US5737451A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for suppressing blocking artifacts in block-transform coded images
Assignee: Eastman Kodak Co
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Filing: 1996-04-10
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Granted: 1998-04-07
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Expires: 2016-04-10
Abstract
Abstract An improved method for removing blocking artifacts in regions of slowly varying intensity in an electronic image decoded from a transform coded representation of an image, includes the steps of: receiving signals indicative of DC and AC coefficient values of transformed blocks of image data; modifying the DC value in each of the blocks based on the level of activity within the block and the DC values in neighboring blocks; performing AC prediction in each block using the modified DC values; replacing the AC values in each block with the AC predicted values based on the level of activity within the block and the modified DC values in neighboring blocks; and reconstructing the image using the modified DC and AC coefficient values.
Inventors
- 👤 Bhavan R. Gandhi
- 👤 Majid Rabbani
- 👤 Rodney L. Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 10:46
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/85; H04N19/86; H04N19/10; H04N19/102; H04N19/117; H04N19/134; H04N19/136; H04N19/14; H04N19/146; H04N19/149; H04N19/154; H04N19/169; H04N19/18; H04N19/44; H04N19/48; H04N19/50; H04N19/503; H04N19/51; H04N19/527; H04N19/60
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
118 words
An improved method for removing blocking artifacts in regions of slowly varying intensity in an electronic image decoded from a transform-coded representation of an image, the method comprising the steps of: (a) receiving signals indicative of DC and AC coefficient values of transformed blocks of image data; (b) dequantizing the quantized coefficient values; (c) modifying the DC value in each of the blocks based on the level of activity within the block and the DC values in neighboring blocks; (d) replacing the AC values in each block with the AC predicted values based on the modified DC values in the block and in neighboring blocks; and (e) reconstructing the image using the modified DC and AC coefficient values.
Claim 2
Dependent Claim
118 words
An improved method for removing blocking artifacts in regions of slowly varying intensity in an electronic image decoded from a transform-coded representation of an image, the method comprising the steps of: (a) receiving signals indicative of DC and AC coefficient values of transformed blocks of image data; (b) dequantizing the quantized coefficient values; (c) modifying the DC value in each of the blocks based on the level of activity within the block and the DC values in neighboring blocks; (d) replacing the AC values in each block with the AC predicted values based on the modified DC values in the block and in neighboring blocks; and (e) reconstructing the image using the modified DC and AC coefficient values.
Claim 3
Dependent Claim
31 words
The method as in claim 1, wherein step (c) further comprises computing the activity level by identifying a highest AC coefficient index that represents a non-zero frequency component in the block.
Claim 4
Dependent Claim
39 words
The method as in claim 1, wherein step (c) further comprises computing the activity level by calculating a maximum absolute value difference between the DC value of a block and its eight nearest neighbors for forming a local gradient.
Claim 5
Dependent Claim
59 words
The method as in claim 1, wherein step (c) further comprises modifying the DC value by convolving a low pass filter with the DC coefficients derived from the received transformed blocks of image data and replacing the DC coefficient derived from the received transformed blocks of image data with the convolved DC coefficient if a predetermined criterion is met.
Claim 6
Dependent Claim
21 words
The method as in claim 4, wherein the predetermined criterion includes determining when the local gradient is less than a threshold.
Claim 7
Dependent Claim
18 words
The method as in claim 1 further comprising performing adaptive AC prediction on the result of step (d).
Claim 8
Dependent Claim
24 words
The method as in claim 1 further comprising performing a consistency check of the results of the modified DC values and AC predicted values.
Claim 9
Dependent Claim
100 words
A computer for receiving signals indicative of DC and AC coefficient values of transformed blocks of image data and for removing artifacts of slowly varying intensity from the image data, the computer comprising: (a) means for dequantizing coefficient values; (b) means for modifying the DC value in each of the blocks based on the level of activity within the block and the DC values in neighboring blocks; and (c) means for replacing the AC values in each block with the AC predicted values based on the level of activity within the block and the modified DC values in neighboring blocks.
Claim 10
Dependent Claim
100 words
A computer for receiving signals indicative of DC and AC coefficient values of transformed blocks of image data and for removing artifacts of slowly varying intensity from the image data, the computer comprising: (a) means for dequantizing coefficient values; (b) means for modifying the DC value in each of the blocks based on the level of activity within the block and the DC values in neighboring blocks; and (c) means for replacing the AC values in each block with the AC predicted values based on the level of activity within the block and the modified DC values in neighboring blocks.
Claim 11
Dependent Claim
30 words
The computer as in claim 8 further comprising means for computing the activity level by identifying a highest AC coefficient index that represents a non-zero frequency component in the block.
Claim 12
Dependent Claim
38 words
The computer as in claim 8 further comprising means for computing the activity level by calculating a maximum absolute value difference between the DC value of a block and its eight nearest neighbors for forming a local gradient.
Claim 13
Dependent Claim
58 words
The computer as in claim 10 further comprising means for modifying the DC value by convolving a low pass filter with the DC coefficients derived from the received transformed blocks of image data and replacing the DC coefficient derived from the received transformed blocks of image data with the convolved DC coefficient if a predetermined criterion is met.
Claim 14
Dependent Claim
20 words
The computer as in claim 11, further comprising means for determining when the local gradient is less than a threshold.
Claim 15
Dependent Claim
106 words
A computer program product comprising: a computer readable storage medium having a computer program stored thereon for performing the steps of: (a) receiving signals indicative of DC and AC coefficient values of transformed blocks of image data; (b) modifying the DC value in each of the blocks based on the level of activity within the block and the DC values in neighboring blocks; (c) replacing the AC values in each block with the AC predicted values based on the level of activity within the block and the modified DC values in neighboring blocks; and (d) reconstructing the image using the modified DC and AC coefficient values.
Claim 16
Dependent Claim
106 words
A computer program product comprising: a computer readable storage medium having a computer program stored thereon for performing the steps of: (a) receiving signals indicative of DC and AC coefficient values of transformed blocks of image data; (b) modifying the DC value in each of the blocks based on the level of activity within the block and the DC values in neighboring blocks; (c) replacing the AC values in each block with the AC predicted values based on the level of activity within the block and the modified DC values in neighboring blocks; and (d) reconstructing the image using the modified DC and AC coefficient values.
Claim 17
Dependent Claim
33 words
The computer program product as in claim 13 further comprising the step of computing the activity level by identifying a highest AC coefficient index that represents a non-zero frequency component in the block.
Claim 18
Dependent Claim
41 words
The computer program product as in claim 14 further comprising the step of computing the activity level by calculating a maximum absolute value difference between the DC value of a block and its eight nearest neighbors for forming a local gradient.
Claim 19
Dependent Claim
61 words
The computer program product as in claim 15 further comprising the step of modifying the DC value by convolving a low pass filter with the DC coefficient derived from the received transformed blocks of image data and replacing the DC coefficient derived from the received transformed blocks of image data with the convolved DC coefficient if a predetermined criterion is met.
Claim 20
Dependent Claim
23 words
The computer program product as in claim 16 further comprising the step of determining when the local gradient is less than a threshold.
Claim 21
Dependent Claim
23 words
The computer program product as in claim 13 further comprising the step of performing adaptive AC prediction on the results of step (c).
Claim 22
Dependent Claim
29 words
The computer program product as in claim 13 further comprising the step of performing a consistency check on the results of the modified DC values and AC predicted values.
Claim 23
Dependent Claim
70 words
An improved method for removing blocking artifacts in regions of slowly varying intensity in an electronic image decoded from a transform-coded representation of an image, the method comprising the steps of: (a) receiving signals indicative of DC and AC coefficient values of transformed blocks of image data; (b) modifying the DC value in each of the blocks; and (c) reconstructing the image using the modified DC and AC coefficient values.
Claim 24
Dependent Claim
70 words
An improved method for removing blocking artifacts in regions of slowly varying intensity in an electronic image decoded from a transform-coded representation of an image, the method comprising the steps of: (a) receiving signals indicative of DC and AC coefficient values of transformed blocks of image data; (b) modifying the DC value in each of the blocks; and (c) reconstructing the image using the modified DC and AC coefficient values.
Claim 25
Dependent Claim
36 words
The method as in claim 20, wherein step (b) further includes modifying the DC value in each of the blocks based on the level of activity within the block and the DC values in neighboring blocks.
Claim 26
Dependent Claim
37 words
The method as in claim 21 further comprising replacing the AC values in each block with the AC predicted values based on the level of activity within the block and the modified DC values in neighboring blocks.
Claim 27
Dependent Claim
31 words
The method as in claim 20, wherein step (b) further comprises computing the activity level by identifying a highest AC coefficient index that represents a non-zero frequency component in the block.
Claim 28
Dependent Claim
39 words
The method as in claim 20, wherein step (b) further comprises computing the activity level by calculating a maximum absolute value difference between the DC value of a block and its eight nearest neighbors for forming a local gradient.
Claim 29
Dependent Claim
59 words
The method as in claim 20, wherein step (b) further comprises modifying the DC value by convolving a low pass filter with the DC coefficients derived from the received transformed blocks of image data and replacing the DC coefficient derived from the received transformed blocks of image data with the convolved DC coefficient if a predetermined criterion is met.
Claim 30
Dependent Claim
21 words
The method as in claim 25, wherein the predetermined criterion includes determining when the local gradient is less than a threshold.
Claim 31
Dependent Claim
18 words
The method as in claim 20 further comprising performing adaptive AC prediction on the result of step (c).
Claim 32
Dependent Claim
24 words
The method as in claim 20 further comprising performing a consistency check of the results of the modified DC values and AC predicted values.
Claim 33
Independent Claim
47 words
A method for verifying the results of adaptive DC correlation, the method comprising: (a) receiving a signal representative of a DC coefficient of adaptive DC correlation; and (b) determining whether the DC coefficient is consistent with a previous computed value from which the DC coefficient is derived.
Claim 34
Independent Claim
47 words
A method for verifying the results of adaptive DC correlation, the method comprising: (a) receiving a signal representative of a DC coefficient of adaptive DC correlation; and (b) determining whether the DC coefficient is consistent with a previous computed value from which the DC coefficient is derived.
Claim 35
Dependent Claim
20 words
The method as in claim 29 further comprising modifying the DC coefficient based on whether the DC coefficient is consistent.
Claim 36
Dependent Claim
40 words
The method as in claim 29 further comprising receiving a signal representative of an AC coefficient of adaptive AC correlation; and determining whether the AC coefficient is consistent with a previous computed value from which the AC coefficient is derived.
Claim 37
Dependent Claim
20 words
The method as in claim 31 further comprising modifying the AC coefficient based on whether the AC coefficient is consistent.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-04-06 | 2001-10-06 | 2002-04-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-04-06 | 2005-10-06 | 2006-04-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-04-06 | 2009-10-06 | 2010-04-07 | $7700.00 | Window Closed / Lapsed |