Log C

ARRI's recording color space

ARRI cameras record and output images in Log C wide gamut color space. Log C images can transport all color information and high dynamic range captured by ARRI’s camera sensors.

Logarithmic encoding - "Cineon" style
Log C (C is for Cineon; The original Cineon log encoding is based on the density of color film negative) encoded images can be identified by their flat and desaturated nature. Whites and blacks are not extended to their maximum values:

Log C is a so-called scene-based encoding. The signal level increases by a fixed amount with each increase of exposure measured in stops. This encoding, which uses an ARRI-specific wide gamut color space, is similar to files from a film scan and ideal to carry image information.
To correctly display Log C material on an HD or UHD monitor (Rec 709/Rec 2020) or in a digital projection (P3), it needs to be tone-mapped and transformed into the target color space. This image conversion can be performed using a 3D Look Up Table (3D LUT).

Nevertheless, Log C is and will be under continuous development to keep up with the demands of current cinema technology.

Video encoding
Rec 709/2020 is a display-based encoding using RGB primaries specified in ITU Recommendation BT.709/2020 and can be directly output to standard HDTV/UHDTV displays without any conversion.

The material can be processed by most HD/UHD video production gear in realtime, which enables short production times. Rec 709/2020, however, provides somewhat reduced choices in color grading and, due to a more contrasty characteristic, cannot hold as much highlight information as the much flatter Log C curve.

To enable productions to shoot in Rec 709 color space without the sacrifice of too much highlight information, ARRI provides a special Low Contrast Characteristic (LCC) Look File that can be applied to change the standard Rec 709 output.

If you have further questions, please have a look at our in-depth information on various color related topics in our FAQs: