An apparatus for classifying a contrast level of an image is provided. One or more processors execute instructions stored in one or more memory devices which configure the one or more processors to obtain an image from an image source, extract intensity values for each pixel of the obtained image, calculate a probability distribution for the obtained image representing a number of pixels at each unique pixel value, determine, from the calculated probability distribution, a spread value representing a series pixel values including at least a predetermined number of pixels at each pixel value in the series of pixel values and classify the obtained image a member of one of three classes based on the calculated probability distribution and the determined spread value.