Light Matte
11 May 2016

The BCC Light Matte filter uses applied light to create or modify an alpha channel. Rays of light spread from the light source point in all directions. As the rays expand, their intensities are affected by the luminosities of the pixels that they cross. The farther from the source the rays extend, the less they are affected by the intensities of new pixels that they crosses. This process is referred to as attenuation, since the affect of the pixels on the intensity of the rays attenuates, or lessens, over time.

The filter allows users to determine which  source color channel is used to create the light and to calculate the intensities of the source pixels. Pixels with higher values in the selected channel are considered to have higher intensities.

  • Luma, Red, Green, and Blue use the corresponding color channel with the source alpha information.
  • Luma Inverse uses the inverted luma channel.
  • Unmultiplied Luma uses the source luma channel but ignores the source alpha information. All pixels in the source are treated as fully opaque.
  • Alpha uses the corresponding source channel.
  • Luma Cartoon Edges and Alpha Cartoon Edges find edges in the corresponding source channel, apply outlines to the edges, and use the resulting image. When Luma Cartoon Edges or Alpha Cartoon Edges is selected, Thickness/Intensity adjusts the width of the outlined edges, and Cartoon Threshold sets the value in the image above which pixels are considered to be fully on.
  • Luma Edges and Alpha Edges find edges in the corresponding source channel and use the resulting image. When Luma Edges or Alpha Edges is chosen,Thickness/Intensity adjusts the intensity of the edges.

The built in PixelChooser, with integrated mocha planar tracking allows for greater control over which areas of the image the filter should affect.

To learn more about this filter, and see a breakdown of the various controls, please click here.