EXR export gamma problem

[ikercito]

Hi guys

I'm having a weird problem when exporting my renders as EXR 32 bit. I'm running 3dsmax 2013 and the current Corona A7.1. Max gamma is set correctly, following the tips of Rawavalanche here on the forum (basically gamma 2,2 everywhere)

The thing is.... When I export, if I use default gamma (output 2,2) the render is completely washed out in photoshop, which is normal behaviour isnt it? But if I override it (gamma 1,0), the render comes out really dark in photoshop. The gamma override that saves the image as similar as the VFB, I found out to be... 1,8! Why is this?

Thanks for your help.

[johan belmans]

Make sure when you save your EXR, it is saved with gamma 1.0

[ikercito]

Thx belly. That's what I always do... But it comes out really dark in Photoshop. The gamma value that best matches the VFB is saving with 1.8... Any explanation?

Should I still save as gamma 1.0, and compensate exposure afterwards? Doesn't seem logical...

[johan belmans]

Hi

Ok It seems I over read some parts of your post :-s
You can always check your EXR with the ram player in MAX, if it is the same as your initial image in the VBF, the file saved well.

Could it be that when you open the exr in photoshop and attaching a colour profile  that the darkening takes places?

My workflow:
-I do not touch the color mapping  values. I only play with exposure. Save out as EXR (half Float).
-Open in Photoshop with sRGB color profile.
-Do all the color mapping with Arion FX for Photoshop

[pokoy]

Have a look in the PS color preferences. You should always set PS to ask you what to do when it opens a file without a profile or with a different profile than what PS expects. If you, by any chance, have set it to convert to your working profile, then it can produce some really weird results with images in 32 bit.

Any image will get the 'profile treatment' in PS so a 32bpc image always be a bit different than the same image saved with 8 or 16 bpc in max.
That said, this difference should be very small and not produce a way too dark image.

[ikercito]

Hi guys, thanks for your help!

Pokoy and Belly, that's exactly the procedure I always use. I'm starting to think it might actually be a bug in Max 2013. Depending what i click first or last (name, filetype, gamma correction) I've been getting different results... So I guess it has nothing to do with Corona, it's probably Max. Never noticed before, but I've only been using EXR for last couple of months.

Belly, I just bought ArionFX yesterday. It's a blast, I'm loving it's tonemapping. :D

[pokoy]

I agree, ArionFX is really cool. There are some bugs and it needs more features to be really flexible but it's quite nice already.

I have no clue where the problems with the EXR come from. As I stated, make sure PS doesn't convert profiles when opening a file with profile mismatch. Other than that - no clue.