Selection of quantization step size in accordance with predicted quantization noise
First Claim
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1. A quantization control apparatus comprising:
- quantization noise curve estimating means for estimating a quantization noise curve by determining quantization noise as a function of a quantization step size for a block of image data and limiting said quantization noise curve to a quantization step size which becomes saturated such that said quantization noise is a maximum for larger values of said quantization step size; and
selecting means for selecting an actual quantization step size in accordance with the estimated quantization noise curve such that said actual quantization step size is not saturated.
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Abstract
A video image encoder estimates a quantization noise curve which will result from quantizing a coefficient data block and uses the estimated quantization noise curve and a specified minimum noise value to select the quantization step size actually used to quantize the coefficient data block. The quantization step size is also selected as a function of transmission buffer occupancy so as to limit the amount of encoded data to a predetermined rate.
118 Citations
19 Claims
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1. A quantization control apparatus comprising:
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quantization noise curve estimating means for estimating a quantization noise curve by determining quantization noise as a function of a quantization step size for a block of image data and limiting said quantization noise curve to a quantization step size which becomes saturated such that said quantization noise is a maximum for larger values of said quantization step size; and selecting means for selecting an actual quantization step size in accordance with the estimated quantization noise curve such that said actual quantization step size is not saturated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A quantization control method comprising the steps of:
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estimating a quantization noise curve by determining quantization noise as a function of a quantization step size for a block of image data and limiting said quantization noise curve to a quantization step size which becomes saturated such that said quantization noise is a maximum for larger values of said quantization step size; and selecting an actual quantization step size in accordance with the estimated quantization noise curve such that said actual quantization step size is not saturated. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. An encoding apparatus comprising:
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quantization noise curve estimating means for estimating a quantization noise curve by determining quantization noise as a function of a quantization-step size for a block of image data and limiting said quantization noise curve to a quantization step size which becomes saturated such that said quantization noise is a maximum for larger values of said quantization step size; selecting means for selecting an actual quantization step size in accordance with the estimated quantization noise curve such that said actual quantization step size is not saturated; and quantizing means for quantizing said block of image data using said actual quantization step size.
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Specification