A technique for combining graphical objects in a computer system works by
removing the destination dependent ROP commands to permit rendering
directly to the device color space and pixel depth. The solution is to
recognize that the GDI command sequences that applications use to
generate various special print effects, such as transparency and complex
clipping. Once recognized, the original application intent can be
determined, allowing the GDI command sequence to be replaced with one
that generates an equivalent output, but without the destination
dependency. This avoids problems that arise when using ROP combinations,
especially when rendering on a print device. This is because the ROP
combinations are defined based on the GDI command sets, which are in an
RGB color space, with a pixel depth of 24 bits. Thus, information can be
lost when combining a series of GDI commands because of the pixel depth
limitations. The problem becomes even more severe when drawing to the
device color space, since it is typically not in the RGB color space and
is usually half-toned. Attempting to apply the ROPs in the device color
space can often produce incorrect or at least suboptimal results.