ARRIRAW | Pre- & Postproduction

What is ARRIRAW?

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. The processing step converts the sensor readout into a color image suitable for normal viewing. ARRIRAW conserves the originally recorded raw data for later use, providing the flexibility to go back and refine the results at any time. 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 ARRIRAW recorder which understands the T-Link signal.

The ARRIRAW ecosystem

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.

ARRIRAW in 3rd-party implementations
In many cases, ARRI's software development kit (SDK) is fast and adaptable enough to satisfy the processing needs of an application. In some cases however, 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.

Infographic explaining the certification process for 3rd party tool processing ARRIRAW

Making the image

Debayering – The first phase of ARRIRAW processing is the most compute intensive. ARRIRAW images (like all CMOS sensor 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:

Infographic showing the de-bayering process from luminance value-image to color array to rgb image

The image above shows a single-channel capture from the sensor on the left, and the reconstructed image on the right. Utilizing the information about its 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. ARRI developed and maintains its own debayer algorithm (ARRI Debayer Algorithm, or ADA for short). ADA is avaialble in the ARRI Reference Tool and 3rd party applications using our SDK.

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's tool for ARRIRAW

The ARRI Reference Tool (ART) is a software application (for Windows or Mac) 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.

Learn more and download your copy of the ARRI Reference Tool!

wkflw_ARRIReferenceTool_screenshot_look_diver

Bulletproof your workflow pipeline

Once you have chosen your tricks of the trade for an upcoming production, ARRI recommends running tests rather than to anticipate that things should work. So, define:

Are the tools up for the task? (Can I import/edit/... format A in tool C?)
Can the invisioned look be achieved using a the toolset? Can the look be shown on set via live grading?
Are special settings required for a chosen tool to more closely match the desired results?
Are there too many steps required for the desired result? Is the post-production chain over-engineerd? Any steps that might cause a delay or hick-up?
Do the results of the tool chain meet the production's expectations of consistent results?

ARRI provides sample footage of all our cameras via FTP server or cloud service.