Banding Problems in post

[undream]

Hi.

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.

[jeremybrown]

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.

[undream]

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 ?

[Coplin]

Maybe try switching to 16-bit mode?

[Loga]

If it's still visible after switching to 16bit it's probably just display banding.

[jeremybrown]

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.

[Coplin]

Actually I don't think the having that "really cool monitor" would matter:

"Banding is typically the result of limitations of 8-bit color, and 16-bit color mode was added to After Effects 5.0 specifically to address that problem. You can switch to 16 bpc by Alt-clicking (Mac: Option-clicking) the bit-depth identifier along the bottom of the Project panel (see Figure 14 (javascript:popUp('/content/images/art_christiansen5_colorfix/elementLinks/fig14.jpg'))) or by changing it in File > Project Settings.:

source: http://www.peachpit.com/articles/article.aspx?p=1276351

[jeremybrown]

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!"

[Coplin]

True. And Adding a little noise can help a LOT.

[Matt P]

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.

-Matt

[theta]

We've had some issues with banding in the past as well. 32-bit mode and a little noise fixed it for me.

[undream]

Ok.

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 ?

[Seriphu]

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.