"Club Penton" - Ask questions to Hollywood insider "Penton-Man"

[micks_address]

but some are darker shades of black than others.. i am not changing display settings... you can clearly see on my display that the black bars on the dark knight arent as black as say the bars on kung fu panda.. its not a big deal at all, just wondering why there's inconsistencies..

Originally Posted by Stacey Spears

The black bars really should be Y 16, Cb 128, CR 128. This is not always the case. For example, some of the sources that StudioCanal used for HD DVD had odd Y values, which were higher than normal.

I could understand why some of the animated content might have lower values for the bars, which would make them look blacker on your display. How much more black could this be? And the answer is none. None more black.

I just looked at Cars and the bars are 16, 128, 128. I took a quick look at Penton's favoriate forum, since they host a number of *Pix*. It turns out the color conversion used on all of the samples I looked at (Dark Knight, King Kong, Serenity and WALL•E) were converted using PC levels, instead of video levels, so all bars are Y 1.

[NutsAboutPS3]

Originally Posted by Stacey Spears

The black bars really should be Y 16, Cb 128, CR 128. This is not always the case. For example, some of the sources that StudioCanal used for HD DVD had odd Y values, which were higher than normal.

I could understand why some of the animated content might have lower values for the bars, which would make them look blacker on your display. How much more black could this be? And the answer is none. None more black.

Don't some video encodes contain "blacker than black" detail, though, i.e. information in the picture below 16? I could swear that often the black bars are lighter than the darkest parts of the picture.

Originally Posted by Oliver K

You are right that the dual score is something that is only possible in an ideal world as most of the time we do not have any info to make that judgement about transparency.

Mostly what we need is clarity as to the rationale behind a review score. I have often wondered what people actually mean by a score of 4 or 5, and what score they would give to:
a) a poor transfer of an exceptional source
b) an exceptional transfer of a poor source
c) an exceptional transfer of an exceptional source
etc
For example, I recently watched The X-Files 2 movie, and I thought the picture quality looked to be right up there in the top percentiles of Blu-ray picture quality. I was particularly struck by the detail in people's faces, and how when their faces moved, the detail moved with the face instead of being stuck in place on the screen due to the all too common temporal filtering we see these days. So I had a look at how people had rated the movie on blu-ray.com and was very surprised to see that some people had rated the video quality as quite poor, but what I did notice was that the video quality scores were correlated with the scores for the movie itself, i.e. people who didn't like the movie seemed very reluctant to give it a good score for video quality. This is what I mean by the important thing being clarity as to what the reviewer is trying to convey with their score.

Originally Posted by Oliver K

I think the approach of trying to look for artefacts and giving a general assessment of how nice the picture looks is what works for most

An obvious example, to me, is that of temporal filtering. If something is shot on film, then temporal artifacts cannot possibly be present in the source because each frame of film is independently exposed. Thus any temporal artifacts must have been introduced at some point afterwards, perhaps some settings in the scanning hardware, or when the DI was created, or in the encoding, but they cannot be present in the original film source.

[Doctorossi]

Originally Posted by NutsAboutPS3

An obvious example, to me, is that of temporal filtering. If something is shot on film, then temporal artifacts cannot possibly be present in the source because each frame of film is independently exposed. Thus any temporal artifacts must have been introduced at some point afterwards, perhaps some settings in the scanning hardware, or when the DI was created, or in the encoding, but they cannot be present in the original film source.

You can make this general statement as long as you can be certain that what you are seeing is truly not a product of the original photographic exposure. What kind of "temporal artifacts" are you talking about?

Another factor is FX work, wherein the image-capture limitations of a 24fps camera are often artificially simulated.

[Jeff Kleist]

but some are darker shades of black than others.. i am not changing display settings... you can clearly see on my display that the black bars on the dark knight arent as black as say the bars on kung fu panda.. its not a big deal at all, just wondering why there's inconsistencies..

On my TV, the bars often appear lighter or darker based on what's on screen, simply because of how the dynamic contrast is handled. That could be the source of your issue

They're added during mastering.

[NutsAboutPS3]

Originally Posted by Doctorossi

You can make this general statement as long as you can be certain that what you are seeing is truly not a product of the original photographic exposure. What kind of "temporal artifacts" are you talking about?

I'm talking about temporal filtering algorithms that compare pixel values in adjacent frames and smooth the data in some way, e.g. by averaging pixels that are within a threshold value of each other. This can drastically reduce grain/noise, but it can also cause "freezing" of subtle detail, because the algorithm doesn't know the difference between noise and subtle detail, both manifest as small changes in pixel values from frame to frame. People's faces are a good example of the type of subtle detail that causes problems for such algorithms - you see a face move, and intead of the subtle details moving with the face, they stay fixed on the screen. An example of a Blu-ray that looks to me to suffer terribly from this is Enter The Dragon.

There is absolutely no way that a movie shot on film can have such artifacts in the original camera negative because there is no way for one frame of film to affect another in this way. A movie shot on digital is another matter, as it is perfectly possible for a digital sensor to have some degree of persistence of signal from frame to frame. Torchwood is an example of a Blu-ray that looked to me to have significant temporal artifacts, but because it was shot on digital I wouldn't like to speculate on how much is due to the original capture vs subsequent processing.

[Doctorossi]

Thanks for clarifying the type of temporal artifacts you're referring to, Nuts.

[Kris Deering]

Originally Posted by Jeff Kleist

On my TV, the bars often appear lighter or darker based on what's on screen, simply because of how the dynamic contrast is handled. That could be the source of your issue

They're added during mastering.

I think Jeff may have nailed it with this one. Your display's contrast abilities change dramatically with the overall APL of what is on the screen. So movies that tend to be brighter or have a lot of bright imagery may appear to have darker bars. This could also be a trick of the eye as things appear darker when they have lighter objects next to them. TDK is a very dark movie so the bars don't have a lot of contrasting objects near them, but they are not elevated.

Don't some video encodes contain "blacker than black" detail, though, i.e. information in the picture below 16? I could swear that often the black bars are lighter than the darkest parts of the picture.

Below black material in film isn't even a consideration if you have a display properly calibrated so that black is at digital 16 as it should be, you would never see it anyways. Anything that is digital 16 or below would be the same value of black on your display.

On another note, Stacey Spears and Don Munsil have just put together an OUTSTANDING Blu-ray calibration disc that will be available for purchase very soon. It is also being bundled with the upcoming Oppo BDP-83 Blu-ray player. If you want to get the most out of your HD display, this is an OUTSTANDING disc with clear explanations on how to use the test patterns to get the most of your display. There is also a great montage shot by Stacey himself with a 4K Red camera!

[Penton-Man]

Originally Posted by Stacey Spears

I took a quick look at Penton's favoriate forum, since they host a number of *Pix*. It turns out the color conversion used on all of the samples I looked at (Dark Knight , King Kong , Serenity and [B]OH WALL Eeee[B] my edit) were converted using PC levels, instead of video levels, so all bars are Y 1.

Well, I think I’m legal as it specifically says at the bottom of each page…….”All models are 18 years or older - which satisfies all laws governing *science*.”

[Penton-Man]

Originally Posted by Kris Deering

On another note, Stacey Spears and Don Munsil have just put together an OUTSTANDING Blu-ray calibration disc that will be available for purchase very soon. It is also being bundled with the upcoming Oppo BDP-83 Blu-ray player. If you want to get the most out of your HD display, this is an OUTSTANDING disc with clear explanations on how to use the test patterns to get the most of your display. There is also a great montage shot by Stacey himself with a 4K Red camera!

As per prior agreement, I am contractually obligated to quote this ^ post.
Stacey, please send my check to the regular address.

[Penton-Man]

Originally Posted by NutsAboutPS3

...There is absolutely no way that a movie shot on film can have such artifacts in the original camera negative because there is no way for one frame of film to affect another in this way....

Just be aware that people can sometimes confuse camera motion blur (even for relatively slow moving shots) with the temporal based median filtering which you are describing.

Because of the low sampling rate of 24fps, a certain amount of “blur” is necessary to have a moving object on one frame blend into the next frame so that the imagery doesn’t appear jittery……and the way this is accomplished by the DP is by adjusting exposure time which essentially controls the amount of motion blur recorded on each frame.

This fact is directly applicable to that previous post I made about LOTR 2 linked a couple pages ago in my “Against All Odds” post. You see, it was felt that motion blur (i.e. shutter blur) on slow moving shots induced while the crew was fighting daylight, would hide any smearing artifacts introduced by the digital temporal based median filtering in post. The Post people arrived at this conclusion by A/Bing prints both with and without digital grain reduction techniques......on a 30 ft. screen.

Another thing to consider (in regards to Kris’s post about peoples’ “display chain”) is that I can see the grain structure of Vision 2 35mm on an HD-RGB scan displayed on large screens in a DI suite but, I wouldn’t be surprised at all if a lot of consumer LCD displays blur out this grain structure due to their poor latency.

[Bobby Henderson]

Originally Posted by NutsAboutPS3

A movie shot on digital is another matter, as it is perfectly possible for a digital sensor to have some degree of persistence of signal from frame to frame.

That kind of lag shows up more often in lower light situations. The CCD array or CMOS sensor struggles to see the image properly, but doesn't have enough time to correctly resolve it because of the demands on getting the next frame of video and the next and so on. Crank up the gain and the sensor will see images faster, but with more noise. With too much noise, you'll have undesirable stuff like bright green or red speckles showing up in the blacks of the image. Usually it's the lesser of two evils to shoot at a lower gain setting and settle with the image smearing and lagging at times.

Originally Posted by Penton-Man

I can see the grain structure of Vision 2 35mm on an HD-RGB scan displayed on large screens in a DI suite but, I wouldn’t be surprised at all if a lot of consumer LCD displays blur out this grain structure due to their poor latency.

There's not only just that. Quite a few LCD displays out there don't have full 1080p resolution. The Bayer-patten factors in a more coarse grid of fewer pixels just won't hold onto nearly as much subtle detail. Even with digital cameras it's going to be better to shoot something in a higher resolution, such as shooting 4K with a Red unit and down-sampling to 2K rather than just doing everything in 2K straight across the board.

[Doctorossi]

Originally Posted by Bobby Henderson

Even with digital cameras it's going to be better to shoot something in a higher resolution, such as shooting 4K with a Red unit and down-sampling to 2K rather than just doing everything in 2K straight across the board.

I'm going to disagree with that unless you can explain your reasoning.

[Jeff Kleist]

The best way to put it is "more is more". Basically the more material that is present, the better the master at lower resolutions will end up being because of all the little things that make it through

[Alan Gordon]

Originally Posted by Jeff Kleist

Basically the more material that is present, the better the master at lower resolutions will end up being because of all the little things that make it through

Here at work, we occasionally use other people's photographs/digital photos, and we TRY to always stress the above... as some people will expect you to do miracles with photos taken using their cell phone cameras.

~Alan

[Doctorossi]

Originally Posted by Jeff Kleist

The best way to put it is "more is more". Basically the more material that is present, the better the master at lower resolutions will end up being because of all the little things that make it through

The thing is, the little things don't make it through- they're too little. I understand the theory, I just don't buy into it.

[Jeff Kleist]

Maybe it doesn't make sense, but in my experience it is almost always the case

You'll often find VFX being rendered at 4K for a 2K end product, simply because the renderer handles them easier at that resolution, perhaps it's a similar phenomenon of how processing occurs

[Doctorossi]

Originally Posted by Jeff Kleist

Maybe it doesn't make sense, but in my experience it is almost always the case

In the case of downconversion, I have indeed witnessed this phenomenon. With origination, I have not.

In other words, if you have two original not-downconverted sources, the lesser of which is already at your target resolution, in my experience, it is not bested by a downconversion of the higher resolution source.

[Penton-Man]

Originally Posted by Stacey Spears

I took a quick look at Penton's favoriate forum, since they host a number of *Pix*. It turns out the color conversion used on all of the samples I looked at (Dark Knight, King Kong, Serenity and WALL•E) were converted using PC levels, instead of video levels, so all bars are Y 1.

lol,
Jeff Kleist, they’re banging your baby Akira now for being *grain deprived*.
http://www.avsforum.com/avs-vb/showp...&postcount=124

Just as a general simplified rule folks, if one sees “inconsistent” grain between scenes of a Blu-ray movie, there is a far greater likelihood that no digital processing has been applied anywhere along the production chain. The reason to apply grain reduction or sharpening is too make all the scenes look as consistent as possible, except for things like flashbacks, dream sequences, historical recollections, etc.

[Penton-Man]

Originally Posted by Doctorossi

The thing is, the little things don't make it through- they're too little. I understand the theory, I just don't buy into it.

I think that’s because ‘the degree’ to which you will appreciate it (the final outcome), is dependent upon a variety of factors including how the scene is lit, the glass used, any camera-based filtering, how much action is involved, etc.

Doc, on your display at home, could you identify any difference in resolution between any or all of the IMAX scenes of The Dark Knight Blu-ray as compared to the 35mm sequences?

[Jeff Kleist]

lol,
Jeff Kleist, they’re banging your baby Akira now for being *grain deprived*.
http://www.avsforum.com/avs-vb/showp...&postcount=124

*Sigh*

I can tell you for a fact that Tatei-san knows his job, and he knows it well, and he's absolutely in our camp when it comes to such things The screenshot scientists have been all over this disc and they have no clue what they're talking about. We spent a solid hour talking, and if anything, he errs on the side of too little, rather than too much.

Given the discs he's put out so far, that philosophy is represented in the final product. Check out his gorgeous "Royal Space Force: Wings of Honneamise" disc. for a great example.