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ARRI LogC False Color Exposure Zones & Key White Paper

ARRI

ARRI has released a ARRI LogC False Color Exposure Zones & Key White Paper. The document describes the computation and application of False Color tables for the ALEXA series of digital cinema cameras to LogC encoded signals.

The document separates between common algorithms that are consistent between camera models and encoding types, and details that are specific to each camera model or encoding.

The white paper goes into a lot of detail and it is worth reading if you are using ARRI cameras.

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The meaning of the zones provided by the False Color are consistent across camera systems. The description of each zone over time has changed; however, the technical calculation has remained consistent so only the present format is covered in the document.

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The LogC4 encoded False Color Zone bounds are split into two types, Exposure Index (EI) dependent and EI independent. EI dependent zones include those which visualize sensor noise or clipping behaviour which scale with the EI gain. Whereas EI independent zones are fixed relative to absolute sensor signal and calculated at a fixed EI of 400. To determine the active zone region, the Lower Bound value is inclusive and the Upper Bound value is exclusive.

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