GH4 Is there anything to be done about banding pixels in blue skies?

Hywel said:
I'm really not a fan of shooting ultra-flat profiles on 4:2:0 8-bit unless the camera has been designed to do it.

You've got very limited dynamic range in the encoding, no matter what's coming off the sensor.

Proper log profiles use a known, well-defined way of mapping the sensor output to an intermediate packed state knowing that an inverse transform is going to be used at the other end to recover maximal information.

Whapping up the master pedestal by +15 just adds a constant offset to the signal and further squeezes your limited range. In this case presumably taking it from 255 grey levels down to 240.

In no way is that a good idea.

If you shoot clear blue skies a lot, I'd suggest a day of testing profiles. See what the contrast, curves and profiles give you. Try higher ISO- the lowest ISO settings are sometimes artificially "squashed", losing a stop or more of dynamic range. A little bit of noise is your friend, it can offset banding as others have said.

When I had an AF100 I never really cracked a profile that matched my RED or avoided hideous banding on plain walls.

I'm glad to say it's been a completely different story with the GH4. Natural profile with Contrast -3, Sharpness -4, Shadows +1 seems to be a good match to Redcolor3/Redgamma 3. So I end up only doing gentle corrections or overall looks in the grade, rather than trying to undo an ad-hoc attempt to create a log profile first.

I've not had major problems with banding so far. I've seen hints a few times, but NOTHING like the scale of the AF100. Granted I'm shooting 4K for HD delivery, which helps. A lot.

But hooray, rejoice in the GH4's 10-bit 4:2:2 output to external recorder. If banding becomes a major issue, at least a proper solution is imminent.
Cheers, Hywel.
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Agreed.
 
I tested a de-band filter in Potplayer. It removed completely my banding issue while playing GH4 4k videos. The video is super clean and sharp. No noise, no banding and still sharp. I am surprised that I didnt try this before. It is now like having GH5 already.
 
David W. Jones said:
+1

absolutely no reason to raise it to +15
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If you're working in 8-bit, NEVER treat it like log. Get as close to the look as you want in camera unless you get yourself a 10-bit external recorder. You're just asking for trouble.

Suggestions: Add noise, reduce saturation, sky replacement.
 
Master pedestrial is not affcting sky anyway because it just raises blacks. Sky is usually not black. GH4 records quite much video processing and codec rubbish. It is not sensor noise. Fortunately the deband filter helps.
 
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