Compositing Tag.

[milanm]

Hi

Sorry for a late reply.

You mentioned on stackexchange that you're doing compositing in 16bit mode. That's why your edges don't work. Passes are not just images, they are DATA so any gamma correction would corrupt them. By default Photoshop will 'think' they are photographs and assume they are gamma corrected. That's why it's best to do compositing in 32bit (float linear) mode. This doesn't mean compositing in linear space is not possible in 16bit mode (not to be confused with 16bit float). It's just harder to setup, involves custom colorspaces and it lacks precision so it might cause banding.

Cheers
Milan

[Bolos]

Thanks for the extra explanation, but it seems to be not enough for me.

I tried to export a new .psd from C4D in 32bits linear (I verified more closely your Lightpasses render settings) but I can't get clean masks in photoshop when I copy a channel and paste it into a layer.

I also tried this technique in your photoshop file and I get the same edges problem.

I then searched the web for copying channel losslessly but didn't return any helpful results.

It would be nice if you could explain me how you transformed your channels information into clean masks, as the solution from stack exchange is somewhat working but still makes edges sharper.

Finally, I'm confused with the gamma correction you're talking about. In your CameraImager exposure and gamma are respectively set to 1.03534 and 2.2 but in the .psd it's set to -0.73 and 1.02. So this doesn't seem to have any link.

[milanm]

Light passes need a black solid color as a foundation, maybe that is what's missing? Notice the solid color fill layer on the bottom in my psd. If you need transparency, this layer would need your alpha channel as a layer mask.

I didn't do anything special to separate the channels. Just 'select all' + 'copy' from channel window -> alt click on layer mask -> paste.

Re gamma: I was referring to the way Photoshop is treating 16bit and 8bit images by default "under the hood". Nothing to do with imager settings or my color correction in the psd, obviously, because we are rendering untonemapped/linear image and passes themselves don't need gamma correction. All I was saying is that the easiest way to force Photoshop to work linearly is to use 32bit mode.

Regards
Milan

[Bolos]

Oh that was it! I forgot to use a black foundation. Not used to work with Linear dodge maybe.

Now I've got super clean edges with my transparency, without the need to mess around with curves.

OK for the gamma, that's what I was thinking but I was getting kinda paranoid.

Thank you a lot for taking the time to help me out milanm.