How to match your V-Ray frame buffer result to external applications' preview when using OCIO

Overview

This article describes the steps to match the VFB result to the external application's preview of the same image when working with OCIO.

This article assumes you have an image rendered in V-Ray with the OCIO defaults. For information on exporting such images, read our working with the 3ds Max color management (new OCIO defaults) article.

Table of contents:

• Matching 8-bit images (.jpg/.png)
  • In Windows Photos
• Matching multichannel images (.exr / .vrimg)
  • Preparation
  • Matching the images
    • In Chaos Player
    • In Photoshop

Matching 8-bit images (.jpg/ .png)

Before continuing, ensure your 8-bit images are correctly outputted with OCIO.  Learn how in the Working with the 3ds Max color management (new OCIO defaults) article.

• In Windows Photos

  Windows Photos' display corrections are controlled through the Windows Color Management settings. Graphics card applications or monitors tend to set and use their own color profiles, which leads to mismatches between the VFB and Windows Photos results.

  To get matching results, make sure the default ICC profile is set to sRGB IEC61966-2.1. 

  To do that:

  1. Open the Color Management control panel (Start > type Color Management)
  2. Choose your device
  3. Tick "Use my settings for this device"
  4. Click "Add" and find the "sRGB IEC61966-2.1" profile
  5. Select the sRGB profile and click the "Set as Default Profile" button
  6. Do this for each of your devices (monitors)

Matching multichannel images (.exr / .vrimg)

Linear images saved through the Render Settings (Render Setup > Frame Buffer > Raw Image File) or from the VFB (Save all image channels to a single file) by default are saved without Display Correction (Raw), even if the VFB OCIO Display Correction layer’s “Save in Image” option is active.

The standard workflow to get matching results between various post-processing applications and the VFB is to apply an identical Display Correction (OCIO configuration and settings) in the post-processing application.

Preparation

Before transferring the image to the post-processing software, decide whether you wish to keep the VFB color corrections if such are present, since by default, multichannel formats do not retain VFB color corrections.

To keep the VFB color corrections, you need to either:

• Export the CCs in a LUT file

  1. Set the VFB's Display Correction to None
  2. Right-click on the Display Correction Layer
  3. Click the "Save all CCs as LUT" option
  4. Load the LUT file in the post-production software

• Save the CCs in the image

  This is done by enabling the "Save VFB color corrections to RGB channel" / "Save Color Corrections to Raw Files" option.
   

  1. In 3ds Max, the option is located in the "Save V-Ray image file" browse menu:

2. In Maya, the option is located in the Image format options (Render Settings > Common > Image File Output):

More info about the option:

• In 3ds Max
• In Maya

IMPORTANT: To avoid double display correction application, you must use only ONE of the methods.

Matching the images

• In Chaos Player:

  1. Open the image in Chaos Player
  2. Go to the Color Mapping rollout
  3. Right-click on the Lookup Table option
  4. Select Import

5. Load the OCIO configuration used in your host application. By default, the file is located:

   • 3ds Max:

   C:\Program Files\Autodesk\3ds Max 20XX\ColorManagement\ocio_configs\3dsmax_default_ocio\
    

   • Maya:

     C:\Program Files\Autodesk\Maya20XX\resources\OCIO-configs\Maya2022-default\

      

6. Match the settings to the ones in the VFB's OCIO layer.  When using the defaults, they should be:
   • Working Space: ACEScg
   • Input Interpretation: Linear
   • Display: sRGB - Display
   • View: ACES 1.0 SDR-video

• In Photoshop:

  1. Open the image in Photoshop (i.e., via the EXR-IO plugin)
  2. Go to Edit > Convert to OpenColorIO

  3. Set the Working space and Input color space to "ACEScg"

     

      

  4. Match the View and Display settings to the ones in the VFB's OCIO layer. 
     These settings can be found in the OpenColorIO menu (Window > OpenColorIO). If using the defaults, they should be:
      
     • Working Space: ACEScg
     • View: ACES 1.0 SDR-video

     • Display: sRGB - Display

       

        

  5. Ensure that the layers are set to the appropriate OCIO Input Color Space. 
     When using the defaults, it should be scene_linear (ACEScg).