Uncompressed, unencrypted, and uncompromised

ARRIRAW is ARRI’s format for uncompressed, unencrypted, and uncompromised sensor data. It can be considered a digital version of the camera negative. ARRIRAW is the only format that fully retains the camera's natural color response and great exposure latitude as unprocessed sensor data.

Like film negative, ARRIRAW data has to be developed – or rather processed – in order to convert the single channel image, which represents the raw Bayer pattern sensor readout, into a color image suitable for normal viewing. The originally recorded raw data remains pristine, always providing the flexibility to go back and refine the results. This makes ARRIRAW the perfect format for digital cinematography and high-quality visual effects production.

Our camera line-up supports in-camera recording of ARRIRAW or MXF/ARRIRAW data. MXF/ARRIRAW is ARRIRAW within a container format (*.mxf), allowing each clip to be contained in just one file, as opposed to several thousand files, because with the regular ARRIRAW format (*.ari) every single frame is a separate file.

Older ALEXA cameras (ALEXA Classic, ALEXA Plus/Plus 4:3, ALEXA M, and ALEXA Studio) require an ARRI-certified external recorder which understands the T-Link signal.

ARRIRAW Processing

ARRI has built long-term relationships with postproduction equipment manufacturers through the ARRI Partner Program. These relationships have facilitated all of the leading compositing and color correction tools being able to process ARRIRAW files out of the box.

In addition, ARRI offers a software development kit (SDK) for ARRIRAW processing, containing documentation of the ARRIRAW processing pipeline and a library – executable code – that the vendor can incorporate into their application. ARRI also supports vendors who wish to implement the ARRIRAW processing procedure on their own, through comprehensive documentation of a three-phase color processing pipeline and continuous direct support.

The first phase of ARRIRAW processing is the most compute intensive. ARRIRAW images (like all camera raw images) have only one ‘color’ channel (in fact, it’s a color-coded luminance channel). A color reconstruction algorithm calculates the missing components for each pixel based on the type and position of colored filters on the camera sensor. ARRI cameras use the Bayer pattern color filter array. The term 'color reconstruction' therefore is also known as ‘debayering’. The Bayer pattern filters the light hitting the sensor so that 50% of the sensor’s photosites are used to represent green, 25% of the photosites represent red, and the remaining 25% represent blue. Therefore, the debayer algorithm needs to reconstruct 75% of red, 50% of green, and 75% or blue color information:

The image above shows a single-channel capture from the sensor on the left, and on the right the reconstructed image facilitating the color filter array. Half of the reconstructed image's green values are interpolated from the surrounding photosites rather than captured, as are three-quarters of the red and three-quarters of the blue.

The output quality of the image depends on the debayering algorithm. Generally speaking, a simpler algorithm will process faster, but will also involve a higher probability of color errors.

For VFX, however, the images are often processed using the native sensor pixel count and then downscaled to e.g. 4K or 2K at a later stage. Using this approach takes advantage of the luminance resolution, which correlates to the sensor pixel count.

ARRIRAW SDK and Third-Party Implementations
In many cases, ARRI's SDK is fast and adaptable enough to satisfy the processing needs of an application. But in some cases, especially when the product uses custom hardware (or standard hardware in a non-standard way), Partner Program members may want to implement the ARRIRAW processing pipeline themselves. In this scenario, the SDK serves as a reference against which the member's developers can test their results before submitting evaluation imagery to ARRI's Workflow Group. In a few applications, the vendor's product offers both processing solutions, giving the user the option of maximum throughput with a very good match to the SDK, or bit-for-bit matching of other products that use the reference SDK implementation.

ARRI Reference Tool (ART) replaces ARRIRAW Converter (ARC)

The ARRI Reference Tool is a software application that provides a graphical user interface for ARRI’s reference SDK. ART is a combined tool for viewing, rendering, metadata, and look files. It combines and therefore replaces the ARRIRAW Converter, ARRI Color Tool, and ARRI Meta Extract.

You can download your copy of the ARRI Reference Tool here.

The legacy version of ARRIRAW Converter can be found here.

Testing Your Workflow
ARRI recommends running tests to define:

  • How the intended look can be achieved using the chosen toolset(s).
  • The different tools that need to be set up to meet the production's expectations of consistent results.
  • The settings required for a chosen tool to most closely match the SDK reference results, if no other reference set of results is available.

You can use an ARRIRAW frame grab as test material. ARRI provides sample footage shot with our cameras on FTP server and Webgate.io.