Patent ID: 6625224
Filing Date: 2003-09-23
Classification: G06T

Abstract:
A trellis coded quantizer for trellis coding of input values to determine respective code words, the quantizer operating on a trellis having at least n+1 trellis columns (n&gE;1) to each of which a predetermined number of possible states are assigned, an input value to the column i (i&lE;n) being assigned to a state of column i and being afforded selection between at least two predetermined admitted paths to respective states of the column i+1, the selection delivering a corresponding input value for assignment to the selected respective state of the respective column and being based on respective deviations between the input value of the column i and respective quantization values of the at least two admitted paths, so that a sequence of paths in a forward direction can be defined by a series of selections, a deviation associated with a current path selection being accumulated selection-by-selection, the quantizer being configured for performing, by means of a path-search algorithm, a search on the trellis in a reverse direction for a reverse sequence of said paths that minimizes accumulated deviation, the quantizer comprising:means for dividing the columns by allocating, to respective windows, the largest number of consecutive ones of the columns so that at least a predetermined level of statistical dependence still exists between any two columns of the window with regard to their respective possible states in relation to said sequence of paths in the forward direction extending from one of said two columns to the other of said two columns; means for storing data determined and data required during processing of a current one of said windows during application of at least one of the trellis coding and the path-search algorithm; and code word determining means, for performing trellis coding in a first window W0 of a sequence of input values defined by said delivering to respective columns allocated to windows, and for further performing for all windows Wk (k&gE;1) of said sequence of input values a trellis coding, followed by said search in the window Wk and subsequently in the window Wkâˆ’1, code words for the input values assigned to trellis column states defined by said reverse sequence being supplied to said means for storing during application of said search to the window Wkâˆ’1.