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US 5,654,760 AGranted
Selection of quantization step size in accordance with predicted quantization noise
AssigneeSony Corporation
InventorTomoyuki Ohtsuki
Life of this patent
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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.
Claims19
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.
A quantization control method comprising the steps of:
- 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.
An encoding 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;
- 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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