Abstract: A method for assigning a color symbol to an image pixel comprises selecting a luminance value from a discrete set of quantized luminance values; selecting a chrominance value from an ordered discrete set of quantized chrominance values; and composing a color symbol from an index of the selected luminance value and an index of an ordinal position of the selected chrominance value. In particular embodiments of the invention, each discrete chrominance value is selected from a Fibonacci lattice on a constant-luminance plane in a perceptually uniform color space such as Lab or Luv.

Abstract: A method for assigning a color symbol to an image pixel comprises selecting a luminance value from a discrete set of quantized luminance values; selecting a chrominance value from an ordered discrete set of quantized chrominance values; and composing a color symbol from an index of the selected luminance value and an index of an ordinal position of the selected chrominance value. In particular embodiments of the invention, each discrete chrominance value is selected from a Fibonacci lattice on a constant-luminance plane in a perceptually uniform color space such as Lab or Luv.

Abstract: Data words are converted to codewords in accordance with a run-length limited (RLL) or maximum transition run (MTR) code in which the codewords are subject to one or more constraints on the number of consecutive like symbols. The data words and codewords are each partitioned into a number of disjoint subsets. Associated with each of the disjoint subsets of data words is a distinct mapping. A given data word is converted to a codeword by applying to the given data word the mapping associated with the subset containing that data word. The mappings are configured to utilize symmetry whenever possible. For example, if Y=&psgr;(X) represents the mapping of a given data word X onto a corresponding codeword Y. then it is preferred that X′ and Y′ representing the words X and Y in reversed order, satisfy the relation Y′=&psgr;(X′).

Abstract: A 16B/18B low disparity code is described. The 16-bit input word is split into two bytes, i.e., into two 8-bit words, and each byte is mapped to a 9-bit word. The image of each input byte under the mapping depends at least in part on its disparity, and also in some cases on the disparity of the other word. Certain of the images under the mapping are then inverted. The decision whether to invert an image depends, at least in part, on the running digital sum (RDS) of the output. The RDS is the sum of all 1's in the data stream from its beginning (or from a designated starting point). Significantly, all possible input words are grouped, by disparity, into four categories. The rule for mapping of input words is different for each of the four categories.

Abstract: A method of decoding a sequence of samples received over a communications channel, such as a partial response channel, in which the sequence represents a length k binary bit stream encoded as a sequence of bipolar symbols comprised of q groups of L symbols, each length L group of said symbols corresponding to one of 2.sup.m subwords having a predetermined block digital sum. The decoding method makes use of the structure of the encoding method by finding, in one illustrative embodiment, for each group of L samples, the maximum likelihood path through a time varying trellis supporting the sets of subwords having predetermined block digital sums to identify said subwords; recording the state metrics and branch metrics for each path and identifying, from the metrics the maximum likelihood path, the order of concatenation of the subwords.

Abstract: A method and apparatus generates a channel codeword based on codewords with arbitrary block digital sums. Respective portions of the channel codeword are generated based on respective sets of input symbols, and the channel codeword is generated from the portions in accordance with another set of input symbols. The potions are advantageously codewords, comprising symbols, generated by selecting, for each set of input symbols, a codeword from a codebook and by adapting, as for example by ordering or by inverting symbols in, the codewords to form the channel codeword.