A method for determining an estimated clutter level of an input digital image based on an inequality index. The inequality index is determined by analyzing the input digital image to determine a set of image features. The image features are associated with a set of designated reference features, and the inequality index is determined based on the statistical variation of the reference features. A set of scene content features relating to spatial structures or semantic content of the input digital image is determined by analyzing the input digital image. The estimated clutter is determined responsive to the inequality index and the scene content features.