US5796875A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective de-blocking filter for DCT compressed images
Assignee: Sony Corp
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Filing: 1996-08-13
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Granted: 1998-08-18
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Expires: 2016-08-13
Abstract
Abstract A method and apparatus to selectively post process decompressed image data to minimize blocking effects. Each pair of pixels across a block boundary is examined to determine whether the boundary pixels should be filtered. In one embodiment, if the difference between boundary pixels is less than a first predetermined threshold and the energy along the boundary is less than a second predetermined threshold, the boundary pixels are filtered to produce an output image having minimized blocking effects along block boundaries.
Inventors
- 👤 Christopher Jensen Read
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:51
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/10; H04N19/102; H04N19/117; G; G06; G06T; G06T5/00; G06T5/20; G06T9/00; H04N19/85; H04N19/86
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
114 words
A method for minimizing blocking effects in an image described by image data, said method comprising the steps of: for each pair of boundary pixels across a block boundary, determining if a difference between boundary pixels is less than a first predetermined threshold, determining if the energy along the boundary is greater than a second predetermined threshold, if the difference between boundary pixels is less than the first predetermined threshold and energy along the boundary is less than a second predetermined threshold, filtering the boundary pixels to minimize blocking effects to generate an adjusted image, said filtering configured to minimize the variance between a filtered pixel and the same pixel in a corresponding original.
Claim 2
Independent Claim
114 words
A method for minimizing blocking effects in an image described by image data, said method comprising the steps of: for each pair of boundary pixels across a block boundary, determining if a difference between boundary pixels is less than a first predetermined threshold, determining if the energy along the boundary is greater than a second predetermined threshold, if the difference between boundary pixels is less than the first predetermined threshold and energy along the boundary is less than a second predetermined threshold, filtering the boundary pixels to minimize blocking effects to generate an adjusted image, said filtering configured to minimize the variance between a filtered pixel and the same pixel in a corresponding original.
Claim 3
Dependent Claim
26 words
The method as set forth in claim 1, further comprising the step of filtering pixels adjacent to the boundary pixels if the boundary pixels are filtered.
Claim 4
Dependent Claim
38 words
The method as set forth in claim 1, wherein the first predetermined threshold is selected to be sufficiently high such that a real edge of the image that occurs along a block boundary is not removed by filtering.
Claim 5
Dependent Claim
23 words
The method as set forth in claim 1, wherein the first predetermined threshold is a value in the range of 16 to 32.
Claim 6
Dependent Claim
36 words
The method as set forth in claim 1, wherein the second predetermined threshold is selected to be sufficiently high to be indicative that filtering of the boundary pixels increases the blocking effects along the block boundary.
Claim 7
Dependent Claim
49 words
The method as set forth in claim 1, wherein the energy is measured as the sum of the absolute differences between the boundary pixels and adjacent pixels along a same edge of the boundary and the second predetermined threshold is set to be the absolute difference between boundary pixels.
Claim 8
Dependent Claim
24 words
The method as set forth in claim 1, wherein the step of filtering the boundary pixels is performed using a finite impulse response filter.
Claim 9
Dependent Claim
14 words
The method as set forth in claim 7, wherein four filter coefficients are used.
Claim 10
Dependent Claim
68 words
The method as set forth in claim 1, wherein the step of filtering the boundary pixels B, C comprises the following steps: adjusting boundary pixel B to be equal to pA+qB+rC+sD, where p, q, r, and s are filter coefficients, A is a pixel adjacent to pixel B and D is a pixel adjacent to boundary pixel C; and adjusting boundary pixel C to be equal to sA+rB+qC+pD.
Claim 11
Independent Claim
133 words
A system comprising: a first logic coupled to receive as input pixel data of an image, said first logic determining if a difference between boundary pixels across a block boundary is greater than a first predetermined threshold and if energy along the block boundary is greater than a second predetermined threshold; and a filter device coupled to the first logic configured to minimize the variance between a filtered pixel and the same pixel in a corresponding original, said filter device filtering the boundary pixels to minimize blocking effects if the difference between boundary pixels across the block boundary is less than the first predetermined threshold and the energy along the block boundary is less than the second predetermined threshold, said filter device outputting an adjusted image having minimized block effects along block boundaries.
Claim 12
Independent Claim
133 words
A system comprising: a first logic coupled to receive as input pixel data of an image, said first logic determining if a difference between boundary pixels across a block boundary is greater than a first predetermined threshold and if energy along the block boundary is greater than a second predetermined threshold; and a filter device coupled to the first logic configured to minimize the variance between a filtered pixel and the same pixel in a corresponding original, said filter device filtering the boundary pixels to minimize blocking effects if the difference between boundary pixels across the block boundary is less than the first predetermined threshold and the energy along the block boundary is less than the second predetermined threshold, said filter device outputting an adjusted image having minimized block effects along block boundaries.
Claim 13
Dependent Claim
60 words
The system as set forth in claim 10, further comprising: an input device for receiving compressed image data; a decoder coupled to the input device for decoding the compressed image data to provide decompressed image data provided to the first logic as the input pixel data; and a display device coupled to the filter device for displaying the adjusted image.
Claim 14
Dependent Claim
38 words
The system as set forth in claim 10, wherein the first predetermined threshold is selected to be sufficiently high such that a real edge of the image that occurs along a block boundary is not removed by filtering.
Claim 15
Dependent Claim
23 words
The system as set forth in claim 10, wherein the first predetermined threshold is a value in the range of 16 to 32.
Claim 16
Dependent Claim
36 words
The system as set forth in claim 10, wherein the second predetermined threshold is selected to be sufficiently high to be indicative that filtering of the boundary pixels increases the blocking effects along the block boundary.
Claim 17
Dependent Claim
48 words
The system as set forth in claim 10, wherein the energy is measured as the sum of absolute differences between the boundary pixels and adjacent pixels on a same edge of the boundary and the second predetermined threshold is set to be the absolute difference between boundary pixels.
Claim 18
Dependent Claim
24 words
The system as set forth in claim 10, wherein the step of filtering the boundary pixels is performed using a finite impulse response filter.
Claim 19
Dependent Claim
58 words
The system as set forth in claim 10, wherein the filter device adjusts boundary pixel B to be equal to pA+qB+rC+sD, where p, q, r, and s are filter coefficients, A is a pixel adjacent to pixel B and D is a pixel adjacent to boundary pixel C, and adjusts boundary pixel C to be equal to sA+rB+qC+pD.
Claim 20
Dependent Claim
125 words
A computer system comprising: an input device for receiving image data; a processor coupled to the input device configured to selectively filter boundary pixels along block boundaries, said processor determining if a difference between boundary pixels across a block boundary is less than a first predetermined threshold and if energy along the block boundary is less than a second predetermined threshold, filtering the boundary pixels to minimize blocking effects if the difference between boundary pixels across the block boundary is greater than the first predetermined threshold and the energy along the block boundary is greater than the second predetermined threshold and outputting an adjusted image having minimized block effects along block boundaries; and a display device coupled to the processor for displaying the adjusted image.
Claim 21
Dependent Claim
125 words
A computer system comprising: an input device for receiving image data; a processor coupled to the input device configured to selectively filter boundary pixels along block boundaries, said processor determining if a difference between boundary pixels across a block boundary is less than a first predetermined threshold and if energy along the block boundary is less than a second predetermined threshold, filtering the boundary pixels to minimize blocking effects if the difference between boundary pixels across the block boundary is greater than the first predetermined threshold and the energy along the block boundary is greater than the second predetermined threshold and outputting an adjusted image having minimized block effects along block boundaries; and a display device coupled to the processor for displaying the adjusted image.
Claim 22
Dependent Claim
79 words
The computer system as set forth in claim 18, wherein the computer system is a video teleconferencing system, and said input device receives compressed image data, said processor further decoding the compressed image data to generate decompressed image data, said boundary pixels of the decompressed image data filtered if the difference between boundary pixels across the block boundary is less than the first predetermined threshold and the energy along the block boundary is less than the second predetermined threshold.
Claim 23
Dependent Claim
58 words
The computer system as set forth in claim 18, wherein the processor adjusts boundary pixel B to be equal to pA+qB+rC+sD, where p, q, r, and s are filter coefficients, A is a pixel adjacent to pixel B and D is a pixel adjacent to boundary pixel C, and adjusts boundary pixel C to be equal to sA+rB+qC+pD.
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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) | 2001-08-17 | 2002-02-16 | 2002-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-08-17 | 2006-02-16 | 2006-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-08-17 | 2010-02-16 | 2010-08-18 | $7700.00 | Window Closed / Lapsed |