Rapid production of reduced-size images from compressed video streams
First Claim
Patent Images
1. 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.
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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.
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Citations
18 Claims
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1. A method for producing reduced-size images from a video stream, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A thumbnail generator comprising:
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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. - View Dependent Claims (16, 17)
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18. A computer readable medium carrying a set of instructions which, when performed, execute a method comprising:
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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.
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Specification