Using SetStretchBltMode with HALFTONE mode? If so:

HALFTONE

Maps pixels from the source rectangle into blocks of pixels in the destination rectangle. The average color over the destination block of pixels approximates the color of the source pixels.
After setting the HALFTONE stretching mode, an application must call the SetBrushOrgEx function to set the brush origin. If it fails to do so, brush misalignment occurs.

This option is not supported on Windows 95/98/Me.