Patent ID: 6757333
Filing Date: 2004-06-29
Classification: H04N

Abstract:
Video signal processing apparatus in which at least two input video signals are combined in proportions determined by a pixel key signal to generate an output video signal for compression, at least one of said input video signals having respective associated compression parameters from a data compression process applied to that video signal;said apparatus comprising: (i) a detector to detect an average pixel key signal value across each of a plurality of blocks of pixels of said output video signal; and (ii) a comparator to compare said average pixel key signal values with first and second thresholds, said first threshold representing a pixel key signal value corresponding to combination having primarily one of said video signals, and said second threshold representing a pixel key signal value corresponding to combination having primarily the other of said video signals; in which: (iii) if said average pixel key signal value for a block lies between said first and second thresholds, that block of said output video signal is compressed using newly derived compression parameters; and (iv) if said average pixel key signal value for a block lies outside the range defined by said first and second thresholds, the compression parameters associated with the corresponding block of said input video signals are made available for re-use in compression of that block of said output video signal.