US 6,445,828 B1 · Transform domain resizing of an image compressed with field encoded blocks

Abstract

A video editing system which resizes a video stream in a transform domain is disclosed. The video editing system partial decodes a compressed video stream in order to obtain a transform domain representation of the video stream. The transform domain representation of the video stream includes both frame encoded blocks and field encoded blocks. The field encoded blocks result from reordering of pels prior to transform domain encoding the pels. The frame encoded blocks, however, result from transform domain encoding pels without reordering pels. Accordingly, the video editing system of the present invention accounts for the encoding differences between the field encoded blocks and the frame encoded blocks when resizing the video stream in the transform domain. To this end, the video editing system includes field resizing matrices for resizing the field encoded blocks and frame resizing matrices for resizing the frame encoded blocks. The video editing system selects and applies appropriate matrices to the encoded blocks the video stream in order to resize the video stream in the transform domain.

Claims8

Dependent claims

A method of resizing a spatial domain image represented in a transform domain by a plurality of transform domain blocks, comprising the steps of:

(A) obtaining from said plurality of transform domain. blocks, a first transform domain block that represents in said transform domain a plurality of pels reordered in a field format in said spatial domain image;
(B) resizing said first transform domain block by operating upon said first transform domain block in said transform domain, said resizing including the steps of:
(B1) obtaining a first resizing matrix that is based upon C 8 ⁢ S f 1 / 2 ⁢ V ⁢ [ C 8 1 0 0 C 8 1 ] ,
wherein C8 represents an 8×8 DCT matrix, and Sf½v represents an 8×16 vertical downsampling matrix that downsamples reordered pels represent by said first transform domain block by a factor of two;
and
(B2) obtaining a second resizing matrix that is based upon C 8 ⁢ S 1 / 2 ⁢ h ⁢ [ C 8 1 0 0 C 8 1 ] ,
wherein S½h represents an 8×16 downsampling matrix;
and
(B3) multiplying said first resizing matrix, said first transform domain block, and said second resizing matrix together to obtain a resized transform domain block having different resolution than said first transform domain block.

6 more elements

A method of resizing a spatial domain image represented in a transform domain by a plurality of transform domain blocks ones of which have been spatially frame-to-field or field-to-frame reordered, comprising the steps of:

(A) obtaining a first transform domain block from said plurality of transform domain blocks;
(B) determining whether said first transform domain block represents in said transform domain (i) spatially frame-to-field reordered pels of said spatial domain image, or (ii) spatially intact non-reordered pels of said spatial domain Image;
(C) performing in said transform domain, field block resizing operations upon said first transform domain block according to the equation
Yf=TfvXfTfh
if said step (B) determines that said first transform domain block represents spatially frame-to-field reordered pels of said spatial domain image, where Xf represents a coefficient matrix of frame-to-field reordered blocks, Tfv represents a DCT vertical resizing matrix for resizing field DCT coded blocks in the vertical direction, Tfh represents a DCT horizontal resizing matrix for resizing field DCT coded blocks in the horizontal direction and Yf represents a resized field DCT block;
(D) performing in said transform domain, frame block resizing operations upon said first transform domain block according to the equation
YF=TFvXFTFh
if said step (B) determines that said first transform domain block represents spatially intact non-reordered pels of said spatial domain image, where XF represents a coefficient matrix of frame ordered blocks, TFv represents a DCT vertical resizing matrix for resizing frame DCT coded blocks in the vertical direction, TFh represents a DCT horizontal resizing matrix for resizing frame DCT coded blocks in the horizontal direction and YF represents a resized frame DCT block;
and
where TFv is not equal to Tfh.

7 more elements

Dependencies are inferred from the claim text.

Transform domain resizing of an image compressed with field encoded blocks

Life of this patent

Transform domain resizing of an image compressed with field encoded blocks

Life of this patent

Abstract

Claims8