I wouldn't call it a bug, but the name of the method is rather misleading (or the msdn documentation is inadequate). "Unscaled" refers to the print size of the image, which means it takes into account the HorizontalResolution and VerticalResolution settings. These will typically vary according to the source of the image -- a graphics program or a digital camera -- and you can of course change them yourself. For many purposes, you don't need to bother about the resolution settings. In that case, just use DrawImage, which will use the system resolution for all images.

Back in .Net Framework 1, there were reports that the "unscaled" DrawImage variants were more efficient than plain DrawImage. The difference, if it existed, seems to have disappeared in later versions of the framework.

BB