1. A method of filtering noise from a picture, comprising: determining a set of pixel noise metrics for a set of selected pixels in the picture based solely on information from the set of selected pixels in the picture; designating as valid a subset of pixel noise metrics in the set of pixel noise metrics whose associated pixels are not located at an edge or are not located in a complicated area of the picture; calculating a set of block noise metrics from the valid subset of pixel noise metrics; ascertaining a global noise metric for the picture from the set of block noise metrics; and filtering the picture using the global noise metric to generate a filtered picture.