// Setup rectangle for the highlighter mark's location.
ImGearRectangle igRectangle = new ImGearRectangle(10, 10, 300, 100);
// Setup color for the highlighter.
ImGearRGBQuad igRGBQuad = new ImGearRGBQuad(40, 200, 40);
// Create highlighter.
ImGearARTHighlighter igARTHighlighter = new ImGearARTHighlighter(
igRectangle, igRGBQuad
);
// Add the annotation to the ARTPage.
igARTPage.AddMark(igARTHighlighter, ImGearARTCoordinatesType.IMAGE_COORD);