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

• US 6,563,875 B2
• Filed: 10/17/2001
• Issued: 05/13/2003
• 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:
  US09/978,376
• Publication Number:
  US 20020039387A1
• Time in Patent Office: 573 Days
• Field of Search: 375/240.02, 375/240.12, 375/240.13, 375/240.14, 375/240.15, 375/240.16, 375/240.18, 375/240.19, 375/240.2, 375/240.24, 382/238, 382/236, 382/248, 382/250, 382/251, 386/111, 348/400.1, 348/403.1, 348/404.1, 348/420.1, 348/406.1
• US Class Current: 375/240.13
• 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 comprising the steps of:

dividing each picture into blocks of picture elements;

representing each block of picture elements by a luminance block and two chrominance blocks;

using two kinds of coding in order to reduce the amount of data, an inter coding which takes into account a corresponding block in a previous picture, and intra coding which is independent from a previous picture;

obtaining a further reduction of data by transmitting high spatial frequencies with less weight than low spatial frequencies by using weighting coefficients accordingly;

applying the same weighting coefficients to the luminance and the chrominance blocks corresponding to the block of picture elements; and

varying the weighting coefficients as a function of whether the block of picture elements is inter coded or intra coded.

2. A method according to claim 1, wherein a picture is coded by performing a cosine transform on the luminance and chrominance blocks to provide blocks of coefficients.

3. A method according to claim 2, wherein the weighting coefficients are applied to the transformed blocks of coefficients.