Image compression by optimal reconstruction

Claim 1

A method of producing a video image from a compressed version of a source video image which has been compressed by transforming to a transform domain and quantizing said source video image in accordance with quantization constraints, comprising: inverse transforming from said transform domain and dequantizing said compressed version to produce a first decompressed video image; reducing total variation in said first decompressed video image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation image; transforming said reduced variation image to produce a revised transform and conforming said revised transform with said quantization constraints of said compressed version so as to produce a constrained transform; and inverse transforming said constrained transform so as to produce a replica of said source video image.

Claim 2

A method of producing a video image from a compressed version of a source video image which has been compressed by transforming to a transform domain and quantizing said source video image in accordance with quantization constraints, comprising: inverse transforming from said transform domain and dequantizing said compressed version to produce a first decompressed video image; reducing total variation in said first decompressed video image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation image; transforming said reduced variation image to produce a revised transform and conforming said revised transform with said quantization constraints of said compressed version so as to produce a constrained transform; and inverse transforming said constrained transform so as to produce a replica of said source video image.

Claim 7

A method of compressing a source video image, comprising: defining plural sub-transform operators corresponding to respective portions of a transform domain; initializing an initial prediction image; performing plural iterations corresponding to said plural sub-transform operators, each iteration comprising the following steps: (a) subtracting the prediction image of the previous iteration from said source video image to produce a residual image; (b) transforming said residual image with the sub-transform operator corresponding to the current iteration; (c) quantizing the result of step (b) by associating it with quantization constraints to produce a quantized transform residual and outputting said quantized transform residual; (d) dequantizing and inverse transforming said quantized transform residual; (e) adding the result of step (d) to the prediction image of the previous iteration to produce a current prediction image; (f) reducing total variation in said current prediction image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation current prediction image; (g) subtracting the prediction image of the previous iteration from said reduced variation current prediction image to produce a revised current residual image; (h) transforming said revised current residual image to produce a current residual transform and conforming said current residual transform with said quantization constraints of said transform residual of step (c) to produce a modified transform residual; (i) inverse transforming said modified transform residual to produce a modified residual image and adding said modified residual image to the prediction image of the previous iteration to produce the prediction image of the current iteration.

Claim 8

A method of compressing a source video image, comprising: defining plural sub-transform operators corresponding to respective portions of a transform domain; initializing an initial prediction image; performing plural iterations corresponding to said plural sub-transform operators, each iteration comprising the following steps: (a) subtracting the prediction image of the previous iteration from said source video image to produce a residual image; (b) transforming said residual image with the sub-transform operator corresponding to the current iteration; (c) quantizing the result of step (b) by associating it with quantization constraints to produce a quantized transform residual and outputting said quantized transform residual; (d) dequantizing and inverse transforming said quantized transform residual; (e) adding the result of step (d) to the prediction image of the previous iteration to produce a current prediction image; (f) reducing total variation in said current prediction image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation current prediction image; (g) subtracting the prediction image of the previous iteration from said reduced variation current prediction image to produce a revised current residual image; (h) transforming said revised current residual image to produce a current residual transform and conforming said current residual transform with said quantization constraints of said transform residual of step (c) to produce a modified transform residual; (i) inverse transforming said modified transform residual to produce a modified residual image and adding said modified residual image to the prediction image of the previous iteration to produce the prediction image of the current iteration.

Claim 15

A method of decompressing an image which has been compressed into successive quantized transform residuals satisfying respective quantization constraints, comprising: initializing an initial prediction image; performing an iteration of the following steps for each of said successive quantized transform residuals: (a) dequantizing and inverse transforming the quantized transform residual corresponding to the current iteration; (b) adding the result of step (a) to the prediction image of the previous iteration to produce a current prediction image; (c) reducing total variation in said current prediction image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation current prediction image; (d) subtracting the prediction image of the previous iteration from said reduced variation current prediction image to produce a revised current residual image; (e) transforming said revised current residual image to produce a current residual transform and conforming said current residual transform with said quantization constraints to produce a modified transform residual; (f) inverse transforming said modified transform residual to produce a modified residual image; combining the modified residual images of all iterations to produce a decompressed image.

Claim 16

A method of decompressing an image which has been compressed into successive quantized transform residuals satisfying respective quantization constraints, comprising: initializing an initial prediction image; performing an iteration of the following steps for each of said successive quantized transform residuals: (a) dequantizing and inverse transforming the quantized transform residual corresponding to the current iteration; (b) adding the result of step (a) to the prediction image of the previous iteration to produce a current prediction image; (c) reducing total variation in said current prediction image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation current prediction image; (d) subtracting the prediction image of the previous iteration from said reduced variation current prediction image to produce a revised current residual image; (e) transforming said revised current residual image to produce a current residual transform and conforming said current residual transform with said quantization constraints to produce a modified transform residual; (f) inverse transforming said modified transform residual to produce a modified residual image; combining the modified residual images of all iterations to produce a decompressed image.

Claim 21

A method of recovering a video image from a compressed version of a source video image which has been compressed by quantizing said source video image so as to impose quantization constraints thereon, comprising: dequantizing said compressed version to produce a first decompressed video image; reducing total variation in said first decompressed video image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation image; conforming said reduced variation image with said quantization constraints of said compressed version so as to produce a replica of said source video image.

Claim 22

A method of recovering a video image from a compressed version of a source video image which has been compressed by quantizing said source video image so as to impose quantization constraints thereon, comprising: dequantizing said compressed version to produce a first decompressed video image; reducing total variation in said first decompressed video image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation image; conforming said reduced variation image with said quantization constraints of said compressed version so as to produce a replica of said source video image.

Claim 25

A method of compressing a source video image, comprising: defining plural sub-transform operators corresponding to respective portions of a transform domain; initializing a prediction image; performing plural iterations corresponding to said plural sub-transform operators, each iteration comprising the following steps: (a) generating and outputting a quantized transform corresponding to the sub-transform operator of the current iteration of a residue of the source image and previous iteration's prediction image falling within certain quantization constraints; (b) generating an inverse transformed de-quantized residue from the result of step (a), adding it to the prediction image of the previous iteration and producing from the sum thereof a reduced-variation image, wherein lengths of level pixel sets in the image are reduced as a function of spatial oscillation of each level set; (c) subtracting the previous iteration's prediction image from said reduced-variation image to generate a revised residue; (d) conforming the transform of the revised residue with said quantization constraints and adding the inverse transform of the result thereof to the prediction image of the previous iteration to produce the prediction image of the current iteration.

Claim 26

A method of compressing a source video image, comprising: defining plural sub-transform operators corresponding to respective portions of a transform domain; initializing a prediction image; performing plural iterations corresponding to said plural sub-transform operators, each iteration comprising the following steps: (a) generating and outputting a quantized transform corresponding to the sub-transform operator of the current iteration of a residue of the source image and previous iteration's prediction image falling within certain quantization constraints; (b) generating an inverse transformed de-quantized residue from the result of step (a), adding it to the prediction image of the previous iteration and producing from the sum thereof a reduced-variation image, wherein lengths of level pixel sets in the image are reduced as a function of spatial oscillation of each level set; (c) subtracting the previous iteration's prediction image from said reduced-variation image to generate a revised residue; (d) conforming the transform of the revised residue with said quantization constraints and adding the inverse transform of the result thereof to the prediction image of the previous iteration to produce the prediction image of the current iteration.

Claim 28

A method of expanding an image of n pixels to an image of m*n pixels from a compressed version of the image which has been compressed by transforming to a transform domain and quantizing said image in accordance with quantization constraints, comprising: defining n blocks of m spatial frequency transform coefficients; defining each zero frequency coefficient in each of said blocks as being the value of the corresponding pixel in said n pixel image; dequantizing the coefficients in each block and inverse transforming each block to produce a trial image; reducing total variation in said trial image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation image; transforming said reduced variation image to produce a revised transform and conforming said revised transform with quantization constraints of the dequantizing step so as to produce a constrained transform; and inverse transforming said constrained transform so as to produce said expanded image.

Claim 29

A method of expanding an image of n pixels to an image of m*n pixels from a compressed version of the image which has been compressed by transforming to a transform domain and quantizing said image in accordance with quantization constraints, comprising: defining n blocks of m spatial frequency transform coefficients; defining each zero frequency coefficient in each of said blocks as being the value of the corresponding pixel in said n pixel image; dequantizing the coefficients in each block and inverse transforming each block to produce a trial image; reducing total variation in said trial image by reducing lengths of level pixel sets in the image as a function of spatial oscillation of each level set to produce a reduced variation image; transforming said reduced variation image to produce a revised transform and conforming said revised transform with quantization constraints of the dequantizing step so as to produce a constrained transform; and inverse transforming said constrained transform so as to produce said expanded image.