Video noise = grain?

[UniSol GR77]

Why do people keep talking about "video noise" or simply "noise" for movies not shot by digital cams? I'm talking about eighties/nineties movies.

What's the difference between "noise" and "grain" then?

I'm LOST!

[Anthony P]

film grain is a term used for the effect created in the image from the natural unevenness spread of the photosensitive chemical molecules used to create film.

noise is anything that “should” not be there (or was not there). You can have audio noise (like hissing and pops in sound), signal noise (snow and ghosts in the old analogue days of TV...), video noise (mosquito noise, compression artefacts.... FG)

FG like many noises in the original product is there from the beginning and so can’t be removed without creating other issues that lessen the product. Like trying to get rid of brush strokes in a painting.

[Deciazulado]

Noise is something that's not part of the original signal (Therefore that's why there's an specification for it: S/N ratio, how much noise is there below the signal)



Film grain is the picture making elements in film that are exposed to light and darken from it, therefore creating the image, like pixels make up an image:




Film grains are microscopic and it's their irregularity in the form of grain clumps that makes them mostly visible and what people call a grainy appearance.



It is the opinion of some that since the scene filmed in front of the camera has no grain, therefore grain is noise. If you see it that way (real life has no grain), grain is noise, but since the image that if exposed on film is formed by the grains, it is not, as grain is the building structure of the film image so it is a basic part of it.




Now, the added grain from subsequent copying (interpositives/intenegatives/prints/dupes) is another thing and that could be considered noise added to the original signal (which as I said above is: the image formed by grain on the negative).

[jadedeath]

Originally Posted by UniSol GR77

Why do people keep talking about "video noise" or simply "noise" for movies not shot by digital cams? I'm talking about eighties/nineties movies.

What's the difference between "noise" and "grain" then?

I'm LOST!

Adding noise is an editing technique.

Grain is something video purists get angry about whenever some director/producer mentions lessening it for the sake of a High def release.

Logan

[UniSol GR77]

I know and "grasp" what is grain... I just can't still figure what is "noise".
Compression artifacts? What are they?
Is Mosquito noise only related to digital cams?

What does it mean: "The movie gets noise in the warmer colours" or "the movie gets noise in the darker scenes"? I think many reviewers mean GRAIN, not NOISE.

[Anthony P]

I just can't still figure what is "noise".

noise simply put is anything that should not be there
Compression artifacts? What are they?[/quote]
they are artifacts like mosquito noise, macroblocking... that happen due to compression. All digital video is extremely compressed and so some pixels won't show what they are supposed to

Is Mosquito noise only related to digital cams?

no, it is a digital noise due to compression, but it could come from a film source which was digitized as well. Here is an example of mosquito noise


the right one is OK, the left one has white arrows pointing to mosquito noise.