A method, apparatus, and computer program product for identifying objects. Pixels for an image of an object are received. A plurality of pixels from the pixels are selected a plurality of times to form groups of sample pixels. Locations in the image for the plurality of pixels in a group of sample pixels are randomly selected for each group in the groups of sample pixels. A vector having a plurality of elements is formed using the groups of sample pixels. Each element in the plurality of elements in the vector corresponds to a group from the groups of sample pixels. The object is identified using the vector.