It’s very effect dependent. I’ve used 8-bit effects in 32-bit comps with any visual change but also ones that completely broke. There is no rule of thumb here as sometimes it appears the developer just has not tested or offer support.

 

But in general I’ve found 8-bit effect more often go wonky in linear light comps.

 

From: After Effects Mail List <AE-List@media-motion.tv>
Sent: Monday, December 17, 2018 10:58 AM
To: After Effects Mail List <AE-List@media-motion.tv>
Subject: Re: [AE] 8 bpc effect on a 16 bpc project

 

It's there, but I wonder if it's not that noticeable because AE seems to be adding some dithering/noise to reduce the obviousness of the 8-bit effect.

 

Here's an example where I see it.  Try this in a 16-bit AE project:

 

- In a 1920x1080 comp, make a new solid

- Apply Gradient Ramp, default black to white settings

- Apply Levels, set gamma to 0.25

- Apply another Levels, set gamma to 4.00

 

Those two gamma adjustments are the inverse of each other and should balance each other out so the original ramp should (theoretically) be unchanged.  At this point, however, you should still see SOME banding in the dark part of the ramp if you zoom in.  Not nearly as bad as if the project was set to 8-bit, but there.  Try switching to 8-bit and you'll see the banding turn very obvious.  

 

Now, with the project set back to 16-bit, apply an 8-bit effect like Card Wipe or Motion Tile and put it in between the two Levels effects on your solid.  The banding suddenly changes and gets ugly.

 

The second levels effect is now applying a gamma of 4 to an 8-bit image instead of the 16-bit one from before.  If you mouse over and look at the color values in the info window (especially in the dark areas of the ramp), you'll see that there are only a few values as you move the mouse around.

 

The interesting part is that the image gets suddenly noisy/grainy.  AE must be adding some dithering or noise the reduce the visual impact of an 8 bit effect in a 16-bit project.  The same way you might add a little noise to a subtle gradient with banding.  It doesn't do this when the project is set to 8-bit.

 

Is the noise/dithering possibly why you're not seeing anything when you put the motion tile effect in?

Hopefully that's helpful,

 - Nathan

 

On Mon, Dec 17, 2018 at 5:35 AM Nick Fox-Gieg <AE-List@media-motion.tv> wrote:

My understanding is the 8bpc penalty only applies to the output of that single effect; the effects before and after can resume processing at their higher bit depth. (Can anybody confirm?)

 

Nick

 

On Mon, Dec 17, 2018, 5:21 AM Roei Tzoref <AE-List@media-motion.tv wrote:

Hey Y'all

in Ae, I am using a 8bit effect on a 16bit effect project (for example - motion tile),  I am not getting a visual penalty for doing that and everything looks exactly the same. I have tested it though makig a gradient and pushing the levels to it to get a banding which 16 bpc project removes. nomatter where I put the motion tile effect, I am not getting a 8bpc result. so how is using an 8bit effect on a 16bit effect actually make a difference? can anyone show an example?

Thanks