View Full Version : Banding Problems in post
February 28th, 2009, 04:45 PM
Fairly, simple question to you.
I'm compositing some 3d elements with a gradient background, and adding DOF.
The problems is, before adding DOF, I set the "ramp scatter" in the background to a good amount (to prevent banding) but after I add depth of field, just because it "blurs" and "softens" all the areas at the background (focusing a foreground object) banding starts to happen again.
How can I prevent/minimise banding in these kind of situations ? For the time being, I dont want to leave this as it is now.
February 28th, 2009, 08:22 PM
add some dithering after the DOF instead of before. not sure what software you're using, so i can't get much more specific than that.
February 28th, 2009, 08:37 PM
I'm using AE, and dithering is one of the settings of the "background" (ramp) itself. so how can I add it to the whole movie ?
March 1st, 2009, 04:09 AM
Maybe try switching to 16-bit mode?
March 1st, 2009, 06:03 AM
If it's still visible after switching to 16bit it's probably just display banding.
March 1st, 2009, 09:32 AM
well, 16-bit wont get you anything unless you have a really cool monitor i dont know about. you'd only need 16-bit output if you're printing something out or using it for film or you'll need to dramatically change the exposure of the element later. our computer monitors are natively 8-bit.
anyway, dithering is simply adding or subtracting a little bit from each pixel. you could add a little noise to the element after you add depth of field. maybe have the dithering use the depth map so you dont dither things that are in focus. there might be a better way to do this in AE that i dont know about... haven't used it in a long time.
March 1st, 2009, 12:37 PM
Actually I don't think the having that "really cool monitor" would matter:
March 2nd, 2009, 10:03 AM
yes... i stand corrected. that certainly seemed to do the trick when i try it on a b/w ramp, but i don't think flipping the 16-bit switch works in every situation. i've had banding problems too, and my first instinct was also to give the image more accuracy, but sometimes, if your colors are just too close together, there's no way you can smoothly go between color values. basically, i'm not an advocate of saying "going 16-bit will solve all your problems!"
March 2nd, 2009, 11:58 AM
True. And Adding a little noise can help a LOT.
March 2nd, 2009, 12:35 PM
i'm not an advocate of saying "going 16-bit will solve all your problems!"
Sure, increasing color depth won't help you score with women or enunciate your vowels - but it will lessen colour banding issues.
March 2nd, 2009, 04:47 PM
We've had some issues with banding in the past as well. 32-bit mode and a little noise fixed it for me.
March 3rd, 2009, 04:46 AM
My DOF is on an adjustment layer that effects all underneath.
I tried adding up to 5% noise, but didnt seem to correct things that much.
More noise ruins the look of my work.
Any more ideas ?
March 5th, 2009, 08:14 AM
I have had the same issues with anything involving a gradient not rendered out of a 3D software. I found that using the layer style gradient overlay gives a bit smoother results. The banding is still there, but less noticeable. If you can use16 bit to your advantage, do it. There is nothing wrong with having more color information to work with.