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How to cure banding in DSLR footage (and GH4 4K holds the key...)


Andrew Reid
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To summarize from the other thread:

 

  • 8-bit monitors can't display 10-bit information without some form of effective dither
  • Banding and blocking are especially noticeable due to the way the eye-brain system detects edges: Mach banding and other illusions: http://www.wikiradiography.com/page/Mach+bands+and+other+Optical+Illusions
  • Noise or image texture from 4K material can be helpful in reducing banding/blocking for material after downsampling to 2K
  • The resulting 2K material won't be the same as 10-bit capture from the sensor, however it can in some cases provide additional tonality for grading latitude
  • In order for this to work, there must be sufficient noise or texture in the 4K material. Increasing ISO might help when shooting sky or other challenging material
  • Adding noise in post can help reduce banding, ideally on the 4K material before downsampling. In the case where downsampling introduces aliasing, applying Gaussian blur before adding noise to the 4K material can help
  • When the final 2K render has banding or blocking when rendered to 8-bit 420 for delivery, a small amount of noise can be added to provide effective dither to preserve tonality for 8-bit quantization
  • It's not clear if NLEs already apply dithering for 32-bit float to 8-bit integer conversion. If not, a plugin could provide more optimal error diffusion dither to the 32-bit material which will survive 8-bit quantization. While Floyd-Steinberg is easy to code, it's not very fast. Newer CPU/GPU versions are much faster: http://web.iiit.ac.in/~ishan.misraug08/research/dithering/dithering.html
  • Challenging areas such as sky can be selectively masked and dithered using tools such as Resolve (External Fill + Power Window)
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JCS-

 

There is a difference between the visual illusion of banding and actual banding in a file. If you run a sampler over a clear band you will see that the numbers don't change at all.. this is not your visual system creating an illusion, this is in the file. It's really when something moves, like the light's dropoff radius, that your eye will not see the noise and will see the bands.. i.e. like the FPN noise videos on Vimeo for the BMPC. Grain can help, but only to an extent. 

 

Increasing bit depth (not post facto) removes banding.

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Na man. You're just not used to it. Tons of pros are switching to Premiere for fast turnaround. Integration with After Effects is amazing. Check out this timeline for an SNL edit done in one day.


I haven't seen the show, but the edit doesn't look too complex. But still, having to edit the audio in a separate window, seriously? It should display the full waveform, not just half of it, on the timeline. Syncing up separate takes of a music video in Premiere would be time consuming. Firstly, because the zoom is really slow, snapping is non responsive, and you can't see the full waveform. So when lining up waveforms, you could easily be missing a peak if it's off axis. I notice FCPX is like that too. Really stupid.

Oh, and by default, if you drag one end of a clip over the top of another, it trims that second clip. Now I'm assuming there may be another option for that, but making it work like that by default? Vegas just crossfades the 2 clips together, which of course can be turned off. But even then, it won't trim that second clip. And it's little things like that, which over time will slow you down quite dramatically.

And when colour grading or adding effects in Premiere. So far I've only found one way of adding effects, and that's dragging them onto the clip. I'm assuming there must be others?

In Vegas there are 4 levels effects can be added. Firstly media fx, which will apply an effect to an imported video file as a whole. I use this for adjusting levels and white balance. Then when editing, the second option is being able to add effects to edited clips on the timeline, as well as crop them, and animate the crop/pan really easily just for that one edit. Thirdly there's track effects which will effect a track as a whole. This is where I'll apply a creative colour grade that will be applied to the whole video, as well as adding Neat Video after that. And lastly there are master effects. And this is good for applying film grain, so it covers the whole video including separate tracks with images or text that are separate from the graded video.

Oh, and another annoyance with Premiere, having to render parts on the timeline just to be able to view them in real time. Those areas that appear red. In Vegas you can just play the whole thing regardless. If there's cpu intensive effects slowing things down, you can view the edit in preview mode, and then if it's still too slow, turn the effects off. So then you can at least make sure the edit is tight.

Of course it's not just Premiere, I find Lightroom and Photoshop to be a bit slow and fiddly too. What ruins all these programs, including After Effects as well, are the scrolling panels where you're continuously opening and closing the panels. In Lightroom for example. If I'm adjusting the exposure for example, and then decide to do a bit of noise reduction, I have to scroll all the way down. And then if I accidentally hit the arrow on the side whilst scrolling (which happens a lot), the whole panel vanishes.

A much quicker more intuitive way of doing things would be to just have each section appear in the same box. Like the effects section in Vegas.

Glenn, not unexpected to be frustrated with a user interface after 1 day of use.
 
I've been using Premiere for 10 years and it still has annoyances ;)


Yes, exactly! It still has annoyances. I used Premiere back in the late 90s, and it was slow then. So I'm amazed that after 15 years, they still haven't improved the workflow. With Vegas, apart from the occasional crash (which happened a couple of times in Premiere yesterday too), I don't have any annoyances. Everything just works, and there's nothing to slow me down.
 

But you get used to it believe me... I like it...Straight forward and quick.


No, I want it off my machine asap :) If a program isn't intuitive enough get a feel for within a day, I don't believe it's worth the effort persisting with. And if Premiere is the best NLE for OSX, then I honestly can't imagine ever switching to a Mac as long as Vegas remains Windows only.

Apologies once again for the rant. And no, I don't work for Sony, even though I use one of their cameras and software. I think their phones are rubbish though.
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"If there's cpu intensive effects slowing things down, you can view the edit in preview mode, and then if it's still too slow, turn the effects off. So then you can at least make sure the edit is tight."

Just a few mouse clicks, and you can turn them off in the effects panel with Premiere too.

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So when lining up waveforms, you could easily be missing a peak if it's off axis. I notice FCPX is like that too. Really stupid.

Vegas just crossfades the 2 clips together, which of course can be turned off. But even then, it won't trim that second clip. And it's little things like that, which over time will slow you down quite dramatically.

And when colour grading or adding effects in Premiere. So far I've only found one way of adding effects, and that's dragging them onto the clip. I'm assuming there must be others?

In Vegas there are 4 levels effects can be added. 

Oh, and another annoyance with Premiere, having to render parts on the timeline just to be able to view them in real time.

 

I've done several music videos with Premiere and it works great. Way better than old FCP7. You can easily align the tracks, I have mapped zoom out/in buttons and can go very, very fast around the timeline, zooming in, snapping, zooming out. I usually don't even look at the waveforms, just scrub, match and edit.

 

Why would you want to NOT trim that second clip if you drop it ON IT? I don't get it. A Vegas thing?

 

You can add effects in Premiere either with clips, nesting or using adjustment layers. If that's not enough you can go to AE. Next CC version will bring with it the capability to add effects into the master clips.

 

I don't even remember the last time I had to render an effect in Premiere or even seen the red line. When I add too many effects and it slows down, I just drop the resolution a bit and off I go. You using GPU acceleration?

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Some 1:1 bits of  1080p clips made from a GH4 4K. test clip dowscaled to 1080p on export. The original clip comes from the other thread, and was heavily banded on purpose.

 

We can safely say working at 4K but exporting at 1080 is good!

 

Transcoding to 1080p at the start is just shooting yourself in the balls, but less sensible.

 

banding.jpg

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P.S. I switched from Avid to Premiere.

 

Find another programme that takes everything natively, non-destructively round-trips to high-end grading software (SpeedgradeCC) with no rendering, sends through to Audition,  and renders After Effects in the timeline... then I'll switch.

 

But since that doesn't exist, you can't ;)

 

Plus using it really pisses off old-schoolers who still think it's a toy, which is satisfying!

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Perhaps, but for downscaling from 4K to 1080p, why bother? The point of 5D to RGB was to simulate a lower level of chroma subsampling from 4:2:0 captured at 1080p (and mainly cos FCP7 did such a bad job of it). And it was just a simulation, a clever form of channel blurring. you can't really make 1080p 420 into 1080p 444.

 

You don't need another process in order to do this when downsampling from 4K to 1080 though.

 

I think most people are overthinking here. If you just work at 4K  in a 32-bit  environment (Premiere for example) and export at 1080p (with all maximum quality options ticked) you get great quality.

 

If you crush to 1080 with some other app, then edit and do your post, you're doing your post with four times fewer pixels.

 

That just ain't too smart...

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Also, the banding that you see in the first place with an 8bit codec on the GH4 is most likely due to the H.264 compression, for instance if you look at those three pictures I have included, one is in PNG 8bit/channel, no loss of information, the other one is JPEG 8bit/channel, lossy. 

I will completely agree with you here, banding/blocking is not 8 bit color representation issue, it's camera's onboard H264 encoder's issue.

Most lightweight cameras nowadays have it in some form, with exception of those who record to DNxHD, ProRes or another sort of proprietary high bitrate codec.

 

Simple test: connect camera's HDMI to monitor/capture card/external recorder and compare picture taken from HDMI with picture recorded by camera to SD-card, the last will be with some or another type banding/blocking artifacts, depending on footage type.

 

Another test: check Vimeo for Sony RX10 footage captured to Atomos Ninja - there is no any visible banding as compared to RX10 internal encoder's picture, the last gets muds and bandings sometimes.

 

Keeping in mind 2 things: 1st - many 10 bit and true 8 bit (not 6bit with FRC) panels on the road to consumers, & 2nd -  free of banding/blocking H264 encoding requires  computing power 4 cores/8 streams x86 CPU @ 3.5-4 GHz for 30fps (I mean x264 here - more viable option to sustaining portfolio in good form through coming years, without banding&added noise will be capturing to external HDMI encoders with little compression, instead of using camera's onboard encoder.

 

Looks like there is still no enough megaflops-per-watt requiered for free of banding H264 hardware encoding in lightweight cameras.

 

As for personal use - adding dithering noise to footage with banding may be the solution.

But, if turning to dithering in audio reproduction - there are many types of dithering noise and those different types are recognizable by listener.

Eye is more sensitive/complex/information dense 'device' than ear, so the question is what type of dithering is the best for videos taken from onboard encoders.

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You can clearly see the banding in the JPEG picture whereas I can barely see it in the PNG one, or maybe what I see is due to my shitty laptop TN display.

 

PNG gradient: http://postimg.org/image/wb5o7976z/

JPEG 75%: http://postimg.org/image/mrxc0lj1b/

JPEG 100%: http://postimg.org/image/u5ouxfsvp/

 

Well, there is still minor banding on PNG gradient at my "8 bit" laptop's not calibrated panel, but it have consistent and uniform decrease of brightness from left to right, JPEG even at 100% is inferior and have additional narrow vertical bands, 75% is even worse. Maybe my panel use some light dithering, maybe it's normal for PNG, maybe it so becuase it not calibrated and use manufacturer's software preset.

 

In any case, external recorder with 8 or 10 bit lossy 'uncompress' would give the best possible image.

Sadly, but with reasonably priced semi-pro recorders only 60i or 30p are possible.

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Good luck doing that in your NLE :)

 

If there is a way, do correct me if I'm wrong :)

You can actually do it in After Effects, Transport your cut from premiere to AE, and work in 16 or 32 bit. Color grade, and if you export on 8bit(or even 10bit DnxHD) AE Dither the images because it has to downsample from your 16bit or 32bit project.  ;)  

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Here's a great example of how far behind Adobe Premiere is. A video outlining a new feature called Master Effects in the latest version which was released just yesterday. http://helpx.adobe.com/premiere-pro/how-to/apply-effects-master-clips.html?set=premiere-pro--whats-new--2014-06

 

"Isn't that amazing?" the guy says as he sees the effect applied to multiple instances of the same clip on the timeline. I mean, come on, seriously? Sony Vegas has been able to do this for well over a decade now in the form of media fx. And it's a feature I use on almost every video I do.

 

Give Adobe another 5 or 10 years, and they might eventually add track effects too. 

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When adding some grain/noise, it is best to do it on the flat nongraded image, and then apply the grading on top of that.

That way the color corrections have a more "dithered" image to work with, and the noise is more prominent in tones that have been stretched by the correction.

 

The "slap grain on top" -method just looks like grain added on top of an image, it's too uniform.

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