US6850650B1
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System and method for recompressing a jpeg image using requantization
Assignee: CA Inc
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Filing: 2001-11-09
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Granted: 2005-02-01
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Expires: 2021-11-09
Abstract
Abstract A system and method for recompressing a JPEG image using requantization is described. DCT transform coefficients for a compressed JPEG image are statistically analyzed to generate a stored numeric error representation. Local minimizers are determined from the stored numeric error representation with selective rounding. A new quantization matrix Q 1 is selected from the local minimizers bounded by a target quantization matrix Q bound . The compressed JPEG image is recompressed using the new quantization matrix Q 1 .
Inventors
- 👤 Heinz Bauschke
- 👤 Mason Macklem
- 👤 Nicholas Swart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:50
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/10; H04N19/102; H04N19/124; H04N19/126; H04N19/40; H04N19/60
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
81 words
A system for recompressing a JPEG image using requantization, comprising: a matrix module statistically analyzing DCT transform coefficients for a compressed JPEG image to generate a stored numeric error representation, determining local minimizers from the stored numeric error representation with selective rounding, and selecting a new quantization matrix Q 1 from the local minimizers bounded by a target quantization matrix Q bound ; and an image recompression module recompressing the compressed JPEG image using the new quantization matrix Q 1 .
Claim 2
Independent Claim
81 words
A system for recompressing a JPEG image using requantization, comprising: a matrix module statistically analyzing DCT transform coefficients for a compressed JPEG image to generate a stored numeric error representation, determining local minimizers from the stored numeric error representation with selective rounding, and selecting a new quantization matrix Q 1 from the local minimizers bounded by a target quantization matrix Q bound ; and an image recompression module recompressing the compressed JPEG image using the new quantization matrix Q 1 .
Claim 3
Independent Claim
73 words
A method for recompressing a JPEG image using requantization, comprising: statistically analyzing DCT transform coefficients for a compressed JPEG image to generate a stored numeric error representation; determining local minimizers from the stored numeric error representation with selective rounding; selecting a new quantization matrix Q 1 from the local minimizers bounded by a target quantization matrix Q bound ; and recompressing the compressed JPEG image using the new quantization matrix Q 1 .
Claim 4
Independent Claim
73 words
A method for recompressing a JPEG image using requantization, comprising: statistically analyzing DCT transform coefficients for a compressed JPEG image to generate a stored numeric error representation; determining local minimizers from the stored numeric error representation with selective rounding; selecting a new quantization matrix Q 1 from the local minimizers bounded by a target quantization matrix Q bound ; and recompressing the compressed JPEG image using the new quantization matrix Q 1 .
Claim 5
Independent Claim
157 words
A system for constructing a new quantization matrix for use in recompressing a JPEG image, comprising: an intermediate constant module determining an intermediate constant k computed in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; a matrix module defining a new quantization matrix Q 1 , comprising a plurality of quantizers q 1 , from an initial quantization matrix Q 0 , comprising a plurality of quantizers q 0 , each such quantizer q 1 computed in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k is odd ; kq 0 + 1 , if k > 0 and k is even . ; and a recompression module recompressing a JPEG image using the new quantization matrix Q 1 .
Claim 6
Independent Claim
157 words
A system for constructing a new quantization matrix for use in recompressing a JPEG image, comprising: an intermediate constant module determining an intermediate constant k computed in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; a matrix module defining a new quantization matrix Q 1 , comprising a plurality of quantizers q 1 , from an initial quantization matrix Q 0 , comprising a plurality of quantizers q 0 , each such quantizer q 1 computed in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k is odd ; kq 0 + 1 , if k > 0 and k is even . ; and a recompression module recompressing a JPEG image using the new quantization matrix Q 1 .
Claim 7
Dependent Claim
22 words
A system according to claim 3 , further comprising: a compression module compressing the JPEG image using a lossy JPEG compression mode.
Claim 8
Independent Claim
147 words
A method for constructing a new quantization matrix for use in recompressing a JPEG image, comprising: determining an intermediate constant k computed in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; defining a new quantization matrix Q 1 , comprising a plurality of quantizers q 1 , from an initial quantization matrix Q 0 , comprising a plurality of quantizers q 0 , each such quantizer q 1 computed in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k is odd ; kq 0 + 1 , if k > 0 and k is even . ; and recompressing a JPEG image using the new quantization matrix Q 1 .
Claim 9
Independent Claim
147 words
A method for constructing a new quantization matrix for use in recompressing a JPEG image, comprising: determining an intermediate constant k computed in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; defining a new quantization matrix Q 1 , comprising a plurality of quantizers q 1 , from an initial quantization matrix Q 0 , comprising a plurality of quantizers q 0 , each such quantizer q 1 computed in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k is odd ; kq 0 + 1 , if k > 0 and k is even . ; and recompressing a JPEG image using the new quantization matrix Q 1 .
Claim 10
Dependent Claim
19 words
A method according to claim 5 , further comprising: compressing the JPEG image using a lossy JPEG compression mode.
Claim 11
Independent Claim
137 words
A system for constructing a new quantization matrix for use in recompressing a JPEG image with selective rounding, comprising: an intermediate constant module determining an intermediate constant k computed in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; a matrix module defining a new quantization matrix Q 1 , comprising a plurality of quantizers q 1 , from an initial quantization matrix Q 0 , comprising a plurality of quantizers q 0 , each such quantizer q 1 computed in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k > 0. ; and a recompression module recompressing a JPEG image using the new quantization matrix Q 1 while rounding each half integer value towards zero.
Claim 12
Independent Claim
137 words
A system for constructing a new quantization matrix for use in recompressing a JPEG image with selective rounding, comprising: an intermediate constant module determining an intermediate constant k computed in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; a matrix module defining a new quantization matrix Q 1 , comprising a plurality of quantizers q 1 , from an initial quantization matrix Q 0 , comprising a plurality of quantizers q 0 , each such quantizer q 1 computed in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k > 0. ; and a recompression module recompressing a JPEG image using the new quantization matrix Q 1 while rounding each half integer value towards zero.
Claim 13
Dependent Claim
22 words
A system according to claim 7 , further comprising: a compression module compressing the JPEG image using a lossy JPEG compression mode.
Claim 14
Independent Claim
127 words
A method for constructing a new quantization matrix for use in recompressing a JPEG image with selective rounding, comprising: determining an intermediate constant k computed in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; defining a new quantization matrix Q 1 , comprising a plurality of quantizers q 1 , from an initial quantization matrix Q 0 , comprising a plurality of quantizers q 0 , each such quantizer q 1 computed in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k > 0. ; and recompressing a JPEG image using the new quantization matrix Q 1 while rounding each half integer value towards zero.
Claim 15
Independent Claim
127 words
A method for constructing a new quantization matrix for use in recompressing a JPEG image with selective rounding, comprising: determining an intermediate constant k computed in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; defining a new quantization matrix Q 1 , comprising a plurality of quantizers q 1 , from an initial quantization matrix Q 0 , comprising a plurality of quantizers q 0 , each such quantizer q 1 computed in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k > 0. ; and recompressing a JPEG image using the new quantization matrix Q 1 while rounding each half integer value towards zero.
Claim 16
Dependent Claim
19 words
A method according to claim 9 , further comprising: compressing the JPEG image using a lossy JPEG compression mode.
Claim 17
Independent Claim
181 words
A system for recompressing a JPEG image using requantization, comprising: a JPEG image stored as compressed image data quantized per an initial quantization matrix Q 0 comprising a plurality of initial quantizers q 0 ; a quantization matrix generator defining a target quantization matrix Q bound comprising a plurality of target quantizers q bound , computing an intermediate constant k in accordance with the equation: k = ⌊ q bound q 0 ⌋ , and constructing a new quantization matrix Q 1 comprising a plurality of quantizers q 1 from the initial quantization matrix Q 0 by computing each such quantizer q 1 in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k is odd ; kq 0 + 1 , if k > 0 and k is even . ; and an image recompression module requantizing the compressed image data using the new quantization matrix Q 1 .
Claim 18
Independent Claim
181 words
A system for recompressing a JPEG image using requantization, comprising: a JPEG image stored as compressed image data quantized per an initial quantization matrix Q 0 comprising a plurality of initial quantizers q 0 ; a quantization matrix generator defining a target quantization matrix Q bound comprising a plurality of target quantizers q bound , computing an intermediate constant k in accordance with the equation: k = ⌊ q bound q 0 ⌋ , and constructing a new quantization matrix Q 1 comprising a plurality of quantizers q 1 from the initial quantization matrix Q 0 by computing each such quantizer q 1 in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k is odd ; kq 0 + 1 , if k > 0 and k is even . ; and an image recompression module requantizing the compressed image data using the new quantization matrix Q 1 .
Claim 19
Dependent Claim
46 words
A system according to claim 11 , wherein the JPEG image comprises a color image, further comprising: a component separation submodule separating the color image into separate color components; and a quantization submodule requantizing each such color component using the new quantization matrix Q 1 .
Claim 20
Dependent Claim
32 words
A system according to claim 11 , wherein the JPEG image comprises a grayscale image, further comprising: a quantization submodule requantizing the grayscale image using the new quantization matrix Q 1 .
Claim 21
Dependent Claim
40 words
A system according to claim 11 , further comprising: a partition submodule partitioning the JPEG image; a transformation submodule transforming each partition using a DCT; and a quantization submodule quantizing the transformed partitions using the quantization matrix Q 0 .
Claim 22
Dependent Claim
21 words
A system according to claim 11 , wherein the JPEG image is compressed using one of baseline sequential encoding and DCT-encoding.
Claim 23
Independent Claim
172 words
A method for recompressing a JPEG image using requantization, comprising: storing a JPEG image as compressed image data quantized per an initial quantization matrix Q 0 comprising a plurality of initial quantizers q 0 ; defining a target quantization matrix Q bound comprising a plurality of target quantizers q bound ; computing an intermediate constant k in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; constructing a new quantization matrix Q 1 comprising a plurality of quantizers q 1 from the initial quantization matrix Q 0 by computing each such quantizer q 1 in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k is odd ; kq 0 + 1 , if k > 0 and k is even . ; and requantizing the compressed image data using the new quantization matrix Q 1 .
Claim 24
Independent Claim
172 words
A method for recompressing a JPEG image using requantization, comprising: storing a JPEG image as compressed image data quantized per an initial quantization matrix Q 0 comprising a plurality of initial quantizers q 0 ; defining a target quantization matrix Q bound comprising a plurality of target quantizers q bound ; computing an intermediate constant k in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; constructing a new quantization matrix Q 1 comprising a plurality of quantizers q 1 from the initial quantization matrix Q 0 by computing each such quantizer q 1 in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k is odd ; kq 0 + 1 , if k > 0 and k is even . ; and requantizing the compressed image data using the new quantization matrix Q 1 .
Claim 25
Dependent Claim
39 words
A method according to claim 16 , wherein the JPEG image comprises a color image, further comprising: separating the color image into separate color components; and requantizing each such color component using the new quantization matrix Q 1 .
Claim 26
Dependent Claim
29 words
A method according to claim 16 , wherein the JPEG image comprises a grayscale image, further comprising: requantizing the grayscale image using the new quantization matrix Q 1 .
Claim 27
Dependent Claim
31 words
A method according to claim 16 , further comprising: partitioning the JPEG image; transforming each partition using a DCT; and quantizing the transformed partitions using the quantization matrix Q 0 .
Claim 28
Dependent Claim
21 words
A method according to claim 16 , wherein the JPEG image is compressed using one of baseline sequential encoding and DCT-encoding.
Claim 29
Independent Claim
161 words
A system for recompressing a JPEG image using requantization with selective rounding, comprising: a JPEG image stored as compressed image data quantized per an initial quantization matrix Q 0 comprising a plurality of initial quantizers q 0 ; a quantization matrix generator defining a target quantization matrix Q bound comprising a plurality of target quantizers q bound , computing an intermediate constant k in accordance with the equation: k = ⌊ q bound q 0 ⌋ , and constructing a new quantization matrix Q 1 comprising a plurality of quantizers q 1 from the initial quantization matrix Q 0 by computing each such quantizer q 1 in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k > 0. ; and an image recompression module requantizing the compressed image data using the new quantization matrix Q 1 by rounding each half integer value towards zero.
Claim 30
Independent Claim
161 words
A system for recompressing a JPEG image using requantization with selective rounding, comprising: a JPEG image stored as compressed image data quantized per an initial quantization matrix Q 0 comprising a plurality of initial quantizers q 0 ; a quantization matrix generator defining a target quantization matrix Q bound comprising a plurality of target quantizers q bound , computing an intermediate constant k in accordance with the equation: k = ⌊ q bound q 0 ⌋ , and constructing a new quantization matrix Q 1 comprising a plurality of quantizers q 1 from the initial quantization matrix Q 0 by computing each such quantizer q 1 in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k > 0. ; and an image recompression module requantizing the compressed image data using the new quantization matrix Q 1 by rounding each half integer value towards zero.
Claim 31
Dependent Claim
46 words
A system according to claim 21 , wherein the JPEG image comprises a color image, further comprising: a component separation submodule separating the color image into separate color components; and a quantization submodule requantizing each such color component using the new quantization matrix Q 1 .
Claim 32
Dependent Claim
32 words
A system according to claim 21 , wherein the JPEG image comprises a grayscale image, further comprising: a quantization submodule requantizing the grayscale image using the new quantization matrix Q 1 .
Claim 33
Dependent Claim
40 words
A system according to claim 21 , further comprising: a partition submodule partitioning the JPEG image; a transformation submodule transforming each partition using a DCT; and a quantization submodule quantizing the transformed partitions using the quantization matrix Q 0 .
Claim 34
Dependent Claim
21 words
A system according to claim 21 , wherein the JPEG image is compressed using one of baseline sequential encoding and DCT-encoding.
Claim 35
Independent Claim
152 words
A method for recompressing a JPEG image using requantization with selective rounding, comprising: storing a JPEG image as compressed image data quantized per an initial quantization matrix Q 0 comprising a plurality of initial quantizers q 0 ; defining a target quantization matrix Q bound comprising a plurality of target quantizers q bound ; computing an intermediate constant k in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; constructing a new quantization matrix Q 1 comprising a plurality of quantizers q 1 from the initial quantization matrix Q 0 by computing each such quantizer q 1 in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k > 0. ; and requantizing the compressed image data using the new quantization matrix Q 1 by rounding each half integer value towards zero.
Claim 36
Independent Claim
152 words
A method for recompressing a JPEG image using requantization with selective rounding, comprising: storing a JPEG image as compressed image data quantized per an initial quantization matrix Q 0 comprising a plurality of initial quantizers q 0 ; defining a target quantization matrix Q bound comprising a plurality of target quantizers q bound ; computing an intermediate constant k in accordance with the equation: k = ⌊ q bound q 0 ⌋ ; constructing a new quantization matrix Q 1 comprising a plurality of quantizers q 1 from the initial quantization matrix Q 0 by computing each such quantizer q 1 in accordance with the equation: q 1 = { q 0 , if k = 0 ; kq 0 , if k > 0. ; and requantizing the compressed image data using the new quantization matrix Q 1 by rounding each half integer value towards zero.
Claim 37
Dependent Claim
39 words
A method according to claim 26 , wherein the JPEG image comprises a color image, further comprising: separating the color image into separate color components; and requantizing each such color component using the new quantization matrix Q 1 .
Claim 38
Dependent Claim
29 words
A method according to claim 26 , wherein the JPEG image comprises a grayscale image, further comprising: requantizing the grayscale image using the new quantization matrix Q 1 .
Claim 39
Dependent Claim
31 words
A method according to claim 26 , further comprising: partitioning the JPEG image; transforming each partition using a DCT; and quantizing the transformed partitions using the quantization matrix Q 0 .
Claim 40
Dependent Claim
21 words
A method according to claim 26 , wherein the JPEG image is compressed using one of baseline sequential encoding and DCT-encoding.
References Cited (Backward Citations)
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