An encoder, a decoder, a method of encoding and a method of decoding

摘要

An encoder (500) for encoding a signal carrying a representation of an image, the encoder (500) comprising a first encoder (504) for encoding a signal carrying a representation of an image at a first quality level; and a second encoder (506) for encoding a signal carrying a representation of the image at a second quality level at greater quality than the first quality level. The encoder (500) also comprises a mixer (346) for mixing a factor of a signal carrying a representation of a prediction of the image at the first quality level and a factor of a signal carrying a representation of a prediction of the image at the second quality level to produce a mixed signal. The encoder (500) is arranged such that: the second encoder (506) encodes the signal carrying a representation of the image at a second quality level based on the mixed signal; and the factors are selected based on a measure of noise introduced by the first encoder (504) and the second encoder (506) when producing the predictions. A corresponding decoder and methods of decoding and encoding are also described.