ASC CDL
Encyclopedia
The American Society of Cinematographers
Color Decision List (ASC CDL) is a format for the exchange of basic primary color grading
information between equipment and software from different manufacturers. The format defines the math for three functions: Slope, Offset and Power. Each function uses a number for the red, green, and blue color channels for a total of nine numbers comprising a single color decision. A tenth number, Saturation, specified in the Version 1.2 release, applies to the R, G, and B color channels in combination.
The ASC CDL was developed by the ASC Technology Committee
, a combined group of cinematographers, post-production engineers, and other motion picture industry professionals.
Although the basic controls of most color correction systems are similar, they differ somewhat in specific implementation and detail. The ASC CDL is a common standard that color correctors can translate their proprietary settings to and from. The ASC CDL functions are mathematically orthogonal primitives that can be used to represent vendor-specific corrections. ASC CDL correction functions also in some cases can appear in the user interface and be used directly.
The ASC CDL allows color corrections made with one device at one location to be applied or modified by other devices elsewhere. For example a cinematographer
filming on location can create a color correction with a small portable device, sending the ASC CDL color correction to a colorist
in post-production
to use as a starting point for final color correction. To communicate "looks" usefully in this fashion, calibrations, viewing environments, devices, and any output transforms (e.g. film look) must be managed very carefully; in general, they should be identical at origination and subsequent viewing.
The ASC has defined an XML schema for exchanging ASC CDL data, along with other metadata
about what image(s) the color corrections were applied to, the type of input signal used, and the viewing device and environment. They have also standardized methods for using ASC CDL data within the following file formats:
where
is the color graded pixel code value
is the input pixel code value (0=black, 1=white)
is slope (any number 0 or greater, nominal value is 1.0)
is offset (any number, nominal value is 0)
is power (any number greater than 0, nominal value is 1.0)
The formula is applied to the three color values for each pixel using the corresponding slope, offset, and power numbers for each color channel.
American Society of Cinematographers
The American Society of Cinematographers is an educational, cultural, and professional organization. It is not a labor union, and it is not a guild. Membership is by invitation and is extended only to directors of photography and special effects experts with distinguished credits in the film...
Color Decision List (ASC CDL) is a format for the exchange of basic primary color grading
Color grading
Color grading or colour painting, is the process of altering and enhancing the color of a motion picture, video image, or still image either electronically, photo-chemically or digitally. The photo-chemical process is also referred to as color timing and is typically performed at a photographic...
information between equipment and software from different manufacturers. The format defines the math for three functions: Slope, Offset and Power. Each function uses a number for the red, green, and blue color channels for a total of nine numbers comprising a single color decision. A tenth number, Saturation, specified in the Version 1.2 release, applies to the R, G, and B color channels in combination.
The ASC CDL was developed by the ASC Technology Committee
ASC Technology Committee
The American Society of Cinematographers Technology Committee is a group of cinematographers and a broad collection of A-list motion picture industry participants working on how to make high quality motion pictures using the new technologies and techniques presented by the massive changes taking...
, a combined group of cinematographers, post-production engineers, and other motion picture industry professionals.
Although the basic controls of most color correction systems are similar, they differ somewhat in specific implementation and detail. The ASC CDL is a common standard that color correctors can translate their proprietary settings to and from. The ASC CDL functions are mathematically orthogonal primitives that can be used to represent vendor-specific corrections. ASC CDL correction functions also in some cases can appear in the user interface and be used directly.
The ASC CDL allows color corrections made with one device at one location to be applied or modified by other devices elsewhere. For example a cinematographer
Cinematographer
A cinematographer is one photographing with a motion picture camera . The title is generally equivalent to director of photography , used to designate a chief over the camera and lighting crews working on a film, responsible for achieving artistic and technical decisions related to the image...
filming on location can create a color correction with a small portable device, sending the ASC CDL color correction to a colorist
Colorist
In comics, a colorist is responsible for adding color to black-and-white line art. For most of the 20th century this was done using brushes and dyes which were then used as guides to produce the printing plates...
in post-production
Post-production
Post-production is part of filmmaking and the video production process. It occurs in the making of motion pictures, television programs, radio programs, advertising, audio recordings, photography, and digital art...
to use as a starting point for final color correction. To communicate "looks" usefully in this fashion, calibrations, viewing environments, devices, and any output transforms (e.g. film look) must be managed very carefully; in general, they should be identical at origination and subsequent viewing.
The ASC has defined an XML schema for exchanging ASC CDL data, along with other metadata
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
about what image(s) the color corrections were applied to, the type of input signal used, and the viewing device and environment. They have also standardized methods for using ASC CDL data within the following file formats:
- Avid Log Exchange (ALE)
- Film Log EDL Exhange (FLEx)
- CMX Edit Decision List
Combined Function
The formula for ASC CDL color correction is:where
is the color graded pixel code value is the input pixel code value (0=black, 1=white) is slope (any number 0 or greater, nominal value is 1.0) is offset (any number, nominal value is 0) is power (any number greater than 0, nominal value is 1.0)The formula is applied to the three color values for each pixel using the corresponding slope, offset, and power numbers for each color channel.
Some systems supporting ASC CDL
- Autodesk finishing, VFX and colour grading systems
- AvidAVIDAVID stands for:* Advancement Via Individual Determination, a college-readiness system designed to increase the number of students who enroll in four-year colleges in the U.S....
editing systems - Codex Digital File-based recording solutions
- Blackmagic Design DaVinci Resolve color correctors
- Mistika finishing, compositing, stereo 3D and colour grading system
- Digilab Services Colour and Exposure Management system
- Digital Vision Film Master color corrector
- FilmLightFilmlightFilmLight Limited is a digital cinema technology company started in 2002 by the Scientific and Technical Academy Award-winning former Computer Film Company R&D team.Their main products are:...
Baselight color correction system - Gamma and Density 3cP on-set color correction system
- IRIDAS SpeedGrade color corrector
- Pandora Revolution color corrector
- Synthetic Aperture Color Finesse
- The Pixel Farm PFClean Film Restoration Software and Systems
- Thomson Grass Valley BONES Dailies
- Workflowers WF_x plugins for color correctors
- HS-Art Digital DIAMANT Digital Film Restoration Software
- Light Illusion LightSpace CMS
- YoYotta YoYo
- Flexxity, BonesDailies DFT, Digital Film Techology Weiterstadt