V-Ray Tip: VFB Color Corrections Pass for Non-Destructive, Consistent Grading

Tip of the day: leverage the V-Ray Color Corrections render element to keep grading flexible, reversible, and consistent across shots.

What it is and why it matters

• The Color Corrections pass stores the V-Ray Frame Buffer (VFB) layer stack (exposure, white balance, curves, LUT/OCIO, etc.) as a separate output so you can iterate in compositing without re-rendering.
• It enables non-destructive look development, easy A/B testing, and reliable handoff to finishing while preserving a true linear beauty for relighting and FX work.

Setup checklist

• Work linear: render to a 32-bit, multi-channel EXR. Keep the beauty un-tonemapped; place tonemapping in the VFB layers.
• Build your look in the VFB: Exposure, White Balance, Curves, Hue/Sat, Filmic/ACES (OCIO), LUTs, Bloom/Glare, Sharpen/Blur—ordered as you intend to see them.
• Enable saving of the VFB layer stack:
  • Add/export the “VFB Color Corrections” (post) pass or enable “Include VFB layers” when saving EXR from the VFB.
  • Optionally save the VFB layer tree as a .vccgl preset for version control and reuse.
• Use compatible color management: if you view through ACES in the VFB, mirror the same OCIO config and view transform in comp.

Compositing workflow

• Import the multi-channel EXR. Keep the beauty in scene-linear. Apply the Color Corrections pass exactly once to avoid double tonemapping.
• If the pass is exported as a ready “post” result, composite it over the beauty according to your host’s guidance (Replace/Over or the dedicated merge mode if provided). If exported as layers, rebuild using native nodes (Exposure/Grade/Curves/LUT) guided by the .vccgl or embedded metadata.
• Use Cryptomatte, Object/Material ID, and Light Select to isolate regions, then duplicate subsets of the corrections for targeted tweaks (e.g., isolate skin tones from highlights).

Best practices

• Do corrections before the display transform/LUT; keep the view transform last. This protects color space integrity and prevents unexpected clipping.
• Avoid hard clamping during look-dev. Use Highlight Burn/shoulder controls rather than hard Clamp Output; clamp only at final delivery.
• Place Denoiser before Color Corrections to prevent amplifying noise and to stabilize animation.
• Bake LightMix to lights for final shots; treat Color Corrections as a look layer on top. Save approved LightMix snapshots in VFB for traceability.
• Standardize: store .vccgl with the shot and note OCIO/LUT versions in your render stamp.

Troubleshooting

• Image looks too contrasty in comp: verify you’re not applying both the VFB view transform and a second display transform downstream.
• Colors don’t match VFB: confirm identical OCIO config/view and that your viewer is set to the same display & view as the VFB.
• Banding or clipped highlights: switch to 32-bit float, remove clamps, and adjust tonemapping shoulder/roll-off.

Pro tip: keep two outputs—(1) pristine linear beauty + AOVs for relighting, (2) the Color Corrections pass for look. This protects flexibility without sacrificing speed.

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