Analog Knowledge brought to Digital Domain
Analog Knowledge brought to Digital Domain
ARRI’s digital cameras produce exceptional image quality with the organic look and feel of film, delivering incredible production value at an affordable cost. Images created with any ALEXA or AMIRA camera contain all the ingredients for best overall image quality: large and therefore sensitive photosites, high dynamic range, sharp and natural images, high sensitivity, natural color reproduction, excellent color separation, and the absence of artifacts.
To create such outstanding images, all components of the imaging chain are custom designed by our engineers and carefully tuned for optimal performance, starting with the optical low pass filter, the CMOS sensor, the imaging electronics, and the image processing software.
Our camera’s unique color processing was developed by the same ARRI color scientists that worked on the ARRILASER and ARRISCAN. Therefore, they are intimately familiar with both film and digital color science. The ALEV sensor renders natural colors, great looking skin tones, and shows accurate color separation (important for green screen and other VFX work) while also demonstrating the ability to resolve mixed color temperature sources.
ALEV III’s unparalleled exposure latitude of over 14 stops (as measured with the ARRI Dynamic Range Test Chart) means high dynamic range images that provide greater flexibility and efficiency for the cinematographer on the set. Overly bright windows will not need to be covered with gels and shooting at night is possible — even with only a few lights. Working with lower light levels opens up new visual possibilities for fresh and unusual images.
Special consideration has been given to highlight treatment. Creating a good-looking roll-off in the highlights is probably one of the most difficult tasks for any sensor designer and we have spent enormous resources to insure exceptional highlight handling.
The sensor’s wide exposure latitude translates into a “thick” digital negative; this means tremendous flexibility when color grading. ALEV III’s ability to retain definition, even when extremely under or overexposed, provides that extra bit of security in post. Its high dynamic range make ALEXA and AMIRA images, from day one, future-proof for high dynamic range (HDR) display technologies. The sensor's unique design ensures wide exposure latitude and low noise at all sensitivity settings without making any compromises in image quality.
For the absolute best in image quality, for the greatest flexibility in post, and for safest archiving, the 16-bit (linear) raw data stream from the sensor can be recorded as 12-bit (log) ARRIRAW files. Nothing is "baked" into an ARRIRAW image: Image processing steps like de-Bayer, white balance, sensitivity, up-sampling or down-sampling, which are irreversibly applied in-camera for compressed recording, HD-SDI outputs, and the viewfinder image, are not applied to ARRIRAW. All these parameters can be applied to the image in post.
ARRIRAW is also an excellent future-proof archiving format. ARRIRAW is uncompressed and unencrypted, which means that anyone can access their ARRIRAW data with standard software tools in the future without any proprietary decryption or decompression. We openly publish our color science as standard SMPTE documents (Recommended Disclosure Document (RDD) 30:2014 and RDD 31:2014).
The RDDs are available from the Society of Motion Picture & Television Engineers (SMPTE)'s website.
While the creation of ARRIRAW inside the camera is relatively straight forward, the creation of color images for compressed recording, HD-SDI and the viewfinder is more complex, as the camera has to create multiple streams of full color images from the raw image data in real-time. Not only that, but the viewfinder image, the recorded image and a number of HD-SDI outputs can have different resolutions and possibly different looks and different output gamma settings. To achieve this, a powerful image processing engine de-bayers the raw image data, applies white balance and sensitivity and up/down-samples the images depending on the required recording/output format.
To achieve the tremendous processing power for all those steps, our cameras’ image processing hardware consists of the latest generation of FPGAs (Field Programmable Gate Array), which are re-programmable processing chips. FPGAs not only have the horse power to deliver multiple streams of the highest image quality, but their re-programmable nature ensures that improvements in processing can be made available to all existing cameras. This happened, for instance, with ALEXA Software Update Packet 11, which provided a better de-bayering algorithm, instantly improving the image quality of all ALEXAs in the field.