Video scaling method and device
First Claim
1. A device for scaling an input of a first plurality of pixels arrayed in horizontal rows and vertical columns that form an image in order to provide an output of a second plurality of pixels that forms the image, each of the pixels having N components, the device comprising as a set:
- an upscaling interpolator comprising (a) a buffer for storing the input pixels, and (b) a linear interpolator that sequentially receives each of the stored input pixels from said buffer and the pixel subsequent thereto for providing interpolated output pixels therefrom responsive to a predetermined upscaling factor; and
a decimating finite impulse response (FIR) filter for reducing the number of output pixels from said upscaling interpolator responsive to a predetermined downscaling factor, said decimating FIR filter comprising no more than two row buffers for each of the pixel components, said second plurality being equal to said first plurality times said upscaling and downscaling factors,wherein repetitive operation of said set of said upscaling interpolator and said decimating FIR filter will provide an output of the second plurality of pixels that forms the image.
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Abstract
A linear interpolator and decimating FIR filter with constant coefficients may be used in various configurations to scale a still or moving color video image horizontally (changing the number of pixels per row) or vertically (changing the number of pixels per column). For downscaling, the input pixel stream is initially upscaled with an interpolator by an upscaling factor of between one and two chosen so that the result can be subsequently downscaled with a decimation-by-power-of-two finite impulse response (FIR) filter to provide the desired final scaling. Upscaling is a special case accomplished by means of linear interpolation. Vertical and horizontal scaling may be performed with different, independent scaling factors.
172 Citations
19 Claims
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1. A device for scaling an input of a first plurality of pixels arrayed in horizontal rows and vertical columns that form an image in order to provide an output of a second plurality of pixels that forms the image, each of the pixels having N components, the device comprising as a set:
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an upscaling interpolator comprising (a) a buffer for storing the input pixels, and (b) a linear interpolator that sequentially receives each of the stored input pixels from said buffer and the pixel subsequent thereto for providing interpolated output pixels therefrom responsive to a predetermined upscaling factor; and a decimating finite impulse response (FIR) filter for reducing the number of output pixels from said upscaling interpolator responsive to a predetermined downscaling factor, said decimating FIR filter comprising no more than two row buffers for each of the pixel components, said second plurality being equal to said first plurality times said upscaling and downscaling factors, wherein repetitive operation of said set of said upscaling interpolator and said decimating FIR filter will provide an output of the second plurality of pixels that forms the image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A device for scaling an input of a first plurality of pixels that form an image in order to provide an output of a second plurality of pixels that forms the image, the device comprising two sets of:
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an interpolator for increasing the number of input pixels to a third plurality of interpolated pixels; and a decimating-by-power-of-two FIR filter with only two row buffers for reducing the number of interpolated pixels to said second plurality of output pixels. - View Dependent Claims (10, 11, 12)
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13. A device for scaling an input of a first plurality of pixels arrayed in horizontal rows and vertical columns that form an image in order to provide an output of a second plurality of pixels that forms the image, each of the pixels having N components, the device comprising:
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first means for vertically scaling pixels responsive to a vertical scaling factor; and second means connected in series with said first means for horizontally scaling pixels responsive to a horizontal scaling factor, said horizontal scaling factor being independent from said vertical scaling factor, each of first and second means comprising an upscaling interpolator and a decimating-by-power-of-two FIR filter with no more than two row buffers per component. - View Dependent Claims (14)
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15. A device for scaling an input of a first plurality of pixels arrayed in horizontal rows and vertical columns that form an image in order to provide an output of a second plurality of pixels that forms the image, each of the pixels having N color components, the device comprising:
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first means for vertically scaling pixels; and second means for horizontally scaling pixels connected in series with said first means, each of said first and second means comprising plural sets of an upscaling interpolator and a decimating FIR filter with no more than two row buffers per color component connected in series therewith, each of said sets for scaling at least one of said N color components. - View Dependent Claims (16, 17)
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18. A method of scaling an input of a first plurality of pixels that form an image to provide an output of a second plurality of pixels that forms the image, each of the pixels having N components, the method comprising the steps of:
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(a) upscaling the input pixels in an interpolator responsive to an upscaling factor; and (b) decimating the upscaled pixels in decimation-by-power-of-two FIR filter using no more than two row buffers, the upscaling factor being selected so that the subsequent decimation by power of two provides the second plurality of pixels. - View Dependent Claims (19)
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Specification