Patent ID: 6058211
Filing Date: 2000-05-02
Classification: H04N

Abstract:
A method of compressing digital data comprising the steps of:step a) inputting a first matrix of elements, a value of each element of the first matrix being represented by a set of a plurality of ""S"" intensity values corresponding to ""S"" quantized levels of a characteristic of each element, each set of intensity values associated with an element in the first matrix being representable by a coordinate of a point in an ""S"" dimensional space, the ""S"" dimensional space having axes representing the intensity of the ""S"" quantized levels of the characteristic as variables;step b) determining an occurrence matrix (O.sub.L1, . . . O.sub.LN . . . O.sub.LW) on an element-by-element basis for the elements in the first matrix, the position of an element in said occurrence matrix (O.sub.L1, . . . O.sub.LN . . . O.sub.LW) being determined by the distance from the origin in the ""S"" dimensional space to the coordinate of the point in the ""S"" dimensional space represented by the set of intensity values for that element as determined by a step-wise space filling curve passing uniquely through each coordinate of the S-dimensional space; and a value of an element (OL.sub.N) of the occurrence matrix (O.sub.L1, . . . O.sub.LN . . . O.sub.LW) being the number of times that a coordinate in ""S"" space represented by the set of intensity values of an element of the first matrix has a particular distance L.sub.N from the origin of the ""S"" space as determined by the step-wise space filling curve; and storing the occurrence matrix (O.sub.L1, . . . O.sub.LN . . . O.sub.LW),step c) replacing each element of the first matrix by the distance from the origin in the s-dimensional space to the coordinate in the S-dimensional space representing the set of intensity values associated with that element to form a second matrix, and storing the second matrix,step d) segmenting the occurrence matrix (O.sub.L1, . . . O.sub.LN . . . O.sub.LW) into a variable finite number ""P"" of occurrence segments, andstep e) determining contour elements of first regions in said second matrix, the contour elements of said first regions being determined by segmenting the second matrix into said first regions using the occurrence segments of the occurrence matrix (O.sub.L1, . . . O.sub.LN . . . O.sub.LW) the distance values in the S-dimensional space of each element of the second matrix in one first region of the second matrix falling into one of the ""P"" occurrence segments.