Abstract: A method of filtering noise from digital pictures includes selecting a first set of pixels including the union of a pixel of the current picture to be filtered and a second set of pixels temporally and spatially near the pixel. A certain number of extended sums of values assumed by as many pre-established weight functions of the intensity of a selected video component on the first set of pixels is also calculated. The second set of pixels may belong to the current picture or to a preceding picture. Several noise filters for digital pictures are also provided.

Abstract: A process for estimating the noise level of a sequence of images comprises the operations of: producing a local estimate of the noise level of the said images, creating the histogram of the said estimate, deriving at least one parameter of the said histogram, and determining, by calculation or by means of an empirical relation, at least one noise level parameter on the basis of the said at least one parameter derived from the histogram. The corresponding device can be incorporated, for example, in an MPEG-2 encoder, where the parameter identifying the noise level is used for the adjustment of the internal variables of the encoding process.