1. A method of detecting faces in an image stream, comprising: receiving an acquired image from said image stream including one or more face regions; sub-sampling said acquired image at a specified resolution to provide a sub-sampled image; identifying one or more regions of said acquired image predominantly including skin tones; calculating a corresponding integral image for at least one of said skin tone regions of said sub-sampled acquired image; applying face detection to at least a portion of said integral image to provide a set of one or more candidate face regions each having a given size and a respective location; and responsive to failing to detect at least one face region for said image, enhancing the contrast of the luminance characteristics for at least a region corresponding to one of said skin tone regions in a subsequently acquired image.