What is ARRIRAW?
Step 1: The Basics of CMOS Sensors
Have you ever wondered how your camera’s sensor works? No, of course not. Most of us don’t. But it turns out to be surprisingly complex. The sensor itself can actually only see bright or dark, so we place a grid of simple RGB filters over the pixels (known as a bayer pattern), so that each one only sees a single color. When light in the form of a photon hits a green pixel, that gives it a small electrical charge that is transferred to the Analog/Digital Converter, which receives that electrical jolt, as well as the jolts from all of its neighbors, into a data point that essentially says “very bright green at location ____.”
Step 2: Signal Compression
But the journey isn’t over yet. Those thousands upon thousands of points are being read out 24, or 60, or even 200 times every second. That’s a whole lot of data that has to go somewhere. For convenience sake, it has one last stop. We take this information into the compressor, where anything that looks like unnecessary data is tossed out and the footage is packaged up in a useful format like ProRes or h.264 for you to view and edit later.
ARRIRAW skips almost all of this.
How is ARRIRAW Different?
Each step in the process described above loses a small amount of image fidelity. Raw formats in general, and ARRIRAW in particular, were invented to avoid these losses by jumping over all of the processing steps. When shooting ARRIRAW, the light hits the sensor in that Bayer-pattern grid, but is NOT interpreted or compressed. It is loosely packaged and dumped straight to the card. Any program that wants to work with this footage has to be able to de-bayer it back into a viewable image on the fly, which is no small task. Currently, the only mainstream editors to support this are Adobe (Premiere, After Effects, Speedgrade) and Blackmagic (Davinci Resolve). For everyone else, ARRI provides a simple converter tool to help you create more workable proxies.
So if you want your footage uncompressed, unprocessed, and pure, then check out ARRIRAW. Just be aware of how many hard drives you will need for all of that footage. There’s a reason we usually shoot in compressed formats.