V-Ray Tip: VRayBitmap Color‑Space Best Practices for Consistent ACES/sRGB Look‑Dev

Correct color space on input textures is the quiet foundation of reliable look‑dev. Here’s how to get consistent, physically‑correct results by using VRayBitmap with proper color space settings across your pipeline. If you need licenses or upgrades, check @NOVEDGE.

• Always prefer VRayBitmap over the host’s default bitmap node. It offers unified color management, better mipmapping, tiled EXR support, and predictable behavior on both CPU and GPU.

Core rules for assigning texture color spaces:

• Color/albedo/diffuse/emissive color: treat as sRGB (display‑referred color). VRayBitmap will convert to your rendering space (linear sRGB or ACEScg) automatically when tagged correctly.
• Data/linear maps (no gamma): roughness, glossiness, metalness, normal, height/displacement, opacity/alpha, curvature, AO, masks. Set these to Raw/Linear (no color transform).
• HDRIs and 32‑bit EXR: usually stored as linear scene‑referred data. Mark them Linear/Raw so you don’t apply an unwanted sRGB transform.
• 8‑bit LDR environment textures (JPG/PNG): sRGB.

Working with ACES/OCIO:

• If rendering in ACEScg, configure color management/OCIO in V-Ray/VFB. Tag texture inputs in VRayBitmap to their true source space (e.g., sRGB for albedo). V-Ray will convert to ACEScg under the hood.
• Display transforms in the VFB (sRGB/OCIO Output) affect only viewing; they should not be baked into textures. Avoid LUTs on data maps.
• When using EXR assets authored in ACEScg, mark their input as ACEScg; do not re‑interpret them as sRGB.

Practical setup checklist:

• Load every texture with VRayBitmap.
• Set input color space per map type:
  • Basecolor/Albedo/Emissive color: sRGB.
  • Roughness/Gloss/Metalness/Opacity/AO/Masks: Linear/Raw.
  • Normal (tangent/object): Linear/Raw. Feed into VRayNormalMap (or equivalent) and keep gamma at 1.0.
  • Height/Displacement: Linear/Raw; match bit depth to range (prefer 16/32‑bit EXR/TIF).
  • HDRI/EXR environments: Linear/Raw.
• Do not combine sRGB and Linear maps inside the same packed texture channel without per‑channel management.
• Disable legacy gamma overrides if your scene uses modern color management to prevent double correction.

Troubleshooting by symptom:

• Washed‑out or milky textures: color map interpreted Linear instead of sRGB (or double‑converted).
• Crunchy/over‑contrasty roughness: roughness interpreted as sRGB instead of Linear/Raw.
• Shimmering or tinted normals: a normal map received a color transform; set to Raw and use a proper normal node.
• Over‑bright HDRI lighting: HDR/EXR tagged as sRGB; switch to Linear/Raw.

Automation tips:

• Adopt filename conventions so batch rules can auto‑assign spaces (e.g., _albedo/_basecolor = sRGB; _n/_normal, _r/_rough, _m/_metal, _disp/_height, _op/_opacity = Linear/Raw).
• Prefer 16/32‑bit for data maps to keep ranges intact; avoid baking display transforms into textures.

Locking color space early eliminates re‑grading later, reduces noise, and keeps materials portable between sRGB and ACES pipelines. For V‑Ray licenses, upgrades, or expert advice, visit @NOVEDGE.