Remove horrible banding

[rrats]

after rendering

ffmpegsource2("ricky.MPG",atrack=-1)
QTGMC(Preset="Slower", EZDenoise=18,   NoisePreset="Slower")
NNEDI3_rpow2(rfactor=2,cshift="spline36resize",fwidth=1440,fheight=1080)
QTGMC(inputtype=1, EZDenoise=5,   NoisePreset="Faster")

script coupled with strong high radius unsharp masking in VirtualDub2, i was left with this video, suffering from tiny banding as well as tiny colour noise. Not sure what's causing it.


Oh yeah and the image attached to this message-board post is from a lossless render so those are definitely not compression artefacts

[poisondeathray]

For a B&W source, you can use greyscale() to get rid of color noise

Banding is common when denoising along gradients. I suspect the banding artifacts were not there , or at least not as bad in the original source. You can either adjust your denoising approach, or add some grain/noise/dither such as f3kdb. Processing at higher bit depth can help, but most of that debanding effect is usually from the dithering step during the down conversion, not some "magic" at higher bit depth

[Skiller]

It's caused by heavy denoising at only 8 bits precision. It is ought to happen.

In my opinion one should not use QTGMC for denoising for this reason and you even used a very strong setting (EZDenoise=18) and then a second instance of QTGMC.


You can either try to deband using flash3kyuu_deband (f3kdb) or GradFun3 – or better yet, do the denoising with something that can do it in 16 Bits in the first place, such as SMDegrain. QTGMC is a deinterlacer after all.

[jagabo]

Gradfun3(thr=1.0)


[Attachment 64279 - Click to enlarge]

[rrats]

Thank you jagabo and Skiller. Will try both