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RSMB Causing Color Banding
Hello:
I’ve rendered a long 3D animation of a tool over a dark grey cyc with pools of light on that backdrop. It’s a 16-bit PNG sequence animated and rendered in Cinema 4D, tagged as sRGB. When I apply RSMB to that sequence I get noticeable color banding in those gradated areas.
I’m working in 16-bit color in AE CS5. The sequence is tagged as sRGB in the Interpret Footage dialog. Color management is set to HDTV rec. 709, compensating for scene-referred profiles.
Changing the AE project color space to sRGB or deactivating Compensate for scene-referred profiles doesn’t mitigate the banding.
I can definitely see the banding come and go as I turn the RSMB effect on and off. What’s really weird is that I created a split screen showing the same frame of the 3D PNG sequence with RSMB applied to one and not to the other. The banding is clearly visible in my AE comp window, but the PNG doesn’t exhibit the banding. I then rendered a ProRes 4444 Quicktime, and that does show the banding, even though it’s Trillions of Colors.
I’ve posted a very short sample here, ProRes 4444:
https://www.marshall-arts.net/Banding/RSMB_Banding.mov
Any guess as to what the issue is? I’m on a 2008 MacPro with an ATI Radeon 2600 card, OS 10.6.8.
Thank you.
Shawn Marshall
Marshall Arts Motion Graphics -
5 Replies
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Yes, very suspicious.
Have you tried to convert to 8bit color mode and apply RSMB then?
Or, maybe, up to 32 bpc.Try to apply the default cc motion blur, and see what happens.
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On review of your sample:
You DO have banding in the original, and it is just that RSMB is “enhancing” it. Note that even applying a simple gaussian blur will bring out the banding. THE REASON: The original has dithering that hides the banding, but adding a blur tends to smooth out the dithering, and this makes the banding easier to see.
The banding in the original is very hard to see but is there – though to be certain, I’d rather look at some of your original PNG files.
TO FIX try one of these solutions:
A) Add noise AFTER the RSMB plugin. a tiny amount of noise will result in dithering and reduce the appearance of banding. Add the NOISE plugin, and try setting it to a very small amount like 0.2%, color OFF and clip OFF.
OR
B) Re-render in C4D to EXR files and use LINEAR light mode in C4D, then work in AE in 32 bit LINEAR mode. When you bring in the EXR files, they will also be in linear mode.
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[Andrew Somers] “B) Re-render in C4D to EXR files and use LINEAR light mode in C4D, then work in AE in 32 bit LINEAR mode. When you bring in the EXR files, they will also be in linear mode.”
I believe there will still be banding in this scenario, although AE should dither an 8bpc render in any case.
I think the real question is whether there is a need to preserve the color values (e.g. handing the footage off to someone else who will benefit from a higher bit depth) or not (e.g. AE is the last step before delivery).
In the former case rendering to a format that supports trillions of colors is not a bad idea. Of course when that video is viewed in AE it will still have banding because of the limits of the display it’s being viewed on, but the color values are still there for coloring or compositing.
I went over a method for checking the banding for the larger range of color values in the Cinema 4D thread on this: https://forums.creativecow.net/readpost/19/878743
If the latter is the case, then I say just render to 8bpc. No need to preserve the high range of colors for later compositing.
Darby Edelen
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As mention above, any blur will do that on this sort of pix, you have to add a tiny bit of noise to dither
see my response to this cross-posthttps://forums.creativecow.net/readpost/69/856482
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[Pierre Jasmin] ” As mention above, any blur will do that on this sort of pix, you have to add a tiny bit of noise to dither
see my response to this cross-post”I believe the question has been answered in 3 different forums now 🙂
Darby Edelen
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