Adaptive deadzone size adjustment in quantization
First Claim
Patent Images
1. A method of encoding image or video information, the method comprising:
- using a computer, dividing the image or a picture associated with the video information into multiple blocks;
getting a texture measurement for the image or video information;
adjusting deadzone size of a quantizer, on a block basis, based at least in part on the texture measurement, so that the deadzone size expands as an amount of texture increases, wherein the texture is related to a smoothness of a block;
quantizing the image or video information using the quantizer with the adjusted deadzone size to transform the image or video information to a quantized version thereof; and
performing a frequency transform that produces a DC coefficient and plural AC coefficients, wherein the plural AC coefficients are the information that is quantized and for at least one of the plural AC coefficients, the adjusted deadzone size of the quantizer is also based at least in part on the AC coefficient.
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Abstract
Techniques and tools are described for adaptive deadzone (“DZ”) resizing during quantization. For example, in some embodiments, for quantization of an AC frequency coefficient of a block, a video encoder adjusts DZ size of a selected quantizer depending on the texture of the block. In other embodiments, a video encoder adjusts DZ size depending on the frequency of a coefficient being quantized. In still other embodiments, for quantization of an AC frequency coefficient of a block, a video encoder adjusts DZ size depending on the texture of the block and the frequency of the coefficient being quantized.
358 Citations
19 Claims
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1. A method of encoding image or video information, the method comprising:
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using a computer, dividing the image or a picture associated with the video information into multiple blocks; getting a texture measurement for the image or video information; adjusting deadzone size of a quantizer, on a block basis, based at least in part on the texture measurement, so that the deadzone size expands as an amount of texture increases, wherein the texture is related to a smoothness of a block; quantizing the image or video information using the quantizer with the adjusted deadzone size to transform the image or video information to a quantized version thereof; and performing a frequency transform that produces a DC coefficient and plural AC coefficients, wherein the plural AC coefficients are the information that is quantized and for at least one of the plural AC coefficients, the adjusted deadzone size of the quantizer is also based at least in part on the AC coefficient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of encoding image or video information, the method comprising:
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using a computer, performing a frequency transform on plural values for image or video information, producing a DC coefficient and plural frequency coefficients including plural AC coefficients; and for at least one of the plural frequency coefficients; adjusting deadzone size of a quantizer based at least in part on frequency of the AC coefficient, so that the deadzone size becomes wider for higher frequency coefficients; and quantizing the coefficient using the quantizer with the adjusted deadzone size. - View Dependent Claims (10, 11, 12, 14, 15, 16)
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13. The method of 12 further comprising computing the weighted deadzone size offset by multiplying a texture-dependent offset by a frequency-dependent weight.
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17. An encoder comprising:
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a frequency transformer for converting values, in a computer, for image or video information into plural frequency coefficients that include a DC coefficient and plural AC coefficients; a module for measuring texture for the image or video information; a quantizer for quantizing the plural frequency coefficients, including, for the plural AC coefficients, adjusting deadzone size of a quantizer on a block-by-block basis based at least in part on the measured texture and frequencies of the plural AC coefficients, so that the deadzone size expands with an increasing amount of measured texture and the deadzone size becomes wider for higher frequency coefficients; and an entropy encoder for entropy encoding results of the quantizing. - View Dependent Claims (18)
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19. A computer-readable non-volatile memory storing instructions for executing a method, the method comprising:
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using a computer, dividing the image or a picture associated with the video information into multiple blocks; getting a texture measurement for the image or video information; adjusting deadzone size of a quantizer, on a block basis, based at least in part on the texture measurement, so that the deadzone size expands as an amount of texture increases, wherein the texture is related to a smoothness of a block; quantizing the image or video information using the quantizer with the adjusted deadzone size to transform the image or video information to a quantized version thereof; and performing a frequency transform that produces a DC coefficient and plural AC coefficients, wherein the plural AC coefficients are the information that is quantized and for at least one of the plural AC coefficients, the adjusted deadzone size of the quantizer is also based at least in part on the AC coefficient.
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Specification