only possible to remove noise without significant detail loss when the detail level is fairly low. Also, there is nothing wrong with having noise present purposefully for artistic reasons. The blu ray specifications are intended to allow adding noise that was originally in the source back after it has been lost due to compression, this is useful for obvious reasons; but I've never actually seen it used myself. There are no noiseless cameras, and thats unlikely to change, I seriously doubt that any studios are adding grain, many of them are doing exactly the opposite, and badly.

[Mug Funky]

There are no noiseless cameras, and thats unlikely to change

http://www.panavisionimaging.com/imagers_DMAX.htm

i'd say it'll still have some noise... but it'll be pushing pretty close to the 10-bit floor i think.

can't wait to see this bugger unleashed.

[Ghitulescu]

There is noise in human vision, it doesn't look much like film grain, but if you don't see it you aren't paying attention.

Of course there is noise in human vision, like there is noise in human hear. But the grain in movies is much much much greater. It's a defect, and people seems to get used to it and don't ask questions. Its removal would take away the "personality" (someone said before) only if it's incorrectly done.
It's like getting used to the saccadated noise of the shutter (of the projector). Would you like to hear it? Maybe you do, since snapshot cameras do this noise, to suggest you the old ambiance of an old SLR.
Remember what Chaplin said? The advent of sound would kill the movie?

[smok3]

examples;
a. if you shoot on 35 film, and then do some sort of compositing, you will have to find a way to add matching grain to the composited elements
b. if film is master, then you want the video to look similar (keep some grain)
c. if workflow is 100% digital, then grain/noise adds some personality (to certain scenes), but it is not needed
d, it should be easy to test the same scene with different amount of grain and see what it means to a person (how much can we abuse the imagination that will fill the grainy gaps)
e. if you check autodesk lustre manual (available online), you will see it mostly talks about grain removal.
http://usa.autodesk.com/adsk/servlet/index?siteID=123112&id=11992855&linkID=10809889

[Astrophizz]

If human vision already has noise there's no need to emulate it in a video as just watching the video with your eyes will add that noise.

[smok3]

yes, but this is a practical world (not theoretical) one valid example for video would be:
1. denoise video (all kind of camera noises types)
2. add some grain (which is sexier that noise and it will mask the remaining noise and denoising artifacts)

[Ghitulescu]

Film grain is a defect that was magically transformed into a feature. This feature even has supporters. Maybe the software developers know this already: it's not a bug, it's a feature!
Why the professional photographs used glass matrixes instead of regular 35 films? Because at their size (10") the emulsion grain was less evident when enlarging the photo for a magazine or a poster. Why using less ISO (under 100, like 60 or even less)? Because it was easier to manufacture fine grain emulsions at lower ISO (the higher the ISO the higher the grain).
Does not sense a professional photograph the artistic value of the grain? I very doubt it...

[Ghitulescu]

yes, but this is a practical world (not theoretical) one valid example for video would be:
1. denoise video (all kind of camera noises types)
2. add some grain (which is sexier that noise and it will mask the remaining noise and denoising artifacts)

The denoising tools a private may have do not match the tools the producers [should] have. If I do a denoising using my knowledge, yes, it would be better to leave the grain where it is. But I'm talking about the movie companies. They should be able to obtain fine granulation movies...