1. A method, comprising: a computer system identifying one or more distortion categories for one or more image frames, wherein the identifying is based on distorted image statistics for the one or more image frames; and the computer system determining a quality of the one or more image frames based on the identified one or more distortion categories by assessing one or more feature scores corresponding to one or more feature vectors of the one or more image frames, and mapping from a multidimensional space to a quality score, wherein the multidimensional space is defined by ranges for the one or more feature scores; wherein reference image frames for the one or more image frames are not available to the computer system in performing the identifying and the determining.
1. A method, comprising: a computer system identifying one or more distortion categories for one or more image frames, wherein the identifying is based on distorted image statistics for the one or more image frames; and the computer system determining a quality of the one or more image frames based on the identified one or more distortion categories by assessing one or more feature scores corresponding to one or more feature vectors of the one or more image frames, and mapping from a multidimensional space to a quality score, wherein the multidimensional space is defined by ranges for the one or more feature scores; wherein reference image frames for the one or more image frames are not available to the computer system in performing the identifying and the determining. 8. The method of claim 1 , further comprising training a distortion classifier that is configured to identify distortion categories based on distorted image statistics, wherein the training includes: applying a given distortion type to a plurality of reference images to produce a plurality of distorted images; and fitting one or more functions to the plurality of distorted images, wherein the one or more functions are usable to determine a probability that the given distortion type applies to a given distorted image.