USH1684H
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fast preview processing for JPEG compressed images
Assignee: Xerox Corp
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Filing: 1995-09-29
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Granted: 1997-10-07
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Expires: 2015-09-29
Abstract
Abstract A method of fast decompressing a document image compressed using transform coding for scaling and previewing purposes. A fast algorithm is derived by utilizing a fraction of all available transform coefficients representing the image. The method is particularly efficient using the discrete cosine transform which is used in the JPEG ADCT algorithm. In JPEG ADCT, a very fast and efficient implementation is derived for a resolution reduction factor of 16 to 1 (4 to 1 in each direction) without needing any floating point arithmetic operations.
Inventors
- 👤 Ricardo L. de Queiroz
- 👤 Reiner Eschbach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 05:24
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/60; H04N19/30
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
103 words
A method of decompressing an image, compressed with a frequency space transform operation, for preview or scaling purposes, while approximating an accurate reproduction thereof, including the steps of: receiving from a transmission line or retrieving from memory storage devices a set of frequency space transform coefficients, representing a compressed image block of image signals; selecting a subset of said coefficients including fewer coefficients than said set thereof, said subset corresponding to coefficients for a predetermined group of low frequency components of said image; recovering an image approximation with a linear transform relating said subset of coefficients to pixels of the said image approximation.
Claim 2
Independent Claim
103 words
A method of decompressing an image, compressed with a frequency space transform operation, for preview or scaling purposes, while approximating an accurate reproduction thereof, including the steps of: receiving from a transmission line or retrieving from memory storage devices a set of frequency space transform coefficients, representing a compressed image block of image signals; selecting a subset of said coefficients including fewer coefficients than said set thereof, said subset corresponding to coefficients for a predetermined group of low frequency components of said image; recovering an image approximation with a linear transform relating said subset of coefficients to pixels of the said image approximation.
Claim 3
Dependent Claim
24 words
A method as described in claim 1, wherein the forward transform coding operation using the frequency space transform operation is a discrete cosine transform.
Claim 4
Independent Claim
131 words
A method of decompressing an image, compressed with a frequency space transform operation, for preview purposes, while approximating an accurate reproduction thereof, including the steps of: receiving from a transmission line or retrieving from a memory storage device, a M×M set of frequency space transform coefficients, representing a compressed M×M image block of image signals; selecting a N×N subset of said coefficients, said subset corresponding to coefficients for a predetermined group of low frequency components of said image; recovering an image approximation from said subset of coefficients, in accordance with the function: ##EQU20## where each z value is a pixel value in the described relative spatial relationship in an set of output image signals; each y value is a received coefficient value; and D N is an N×N inverse transform matrix.
Claim 5
Independent Claim
131 words
A method of decompressing an image, compressed with a frequency space transform operation, for preview purposes, while approximating an accurate reproduction thereof, including the steps of: receiving from a transmission line or retrieving from a memory storage device, a M×M set of frequency space transform coefficients, representing a compressed M×M image block of image signals; selecting a N×N subset of said coefficients, said subset corresponding to coefficients for a predetermined group of low frequency components of said image; recovering an image approximation from said subset of coefficients, in accordance with the function: ##EQU20## where each z value is a pixel value in the described relative spatial relationship in an set of output image signals; each y value is a received coefficient value; and D N is an N×N inverse transform matrix.
Claim 6
Dependent Claim
40 words
A method as described in claim 3, wherein the forward transform coding operation using the frequency space transform operation is a discrete cosine transform of M channels and the inverse transform operation is the discrete cosine transform of N channels.
Claim 7
Independent Claim
123 words
A method of decompressing an image, compressed with a frequency space transform operation, for preview purposes, while approximating an accurate reproduction thereof, including the steps of: receiving from a transmission line or retrieving from a memory storage device, an 8×8 set of frequency space transform coefficients, representing a compressed 8×8 image block of image signals; selecting a 2×2 subset of said coefficients, said subset corresponding to coefficients for a predetermined group of low frequency components of said image; recovering an image approximation from said subset of coefficients, in accordance with the function: ##EQU21## where each z value is a pixel value in the described relative spatial relationship in an set of output image signals; and each y value is a received coefficient value.
Claim 8
Independent Claim
123 words
A method of decompressing an image, compressed with a frequency space transform operation, for preview purposes, while approximating an accurate reproduction thereof, including the steps of: receiving from a transmission line or retrieving from a memory storage device, an 8×8 set of frequency space transform coefficients, representing a compressed 8×8 image block of image signals; selecting a 2×2 subset of said coefficients, said subset corresponding to coefficients for a predetermined group of low frequency components of said image; recovering an image approximation from said subset of coefficients, in accordance with the function: ##EQU21## where each z value is a pixel value in the described relative spatial relationship in an set of output image signals; and each y value is a received coefficient value.
Claim 9
Dependent Claim
24 words
A method as described in claim 5, wherein the forward transform coding operation using the frequency space transform operation is a discrete cosine transform.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-10-06 | 2001-04-07 | 2001-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-10-06 | 2005-04-07 | 2005-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-10-06 | 2009-04-07 | 2009-10-07 | $7700.00 | Window Closed / Lapsed |