Abstract: The present invention detects backlit images by analysis of the shape of its luminance histogram, and enhances backlit and low contrast images by application of a mask in the frequency, rather than spatial domain. More particularly, the present invention detects backlit images by analysis of a luminance histogram to determine if the histogram is inverse-bell-shaped or double-peaked, by smoothing the histogram, converting the smoothed histogram into a curve function, counting the number of crossings of the curve function at a baseline, and designating the image as backlit if the number of crossings is four or more. The invention preferably adjusts the image's luminance histogram vertically, along the Y-axis, and counts crossings at the X-axis.