Method and a system for coding rois

(54) METHOD AND A SYSTEM FOR CODING ROIS

(75) Inventors: Charilaos Christopoulos, Sollentuna (SE); Joel Askelof, Uppsala (SE); Mathias Larsson, Saltsjobaden (SE)

(73) Assignee: Telefonaktiebolaget LM Ericsson (publ), Stockholm (SE)

( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.

(21) Appl. No.: 09/827,313

(22) Filed: Apr. 6, 2001

(65) Prior Publication Data

US 2002/0126906 Al Sep. 12, 2002

Related U.S. Application Data

(63) Continuation of application No. PCT/SE99/01785, filed on Oct. 6, 1999.

(30) Foreign Application Priority Data

Oct. 9, 1998 (SE) 9803454

(51) Int. C I. G06K 9/36

(52) U.S. CI 382/243; 382/240; 382/248

(58) Field of Search 382/239, 240,

382/243, 232, 244, 248, 251; 375/240.19,

240.02

(56) References Cited

U.S. PATENT DOCUMENTS

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5,333,212 A 7/1994 Ligtenberg 382/250

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5,363,138 A 11/1994 Hayashi et al 348/390.1

In a method and a system for encoding and transmission of still images having at least one region of interest (ROI), the ROI coefficients of an image transformed into the frequency domain, preferably using a wavelet transform are encoded so that they are transmitted first and can be decoded by a receiver without transmission of the boundary of the ROI. In a preferred embodiment the coefficients belonging to the ROI are shifted so that the minimum ROI coefficient is larger than the largest background coefficient. A receiver can then perform an opposite procedure and thereby obtain the ROI. By specifying how much the coefficients need to be shifted in order to avoid sending shape information several advantages are achieved. Thus, it is possible to avoid sending shape information and to avoid shape encoding at encoder side. Furthermore, there is no need for a shape decoder at receiver side, and there is no need for the receiver to produce the ROI mask. Also, in another preferred embodiment, the shifting (or scaling operations) required at encoder and decoder are also avoided.

43 Claims, 4 Drawing Sheets

OBTAIN I (QUANT.) L MAX COEFF.

OTHER PUBLICATIONS

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* cited by examiner