oiiotool Skill

Command-line image processing with OpenImageIO's oiiotool. Industry-standard tool used across VFX, CGI, game dev, and photography for format conversion, color management, compositing, and batch image operations.

Setup

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This installs both the oiiotool CLI and the OpenImageIO Python module.

Verify:
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OCIO / ACES Configuration

oiiotool uses OpenColorIO for color management. Since OCIO 2.2+, built-in ACES configs are available — no file download needed:

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Available built-in configs:

• - ocio://cg-config-latest — CG-focused config (no camera color spaces, lean). Recommended.
• INLINECODE3 — Full studio config (includes camera color spaces).
• INLINECODE4 — Pin to a specific version.

For production studios with a custom config:
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Check what's available:
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Core Concept: Stack-Based Processing

oiiotool processes commands left to right on a stack:

• - Naming a file pushes it onto the stack
• Commands pop inputs, process, and push results
• INLINECODE5 writes the top of stack to a file

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File Info & Metadata

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Format Conversion

Supported formats: EXR, TIFF, PNG, JPEG, DPX, HDR (Radiance), BMP, TGA, GIF, WebP, JPEG2000, PSD, ICO, FITS, and more.

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Production Tip: Selective Channel Reading

For large multichannel EXRs (beauty + depth + normals + crypto), read only what you need to save memory and time:

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This is critical in production where EXRs can have 50+ channels and be hundreds of MB each.

Color Management (OCIO)

Color Space Conversion

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ACES Display Transforms (Tone Mapping)

The proper way to view HDR content. Applies the ACES Reference Rendering Transform (RRT) + Output Device Transform (ODT) for correct highlight rolloff:

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When to use display transforms vs colorconvert: Use --ociodisplay when converting HDR scene-referred data to a display for viewing (applies tone mapping). Use --colorconvert when converting between working color spaces (no tone mapping, preserves linearity).

OCIO Looks & File Transforms

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Manual Matrix Color Conversion

When you don't have OCIO or need a specific 3x3 matrix:

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Exposure Adjustment

EXR stores linear light values. Exposure in stops is powers of 2:

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Exposure + ACES display transform (most useful combo for HDR review):

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Exposure Reference Table

Ready-Made Scripts

Exposure Sweep

Generate a composite contact sheet of multiple exposures from an HDR EXR:

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EXR Sequence to Video

Convert an EXR image sequence to MP4:

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Requires ffmpeg in PATH.

Image Operations

Resize & Fit

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Available filters: box, triangle, gaussian, catmull-rom, blackman-harris, sinc, lanczos3, mitchell, bspline, cubic. Default lanczos3 is good for most uses.

Crop & Cut

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Rotate & Flip

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Blur & Sharpen

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Channel Operations

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Compositing

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Color & Value Adjustments

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Drawing & Annotation

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Sequence Processing

oiiotool supports frame number wildcards for batch operations:

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Sequence to Video (with ffmpeg)

Two-step process:

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Or use the helper script: INLINECODE20

Texture Baking

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Image Comparison

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Patterns & Test Images

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Metadata Manipulation

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Deep Image Operations

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Cryptomatte Visualization

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For advanced cryptomatte extraction with custom palettes and batch processing, see the exr skill.

Performance Tips

• - --threads N — control parallelism (default: all cores)
• INLINECODE22 — parallelize sequence processing
• INLINECODE23 — read only needed channels from multichannel EXRs
• INLINECODE24 — increase image cache for large files
• INLINECODE25 — bypass cache for one-shot operations
• INLINECODE26 — better cache performance with large scanline images
• INLINECODE27 — update mode: skip outputs newer than inputs

Related Skills

• - exr — Python-level EXR internals: channel inspection, cryptomatte extraction with custom palettes, beauty pass extraction with ACEScg matrix. Use when you need fine-grained channel access or cryptomatte decoding beyond what --cryptomatte-colors provides.