Hi there! 

I'm new to this forum with a question ! Upon exporting with Quicktime DnxHD, I'm seem to be getting some serious banding issues in darkish gradient areas. Is there anything I can do about this ?

I'm using RGB levels, no alpha, 1080p/25 DNxHD 185-8 bit, but other setting don't seem to do any better.

Thanks to anyone who can help !

Fred

PS: I've brightened the images to see the problem better

Fred,

Banding will occur when you remap 8 bit images more than a couple of times.

You are remapping on export, what is the footage and where else are you re-mapping it?

I cannot tell much from the shot.

Hi David,

Thanks for the reply.

They are shots from the Sony FS700, avchd mts files, composed in After Effects, exported in DnxHD, and brought into Premiere. Banding occurs on export from After Effects, but I also had the same effect when exporting from Premiere after bringing in an uncompressed file from After effects.

I have done a few tests, and things seem a lot better when I export with 64bit depth from premiere, however I can't seem to do this from After effects, which is what I'll eventually need to do. Any ideas?

Thanks again,

Fred

Ah right, so no Media Composer involved.

However, the same criteria apply, work in 709 colorspace in AE and avoid any changes in the colorspace.

Using the DNxHD185X Codec will help as an intermediary as it is a 10 bit codec.

If you want to stay 444 there is a DNxHD444 codec.

Thanks David. 

No real difference with the 10 bit codec, I had already given it a go. Switching to 709 colorspace now just messes the work up (I suppose this is normal ?)

Sorry, this is all a little hard for me to keep up with.

Hi,

David is right, for best experience you should work in 709, and don't select RGB option during QuickTime export, since it involves color remap on QuickTime side.

If you use DNx only as an intermediate AE -> Premiere, try work as usual but export from AE with 709 option and import into Premiere with the same 709 option selected.

Best regards,

Nikita.

The issue is that your source is limited to 8 bit and AVCHD compression is tough.

Remapping levels is forcing data values into bands. Upsampling to a higher sample rate like 64bit can help but eventually for display you will likely end up at 8 bit again and all those errors will become visible again.

There are some tricks for helping with banding like adding noise to dither values.

If the issue is only in the blacks you could try a late step of crushing the blacks to re-establish a black level.