Abstract: Error concealment apparatus for concealing corrupted data elements in frequency separated digital image data (such as sub-band coded image data) is described. Depending on the spatial frequency represented by a corrupted data element, one of a number of error concealment means is selected to conceal the error. In this way the error concealment used can be tailored to suit the different properties of the various spatial frequency components in the frequency separated image.

Abstract: A composite digital video signal encoder comprises crosstalk measuring filters for measuring crosstalk between luminance and chrominance components of a composite digital video signal, a vertical comb filter and a vertical/temporal filter each operative to separate one of the luminance and chrominance components from the composite signal, a mixer for mixing output signals produced by the vertical and vertical/temporal filters, and a mixer control means responsive to the measured crosstalk to control the mixing ratio of the mixer in a sense to reduce cross effects in the mixed output signal resulting from the crosstalk.