Patent ID: 6415059
Filing Date: 2002-07-02
Classification: H04N

Abstract:
Data compression apparatus in which input data is compressed according to a target output data quantity using a stage of data quantisation, said apparatus comprising:(i) a data selector for selecting a subset of current data to be quantised; (ii) a data store for storing said subset of data; (iii) a backsearch quantiser and dequantiser for sequentially quantising and dequantising said subset of data at a plurality of degrees of quantisation, wherein said quantising and dequantising is performed sequentially and each successive sequence of said quantising and dequantising applies a respective degree of quantisation to said subset of data; (iv) a comparator for comparing data quantised and dequantised by said backsearch quantiser with said stored subset of data, to detect errors introduced by said quantisation and dequantisation by said backsearch quantiser; and (v) a quantisation selector for selecting a final degree of quantisation for use in compression of said current data, said final degree of quantisation being that degree detected by the comparator to introduce the fewest errors during quantisation and dequantisation of said subset of data by said backsearch quantiser.