These options are common to GEGL-based filters. Please refer to Section 2, “Common Features”.
Component to extract. Default is RGB Red: all layer pixels that have the red component in their color will be extracted to create gray pixels; gray pixel value is that of the red channel (e.g a 153;70;17 RGB pixel will give a 153;153;153 gray pixel).
Invert the extracted component.
Use linear input instead of gamma corrected.