Patent ID: 6298166
Filing Date: 2001-10-02
Classification: G06T,H04N

Abstract:
A method for performing a dihedral symmetry operation on a spatial domain representation of a digital image by manipulating a linear transform domain representation of the digital image, said method comprising the steps of:parsing compressed image data of the digital image to extract an offset value and a DC value for each of a plurality of linear-transform-based coded data blocks, wherein elements of the data blocks were previously coded as a sequence of symbol trios so that the steps of said method are performed without de-zigzagging and zigzagging the elements of each data block;accessing each of the plurality of linear-transform-based coded data blocks by using the corresponding offset value;extracting a sequence of non-zero elements from each of the plurality of linear-transform-based coded data blocks;transposing the sequence of non-zero elements within each data block without expanding into a full data block; andcoding the transposed sequence of non-zero elements of each data block;wherein the spatial domain representation of the digital image undergoes a dihedral symmetry operation.