Apparatus for data compression and data decompression
First Claim
1. An apparatus for data compression comprising:
- a block-sorting transforming unit generating a new two-dimensional character matrix with rotating a character string in a block by a number of times equal to a number of characters in the block, the block which is obtained through dividing input data of a string into predetermined size of blocks, sorting rows in the matrix lexicographically, picking up last characters in the matrix in a sorted order, and outputting them as a block-sorted character string;
a move-to-front (hereinafter;
MTF) transforming unit having a reference list including all of characters composing said block-sorted character string, transforming each character of said block-sorted character string from a first character in turn into a code showing a registered position on said reference list, subsequently transforming a next character after moving the transformed character to the head of the reference list, transforming said block-sorted character string into an intermediate code string showing registered positions on said reference list, and outputting the intermediate code; and
an entropy coding unit having a plurality of code tables corresponding to a change of an input character string, and applying entropy coding to the intermediate code inputted from said MTF transforming unit with using the plurality of code table.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention provides a plurality of code tables such as a high-usage code table and a low-usage code table in an entropy coding unit, and transforms a block-sorted last character string from a block-sorting transforming unit into an MTF code string in an MTF transforming unit. The entropy coding unit switches the code tables at a discontinuous part of the MTF code string to perform entropy coding. In addition, the present invention stores reference lists, whose number is equal to the number of kinds of used characters, in a reference list memory. The MTF transforming unit selects a reference list corresponding to a first character of the block-sorted character string to perform an MTF transformation.
104 Citations
24 Claims
-
1. An apparatus for data compression comprising:
-
a block-sorting transforming unit generating a new two-dimensional character matrix with rotating a character string in a block by a number of times equal to a number of characters in the block, the block which is obtained through dividing input data of a string into predetermined size of blocks, sorting rows in the matrix lexicographically, picking up last characters in the matrix in a sorted order, and outputting them as a block-sorted character string; a move-to-front (hereinafter;
MTF) transforming unit having a reference list including all of characters composing said block-sorted character string, transforming each character of said block-sorted character string from a first character in turn into a code showing a registered position on said reference list, subsequently transforming a next character after moving the transformed character to the head of the reference list, transforming said block-sorted character string into an intermediate code string showing registered positions on said reference list, and outputting the intermediate code; andan entropy coding unit having a plurality of code tables corresponding to a change of an input character string, and applying entropy coding to the intermediate code inputted from said MTF transforming unit with using the plurality of code table. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. In an apparatus for data decompression:
-
generating a new two-dimensional character matrix with rotating a character string in a block by a number of times equal to a number of characters in the block, the block which is obtained through dividing input data of a string into predetermined size of blocks, sorting rows in the matrix lexicographically, picking up last characters of the two-dimensional character matrix in a sorted order, and outputting them as a block-sorted character string; having a reference list including all of characters composing said block-sorted character string, transforming each character of said block-sorted character string from a first character in turn into a code showing a registered position on said reference list, subsequently transforming a next character after moving the transformed character to the head of the reference list, transforming said block-sorted character string into an intermediate code string showing registered positions on said reference list, and outputting the intermediate code; and having a plurality of code tables corresponding to a change of an input character string, applying entropy coding to the intermediate code inputted from said MTF transforming unit, and decompressing said entropy-coded code string into an original character string, the apparatus for data decompression comprising; an entropy decoding unit having a plurality of code tables corresponding to a change of an input string, inputting said entropy-coded code string and decoding the string into said intermediate code string; an MTF inverse transforming unit restoring the intermediate code to said block-sorted character string using said reference list; and a block-sorting inverse transforming unit restoring to an original character string the block-sorted character string transformed by said MTF inverse transforming unit. - View Dependent Claims (9, 10, 11, 12, 13, 14)
-
-
15. An apparatus for data compression comprising:
-
a block-sorting transforming unit generating a new two-dimensional character matrix with rotating a character string in a block by a number of times equal to a number of characters in the block, the block which is obtained through dividing input data of a string into predetermined size of blocks, sorting rows in the matrix lexicographically, picking up last characters in the matrix in a sorted order, and outputting them as a block-sorted character string; a reference list memory storing a plurality of reference lists including characters composing said block-sorted character string; an intermediate code transforming unit selecting one of said plurality of reference lists, transforming each character of said block-sorted character string from a first character in turn into a code showing a registered position on said reference list, subsequently transforming a next character after moving the transformed character to the preceding position of the reference list, transforming said block-sorted character string into an intermediate code string showing registered positions on said reference list, and outputting the intermediate code; and an entropy coding unit having a plurality of code tables corresponding to a change of an input character string, and applying entropy coding to identification information on the used reference list and the intermediate code inputted from said intermediate code transforming unit. - View Dependent Claims (16, 17, 18, 19)
-
-
20. In an apparatus for data decompression:
-
generating a new two-dimensional character matrix through rotating a character string in a block by a number of times equal to a number of characters in the block, the block which is obtained through dividing input data of a string into predetermined size of blocks, sorting rows in the matrix lexicographically, picking up last characters of the two-dimensional character matrix in a sorted order, and outputting them as a block-sorted character string; having a plurality of reference lists including all of characters composing said block-sorted character string, selecting one of them, transforming each character of said block-sorted character string from a first character in turn into a code showing a registered position on said reference list, subsequently transforming a next character after moving the transformed character to a preceding position of the reference list, transforming said block-sorted character string into an intermediate code string showing registered positions on said reference list; and having a code table corresponding to a change of an input character string, inputting said intermediate code string and identification information on the reference list used for the transformation, applying entropy coding to them and decompressing the entropy-coded code string into the original character string, the apparatus for data decompression comprising; an entropy decoding unit having a code table corresponding to a change of an input string, inputting said entropy-coded code string and decoding the string into said intermediate code string and identification information on the reference list; a reference list memory storing a plurality of reference lists including all characters composing said block-sorted character string; an MTF inverse transforming unit restoring the intermediate code to said block-sorted character string with selecting a reference list specified by said identification information from said reference list memory; and a block-sorting inverse transforming unit restoring to the original character string the block-sorted character string transformed by said MTF inverse transforming unit. - View Dependent Claims (21, 22, 23, 24)
-
Specification