Batch rendering different between Vray 3.0 and Vray 3.1

[Studio3D]

Hello, I have an issue, when I render a Vray 3.0 scene with Vray 3.0, the color management seems OK, but when I render the same scene on a Vray 3.1 computer, the color management seems to convert to SRGB (much brighter).
Is there a solution ?
Thank you.

[ivaylo.ivanov]

8-bit image format are saved in sRGB space since they don't have enough resolution to handle linear space. I think there was a bug in 3.0 that this wasn't working in batch (which was fixed in 3.1). You can set VRAY_WRITE_COLOR_CORRECTIONS env var to 0 if you are really sure that linear space is what you want.

[t.petrov]

<<< ignore I was wrong>>>

[Studio3D]

OK thank you, I'll try it.

[Studio3D]

I found how to solve it. Color mapping mode from "Color mapping only and gamma" to "Color mapping only, no gamma" and check "Convert image to sRGB for RenderView"
Now it's OK, the RenderView and the batch render show the same images.

[Studio3D]

Ok, so now it won't work with all scenes. I don't understand that issue.
Can't we get the same image between RenderView and a batch render job ?

[Zdravko.Keremidchiev]

Can't we get the same image between RenderView and a batch render job

This shouldn't be a problem. Can you attach a screenshot with your color mapping settings?

[Studio3D]

Here it is. I just send and email 2 minutes ago (before I saw your response) to vraymaya@chaosgroup.com

[Zdravko.Keremidchiev]

The issue with the old V-Ray 3.0 version was that the batch rendering will not convert the output to sRGB (which is the default color profile for 8 bit images like jpg, png and so on) and instead leave them in a linear gamma. In contrast to the regular saved image which will be baked with sRGB gamma and will be brighter. This was fixed in V-Ray 3.1 where both approaches will generate the same result. Now when you compare the outputs from V-Ray 3.0 and 3.1 (rendered in batch mode) you will see the brightness difference.
The easiest way to get an identical output (t.e. linear gamma 8bit image) as in V-Ray 3.0 batch rendering, although incorrect, will be to use the environment variable "VRAY_WRITE_COLOR_CORRECTIONS" which Ivailo already mentioned. One can achieve the same effect by changing the Gamma in the Color mapping settings but this will result in under sampled output.