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8bit Banding

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Jon Merrifield
8bit Banding
on Feb 28, 2012 at 2:01:19 am

This isn't really and AE only thing but since Dave LaRonde is here and AE is my main tool. I thought I would post it here.

I was a Quantel Artist for for 17 years. Back in the that day, we never really had to worry about banding because Quantel had a process, still in their systems, called "Dynamic Rounding". (patented) This solved most of the issues inherent in the banding generated when you had a gradation from light to dark or large soft edges, what have you.

Currently our external monitors are FSI 2450s (8bit because TV is 8bit, just saying). Often there are banding issues, I try and solve these with color corrections, add some noise etc.

Are there any software solutions that aid in correcting banding of this type besides my techniques listed.

thank you,
-Jon

From Quantel's web site:

Dynamic Rounding is a clever technique devised by Quantel for truncating the word length of pixels – a process you can't avoid when you are processing images. Rather than simply losing the lower bits, Dynamic Rounding uses their information to control, via a randomiser, the dither of the LSB of the truncated result. This effectively removes any artefacts that would otherwise be visible. Dynamic rounding is non-cumulative on any number of passes and produces statistically correct results. Dynamic rounding eliminates any truncation artefacts leaving you great looking pictures whatever the bit depth, whatever the processing. Dynamic Rounding is patented technology that you simply can't get anywhere else.

Jon Merrifield
VFX Artist / Supervisor
PELi Studios, Austin TX


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John Cuevas
Re: 8bit Banding
on Feb 28, 2012 at 2:14:10 pm

Here's another approach to get at banding from Roland Kahlenberg:

Blurring one or more of the color channels does a better job for reducing or eliminating banding problems. Adding noise more to a comp which may be destined for Web delivery will only result in a poorer quality web version as compressors usually have a harder time compressing noise.

Use Effect>Channel Blur and increase one of the values to solve your problem. You can tell which channel needs more attention by looking at the individual color channels in the Comp Panel prior to applying Channel Blur.

Johnny Cuevas, Editor
Thinkck.com

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.


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Jon Merrifield
Re: 8bit Banding
on Feb 28, 2012 at 2:57:02 pm

Channel Blur, that's a good idea John, thank you.

this is a broadcast issue for me and the images I am working on are so high end, very detailed in quality and fine tuned to exacting beauty, fashion work for example, that the noise of web versions is a non-issue and of course I basically add grain blur, add grain again, all in subtle ways to reduce the banding.

Thanks again for your excellent suggestion.

Jon Merrifield
VFX Artist / Supervisor
PELi Studios, Austin TX


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Kevin Camp
Re: 8bit Banding
on Feb 28, 2012 at 6:11:39 pm

i was also a quantel artist for many years and remember the soft dithering that it produced...

some effects do have a similar technique... the ramp effect for instance has a 'ramp scatter' property to that can be adjusted when it produces banding.

adding noise or grain (as you mentioned) is a way to reduce banding more universally by effectively creating dither.

greyscalegorilla shows another method that adds tonal variation to reduce banding:

http://greyscalegorilla.com/blog/2009/10/how-to-remove-banding-artifacts-in...

genarts also has an effect called 'deband'.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Jon Merrifield
Re: 8bit Banding
on Feb 28, 2012 at 9:21:57 pm

Awesome, Thanks Kevin

Jon Merrifield
VFX Artist / Supervisor
PELi Studios, Austin TX


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Erik Lindahl
Re: 8bit Banding
on Feb 29, 2012 at 3:01:34 pm

Might be a silly remark but I guess you've tried rendering everything in 16-bit? What is the output format? Even if rendering to an 8-bit file, working in 16-bit in AE will greatly decrease banding issues.

Otherwise noise, grain, channel-blur are good techniques. I tend to add 2-8% noise with a 0.2-0.4 fast blur on them or grain depending on the raw footage. Also, avoiding using 8-bit files are good if possible. Some filters in AE also still are only 8-bit and cause issues with banding.


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Jon Merrifield
Re: 8bit Banding
on Feb 29, 2012 at 4:39:53 pm

Hi Erik, yes, the lowest I work in is 16bit and usually do all my VFX in 32 bit and render DPX LOG sequences, of course, I still have an 8bit reference monitor (since television broadcast and most of my work is for broadcast and is 8bit and I am stickler for accurate reference).

If you do a grad in 32 bit, you will get banding on any 8bit monitor. just saying...
I rarely use the 8bit filters and when I do, I use the HDR compander utility.

cheers

Jon Merrifield
VFX Artist / Supervisor
PELi Studios, Austin TX


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Erik Lindahl
Re: 8bit Banding
on Feb 29, 2012 at 4:47:27 pm

Very true! Sometimes 8-bit is enough hence my somewhat elemtary question. But working with fine gradients 16-bit (or higher) is a must and in general very much preferred.

As for monitoring in 8-bit that gave me a thinker… Would one get an accurate 8-bit "monitoring" on a 10-bit monitor using an 8-bit file or will the monitor always give a "better than you can expect" view of things?


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Jon Merrifield
Re: 8bit Banding
on Feb 29, 2012 at 5:31:03 pm

That's Interesting Erik, I would assume that any artifacts that are the result of the 8bit rendering will remain but your 10bit monitor will not produce any new ones....

Jon Merrifield
VFX Artist / Supervisor
PELi Studios, Austin TX


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Erik Lindahl
Re: 8bit Banding
on Feb 29, 2012 at 5:43:31 pm

I actually haven't though of the issue you bring up here. All our masters are 10-bit uncompressed or 10/12-bit ProRes footage and our reference monitor is 10-bit. For mastering purposes, it might be worth looking into making 8-bit files.

That said, most of our TV-deliveries are 8-bit 4:2:0 MPEG2 files. When viewed on an 8-bit TFT computer monitor we should see any banding artifacts clearly.


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Jon Merrifield
Re: 8bit Banding
on Feb 29, 2012 at 5:51:00 pm

I typically don't see any banding on my computer monitors, mac book, cheap HP, etc. But I do on my FSI2450. The acid test is to view it on your television or if you see some of your work broadcast.

I was going to get a 10bit FSI at first, but my colorist friend, who does very high end color work on SpeedGrade and also uses 8bit FSI's, suggested 8bit to see what it is when truly in the broadcast world.

Jon Merrifield
VFX Artist / Supervisor
PELi Studios, Austin TX


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Erik Lindahl
Re: 8bit Banding
on Feb 29, 2012 at 6:19:23 pm

Very interesting! What 8-bit monitors would you recommend in Europe / Sweden primarily? Could be worth looking into.


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Jon Merrifield
Re: 8bit Banding
on Feb 29, 2012 at 6:28:39 pm

sorry, under deadline to delivery project. You can easily find many things about good monitors right here on creative cow. I love my FSI, Ditched my high end Sony Tubes BVM205 HD about 6 months ago...

Jon Merrifield
VFX Artist / Supervisor
PELi Studios, Austin TX


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