Patent ID: 8255445

Claim:
A process implemented using instructions encoded on computer readable storage medium for deriving an order-16 integer transform using a plurality of order-8 integer transforms in image and video coding, the process comprising: retrieving a data matrix X 16×16 to be transformed; determining C m , the m th vector of an intermediate matrix C 16×16 , based on the retrieved matrix X 16×16 , by carrying out eight additions and eight subtractions in accordance with a rule of C m = [ c 0 , m c 1 , m … c 7 , m c 8 , m c 9 , m … c 15 , m ] = [ x 0 , m + x 1 , m x 2 , m + x 3 , m … x 14 , m + x 15 , m x 0 , m - x 1 , m x 2 , m - x 3 , m … x 14 , m - x 15 , m ] wherein c i,m is the (i, m) th element of C 16×16 , and x i,m is the (i, m) th element of X 16×16 , 0≦m≦15 and 0≦i≦15; deriving the order-16 integer transform by carrying out the order-8 integer transform for the first 8 vectors of the matrix C 16×16 , and carrying out one more order-8 integer transform for the last 8 vectors of the matrix C 16×16 ; and normalizing the order-16 integer transform by using a scaling matrix K 16×16 , where, and where a = 1 512 , b = 1 578 ⁢ ⁢ and ⁢ ⁢ c = 1 320 .