ways to reduce banding?

[Darby Edelen]

[paul nevison] “working on a project and experiencing some pretty yuck banding issues, particularly with gradients and DOF blur.

i was in a 16bit comp and moving to 32bit has had very little if any impact on the visuals.”

One thing to note is that most (i want to say all) LCD monitors cannot display all of colors that can be represented even with 16 bits per channel.

Other than that, the classic technique for reducing banding is adding a small amount of noise to the image.

Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA

[Paul Nevison]

thanks darby,

when you say add noise…do you mean add a grain filter to an adjustment layer or similar?

thanks

Macpro Duel core 3Ghz
4.0G RAM
OS 10.4.11
QT 7.3.1
FCP 6.0.2
AE CS3 8.0.1.8
BMD Decklink HD Extreme 6.6
PAL Land

[Darby Edelen]

[paul nevison] “when you say add noise…do you mean add a grain filter to an adjustment layer or similar? “

Yes. Subtle grain or noise should work similarly well to dither the image.

While we’re talking about this, what is your final deliverable? If you’re going to be outputting a Cineon sequence, or some other sequence of HDR compatible images (OpenEXR, Photoshop, TIFF, etc.) for film then you probably wouldn’t want to add noise since the gradient you’re seeing on your monitor most likely wouldn’t appear on film.

Here’s an article that might help explain:

https://compreviews.about.com/od/multimedia/a/LCDColor.htm

So in the best case an LCD monitor will be able to display

2^8 x 2^8 x 2^8 = 256 x 256 x 256 = 16,777,216 unique colors

And in the worst case it will be able to display

2^6 x 2^6 x 2^6 = 64 x 64 x 64 = 262,144 unique colors

To get around this, LCD monitors often use a process of dithering to increase the perceived number of colors.

However, even those LCD monitors capable of displaying 16,777,216 unique colors will not be able to represent all of the color values in a 16bpc image:

2^16 x 2^16 x 2^16 = 65536 x 65536 x 65536 = 281,474,976,710,656 unique values

So you are inevitably limited by the display device as to the number of colors you can actually see. This isn’t to say that 16bpc and 32bpc aren’t valuable, because they certainly are, I won’t get into all of the reasons here, but there are definitely reasons to use them and one of them is reducing banding. At least you can sleep comfortably knowing that all of those 281 trillion (or more) colors are represented in the code values even if they’re not on screen =)

Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA

[Paul Nevison]

thanks for the detailed reply.

I’m looking at the output on both my apple 23″ cinema display as well as broadcast monitor and the banding is apparent in both.

the final deliverable will be SD dvd and online web content. the project is a DVCPRO HD 1080 comp with stills, graphics and DV, HDV and DVCPRO HD video.

i will try the grain option and see how it goes.

thanks

Macpro Duel core 3Ghz
4.0G RAM
OS 10.4.11
QT 7.3.1
FCP 6.0.2
AE CS3 8.0.1.8
BMD Decklink HD Extreme 6.6
PAL Land

[Darby Edelen]

[paul nevison] “the final deliverable will be SD dvd and online web content. the project is a DVCPRO HD 1080 comp with stills, graphics and DV, HDV and DVCPRO HD video. “

If you want to reduce banding as much as possible then I would recommend working in 16bpc (32bpc is overkill unless you’re trying to get some nice HDR lighting out of the process) and adding a small amount of noise to the render.

The Add Grain effect usually takes a fair amount of time to render (longer than you’d think), so I would recommend comparing that to the Noise HSL effect as well.

Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA

[Jan Sherlink]

And don’t forget that MPG2 for DVD is 8bit, so even if you have a 10-12bit Panel, your DVD-source will contain banding !
Adding a small amount of noise is the only way !

cya,

Jan