US5845010A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compression enhancement in graphics system
Assignee: Canon Inc
•
Filing: 1995-05-26
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Granted: 1998-12-01
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Expires: 2015-05-26
Abstract
Abstract Disclosed is an arrangement which lessens the effects of compression artifacts resulting from the compression of graphic images having high spatial frequency components. Such graphic images are typically text related in view of the high contrast required for text outlines. The arrangement includes a text detector configured to detect cells of a source image which are likely to create compression artifacts when each of the cells is compressed by a compressor for storage in a compressed image store. The text detector creates a bit table in a text detect store of those cells which include high spatial frequency components. Upon expansion, of the compressed image by an expander, the cells are passed through a pixel saturator which, if the cell is a "text" cell referenced in the text detect store, all pixels within that text cell are saturated to colours from a predetermined set of colours. The expanded image is then restored to an image store.
Inventors
- 👤 Kia Silverbrook
- 👤 James Robert Metcalfe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 11:26
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/60; G; G06; G06T; G06T9/00; G06T9/007; H04N1/00; H04N1/41; H04N1/46; H04N1/64; H04N1/642
Claims Analysis
Total Claims: 58
Claim 1
Independent Claim
137 words
A method of removing compression artifacts in graphics systems, said method comprising the steps of: (a) examining an image comprising high frequency regions and low frequency regions to identify said high frequency regions at which compression artifacts are likely to be produced, deeming those regions as selected regions, and storing information regarding said selected regions; (b) lossy compressing the image, including the selected regions, to thereby produce compression artifacts, and subsequently expanding the compressed image; (c) identifying the expanded selected regions by way of said stored information; and (d) manipulating the expanded selected regions to reduce the visual impact of said produced compression artifacts by resetting the colour of a pixel, for each pixel within the expanded selected regions, to a colour of a first predetermined set of colors closest to the previous colour of the pixel.
Claim 2
Independent Claim
137 words
A method of removing compression artifacts in graphics systems, said method comprising the steps of: (a) examining an image comprising high frequency regions and low frequency regions to identify said high frequency regions at which compression artifacts are likely to be produced, deeming those regions as selected regions, and storing information regarding said selected regions; (b) lossy compressing the image, including the selected regions, to thereby produce compression artifacts, and subsequently expanding the compressed image; (c) identifying the expanded selected regions by way of said stored information; and (d) manipulating the expanded selected regions to reduce the visual impact of said produced compression artifacts by resetting the colour of a pixel, for each pixel within the expanded selected regions, to a colour of a first predetermined set of colors closest to the previous colour of the pixel.
Claim 3
Dependent Claim
17 words
A method as claimed in claim 1, wherein the selected regions comprise image pixels that are correctable.
Claim 4
Dependent Claim
55 words
A method as claimed in claim 2, wherein step (a) comprises the steps of identifying from the image those regions that include a predetermined proportion of pixels that are represented by a second predetermined set of colours, and a pixel transition between any two colours of said set, and deeming same as a selected region.
Claim 5
Dependent Claim
18 words
A method as claimed in claim 3, wherein the second predetermined set of colours comprises black and white.
Claim 6
Dependent Claim
24 words
A method as claimed in claim 3, wherein the second predetermined set of colours comprises red, green, blue, yellow, cyan, magenta, black and white.
Claim 7
Dependent Claim
15 words
A method as claimed in claim 3, wherein the predetermined proportion is greater than 50%.
Claim 8
Dependent Claim
26 words
A method as claimed in claim 3, wherein a predetermined rate of change between said two colours is required in order to determine a selected region.
Claim 9
Dependent Claim
13 words
A method as claimed in claim 4 wherein the predetermined proportion is 100%.
Claim 10
Dependent Claim
44 words
A method as claimed in claim 2, wherein step (a) comprises the steps of identifying from the image those regions that include a predetermined proportion of pixels that are represented by a second predetermined set of colours, and deeming same as said selected regions.
Claim 11
Dependent Claim
18 words
A method as claimed in claim 9, wherein the second predetermined set of colours comprises black and white.
Claim 12
Dependent Claim
24 words
A method as claimed in claim 9, wherein the second predetermined set of colours comprises red, green, blue, yellow, cyan, magenta, black and white.
Claim 13
Dependent Claim
15 words
A method as claimed in claim 9, wherein the predetermined proportion is greater than 50%.
Claim 14
Dependent Claim
42 words
A method as claimed in claim 2, wherein step (a) comprises the step of identifying from the image those regions that include a pixel transition between any two colours of a second predetermined set of colours, and deeming same as selected region.
Claim 15
Dependent Claim
18 words
A method as claimed in claim 13, wherein the second predetermined set of colours comprises black and white.
Claim 16
Dependent Claim
24 words
A method as claimed in claim 13, wherein the second predetermined set of colours comprises red, green, blue, yellow, cyan, magenta, black and white.
Claim 17
Dependent Claim
26 words
A method as claimed in claim 13, wherein a predetermined rate of change between said two colors is required in order to determine a selected region.
Claim 18
Dependent Claim
24 words
A method as claimed in claim 16, wherein the rate of change is such that the separation between said two colours is one pixel.
Claim 19
Dependent Claim
18 words
A method as claimed in claim 1, wherein the first predetermined set of colours comprises black and white.
Claim 20
Dependent Claim
24 words
A method as claimed in claim 1, wherein the first predetermined set of colours comprises red, blue, green, magenta, cyan, yellow, black and white.
Claim 21
Dependent Claim
124 words
A compression enhancement arrangement for graphics systems, said arrangement comprising: detecting means for detecting high frequency regions of an image, comprising said high frequency regions and low frequency regions, in which compression artifacts are likely to be produced and deeming those regions as selected regions; storage means for maintaining a record of said selected regions; and restoring means for, after lossy compression of said image and subsequent expansion of said compressed image, manipulating the expanded selected regions based on said record to reduce the visual impact of any produced compression artifacts by resetting the colour of a pixel, for each pixel within the expanded selected regions, to a colour of a first predetermined set of colours closest to the previous colour of the pixel.
Claim 22
Dependent Claim
124 words
A compression enhancement arrangement for graphics systems, said arrangement comprising: detecting means for detecting high frequency regions of an image, comprising said high frequency regions and low frequency regions, in which compression artifacts are likely to be produced and deeming those regions as selected regions; storage means for maintaining a record of said selected regions; and restoring means for, after lossy compression of said image and subsequent expansion of said compressed image, manipulating the expanded selected regions based on said record to reduce the visual impact of any produced compression artifacts by resetting the colour of a pixel, for each pixel within the expanded selected regions, to a colour of a first predetermined set of colours closest to the previous colour of the pixel.
Claim 23
Dependent Claim
23 words
An arrangement as claimed in claim 20, wherein said detecting means comprises means for identifying regions that comprise image pixels that are correctable.
Claim 24
Dependent Claim
34 words
An arrangement as claimed in claim 21, wherein said detecting means comprises means for identifying those regions that include a predetermined proportion of pixels that are represented by a second predetermined set of colours.
Claim 25
Dependent Claim
33 words
An arrangement as claimed in claim 21, wherein said detecting means comprises means for identifying those regions that include a pixel transition between any two colours of the second predetermined set of colours.
Claim 26
Dependent Claim
52 words
An arrangement as claimed in claim 21, wherein said detecting means comprises means for identifying those regions that include a predetermined proportion of pixels that are represented by a second predetermined set of colours, and means for identifying those regions that include a pixel transition between any two colours of said set.
Claim 27
Dependent Claim
18 words
An arrangement as claimed in claim 22, wherein the second predetermined set of colours comprises black and white.
Claim 28
Dependent Claim
24 words
An arrangement as claimed in claim 22, wherein the second predetermined set of colours comprises red, green, blue, cyan, magenta, yellow, black and white.
Claim 29
Dependent Claim
15 words
An arrangement as claimed in claim 22, wherein said predetermined proportion is greater than 50%.
Claim 30
Dependent Claim
18 words
An arrangement as claimed in claim 23, wherein the second predetermined set of colours comprises black and white.
Claim 31
Dependent Claim
24 words
An arrangement as claimed in claim 23, wherein the second predetermined set of colours comprises red, green, blue, cyan, magenta, yellow, black and white.
Claim 32
Dependent Claim
24 words
An arrangement as claimed in claim 23, wherein a predetermined rate of change between said two colours is required to determine a selected region.
Claim 33
Dependent Claim
24 words
An arrangement as claimed in claim 30, wherein the rate of change is such that the separation between said two colours is one pixel.
Claim 34
Dependent Claim
18 words
An arrangement as claimed in claim 24, wherein the second predetermined set of colours comprises black and white.
Claim 35
Dependent Claim
24 words
An arrangement as claimed in claim 24, wherein the second predetermined set of colours comprises red, green, blue, cyan, magenta, yellow, black and white.
Claim 36
Dependent Claim
15 words
An arrangement as claimed in claim 24, wherein said predetermined proportion is greater than 50%.
Claim 37
Dependent Claim
24 words
An arrangement as claimed in claim 24, wherein a predetermined rate of change between said two colours is required to determine a selected region.
Claim 38
Dependent Claim
13 words
An arrangement as claimed in claim 32, wherein said predetermined proportion is 100%.
Claim 39
Dependent Claim
32 words
An arrangement as claimed in claim 20, wherein said storage means comprises a memory configured to retain a bit map of the image divided into said regions that identifies said selected regions.
Claim 40
Dependent Claim
24 words
An arrangement as claimed in claim 20, wherein said restoring means comprises a saturator for fully saturating each pixel within the expanded selected regions.
Claim 41
Dependent Claim
18 words
An arrangement as claimed in claim 20, wherein said first predetermined set of colours comprises black and white.
Claim 42
Dependent Claim
24 words
An arrangement as claimed in claim 20, wherein said first predetermined set of colours comprises red, green, blue, cyan, magenta, yellow, black and white.
Claim 43
Dependent Claim
32 words
An arrangement as claimed in claim 20, wherein said first predetermined set of colours can be switched between two different sets to provide a colour mode, and a black and white mode.
Claim 44
Dependent Claim
20 words
An arrangement as claimed in claim 41, wherein said colour mode is based upon red, green and blue colour data.
Claim 45
Dependent Claim
20 words
An arrangement as claimed in claim 41, wherein said black and white mode is based upon green colour data only.
Claim 46
Dependent Claim
146 words
A graphics system including: compressor/expander means for lossy compressing image data, comprising high frequency regions and low frequency regions, and for expanding compressed image data, wherein said compressor/expander means permits the storage of compressed image data; and a compression enhancement arrangement coupled to said compressor/expander means, said arrangement comprising: detecting means for detecting said high frequency regions of image data in which compression artifacts are likely to be produced and deeming those regions as selected regions; storage mans for, after lossy compression of said image data and subsequent expansion of said compressed image data, manipulating the expanded selected regions based on said record to reduce the visual impact of any produced compression artifacts by resetting the colour of a pixel, for each pixel within the expanded selected regions, to a colour of a first predetermined set of colours closest to the previous colour of the pixel.
Claim 47
Dependent Claim
146 words
A graphics system including: compressor/expander means for lossy compressing image data, comprising high frequency regions and low frequency regions, and for expanding compressed image data, wherein said compressor/expander means permits the storage of compressed image data; and a compression enhancement arrangement coupled to said compressor/expander means, said arrangement comprising: detecting means for detecting said high frequency regions of image data in which compression artifacts are likely to be produced and deeming those regions as selected regions; storage mans for, after lossy compression of said image data and subsequent expansion of said compressed image data, manipulating the expanded selected regions based on said record to reduce the visual impact of any produced compression artifacts by resetting the colour of a pixel, for each pixel within the expanded selected regions, to a colour of a first predetermined set of colours closest to the previous colour of the pixel.
Claim 48
Dependent Claim
36 words
A graphics system as claimed in claim 44, wherein said compression enhancement arrangement interconnects between an image store and said compressor/expander means, and said storage means is formed in a primary memory of said graphics system.
Claim 49
Dependent Claim
23 words
A graphics system as claimed in claim 45, wherein compressed image data is also stored in said primary memory along with said record.
Claim 50
Dependent Claim
17 words
A graphics system as claimed in claim 45, wherein said image store is a full frame store.
Claim 51
Dependent Claim
26 words
A graphics system as claimed in claim 45, wherein said image store is of limited capacity sufficient to store only a portion of said image data.
Claim 52
Dependent Claim
177 words
A graphics system comprising: a host processor for generating and instructing manipulations of image data comprising high frequency regions and low frequency regions; compression and expansion means interconnected with a main storage means for lossy compressing said image data prior to storage in said main storage means and for expanding said compressed image data upon retrieval from said main storage means; a compression enhancement arrangement comprising: detecting means for detecting said high frequency regions of said image data in which compression artifacts are likely to be produced and for deeming said regions as selected regions; record means for maintaining a record of said selected regions; restoring means for, after compression and subsequent expansion of said image data, manipulating the expanded selected regions based on said record to reduce the visual impact of any produced compression artifacts by resetting the colour of a pixel, for each pixel within the expanded selected regions, to a colour of a first predetermined set of colours closest to the previous colour of the pixel; and display means for displaying said image data.
Claim 53
Dependent Claim
177 words
A graphics system comprising: a host processor for generating and instructing manipulations of image data comprising high frequency regions and low frequency regions; compression and expansion means interconnected with a main storage means for lossy compressing said image data prior to storage in said main storage means and for expanding said compressed image data upon retrieval from said main storage means; a compression enhancement arrangement comprising: detecting means for detecting said high frequency regions of said image data in which compression artifacts are likely to be produced and for deeming said regions as selected regions; record means for maintaining a record of said selected regions; restoring means for, after compression and subsequent expansion of said image data, manipulating the expanded selected regions based on said record to reduce the visual impact of any produced compression artifacts by resetting the colour of a pixel, for each pixel within the expanded selected regions, to a colour of a first predetermined set of colours closest to the previous colour of the pixel; and display means for displaying said image data.
Claim 54
Dependent Claim
15 words
A graphics system as claimed in claim 49, wherein said display means comprises a printer.
Claim 55
Dependent Claim
17 words
A graphics system as claimed in claim 49 wherein said display means comprises a video display unit.
Claim 56
Dependent Claim
18 words
A graphics system as claimed in claim 49 further comprising an input means for inputting pixel-based image data.
Claim 57
Dependent Claim
15 words
A graphics system as claimed in claim 52 wherein said input means comprises a scanner.
Claim 58
Dependent Claim
55 words
A graphics system as claimed in claim 49, further comprising a memory connected to said compression and expansion means in which portions of said image data are manipulated after retrieval from said main storage means, and graphics engine means connected between said memory and said host processor for implementing pixel-based image manipulations on said portions.
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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) | 2001-11-30 | 2002-06-01 | 2002-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-30 | 2006-06-01 | 2006-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-30 | 2010-06-01 | 2010-12-01 | $7700.00 | Window Closed / Lapsed |