US 4,399,467 A · Method and apparatus for image data compression and decompression

Abstract

A data compression system which generates several types of symbols from bands of data derived from the digital image. Each group of data bits located in the same bit position across the data band is represented by a mode symbol, which signifies the decimal value of the binary combination of the data contained in that group. The mode symbol is followed by a run symbol, which represents the number of times or incremental positions that the same mode occurs successively until a different mode is generated. Mode and run symbols are transmitted in alternation, with each mode symbol followed by its corresponding run symbol, to an encoder, which generates variable length code words that are transmitted to a receiving station and decoded to provide symbols which are used to form a facsimile image. In one embodiment of this system, the mode and run symbols are combined to form a different type of symbol, known as a ternary octade symbol, to further improve the compression performance of the system.

Claims27

Dependent claims

An apparatus for the processing of digital data derived from an image, comprising:

means for separating said digital data into a plurality of data bands, with each of said data bands comprising a predetermined number of scan lines from said image;
first means for generating a plurality of first symbols, with each of said first symbols representative of a binary value of a series of data bits contained within a specific bit position in each of said scan lines within said data band;
second means for generating a plurality of second symbols, with each of said second symbols representing a number indicative of consecutive occurrences of an associated first symbol;
third means for generating a plurality of third symbols, with each of said third symbols comprising a section of data representing a first symbol and a section of data representing a second symbol, where said second symbol is associated with said first symbol;
and means for generating a plurality of code words representative of each of said third symbols.

2 more elements

An apparatus for the processing of digital data derived from an image, comprising:

means for separating said digital data into a plurality of data bands, with each of said data bands comprising a predetermined number of scan lines from said image;
first formation means, coupled to said separating means, for forming a plurality of first symbols, with each of said first symbols representative of a binary value of a series of data bits contained within a specific bit position in each of said scan lines within said data band;
counting means, responsive to said first formation means, for generating a plurality of second symbols, with each of said second symbols representing a number indicative of consecutive occurrences of an associated first symbol within said first formation means;
second formation means, coupled to said first formation means and said counting means, for forming a plurality of third symbols, with each of said third symbols comprising a section of data representing a first symbol from said first formation means and a section of data representing a second symbol from said counting means, where said second symbol is associated with said first symbol;
first storage means for storing a plurality of code words which are representative of each of said third symbols;
means for causing the generation of code words from said first storage means;
and means for outputting said generated code words over a transmission medium.

4 more elements

A method of processing digital data derived from an image, comprising the steps of:

(a) receiving a continuous stream of data bits which are derived from said image;
(b) storing a plurality of said data bits in a first storage means, wherein said first storage means separates said data bits into a plurality of data bands, with each of said data bands comprising a predetermined number of scan lines from said image;
(c) forming a plurality of first symbols using said data bits from said first storage means, with each of said first symbols representing a binary value of a series of data bits contained in a specific bit position in each of said scan lines within said first storage means;
(d) forming a plurality of second symbols, with each of said second symbols representing a number indicative of consecutive occurrences of an associated second symbol within said first storage means;
(e) forming a plurality of third symbols from said first and second symbols, where each of said third symbols contain a section of data representing said first symbol and a section of data representing said second signal, where said second signal is associated with said first symbol;
(f) inputting each of said third symbols to a second storae means as an address thereof;
(g) outputting from said second storage means a code word representative of each of said third symbols which are inputted;
and
(h) transmitting said code words over a transmission medium.

6 more elements

Dependencies are inferred from the claim text.

Method and apparatus for image data compression and decompression

Life of this patent

Method and apparatus for image data compression and decompression

Life of this patent

Abstract

Claims27