Rapid production of reduced-size images from compressed video streams
AssigneeVMark, Inc.
InventorsSanghoon Sull, Sungjoo Suh, Jung Rim Kim, Seong Soo Chun
Life of this patent
Estimating the term…
Abstract
Methods for fast generating spatially reduced-size images directly from compressed video streams supporting the coding of interlaced frames through transform coding and motion compensation. A sequence of reduced-size images are rapidly generated from compressed video streams by efficiently combining the steps of inverse transform, down-sampling and construction of each field image. The construction of reduced-size field images also allows the efficient motion compensation. The fast generation of reduced-size images is applicable to a variety of low-cost applications such as video browsing, video summary, fast thumbnail playback and video indexing.
Claims18
A method for producing reduced-size images from a video stream, comprising:
- selecting a reduced set of transform coefficients from each of a plurality of macroblocks by discarding higher-frequency coefficients in response to a reduction factor;
- and
- performing an inverse transformation and field separation process on the selected coefficients to produce reduced-size top-field and bottom-field image blocks.
A thumbnail generator comprising:
- means for determining a reduction factor for a reduced size image;
- means, responsive to said reduction factor, for selecting a reduced set of transform coefficients from each of a plurality of macroblocks by discarding higher-frequency coefficients;
- and
- means for performing an inverse transformation and field separation process on the selected coefficients to produce reduced-size top-field and bottom-field image blocks.
A computer readable medium carrying a set of instructions which, when performed, execute a method comprising:
- selecting a reduced set of transform coefficients from each of a plurality of macroblocks by discarding higher-frequency coefficient in response to a reduction factor;
- and
- performing an inverse transformation and field separation process on the selected coefficients to produce reduced-size top-field and bottom-field image blocks.
Dependencies are inferred from the claim text.