Cineon Extract Node

The Cineon Extract node enables you to convert Cineon Linear imagery back to native Cineon 10-bit log format. "Cineon Linear" refers to Cineon log data that has previously been converted to 16-bit linear using the "insert" method, which maps the log 90% white point to 90% white in linear space (e.g., 4095 in 16-bit). Cineon Extract performs the inverse operation of the Cineon Insert node.

In most cases, you would convert Cineon Linear back to Cineon log in the Disk Output node. However, the Cineon Extract node gives you the option of converting Cineon Linear back to 10-bit log at an earlier point in a network, in case you want to perform an operation on log data before output.

Note:
To convert any other type of data (any type of data besides Cineon Linear) to 10-bit log format, use the Bit Expand Node .

Cineon Extract Parameter Tab

The Cineon Extract tab provides controls for the Log 90% White card, the Film Gamma, and the Linear 90% White code value. These parameters control the overall brightness and color distribution of the output image. The defaults are based on Cineon specifications.

Log 90% White

The Log 90% White parameter enables you to set the values of the 90% white card, which is used as the reference for a relative log exposure of 0 in 10-bit log space. The default value is 685.

Film Gamma

The Film Gamma parameter enables you to set the conversion values for film gamma, which controls the straight-line portion of the characteristic curve for typical negative film. The default value is 0.6.

Linear 90% White

The Linear 90% White value allows you to specify the 90% point in the linear output. The Log 90% White point maps to this value. The default is 4095.

The above parameters contain separate entries for the Red, Green, Blue, Alpha, and Other parameters, enabling you to vary the conversion from channel to channel. If you wish to enter a value into all parameters, key the value into the Red parameter and click the Cascade button. You can also suppress an operation for a channel using the Channel Mask buttons.

About the Conversion Algorithm

The values in the above parameters specify certain variables in the conversion equation. The operation sends out a scaled, adjusted logarithmic conversion of the linear input. Note that the equation is the inverse of the Cineon Insert conversion:

Output = log10 (Input / Linear 90% White) / (0.002 / Film Gamma) + Log 90% White

The above equation is based on the algorithm provided in "Conversion of 10-bit Log Film Data To 8-bit Linear or Video Data for the Cineon Digital Film System," published by Kodak Motion Picture & Television Imaging.

For more information on the Log 90% White card, Film Gamma, and the Linear 90% White code value, see either the document referred to above or "Grayscale Transformations of Cineon Digital Film Data for Display, Conversion, and Film Recording," published by the Cinesite Digital Film Center.

Both of these documents are available for downloading from the Silicon Grail website (www.sgrail.com).




Table of Contents | Index



Copyright 1996-1999 by Silicon Grail Corporation