Cineon

“Cineon” was a computer system, augmented by film scanning and recording hardware, designed by Kodak, for digital intermediate film production. It included a scanner, tape drives, workstations with digital compositing software, and a film recorder. The system was first released in 1993 and was abandoned by 1997. As an end-to-end solution for 2K and 4K digital film production, the system was well ahead of its time. The major components of the system (scanner, workstation software, and recorder) have all received AMPAS Scientific and Technical Awards.

Kodak no longer sells the system or its components; however, the “Cineon” (.cin) file format that Kodak defined still is commonly used in the film visual effects world. (The Digital Picture Exchange (DPX) file format is also used in those applications; DPX files commonly store pixel data encoded according to Cineon Printing Density.)

Cineon file format

The Cineon file format was designed specifically to represent scanned film images, and it has some interesting differences from other formats such as TIFF and JPEG:

• The pixel data represents "printing density", the density that is seen by the print film. Thus, Cineon files are assumed to operate as part of a reproduction chain keeping whatever values are originally scanned from a negative or positive film. Any negative can be reproduced on the recorder retaining the original neg's characteristics (such as color component crosstalk and gamma) - and thereby retaining the negative's “look” if it were directly printed. The original Cineon color data metric printing densities were based upon 5244 intermediate film. Conversion of Cineon Printing Density (CPD) to Status-M can be estimated with a 3x3 matrix or by using tables contained in the Kodak 'Digital LAD' document. This document shows a specific relation between Cineon Code values and Status-M densities.
• The data is stored in log format, directly corresponding to density of the original negative. Since the scanned material is likely a negative, the data can be said to be "gamma with log encoding".
• To evaluate original scene luminances from Cineon data, the camera negative characteristics must be known. (Such characterization is known as "unbuilding.") Such characterization is aided by exposing a sensitometric strip so that the actual developing gamma can be determined. The film can be unbuilt by using the unique per-layer contrasts of the color negative.
• In a Cineon (.cin) file, each channel (R,G,B) is 10 bits, packed 3 per 32-bit word, with two bits unused.
• Conversion to computer displays or to video typically involves the notion of the "black point" and "white point" used for conversion to more limited range video signals. Conventionally, these points are 95 and 685 on the 0-1023 scale (but should be adjusted based upon actual negative content). Pixel values above 685 are "brigher than white", such as the sun, chrome highlights, etc. The concept of a 'soft clip' was introduced to make the rolloff of whites more natural. Pixel values below 95 represent black values exposed on the negative (the clear base of the film). These values can descend in practice as low as pixel values 20 or 30.

Documentation

Conversions to the Cineon format were defined in a Kodak document by Glenn Kennel, Conversion of 10-bit Log Film data to 8-bit Linear or Video Data

SMPTE standardized the format further into a related format called DPX which can store more varieties of image information as well as additional header information.

What is the 10-bit advantage?

Working in 10 bits per pixel color space provides 1024 levels of color as opposed to 256 levels of color in 8 bits per pixel color space.

10 bit YUV and 10 bit RGB are industry standard. This is documented and recognized by the Society Of Motion Picture Television Engineers:

SMPTE 259M SMPTE 292M SMPTE 296M SMPTE 372M

History

In 1993 Snow White and the Seven Dwarfs became the first film to be entirely scanned to digital files, manipulated, and recorded back to film. The restoration project was done entirely at 4K resolution and 10-bit color depth using the Cineon system to digitally remove dirt and scratches and restore faded colors.

Cineon AIM Calibration

For a digital film system to operate correctly with Cineon 10-bit aims, the following calibration is desired mapping code values to StatusM densities. These are in the form of the AIM for a film recorder (where the Dmin should be adjusted based upon what the real lab creates on its '42 negative.

See also

• DPX
• OpenEXR

External links

• Cineon Image File Format Draft
• Cineon Users' Information Site
• Conversion of 10-bit Log Film Data To 8-bit Linear or Video Data