color shift after prerender

[derlco]

for the complexity of the project (multiple mask tracking, content-aware fill and many layers as reference frames) I started to piled prerenders of the video I was working in. After a couple of them I notice I shift in color for every prerenders I was putting back into the composition. Because I was making some levels adjustments in the fills, although they were applied within the mask area (some of them really small compare to the whole video), I though there was the reason of the shift.

I had to drop the idea of the prerender and finish my work. Nevertheless I recreate the issue with an image and it behaved the same. Any thought on this behavior?

The test. A single image, prerender six times, piled it in the same composition. Every time it shift even more in contrast/saturation. I put the comparison from the first image with its scopes and the sixth image with scope. I checked the color depth and the render settings but can't find anything out of place (I put screenshots of the Output module, Color depth settings, the file info in the project and from the render settings).

[Mylenium]

You answered your own question with your screenshots - you are not using any actual color management and are inflating the bit depth with your pre-render to ProRes 444, then import back to an 8 bit project. Even if everything was perfectly calibrated, eventually you'd see slight shifts simply due to quantization issues. After a few rounds, the cumulative effects would become noticeable. So there you go. You need to establish an actually color managed workflow and use a consistent bit depth. This is not even specific to AE, you'd see those problems in e.g. Photoshhop as well.

Mylenium

[derlco]

Thanks for your reply. You are right. And it seems to be something that is not consider before jumping to work knowing the differences from camera output, post work and client side.

As a comment I could say that I thought that when choosing the prerender option the default settings takes care everything to be consistent with the comp to make it as smooth as possible, different to a common render/export workflow with all its flavors.

Two things keeps me confuse. When picking options on the render settings the color depth is set to current (which is 8 bit just as the project). Doesn't this helps keep consistency thru the render?

In the other side, the options of the Color management tab in the Output module only let me change the output profile (working space) which now, that I'm testing again, is set to sRGB just as the project but, again, I get the color shift.

I'm still missing something?

[Mylenium]

Bit depth doesn't equal color management and again, your problem is not that the default settings would be inconsistent within their limited logic, but that you work against them by arbitrarily expanding and compressing color ranges. You need to assign an actual color profiel to the project, the footage interpretation and instate a correct comp preview as well to make your output predictable.

Mylenium