Debanding

[leif]

hello,

Does anyone know of a debanding trick in smoke like spatter in photoshop?

thanks,

Leif

[peppermintpost]

hey Leif,

you can fix this problem, but a little more information would be helpfull, coz at first i need to know where the danding happens,

is there banding in your source footage, or is that banding in a comp or a color correction you applied in smoke?

Some things you should know first. When your color resolution is not appropriate to you framesize, then you will run into banding very often, so it is a good idea to have your color resolution allways higher than you need it, or just dont think about it and use the highest resolution in general, for what ever you do.

i.e. 8bit can create banding in an SD comp, to be save use 10bit. 10bit can create banding in a HD comp so use 12bit or more

and for 4k you must use 16bit float.

ok. now lets say your comp is in 16bit float and your footage is some odd 8bit-h264-dslr video with a compression ratio of 100millions to1 (what it usually is) and you shoot a nice landscape, then you can more or less bet, that there is banding in your footage. So how can you get rid of it?

The easiest way to get rid of banding is by adding color noise (grain) to the area that has this banding. It is surely not the nicest way, but it mostly works.

The way that is a little more advanced is to blur the area. Of course a simple blur will not do the trick, coz you will kill all your details, and usually heavy compressed footage is not the best source for a good key.

So what you do is, you go to CFX and you change the color space of your footage from RGB tu YUV, then you split the channels and blur just the U and V channel. Then you combine the channels again and convert the color back to RGB.

When you do it this way, your image should still look sharp, but the color channels should have a higher bit depth now and the banding should be gone.

Smoke has a very powerful regrain and degrain, so maybe before you split the channels you want to degrain your footage, and after combining the channels again you regrain your plate.

This approach should do what you want. But keep in mind, that you have to do it in an appropriate color resolution, when you do this with 8bit footage in an 8bit project it will not work.

let me know if this is helpfull.