Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: John.McWaters on 2025-02-27, 14:15:11

Title: CMasking masks aren't completely white
Post by: John.McWaters on 2025-02-27, 14:15:11
Why would the white portions in my CMasking element not be fully white when opened in PS? I'm saving them as pngs. The white portion is RGB 207 207 207 when opened in PS.
Title: Re: CMasking masks aren't completely white
Post by: RecentSpacesSam on 2025-02-27, 14:31:57
This is possibly due to either colour space or CMYK preview in photoshop. Did you by any chance run them through the Corona Image Editor before importing into PS?
Title: Re: CMasking masks aren't completely white
Post by: John.McWaters on 2025-02-27, 14:47:51
This is possibly due to either colour space or CMYK preview in photoshop. Did you by any chance run them through the Corona Image Editor before importing into PS?

I didn't open them in the Image Editor. They are straight from the VFB save. In PS, the image and mask are in RGB mode. The render element is also set to Monochromatic Mode.
Title: Re: CMasking masks aren't completely white
Post by: pokoy on 2025-02-27, 14:58:09
Any exposure/tone mapping involved? Sometimes I'm rendering masks 'manually' by using LightMtls to work around limitations and typically have to disable exposure/tone mapping (because I'm using the RGB output, not the alpha channel).
Title: Re: CMasking masks aren't completely white
Post by: John.McWaters on 2025-02-27, 15:09:38
I suspect it has something to do with how I'm saving it because as the mask renders in the VFB, it appears pure white as it should.

I'm saving the masks as PNG's (using the Save All button), but even if I save as a png in greyscale mode I still don't get a pure white mask.
Title: Re: CMasking masks aren't completely white
Post by: John.McWaters on 2025-02-27, 15:13:42
Any exposure/tone mapping involved? Sometimes I'm rendering masks 'manually' by using LightMtls to work around limitations and typically have to disable exposure/tone mapping (because I'm using the RGB output, not the alpha channel).

I do have an exposure set, but I don't believe that should affect a CMasking element.
Title: Re: CMasking masks aren't completely white
Post by: maru on 2025-02-27, 15:23:56
I can reproduce this. We are investigating.
Title: Re: CMasking masks aren't completely white
Post by: John.McWaters on 2025-02-27, 15:29:35
I can reproduce this. We are investigating.

Thanks Maru!
Title: Re: CMasking masks aren't completely white
Post by: maru on 2025-02-27, 16:13:14
I think it's 3ds Max color management kicking in. The workaround is to use the "data image" option when saving the file or set color conversion to no conversion.
I don't think we can detect that we are saving a mask, but I will share it with devs anyway.
Update: it's the same with V-Ray.
Title: Re: CMasking masks aren't completely white
Post by: John.McWaters on 2025-02-27, 16:40:47
I think it's 3ds Max color management kicking in. The workaround is to use the "data image" option when saving the file or set color conversion to no conversion.
I don't think we can detect that we are saving a mask, but I will share it with devs anyway.
Update: it's the same with V-Ray.

If I keep doing a 'Save All' when a rendering is completed, would there be any harm in setting the Color Conversion to 'No Conversion' even for the non-mask images? I've been leaving it set to Automatic this entire time.
Title: Re: CMasking masks aren't completely white
Post by: maru on 2025-02-28, 10:48:19
For now I can recommend saving render elements in .exr format or switching to 3ds Max Gamma 2.2 color management mode.

(Report ID=CMAX-1503)
Title: Re: CMasking masks aren't completely white
Post by: shortcirkuit on 2025-03-01, 01:48:02
Thanks for confirming that - i thought i was going crazy all these years.  Funny thing is that, when i first started with VRAY over 10 year ago, i never had this problem.  It has always been a corona issue.
FOr me personally, think its super important.

For now I can recommend saving render elements in .exr format or switching to 3ds Max Gamma 2.2 color management mode.

(Report ID=CMAX-1503)
Title: Re: CMasking masks aren't completely white
Post by: Aram Avetisyan on 2025-03-03, 11:39:14
Quote
If I keep doing a 'Save All' when a rendering is completed, would there be any harm in setting the Color Conversion to 'No Conversion' even for the non-mask images? I've been leaving it set to Automatic this entire time.

it should be fine if you are saving in high dynamic range format (e.g. EXR). View transform should be automatically ignored for these formats.