2011

All images read by the PXL script are read at the current time t. There is no
way to read images at a time different from t within a PXL script. To do so, a
user must use external Composite Retimer or Time Offset tools before inputting
images to the PXL tool.
CTL Tool
Use the CTL tool to write a color transformation language (CTL) expression
to control the resulting color of a pixel.
NOTE The CTL tool can only perform point operations—see Image Processing
Algorithm Categories
on page 457.
The CTL tool uses the same UI as the PXL tool—see
PXL Tool UI on page 441.
The CTL tool supports every feature of CTL except print statements. For a
more complete list, refer to the CTL manual:
http://ampasctl.sourceforge.net/CtlManual.pdf. The main function of the script
will be called for each pixel of the output image.
Before applying a script, several conventions must be respected:
■ The entry point of the script is the “main” function. This function must
be present in every script.
■ The main function return value is ignored.
■ The main function must have four parameters for each input image. They
correspond to the RGBA channels of the pixel of the input image. They
must be of type float, and be qualified as “input varying”. The name of
these parameters must be the component letter in lower case (i.e. “r”, “g”,
“b”, and “a”), concatenated with the name of the input image. Because
the primary input of the CTL tool is called “In”, the corresponding
arguments to the main() function for that input image will be:
■ input varying float rIn
■ input varying float gIn
■ input varying float bIn
■ input varying float aIn
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