We used a 2-IFC discrimination task, in which observers reported the interval that contained more blur levels and a classification task, in which observers reported the number of perceived blur levels. To estimate this value, observers discriminated and classified dead leaves patterns that contained a controlled distribution of blur levels but are more complex or naturalistic than stimuli typically used in blur research. Here, to evaluate the usefulness of blur as a depth cue, we estimate the number blur levels that observers can perceive simultaneously. Natural images contain objects at a range of depths whose depth can be signaled by their perceived blur.
