Working with ARRIRAW
Log C ALEXA Wide Gamut Grading
When Log C footage is brought into the grading project, the colorist needs to apply a conversion LUT to get a correct image on his display device. This would be a Log C to P3 video LUT when grading on a Digital Cinema compliant projector, or a Log C to Rec 709 video LUT, when using an HD monitor for display. The ARRI LUT Generator can output these conversion LUTs in a variety of notations for a number of grading applications.
The colorist can then perform his/her grading underneath/in front of the conversion LUT, but also has the option to alter the image after it is converted to DCI P3 or Rec 709 video. The final grade is then converted to the destination color space using standard output LUTs, such as an XYZ output LUT for a Digital Cinema Distribution Master. These output LUTs are vendor-specific and not provided by ARRI.
Log C Film Grading (not using ARRI Color Processing)
If a production is exclusively intended for analogue projection, the ARRIRAW footage could also be processed in Log C with emulated film color space (ARRIRAW SDK setting Log C - Film). This allows the colorist to utilize a traditional DI setup where all grading is applied on the Log C material and the result of the film output is previewed/emulated on his display or projector with a standard Print Film Emulation (PFE) LUT.
Please note that the ARRI LUT Generator can only output a conversion LUT to get from ALEXA wide gamut to ALEXA film for this setup as shown below. ARRI does provide ALEXA Log C Print Film Emulation LUTs for P3 or HD displays and has no influence on the quality of color rendition in this kind of setting.
To find out more about the color processing and gamma options of ALEXA cameras, please check the documentation in the download section.