Rapid production of reduced-size images from compressed video streams
AssigneeVMark, Inc.
InventorsSanghoon Sull, Sungjoo Suh, Jung Rim Kim, Seong Soo Chun
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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.
Claims23
A method for producing reduced-size images from a video stream, comprising:
- determining a reduction factor for a reduced size image;
- selecting a reduced set of transform coefficients from each of a plurality of macroblocks by discarding higher-frequency coefficients;
- and
- performing an inverse transformation and field separation process on the selected coefficients to produce reduced-size pixels of the reduced size image.
A method for producing a reduced-size images from a video stream, comprising:
- determining DC values for frame encoded transform blocks within the video stream;
- determining half DC values for field encoded transform blocks within the video stream;
- and
- assigning pixel values in a reduced-size image based upon the DC values and half DC values.
A thumbnail generator comprising:
- means for determining a reduction factor for a reduced size image;
- means 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 pixels of the reduced size image.
Dependencies are inferred from the claim text.