I am still somewhat confused by the discussion on this forum, and think it needs to be clarified.

1. Shouldn't blue ray be free of noise compression? I was of the understanding noise results from mpeg2 compression.

2. DNR should not remove grain. I purchased a flea this week so I will have to try it on blue ray but I am of the understanding despite it being the best noise reduction on the market, algolith the company that made it said it wont do anything for blue ray since blue ray does not need noise reduction. Yet I see people stating some projectors with dnr circuts remove grain. Shouldn't DNR only remove compression noise and artifacts?

3. It was brought to my attention that the sim2 380 on the fog scene in pirates COTBP had a DNR circut and removed grain, although some claim it is noise and should not be there? I am guessing even though I have not seen any of the pirates movie on blue ray, being a top tier movie is not suffering from noise, but rather the fog scene has grain that should be displayed? Maybe someone can clarify. Some people who see it claim that projectors like the w5000 are broke, and suffer from adding noise. I am under the belief it simply is showing the grain its suppose to thats in the film.

On blu ray sometimes the transfer undergoes digital noise reduction, with the intent to remove film grain.

But that still does not make much sense. Noise and grain are two different things. Noise is a result of compression, you see it on tv broadcasts or regular dvd.

Grain is completely different and is part of film.

But that still does not make much sense. Noise and grain are two different things. Noise is a result of compression, you see it on tv broadcasts or regular dvd.

Grain is completely different and is part of film.

From the perspective of a noise reduction filter, there's little way to tell the difference. They are both random patterns of high frequency information that vary from frame to frame. As far as the filter is concerned, it's all noise. Real picture detail is usually also wiped out in the process.

There are certain parameters that can be programmed to identify and address specific types of noise (e.g. noise manifested in blocks). But, at the end of the day, any filter you turn up too high or use inappropriately is going to remove information that shouldn't be removed. These things need to be very carefully considered on a case-by-case basis.

But that still does not make much sense. Noise and grain are two different things. Noise is a result of compression, you see it on tv broadcasts or regular dvd.

Grain is completely different and is part of film.

This post is brilliant. Murilo, you, like myself and others, see film grain as PART of a movie. When I read this post, I got the impression that you cannot even fathom why anyone would want to remove it. Yet that is why DNR is used, TO REMOVE film grain. For some reason, many people see grain as a problem in a movie's transfer, much like compression noise. If a movie is grainy, it obviously does not look good, in the minds of these people.

Early last year, when 300 was released, many people said they thought the movie looked horrendous. This is because the filmmakers purposefully inserted heavy grain into the image as part of the style. The BD (And HD DVD) was a very accurate representation of the movie, yet because it did not look the way people THOUGHT it should look, it's transfer was seen as bad.

Yes I just watched 300 last night. It was clear grain was intentional and suppose to be there.

I have a different view of noise, and that is it should not be there. When I watch HD and see noise compression it does not look like artistic grain, it looks like flaws from compression. As I read up on noise in the flea manual it becomes an entirely different from grain.

"Digital video compression has introduced a new set of picture artifacts known in the
industry as «mosquito noise» and «blocking artifacts». These new degradations coexist
with analog video noise and become quite objectionable when seen on today’s large
screen displays
Algolith’s Flea has been engineered to reduce the appearance of noise compression.

Flea is a three-dimensional digital noise
reduction processor, designed to clean up signals
from DVD Players/Recorders, Satellite Receivers,
Cable Decoders, PVRs and other digital devices
using MPEG compression."

As mentioned algolith does not believe the product has any benifit to blue ray which does not suffer from noise compression. The difference to me is grain is suppose to be there, noise is a result of compressing the image.

Noise - Artifacts introduced as part of the compression. Shouldn't be there.
Grain - Present in the original film negative. Should be there.

"Mosquito noise" merely a subset of the vast category of "Noise". There are ALL kinds of noise, which can come from any particular stage of the production process. It is hardly constrained to simply a result of digital compression (it existed in the analog domain in various forms well before digital came on the scene). "Grain" is just another kind of "noise" that is inherent to how film media does what it does. A noise reduction process can be either very general or tuned to attack very specific kinds of noise (and all sorts of varied degrees, in between). It can be very difficult to target a specific kind of noise while leaving all other noise unaffected. Most typically, a noise reduction process has to be handled very carefully, and usually, it is not possible to hit only one kind of noise w/o affecting others to some degree, as well. Mosquito noise just happens to be a fairly distinct case that can be isolated fairly well. Mosquito noise is usually a problem when it comes to low bitrate encodings (digital satellite/cable, downloads, sometimes even ota broadcast). One of the main precepts of br is to stay out of that low bitrate domain to avoid compression artifacts of that nature, altogether. That is why a mosquito noise filter is not likely to do anything beneficial or useful on br encodings.

Early last year, when 300 was released, many people said they thought the movie looked horrendous. This is because the filmmakers purposefully inserted heavy grain into the image as part of the style. The BD (And HD DVD) was a very accurate representation of the movie, yet because it did not look the way people THOUGHT it should look, it's transfer was seen as bad.

See that's where I have a problem with grain, or dare I say "digital grain": when it's deliberately added to look like a film... Because it often doesn't look real actually.I mentioned Attack Of The Clones in another thread; and I didn't refer to the DVD, but to the actual theater experience... LOTR has a lot less grain at the theater... Anyway, we could probably compare dozens of different movies, but you see my point.

Grain is completely different and is part of film.


Murilo, you, like myself and others, see film grain as PART of a movie. When I read this post, I got the impression that you cannot even fathom why anyone would want to remove it. Yet that is why DNR is used, TO REMOVE film grain.

In the process of digitizing an analog medium, film grain is often accentuated by the scanner resulting in noise and artifacts. So some level of noise reduction is needed to bring the apparent grain in the digital version back in line with the projected analog image. This becomes a problem when applying too much filtering as it takes away fine detail as well. As stated by Josh Z and many others, the process needs to be overseen carefully by a skilled operator.

I am still somewhat confused by the discussion on this forum, and think it needs to be clarified.

1. Shouldn't blue ray be free of noise compression? I was of the understanding noise results from mpeg2 compression.

"Noise" doesn't necessarily refer to compression artifacts, and the other codecs can have them just the same depending on how hard they're pushed. I believe the other noise people talk about stems from dithering to smooth color transitions with the low-res color formats we get for consumer video.

What I want to know is: can video noise be introduced by the telecine/datacine? As I understand it, they just use CCDs to capture the image, and I know my digital cameras introduce plenty of noise into their "pure digital" images.

Grain is something Made and sometimes Removed by Studios.
Noise is something that is Made by Customers.

Both are Necessary Evil and perfectly fits the Cause (Grain) and Effect (Noise) Phenomenon.:D