1. A method of controlling a compression of an input image according to a degree of photo-realism in the input image, comprising: computing a photo-realism value indicating a degree of photo-realism for the input image based on a numerical distribution of pixel luminance values within the input image, including processing a histogram of the input image which denotes the numerical distribution of pixel luminance values within the input image, wherein said processing comprises computing a relation among histogram bins having a value that is above an average and histogram bins having a value below the average; calculating a configuration parameter based on the photo-realism value for the input image; and configuring an encoder to compress the input image according to the configuration parameter.