Calibration transforms

Open the Compositor or Shader Editor and select the MacBlend sidebar tab after sampling the source image.

Configure the solve

Start by selecting the sampled source under Image. The other settings default to a reference-based, normalized calibration:

  • Use reference values as target is enabled.

  • Target is Linear sRGB D65 (Internal).

  • Normalize and Create Exposure Node are enabled.

  • Node Name is MacBlendCalibration.

When using reference values, change Target to the gamut in which the source was recorded when appropriate, such as V-Gamut for Panasonic V-Gamut footage. The image’s IDT must also be set correctly in the Image Editor before sampling. To match one sampled chart image to another instead, disable Use reference values as target and select the second image under Target.

With the default normalization, MacBlend uses the Neutral 5 patch and Rec.709 luminance coefficients to separate a broad brightness difference before fitting the matrix. Create Exposure Node represents that separated scale as an adjustable node after the matrix. Disable Normalize when the solve should include the brightness difference in the matrix; disable Create Exposure Node when the separate node is not wanted.

Change Node Name only when generated node groups need a different base name.

Forward

Forward creates the fitted calibration matrix. It transforms material or compositor data from the sampled source toward the selected target. When enabled, the exposure node receives the stored normalization scale.

Inverse

Inverse creates the inverse of the fitted calibration matrix. It transforms data from the selected target back toward the sampled source. When exposure-node creation is enabled, MacBlend adds the reciprocal normalization scale after the matrix.

Both commands require a valid source and target and a supported node editor. A singular fitted matrix cannot be inverted for Inverse.

Matrix result

After a successful solve, the panel displays the fitted matrix. The generated node group applies the RGB matrix while preserving alpha in compositor workflows.

Always inspect the result on representative imagery. A chart fit can be numerically valid while still reflecting poor lighting, clipped patches, incorrect input color spaces, or a chart overlay aligned in the wrong orientation.

See Method and limitations for a plain-language explanation of the workflow, its limits, and links to the deeper technical resources.