RESAMPLING AND PICTURE RESIZING OPERATIONS FOR MULTI-RESOLUTION VIDEO CODING AND DECODING
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Abstract
Techniques and tools for high accuracy position calculation for picture resizing in applications such as spatially-scalable video coding and decoding are described. In one aspect, resampling of a video picture is performed according to a resampling scale factor. The resampling comprises computation of a sample value at a position i,j in a resampled array. The computation includes computing a derived horizontal or vertical sub-sample position x or y in a manner that involves approximating a value in part by multiplying a 2n value by an inverse (approximate or exact) of the upsampling scale factor. The approximating can be a rounding or some other kind of approximating, such as a ceiling or floor function that approximates to a nearby integer. The sample value is interpolated using a filter.
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Citations
30 Claims
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1-2. -2. (canceled)
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3. A computer system adapted to perform a method comprising:
performing upsampling of a video picture according to a horizontal upsampling scale factor and a vertical upsampling scale factor, wherein the upsampling comprises computation of an interpolated sample value at horizontal position i and vertical position j in an upsampled array, and wherein the computation comprises; computing a derived horizontal sub-sample position x in a manner that is mathematically equivalent in result to the formula x=(i*C+D)>
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S, wherein C is derived by approximating a value equivalent to 2S+F multiplied by an inverse of the horizontal upsampling scale factor, and wherein F, C, D, and S are integer values;computing a derived vertical sub-sample position y in a manner that is mathematically equivalent in result to the formula y=(j*C+D)>
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S, wherein C is derived by approximating a value equivalent to 2S+F multiplied by an inverse of the vertical upsampling scale factor; andinterpolating a sample value at the derived sub-sample position x, y. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 18)
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13. (canceled)
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15-17. -17. (canceled)
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19-22. -22. (canceled)
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23. A method of performing upsampling of base layer image data with a computing device that implements an image or video encoder or decoder, the method comprising, for a position in an upsampled array:
with the computing device, computing a position in the base layer image data, wherein x indicates a value for the position in the base layer image data, wherein derivation of x includes computation that is mathematically equivalent in result to (j*C+D)>
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S, and wherein;j indicates a value for the position in the upsampled array; C approximates 2S+F multiplied by an inverse of a scale factor; D is an offset; S is a shift value; and F is based on a number of bits in a fractional component of x.
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24. In a computer system, a method comprising:
processing spatially scalable video using a resampling filter that produces correct relative luma and chroma alignment for plural alignment structures, the spatially scalable video capable of being processed at plural spatial resolutions. - View Dependent Claims (25, 26, 27, 28, 29, 30)
Specification