Working with ProRes/DNxHD
Log C, Film Matrix OFF Color Grading With ARRI Color Science
Material output in Log C with ALEXA-specific wide gamut color space (Gamma setting: Log C, Film Matrix: OFF) can be converted to video using ARRI conversion LUTs. In the grading application, the colorist needs to apply a Log C to DCI P3 video LUT when using a Digital Cinema compliant projector, or a Log C to Rec 709 video LUT, when using an HD monitor for display. The colorist can take advantage of grading operations in front of and after the applied LUT, so he or she can work in both Log C and DCI P3/Rec 709 color space. The final grade then will be converted from DCI P3/Rec 709 to the delivery color space using e.g. a standard DCI P3 to XYZ conversion LUT to create a Digital Cinema Distribution Master. Such LUTs are vendor-specific and not provided by ARRI.
As most of the mastering tools use their own notation for look up tables, ARRI offers the LUTs through the online ARRI LUT Generator, which can create over a dozen different LUT formats.
Log C, Film Matrix ON Color Grading Without ARRI Color Science
When a production is intended for exclusive distribution on film, the camera may also be set to deliver Log C material in emulated film color space (Gamma setting: Log C, Film Matrix: ON). This will allow the colorist to resort to a traditional DI setup where all grading is performed on the Log C material and the result from the film output is previewd or emulated using a standard Print Film Emulation (PFE) LUT.
This option is also applicable when material shot on ALEXA shall be combined with footage shot on film negative.
Note: It is possible to convert the ALEXA-specific wide gamut color space to film color space using a 3D LUT created with the ARRI LUT Generator. The according settings in the LUT generator are shown below.
Postproduction or Advanced Preset
To find out more about the color processing and gamma options of ALEXA cameras, please check the download section.