Converts a GdPicture image to an 8-bits gray-scaled indexed color image. 

This function uses a basic grayscale color reduction algorithm. 

The color table has 256 entries.

public GdPictureStatus ConvertTo8BppGrayScale(
    int ImageID
);

Public Function ConvertTo8BppGrayScale(
    ByVal ImageID As Integer
) As GdPictureStatus

A member of the GdPictureStatus enumeration.