Working with HD Video
Since the introduction of Software Update Packet (SUP) 4.0, ALEXA cameras can apply user-defined looks to customize the rendering of video images for different applications and individual preferences. This enables DPs to show images on set that convey their full creative intentions. When a look file is activated, it automatically travels as metadata in recorded QuickTime ProRes clips and in the SDI output.
The camera can be set to apply the look on any output. Typically, the monitoring outputs are used while the recording output gets an unmodified image, allowing maximum flexibility in later editing and color grading (non-destructive mode). It is also possible to have a look ‚baked in’ to material recorded on to card or as HD video over SDI (destructive mode). ARRIRAW clips are always recorded non-destructively.
ARRI Look Files offer greater and earlier creative interaction between DP and colorist, and between production and postproduction. An ARRI Look File can be created based on a Log C DPX grab or a ARRIRAW clip that was stored by the camera. It contains parameters for saturation, for printer lights (RGB offsets) and for ASC color decision list (CDL) slope/offset/power parameters. Optionally, a look file may also include a freeform curve (grey scale tone map LUT) that will be applied instead of the standard Log C to Video tonemapping curve.
The free ARRI Look Creator (ALC) allows the creation of camera look files based on Log C DPX frame grabs. Creating looks based on ARRIRAW is possible using the ARRIRAW Converter (ARC).
Third party software, such as Pomfort Silverstack, can create ALEXA Look Files based on Log C Quicktime clips. The ALEXA Look file is also supported in Autodesk's applications Flame and Lustre as well as in Colorfront's OSD.