2k trailer & banding

[Colin Hubick]

Hello all, I downloaded the 2k ProRes trailer last night, and brought it into my suite this morning to have a look. I am running FCS 2 with a Kona3 which is attached via HD-SDI to a Cinemage Cine-Tal reference monitor. I noticed especially on the dissolves the skies tend to show banding in the gradients. Has anybody else noticed this? and are there any theories where the banding is coming from?

cheers
Colin

[Corrado Silveri]

H264 compression. When you fade out a gradient (like a sky) you will notice banding in the compressed result.

No matter how much quality you have in the original file.

My opinion.

[Álex Montoya]

He said he is playing the prores file.

Anyway, my take is that any 8 bit codec is liable of showing banding in things so subtle as fading a gradient.

[Antoine Fabi]

Yep...typical for H264 compression.

Also visible from any 8 bit codecs in very smooth surfaces (gradients).

[Corrado Silveri]

He said he is playing the prores file.

Anyway, my take is that any 8 bit codec is liable of showing banding in things so subtle as fading a gradient.


Sorry, not seen the Prores note.
And yes, you're right.
Even an 8 bit uncompressed file (in that condition) will show banding...

[jbeale]

I don't know anything about how ProRes works, is it really H264 inside? Anyway H264 is not just one thing, for example there is H264 Main Profile (8 bit), High 10 (9 & 10 bit) and High444PP (11-14 bit). And then there is your display and how many bits of resolution it shows.

Banding on gradients will show up whenever you don't have enough bit depth anywhere in the process, from grading to distribution to display device. As far as I know, if you double the resolution (eg. from 1k to 2k) you also need one more bit of intensity resolution (bit depth) on each pixel for the same amount of banding, other things being equal.

[laguun]

I noticed especially on the dissolves the skies tend to show banding in the gradients. Has anybody else noticed this? and are there any theories where the banding is coming from?


I have no explanation, and can´t see the trailer as it only has been published in prores. however some things to take into consideration:
1) prores - is the trailer 10bit?
2) your project setting for the aja - is it 10bit?
3) do you work in yuv or rgb? the file has been probably colorspace & model converted from rgb to 709, i suppose - so it now should stay in yuv.
4) you are sure that you didn´t get one of the grown in the wild h264 files? Was the original file ~2 GB? Several versions are floating through the internet, and the encoding is not 10bit and has a high datareduction.

[Gavin Greenwalt]

Part of it is that the image is so clean.

Normally noise conceals banding. That's why you add an unnoticeable touch of noise to CG renders. Without it, you get terrible banding.

[Petr Dvorak]

Did I miss release of 2K version or is this 2K trailer just unofficial version Posted by Jeff K. (and only 1920 x 1080)?

[Jim Arthurs]

Part of it is that the image is so clean.

Normally noise conceals banding. That's why you add an unnoticeable touch of noise to CG renders. Without it, you get terrible banding.

Back in the late '90's I started doing Spirit Datacine transfers of my 35mm time lapse cloud sequences to D1. Before that, I had been using a Rank to BetaSP for my workflow. I compared the same footage done both ways and was stunned at what I saw...

The good and the bad...

The good... My 5245 filmstock always appeared noisey using the Rank to transfer, the blue channel was terrible! The Spirit tranfer showed that the stock wasn't the problem... no more noise anywhere in the footage, it was clean as could be and refirmed my faith in film again.

The bad... because it was noiseless, the final image on 8bit D1 was banding like crazy in the subtle gradients of my sky photography. Between the noise of the Rank and the grunge of BetaSP, all this was hidden and masked.

So, I had a choice... a tack sharp noiseless banding image, or a grainy soft footage with no banding... gads.

[Nick Shaw]

I'm looking at the ProRes version on a Panasonic HD-SDI CRT monitor via the 10 bit output of a Decklink card. I can't see any visible banding. ProRes is a 10 bit codec, so with a 10 bit (or more) all the way signal path, I would not expect to see any banding.

I wonder whether what you're seeing is specific to your setup? I know it's been asked by somebody else, but is your Kona definitely set to 10 bit? Also, I don't know the Cine-tal, but if it is an LCD, even a broadcast quality one, the LCD panel itself will only be 8 bit, so could introduce banding there.

EDIT: Via my HDLink on a 37" LCD display, the banding is very noticeable – as I would expect. That's why I use the CRT as my reference monitor.

[albert rudnicki]

The only bending is visible on the fades, which means it's software only related (FCP, Codec...etc)
Cheers
Albert