Adaptive method of encoding and decoding a series of pictures by transformation, and devices for implementing this method

• US 6,661,844 B2
• Filed: 02/08/2002
• Issued: 12/09/2003
• Est. Priority Date: 12/30/1987
• Status: Expired due to Term

• Current Assignee: Thomson Licensing SA (Vantiva SA)
• Original Assignee: Thomson Licensing SA (Vantiva SA)
• Inventors: Ferre, Alain, Perron, Claude, Auvray, Eric
• Primary Examiner(s): Le, Vu
• Application Number:
  US10/071,686
• Publication Number:
  US 20020101928A1
• Time in Patent Office: 669 Days
• Field of Search: 375/240.02, 375/240.03, 375/240.12, 375/240.13, 375/240.14, 375/240.15, 375/240.16, 375/240.18, 375/240.2, 375/240.23, 375/240.24, 375/240.25, 375/240.26, 375/240.27, 375/240.28, 348/400.1, 348/403.1, 348/406.1, 348/409.1, 348/420.1, 348/425.2, 382/232-233, 382/236, 382/238, 382/245-246, 382/248, 382/250-251, 386/109, 386/111
• US Class Current: 375/240.18
• CPC Class Codes: H04N 11/044 involving transform coding
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/619 the transform being operated outside the prediction loop

Abstract

A method and a device for coding and decoding a sequence of images or pictures is disclosed. One exemplary embodiment disclosed codes by dividing each picture into blocks of picture elements. Each element of a block being represented by a digital value. Two types of coding are utilized in order to reduce the amount of data; inter-coding, which takes into account a corresponding block in a previous picture and intra coding, which is independent from a previous picture. Blocks being thus coded so that a further reduction of data is obtained by transmitting high spatial frequencies with less weight than low spatial frequencies. This is accomplished with the use of weighting coefficients. Weighting coefficients are variable as a function of the quantity of information to be transmitted.

Claims

1. A method for coding a sequence of pictures wherein each picture is divided into blocks of picture elements and a cosine transform is performed on the picture blocks to provide blocks of coefficients, the coding using a zigzag path to define the order to code the coefficients of each block and a variable length, or Huffman code, wherein the variable length or Huffman code comprises at least coding for coefficients which are preceded by a sequence of zero values;

for each block, the last sequence of zeros is not encoded and an inter-block word is inserted; and

between encoded data corresponding to two consecutive pictures, a picture separator word is inserted, each picture separator comprised of a pattern which cannot be imitated by licit concatenations of encoded data.