Converts a GdPicture image to a 1-bit BW indexed color image. This function calculates the luminance of each pixel before applying the conversion. The color table has 2 entries: 1 Black & 1 White.

public GdPictureStatus ConvertTo1BppLum(
    int ImageID
);

Public Function ConvertTo1BppLum(
    ByVal ImageID As Integer
) As GdPictureStatus

A member of the GdPictureStatus enumeration.