US4979038A
Expired / Lapsed
US
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Variable threshold quantification process in encoding by transformation for the transmission of image signals
Assignee: France Telecom R&D SA
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Filing: 1989-09-18
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Granted: 1990-12-18
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Expires: 2009-09-18
Abstract
Abstract The invention relates to a quantization process in an encoding by transformation for transmission on a low rate link of an image signal, said image signal being processed in the form of blocks, each containing a set of digital data, each block being transformed to produce a transformed block of coefficients (Ci) representing the frequency components of the block, each transformed coefficients of a block being quantified during a scan by comparison with quantization levels, the first being called the threshold, the process being characterized in that the quantization is performed with a threshold (T) able to vary between one transfored coefficient (Ci) and the next (Ci+1) in the scan, depending on whether the transformed coefficient does or does not fulfil the conditions -T<Ci<+T.
Inventors
- 👤 Jacques Guichard
- 👤 Geard Eude
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:29
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/60; H04N19/10; H04N19/102; H04N19/124; H04N19/13; H04N19/132; H04N19/90; H04N19/91
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
173 words
A quantization process for encoding by transformation the transmission on a low rate link of an image signal, the latter being treated ion the form of blocks, each containing a set of digital data organized in matrix form and representing part of an image or a difference between two image parts, comprising the steps of: transforming each block by a transformation operator to produce a transformed block of transformed coefficients (C 1-N ) organized in matrix form and representing the frequency components of said image part or said different between two image parts; applying said quantization process to each transformed block; performing a comparison of each transformed coefficient of a transformed block being quantized, at the end of a scan of the block with quantization levels; and wherein the quantization is performed with a quantization step G and a threshold T liable to vary between one transformed coefficient (Ci) and the next coefficient (Ci+1) in the scan, depending on whether the transformed coefficient Ci is higher, lower or equal to said quantization step.
Claim 2
Dependent Claim
173 words
A quantization process for encoding by transformation the transmission on a low rate link of an image signal, the latter being treated ion the form of blocks, each containing a set of digital data organized in matrix form and representing part of an image or a difference between two image parts, comprising the steps of: transforming each block by a transformation operator to produce a transformed block of transformed coefficients (C 1-N ) organized in matrix form and representing the frequency components of said image part or said different between two image parts; applying said quantization process to each transformed block; performing a comparison of each transformed coefficient of a transformed block being quantized, at the end of a scan of the block with quantization levels; and wherein the quantization is performed with a quantization step G and a threshold T liable to vary between one transformed coefficient (Ci) and the next coefficient (Ci+1) in the scan, depending on whether the transformed coefficient Ci is higher, lower or equal to said quantization step.
Claim 3
Dependent Claim
126 words
A quantization process according to claim 1 further comprising: selecting for one block of a given image a first threshold equal to the quantization step (T=G); defining two first quantization thresholds by the interval ]-G, +G[; performing a comparison on each coefficient C 1-N to establish whether said coefficient fulfils the following condition (III): -T<Ci<T, the same threshold T=G is retained for the following coefficient Ci+1 in the case where the coefficient Ci does not fulfil this condition, a code Ki being transmitted on the transmission link in place of CI, the threshold T (T=T+a) is incremented for the following coefficient Ci+1 in the case where the coefficient Ci fulfills the condition (III), a code Ki=0 being transmitted on the transmission link in place of Ci.
Claim 4
Dependent Claim
26 words
A quantization process according to claims 1 or 2, further comprising: incrementing successively the threshold T; and performing a comparison with a predetermined maximum threshold Tmax.
Claim 5
Dependent Claim
18 words
A quantization process according to claim 3, further comprising: selecting a maximum threshold Tmax of the form G+ki.
Claim 6
Dependent Claim
22 words
A quantization process according to claim 4, further comprising: selecting a non-zero code Ki for encoding a coefficient Ci such that: G.(Ki+1)≦Ci≦G.Ki.
Claim 7
Dependent Claim
45 words
A quantization process according to claim 5, further comprising: performing a double scan consisting of scanning the coefficients in two opposite directions, one passing from a first coefficient Co to a final coefficient Cp and the other from the final coefficient to the first coefficient.
Claim 8
Dependent Claim
13 words
A quantization process according to claim 6, further comprising: performing a diagonal scan.
Claim 9
Dependent Claim
13 words
A quantization process according to claim 6, further comprising: performing a horizontal scan.
Claim 10
Dependent Claim
13 words
A quantization process according to claim 6 further comprising: performing a vertical scan.
Claim 11
Dependent Claim
20 words
A quantization process according to claim 6, characterized in that the blocks are thresholded and encoded following a Peano scan.
Claim 12
Dependent Claim
39 words
A quantization process according to claim 10, characterized in that the quantization step chosen for a block can be modified between one image and the other, between one block group and the other and one block and the other.
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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) | 1993-12-17 | 1994-06-18 | 1994-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-17 | 1998-06-18 | 1998-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-17 | 2002-06-18 | 2002-12-18 | $7700.00 | Window Closed / Lapsed |