If the image to be loaded is 12, 16 or 32-bit grayscale and 0 is passed for the parameter that controls the number of bits per pixel at which to load the image, then if Leadtools.RasterSupportType.ExtGray support is locked, the image will be loaded as 8-bit grayscale, instead of the original bits per pixel.
For more information on Leadtools.RasterSupportType.ExtGray support, refer to Leadtools.RasterSupport and Leadtools.RasterSupport.Unlock(Leadtools.RasterSupportType,System.String).