Patent Document ID: 8208558
Application ID: 12135430
Patent Status: 1

Claim One:
1. A method for determining direction mode for an image block in intra prediction of video frames comprising the steps of: limiting the image blocks to 4×4 blocks; transforming the image block into spatial frequency domain including calculating spatial frequency components of the form X ij for i=0 to 3 and j=0 to 3 and calculating a plurality of energy terms E dc , E vert , E horz and E diag as follows: 
 E DC =|X 00 |, 
 E vert =|X 01 |+|X 02 |+|X 03 |, 
 E horz =|X 10 |+|X 20 |+|X 30 |, and 
 E diag =|X 11 |+|X 12 |+|X 13 |+|X 21 |+|X 22 |+|X 23 |+|X 31 |+|X 32 |+|X 33 |; calculating a plurality of energy terms from the spatial frequency domain transformed image block; determining a coarse classification from said plurality of energy terms; and for spatial frequency domain transformed image blocks having at least one coarse classification, searching for a direction mode from among a subset of less than all possible direction modes dependent upon the coarse classification.