Noise and Grain

[x265]

How do i differentiate between noise and grain?

[feisty2]

I think grain is one kind of noise, there're also some other kinds of noise like "Mosquito Noise" "Gaussian Noise" or so.

[x265]

from what i know grain is "good" and noise is "bad" but im having a hard time telling the difference between the both.

[Sharc]

from what i know grain is "good" and noise is "bad" but im having a hard time telling the difference between the both.
Simply speaking, noise is a general term used for any unwanted distortion of a clean (wanted) signal.
Grain (film grain) is a special form of noise found in photographic film sources. It is sometimes (as a matter of taste) considered as "good" because it preserves the look and feel of the original photographic film after compression and conversion to a digital format (DVD, Blu-ray). Retaining the original film grain is a challenge for the encoder at low bitrates i.e. heavy compression.

How do i differentiate between noise and grain?
By experience. Can be difficult for good encodes. Sometimes noise is added to imitiate the original film grain. In best case even compression artefacts may imitate grain for casual viewing.

[x265]

Visually they look the same.

[x265]

http://img4.imageshack.us/img4/4671/newfile021931.png
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Is this noise or grain?

[Bleck]

Noise, I bet.

http://s11.postimage.org/ld9b7a5r7/fatality.jpg

[Ghitulescu]

Grain is due to the presence of "grains", noise is due to the presence of "noise".

Grains are the minimal unit of storing image on analogue films. They are there to stay, the only countermeasure being to make them as small as possible. They are, simplistic speaking, the pixels of analogue.

Noise is anything that is not image. Yes, grain is also a noise, to some extension. Noise appear both in analogue and digital worlds. However, due to its auto-corrective nature, the digital is more or less immune to noise (unless one creates intentionally noise - for instance by lossily compressing the video). Denoising a video (like all anime lovers do) actually creates another type of noise, most of the times.

[x265]

Do you think i should remove the noise or does it look good with it?

[poisondeathray]

Do you think i should remove the noise or does it look good with it?

This is a subjective question. It's like do you like green or red better? Maybe purple ?

Some people might want to keep it, some might want to remove it . Some might choose for something in between

On animation, most people probably tend to favor less grain or noise, on live action sources, the preference is more varied

Removing it will enable better compression , but might predispose you to banding problems

Search for discussions on grain, there are 100's of pages on it

[x265]

Poisondeathray >> It compresses quite well even without denoising. The size of the encode of the first ep. of this show came out as 450MB.