Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: vogor on 2017-02-11, 09:45:53

Title: Dark exr render
Post by: vogor on 2017-02-11, 09:45:53

Hi, i have asion. question - why render in 32bit .exr darker than the one that appears in a frame buffer?

Title: Re: Dark exr render
Post by: 3DsChobo on 2017-02-13, 13:32:08

Actually i can not tell you why, but that this is quite normal and also not a problem since all the information is still in the image.
Some programs for example XNView and Fusion will show the image darker. My educated guess is that there is no gamma value saved with it or just interpreted as 1.0 but you can manually lift the gamma to 2.2 and it should look the same as in the framebuffer. Other Programs like After Effects and Premiere will automatically guess the correct gamma and it shows up the way you expect it to be.

Title: Re: Dark exr render
Post by: maru on 2017-02-14, 11:37:27

Hi, can anyone with this problem provide some example files, screenshot of their EXR save settings, and detailed instructions of how they are proceeding? Here or via support@corona-renderer.com. We've had one similar report in our support recently, but we were unable to reproduce it. It also seems that some applications treat EXRs different than other ones. From my experience Fusion (which is free) usually treats them correctly (or in other words - as one would expect).

Title: Re: Dark exr render
Post by: 3DsChobo on 2017-02-14, 18:07:48

So you are saying you load in an EXR file in fusion and when you view the loader node you instantly see the right gamma displayed?

Even in the video on how to use the world position pass in the corona channel a gamut node was used to set the output to srgb.
Alternatively you can use a color corrector node and increase the gamma.

Anyhow I dont think this is a corona problem.

I just made a short test on this and rendered some boxes with corona and scanline and saved the output as exr.
The gamma issue in fusion remains and is somehow not present in After effects.

Title: Re: Dark exr render
Post by: maru on 2017-02-16, 13:53:54

Sorry, I must have messed something up.
I can confirm what 3DsChobo wrote.
I also have PS configured to always ask me what to do when loading a file with no color profile embedded. I can then select sRGB and it looks exactly the same as in vfb. (Edit > Color Settings > select all "ask when opening" checkboxes)

It would be good to have some official FAQ on this, probably added here: https://forum.corona-renderer.com/index.php/topic,13833.msg89050.html#msg89050