Patent ID: 7551789

Claim:
A method of coding image data for compression, the method comprising: using an encoder for processing the image data using a lapped transform applied to blocks of the image data, wherein said processing using a lapped transform comprises, in part: processing a set of four points of image data straddling a block boundary using a four point overlap operator implemented by performing operations on first through fourth signal paths, said operations comprising at least: first lifting steps having a coefficient of one of the fourth signal path into the first signal path, and of the second signal path into the third signal path, second lifting steps having a coefficient of negative one half of the first signal path into the fourth signal path, and of the third signal path into the second signal path, third lifting steps having a coefficient of one half of the first signal path into the fourth signal path, and of the second signal path into the third signal path, fourth lifting steps having a coefficient of negative twenty-nine thirty-seconds of the fourth signal path into the first signal path, and of the third signal path into the second signal path, fifth lifting steps having a coefficient of three sixteenths of the first signal path into the fourth signal path, and of the second signal path into the third signal path, sixth lifting steps having a coefficient of three thirty-seconds of the fourth signal path into the first signal path, and of the third signal path into the first signal path; encoding coefficients produced by said processing using the lapped transform into a bitstream; and outputting the bitstream.