VFB save to JPG/PNG incorrect gamma curve.

[DestinHalfmann]

Hello,

This has been mentioned before in this thread:
https://forums.chaos.com/forum/v-ray...apping-checked

But I'm having the same issue, but I lack understanding on whether this is render related, issue with ICC etc.

Using V-Ray 6.1

So basicly, when saving directly from VFB to PNG/JPG the result looks like if the VFB had gamma 2.2 enabled instead of sRGB.
Rendering to EXR/Vrimg the result is identical to VFB/sRGB.

If I save image channel to clipboard and paste to eg. photoshop and save to JPG/PNG the result is identical to VFB/sRGB

So Is this a V-Ray thing? Limitation of the file format? VFB?
maybe I've misunderstood how to work with JPG/PNG and the VFB.
I don't recall this having this issue in previous V-Ray versions.

1 image: VFB Display Correction sRGB, Save to JPG from VFB
2 image: VFB Display Correction sRGB, Paste to PS from from VFB, save to JPG
3 image: VFB Display Correction 2.2, Paste to PS from from VFB, save to JPG

[vladimir_krastev]

HI, thanks for posting. When you save in other than exr/vrimg, 3ds Max applies Gamma 2.2 regardless of the VFB display correction mode.

[DestinHalfmann]

HI, thanks for posting. When you save in other than exr/vrimg, 3ds Max applies Gamma 2.2 regardless of the VFB display correction mode.

Hi Vladimir,
Thank you for the quick response.

According to the help docs see below:

"If an 8-bit file is saved through the VFB or the Render Output / Save image settings, the color space (for example sRGB) is embedded and the image appears as in the frame buffer when loaded in an external image viewer. If a 32-bit (exr, hdr, tif) image is saved, it remains linear and relies on the external image viewer to handle the display color space."

This seems to contradict that max is embedding gamma 2.2 instead of sRGB to non exr/vrimg files.

Has something changed, or maybe a misunderstanding on my part.

[vladimir_krastev]

Hi, thanks for pointing this out. The Gamma 2.2 gets embedded if you save a image file in a format different to exr/vrimg. This is done like this because of a limitation in 3ds Max.
You've found a slight mistake in our documentation. We have already reported this to the docs team and they will fix it very soon.

[seandunderdale]

This is done like this because of a limitation in 3ds Max.

Is this an issue in Maya also?

[vladimir_krastev]

Is this an issue in Maya also?

Hi, in Maya it is not.

[mady_mad]

is there any solution for this or any workflow to follow ?
please reply & thanks

[piotrus3333]

This is not a limitation of 3dsMax. Every time you save an image in 3dsMax you have an option do save it with gamma transform or without. And if you are saving with some gamma transform you should use the same gamma as view transform in VFB.

[mady_mad]

please if possible show with screenshot

[piotrus3333]

please if possible show with screenshot

Automatic means 2.2 if format you are saving to is jpg or png.

[mady_mad]

i am saving in jpg but copy paste from vfb to photoshop & comparing with saved jpg it is little different it think it is a bug

[piotrus3333]

compare them both in vfb.

[Crayox13]

Has this been solved? I'm just testing things, and in VFB my colours are more saturated than after I open a saved jpg. Not enough to warrant a gamma difference. Like VFB just shows them differently.

I tried screen capturing VFB, and that made it look as if I saved a jpg. So weird! I do have a hardware calibrated screen, could that be the reason?

[vladimir_krastev]

I do have a hardware calibrated screen, could that be the reason?

This is unlikely but not impossible If you have different settings for each viewer.
Check again how you save your image and how you open it. Are you using ACEScg? Please share a bit more details about your workflow.

[Crayox13]

I don't think I'm using ACEScg. I do have my gamma setup, if that's what it is also. Just realized that I see the same colours after I turn on proof colours in PS and set Monitor RGB. But if I view the jpg with default Windows jpg photo viewer they are slightly different. So I guess that's how my clients see them also, or?