CDL

     

The Color Decision List (CDL) allows you define the look of the camera's colors in your project.

Use the CDL menu to:

Manage CDLs

Use the CDLs menu to import and export CDLs.

CDLs can be stored on the camera or transferred to media to be shared with other cameras. When exporting CDLs from camera to media, the CDLs are saved to a folder on the media called “cdls”. When importing CDLs from media to the camera, the CDLs must be stored on the media in a folder called “cdls.”

NOTE: When you record with a CDL in both ProRes and R3D formats, the camera automatically saves the CDL together with the clip.

To export selected CDLs from the camera to the media, refer to the In Camera CDLs section.

To import selected CDLs from the media to the camera, refer to the On Media CDL section.

CDL Overview

A Color Decision List (CDL) is a metadata file format developed by the American Society of Cinematographers (ASC) to exchange standard color correction information between post production tools. This non-destructive color adjustment layer simplifies the versioning of looks by updating simple metadata without the need to re-transfer the image data.

CDLs are very common in VFX workflows because the VFX artist needs both the ungraded shot and the intended look. The ungraded shot allows the artist to comp in truly linear light, and the intended look is needed to confirm that the individual plates still hold together after the grade is applied.

Slope, Offset and Power

The three CDL tone curve parameters are Slope, Offset and Power. These algorithms allow the camera to modify the recorded image.

  • Slope multiplies the incoming data
  • Offset is sum of the incoming data
  • Power is a power function to the incoming data

These three relate to Gain, Lift, and Gamma in the following ways:

  • Slope = Gain
    Gain Adjusts highlights.
  • Offset = Lift
    Lift Increases the value of dark colors.
  • Power = Gamma
    Gamma adjusts midtones.

These three relate to each other in the following ways:

Slope= input x slope

Offset= (input x slope) + offset

Power= ((input x slope) + offset) ^ power

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.

Saturation

A fourth parameter “Saturation” is achieved by converting the out data in a Luma and Chroma component. The Chroma Signal is then multiplied by the “Saturation” parameter.

Film Grade and Video Grade

With Slope and Offset you can produce both a Film Grade “Exposure” and “Contrast” and a Video Grade “Lift” and “Gain”.

  • Exposure is achieved by Offset
  • Contrast is achieved by a combination of Offset and Slope
  • Gain is achieved by Slope
  • Lift is achieved by a combination of Offset and Slope
  • Gamma is achieved by Power