An apparatus and method for performing multisampling anti-aliasing. For example, one embodiment of an apparatus samples multiple locations within each pixel of an image frame to generate a plurality of image slices. Each image slice comprises a different set of samples for each of the pixels of the image frame. Anti-aliasing is then performed on the image frame using the image slices by first subdividing the plurality of image slices into equal-sized pixel blocks and determining whether each pixel block has one or more different pixel values in different image slices. If so, then edge detection and simple shape detection is performed using pixel data from a pixel block in a single image slice; if not, then edge detection and simple shape detection is performed using the pixel block in multiple image slices.