Help with Linear workflow

Forums: Help with Linear workflow
Generic forum to discuss Octane Render, post ideas and suggest improvements.
Forum rules
Please add your OS and Hardware Configuration in your signature, it makes it easier for us to help you analyze problems. Example: Win 7 64 | Geforce GTX680 | i7 3770 | 16GB

Help with Linear workflow

Postby Rikk The Gaijin » Wed Jun 05, 2013 1:44 am

Rikk The Gaijin Wed Jun 05, 2013 1:44 am
Hi, I know the topic has been discussed before, but I couldn't find a proper answer to my needs.
So, my company has decided we need to unify all our rendering outputs (Vray, Octane and our engine) to a linear workflow. In Vray it's easy to setup, but I'm having hard time to find the correct settings for Octane.

So, here are my Vray settings, and below you can see the correct image.

Image
Image

However, in Octane I cannot find a way to render my image correctly. If I set the gamma to 2.2, all the colors are washed out, and the overall image is dark. With a gamma of 1.0 the colors appear correct, but the image still very dark.

Image
Image

What am I doing wrong?! Is there some hidden setting I don't know about?

Please help! :(
Rikk The Gaijin
Licensed Customer
Licensed Customer
 
Posts: 1507
Joined: Tue Sep 20, 2011 2:28 pm
Location: Japan

Re: Help with Linear workflow

Postby abstrax » Wed Jun 05, 2013 2:05 am

abstrax Wed Jun 05, 2013 2:05 am
If you set the camera response curve to "Linear/Off" and gamma to 1.0, the output will have no gamma correction applied. If it's too dark, you have to increase exposure ;)
In theory there is no difference between theory and practice. In practice there is. - Yogi Berra
User avatar
abstrax
OctaneRender Team
OctaneRender Team
 
Posts: 5141
Joined: Tue May 18, 2010 11:01 am
Location: Auckland, New Zealand

Re: Help with Linear workflow

Postby Rikk The Gaijin » Wed Jun 05, 2013 2:11 am

Rikk The Gaijin Wed Jun 05, 2013 2:11 am
But increasing the exposure (as well as decreasing the fstop or increasing the ISO) will burn my image. :|

Image
Rikk The Gaijin
Licensed Customer
Licensed Customer
 
Posts: 1507
Joined: Tue Sep 20, 2011 2:28 pm
Location: Japan

Re: Help with Linear workflow

Postby Rikk The Gaijin » Wed Jun 05, 2013 2:34 am

Rikk The Gaijin Wed Jun 05, 2013 2:34 am
Here's an interesting thing: if I turn OFF the Linear workflow in Vray, and in Octane I save an Untonemapped exr file and open it in Photoshop, the two images appear identical... :|

Image

What does this mean?! :(
Octane does NOT support linear workflow???

Help!!!!! :|
Rikk The Gaijin
Licensed Customer
Licensed Customer
 
Posts: 1507
Joined: Tue Sep 20, 2011 2:28 pm
Location: Japan

Re: Help with Linear workflow

Postby Rikk The Gaijin » Wed Jun 05, 2013 4:45 am

Rikk The Gaijin Wed Jun 05, 2013 4:45 am
Anyone? I can't believe nobody have had this problem before, I really need to sort this out. :(
Rikk The Gaijin
Licensed Customer
Licensed Customer
 
Posts: 1507
Joined: Tue Sep 20, 2011 2:28 pm
Location: Japan

Re: Help with Linear workflow

Postby roeland » Wed Jun 05, 2013 7:56 am

roeland Wed Jun 05, 2013 7:56 am
Octane assumes you are using a linear workflow. Anything else usually gives wrong results.

You need to get two parts right:

Getting data into Octane:
  • RGB colors: If you have 8-bit colors given these are usually in sRGB. If you get a hex value (like ff0807) you can paste it into the hex input at the bottom. Otherwise you may have to convert it to [0-1] range and use the sliders just above the hex input. In preferences » Application make sure the color picker space is set to sRGB. The sliders in the node inspector are linear, only use those if you know the RGB values are in linear space.
  • Images are always encoded for a certain display gamma. You need to set the gamma slider of images to this value.
    • For most low dynamic range images (PNG, JPG, etc.) this is 2.2.
    • For most alpha images this is 1.0.
    • HDR images typically have linear encoding → 1.0.

    If you have a known gamma value less than 1.0, this is the encoder gamma, which is the inverse of the display gamma.

Getting the rendered image:
  • If you want a linear HDR image choose openEXR Untonemapped as format when saving.
  • To save a LDR image set the gamma slider in the tone mapping to 2.2. This is the standard value used on the web.
  • For viewing on your monitor you are currently limited to sRGB—Octane doesn't have display color management yet. The gamma slider in the tone mapping settings is the intended display gamma, which should match your screen, most commonly 2.2, although macs may use 1.8.

The film response curve doesn't have any effect if you save as untonemapped openEXR. For the other cases you may have to use different gamma values if you enable one, some film curves have gamma correction built-in.


Now, about your scene:
Your tone mapping settings are correct. The contrast and saturation in the wood texture are consistent between Octane (Untonemapped EXR) and VRay, but there is some difference in contrast in the reflections of the environment. My guess is that your environment map is encoded with gamma = 2.2.

--
Roeland
User avatar
roeland
OctaneRender Team
OctaneRender Team
 
Posts: 1750
Joined: Wed Mar 09, 2011 10:09 pm

Re: Help with Linear workflow

Postby Rikk The Gaijin » Wed Jun 05, 2013 9:18 am

Rikk The Gaijin Wed Jun 05, 2013 9:18 am
OMG thank you Roeland, I finally understand where the problem was.
So, initially I wasn't using any texture, just RGB colors, but RGB color DOES NOT have a gamma input, that's why the colors were washed out!
Now I have replaced the RGB with a texture containing the same RGB values, and the gamma input is set on 2.2 (by default), so finally I get the exact same image between Vray and Octane!

Image

Thank you so much, this make me understand a lot more about Linear workflow (which I'm new to it), again thank you so much! :lol:
Rikk The Gaijin
Licensed Customer
Licensed Customer
 
Posts: 1507
Joined: Tue Sep 20, 2011 2:28 pm
Location: Japan

Re: Help with Linear workflow

Postby kavorka » Wed Jun 05, 2013 2:20 pm

kavorka Wed Jun 05, 2013 2:20 pm
Hey Rikk.
I am curious what exactly your workflow is.
Also, what advantage does a linear workflow have over a non linear workflow?

thanks!
Intel quad core i5 @ 4.0 ghz | 8 gigs of Ram | Geforce GTX 470 - 1.25 gigs of Ram
kavorka
Licensed Customer
Licensed Customer
 
Posts: 1351
Joined: Sat Feb 04, 2012 6:40 am

Re: Help with Linear workflow

Postby badmilk69 » Wed Jun 05, 2013 2:43 pm

badmilk69 Wed Jun 05, 2013 2:43 pm
So basically octane is using linear workflow from the start, we just have to take care that the colors that we use from other applications are in sRGB space.
i7 2600, 16 GB RAM, 2x Evga 670 SC 4gb, dual boot win7/osxML, 2 SSDs, 3 HDs.
badmilk69
Licensed Customer
Licensed Customer
 
Posts: 122
Joined: Sat Sep 03, 2011 4:24 am

Re: Help with Linear workflow

Postby glimpse » Wed Jun 05, 2013 4:22 pm

glimpse Wed Jun 05, 2013 4:22 pm
Great topic! thanks for all the info /& good questions/ - usefull to say at least =)
I was skipping linear workflow with Octane, but now it's time to use it! thanks!!!
tomGlimps | [email protected] | 32GB | TitanBlack
Available for Freelance, Coaching & Mentoring
User avatar
glimpse
Licensed Customer
Licensed Customer
 
Posts: 3630
Joined: Wed Jan 26, 2011 2:17 pm
Next

Return to General Discussion


Who is online

Users browsing this forum: No registered users and 6 guests

Thu Jul 09, 2020 1:56 am [ UTC ]