Patent US7020332B2 successfully refreshed from Google Patents.
US7020332B2
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Method and apparatus for enhancing a digital image by applying an inverse histogram-based pixel mapping function to pixels of the digital image
Assignee: WSOU Investments LLC
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Filing: 2000-12-22
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Granted: 2006-03-28
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Expires: 2020-12-22
Abstract
Abstract A method and associated device wherein an inverse histogram based pixel mapping step is combined with an edge enhancement step such as unsharp masking. In such an arrangement the inverse histogram based pixel mapping step improves the performance of the unsharp masking step, serving to minimize the enhancement of noise components while desired signal components are sharpened.
Inventors
- 👤 Petri Nenonen
- 👤 Markku Vehvilainen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 10:19
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/73; G06T5/75
Claims Analysis
Total Claims: 80
Claim 1
Independent Claim
73 words
A method for enhancing a digital image which includes a plurality of image pixels, said method comprising: constructing a histogram of pixel values from at least part of said image pixels; forming an inverse histogram from said histogram; forming a cumulative inverse histogram from said inverse histogram; deriving an inverse histogram-based pixel mapping function from said cumulative inverse histogram; and applying the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 2
Independent Claim
73 words
A method for enhancing a digital image which includes a plurality of image pixels, said method comprising: constructing a histogram of pixel values from at least part of said image pixels; forming an inverse histogram from said histogram; forming a cumulative inverse histogram from said inverse histogram; deriving an inverse histogram-based pixel mapping function from said cumulative inverse histogram; and applying the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 3
Dependent Claim
41 words
A method according to claim 1 , wherein said inverse histogram-based pixel mapping function is modified to form a modified inverse histogram-based pixel mapping function and said modified inverse histogram-based pixel mapping function is applied to the set of image pixels.
Claim 4
Dependent Claim
20 words
A method according to claim 1 , wherein said histogram is constructed from all image pixels of said digital image.
Claim 5
Dependent Claim
23 words
A method according to claim 1 , wherein said histogram is constructed from a part of all image pixels of said digital image.
Claim 6
Dependent Claim
31 words
A method according to claim 1 , wherein the inverse histogram-based pixel mapping function is applied to the set of image pixels prior to or after applying an edge enhancement function.
Claim 7
Dependent Claim
52 words
A method according to claim 1 , wherein the step of constructing a histogram of pixel values comprises: defining a set of pixel value ranges; and for each pixel value range, counting the number of image pixels from said at least part of said image pixels that have values within that range.
Claim 8
Dependent Claim
60 words
A method according to claim 6 , wherein said step of forming an inverse histogram from said histogram comprises: identifying a pixel value range having a maximum number of image pixels; and for each pixel value range, subtracting the number of image pixels within that range from said maximum number, thereby forming a modified value for each pixel value range.
Claim 9
Dependent Claim
52 words
A method according to claim 6 , wherein said step of forming an inverse histogram from said histogram comprises: defining a reference value; and for each pixel value range, subtracting the number of image pixels within that range from said reference value, thereby forming a modified value for each pixel value range.
Claim 10
Dependent Claim
69 words
A method according to claim 6 , wherein said step of forming an inverse histogram from said histogram comprises: identifying a pixel value range having a maximum number of image pixels; defining a reference value greater than said maximum number; and for each pixel value range, subtracting the number of image pixels within that range from said reference value, thereby forming a modified value for each pixel value range.
Claim 11
Dependent Claim
85 words
A method according to claim 7 , 8 , or 9 , wherein said step of forming a cumulative inverse histogram comprises: for each pixel value range, adding to the modified value for that range, formed during said step of forming an inverse histogram, the modified values for all pixel value ranges comprising smaller pixel values than that range, formed during said step of forming an inverse histogram; and storing the value thus obtained in a corresponding pixel value range of the cumulative inverse histogram.
Claim 12
Dependent Claim
34 words
A method according to claim 10 , wherein said inverse histogram-based pixel mapping function is derived from said cumulative inverse histogram using the value of each pixel value range of said cumulative inverse histogram.
Claim 13
Dependent Claim
32 words
A method according to claim 10 , wherein said inverse histogram-based pixel mapping function is derived from said cumulative inverse histogram by interpolating between pixel value ranges of said cumulative inverse histogram.
Claim 14
Dependent Claim
21 words
A method according to claim 1 , wherein said inverse histogram-based pixel mapping function is scaled to a predetermined maximum value.
Claim 15
Dependent Claim
28 words
A method according to claim 1 , wherein said histogram of pixel values is processed to form a modified histogram before said step of forming an inverse histogram.
Claim 16
Dependent Claim
28 words
A method according to claim 1 , wherein said inverse histogram is processed to form a modified inverse histogram before said step of forming a cumulative inverse histogram.
Claim 17
Dependent Claim
32 words
A method according to claim 1 , wherein said cumulative inverse histogram is processed to form a modified cumulative inverse histogram before said step of deriving an inverse histogram-based pixel mapping function.
Claim 18
Independent Claim
72 words
A method for enhancing a digital image which includes a plurality of image pixels, said method comprising: constructing a histogram of pixel values from at least part of said image pixel values; forming a cumulative histogram from said histogram; deriving a mapping function from the cumulative histogram; forming an inverse histogram-based pixel mapping function from said mapping function; and applying the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 19
Independent Claim
72 words
A method for enhancing a digital image which includes a plurality of image pixels, said method comprising: constructing a histogram of pixel values from at least part of said image pixel values; forming a cumulative histogram from said histogram; deriving a mapping function from the cumulative histogram; forming an inverse histogram-based pixel mapping function from said mapping function; and applying the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 20
Dependent Claim
56 words
A method according to claim 17 , wherein said step of forming the inverse histogram-based pixel mapping function from said mapping function comprises: differentiating said mapping function to form a differentiated mapping function; finding the maximum value of said differentiated mapping function; and subtracting said maximum value from said differentiated mapping function and integrating the result.
Claim 21
Dependent Claim
52 words
A method according to claim 17 , wherein the step of constructing a histogram of pixel values comprises: defining a set of pixel value ranges; and for each pixel value range, counting the number of image pixels from said at least part of said image pixels that have values within that range.
Claim 22
Dependent Claim
48 words
A method according to claim 19 , wherein said step of forming a cumulative histogram comprises: for each pixel value range, adding to the number of image pixels within that range the number of image pixels in all pixel value ranges comprising smaller pixel values than that range.
Claim 23
Dependent Claim
32 words
A method according to claim 20 , wherein said mapping function is derived from said cumulative histogram using a number of image pixels within each pixel value range of said cumulative histogram.
Claim 24
Dependent Claim
27 words
A method according to claim 20 , wherein said mapping function is derived from said cumulative histogram by interpolating between pixel value ranges of said cumulative histogram.
Claim 25
Dependent Claim
28 words
A method according to claim 17 , wherein said histogram of pixel values is processed to form a modified histogram before said step of forming a cumulative histogram.
Claim 26
Dependent Claim
27 words
A method according to claim 17 , wherein said cumulative histogram is processed to form a modified cumulative histogram before said step of deriving a mapping function.
Claim 27
Dependent Claim
30 words
A method according to claim 17 , wherein said mapping function is processed to form a modified mapping function before said step of forming the inverse histogram-based pixel mapping function.
Claim 28
Dependent Claim
31 words
A method according to claim 1 , wherein said inverse histogram-based pixel mapping function is applied to the set of image pixels prior to or after applying another image processing function.
Claim 29
Dependent Claim
21 words
A method according to claim 26 , wherein said other image processing function has the effect of increasing pixel value variation.
Claim 30
Dependent Claim
37 words
A method according to claim 1 , wherein the inverse histogram-based pixel mapping function is applied in an original signal branch and an edge enhancement unit is applied in a branch parallel to the original signal branch.
Claim 31
Dependent Claim
36 words
A method according to claim 1 , wherein the inverse histogram-based pixel mapping function is applied in an original signal branch and in a branch parallel to the original signal branch having an edge enhancement unit.
Claim 32
Dependent Claim
30 words
A computer program product comprising a computer usable medium having computer readable program code embodied therein for performing a method for enhancing a digital image according to claim 1 .
Claim 33
Dependent Claim
36 words
A method according to claim 1 , wherein the inverse histogram-based pixel mapping function decreases the contrast of the digital image for image pixels that have values with a frequency of occurrence exceeding a pre-determined amount.
Claim 34
Dependent Claim
36 words
A method according to claim 31 , wherein the inverse histogram-based pixel mapping function increases the contrast of the digital image for image pixels having values with a frequency of occurrence less than said predetermined amount.
Claim 35
Dependent Claim
19 words
A method according to claim 17 , wherein said inverse mapping function is scaled to a predetermined maximum value.
Claim 36
Dependent Claim
37 words
A method according to claim 17 , wherein the inverse histogram-based pixel mapping function is applied in an original signal branch and an edge enhancement unit is applied in a branch parallel to the original signal branch.
Claim 37
Dependent Claim
36 words
A method according to claim 17 , wherein the inverse histogram-based pixel mapping function is applied in an original signal branch and in a branch parallel to the original signal branch having an edge enhancement unit.
Claim 38
Dependent Claim
20 words
A method according to claim 17 , wherein said histogram is constructed from all image pixels of said digital image.
Claim 39
Dependent Claim
23 words
A method according to claim 17 , wherein said histogram is constructed from a part of all image pixels of said digital image.
Claim 40
Dependent Claim
31 words
A method according to claim 17 , wherein said inverse histogram-based pixel mapping function is applied to the set of image pixels prior to or after applying another image processing function.
Claim 41
Dependent Claim
21 words
A method according to claim 38 , wherein said other image processing function has the effect of increasing pixel value variation.
Claim 42
Dependent Claim
31 words
A method according to claim 17 , wherein the inverse histogram-based pixel mapping function is applied to the set of image pixels prior to or after applying an edge enhancement function.
Claim 43
Dependent Claim
30 words
A computer program product comprising a computer usable medium having computer readable program code embodied therein for performing a method for enhancing a digital image according to claim 17 .
Claim 44
Dependent Claim
36 words
A method according to claim 17 , wherein the inverse histogram-based pixel mapping function decreases the contrast of the digital image for image pixels that have values with a frequency of occurrence exceeding a pre-determined amount.
Claim 45
Dependent Claim
36 words
A method according to claim 42 , wherein the inverse histogram-based pixel mapping function increases the contrast of the digital image for image pixels having values with a frequency of occurrence less than said predetermined amount.
Claim 46
Dependent Claim
84 words
A portable radio communication device comprising: an input which inputs image pixels of a digital image; and an image processor for enhancing said digital image, wherein said image processor constructs a histogram of pixel values from at least part of said image pixel values, forms a cumulative histogram from said histogram, derives a mapping function from the cumulative histogram, forms an inverse histogram-based pixel mapping function from said mapping function, and applies the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 47
Dependent Claim
84 words
A portable radio communication device comprising: an input which inputs image pixels of a digital image; and an image processor for enhancing said digital image, wherein said image processor constructs a histogram of pixel values from at least part of said image pixel values, forms a cumulative histogram from said histogram, derives a mapping function from the cumulative histogram, forms an inverse histogram-based pixel mapping function from said mapping function, and applies the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 48
Dependent Claim
84 words
A portable radio communication device comprising: an input which inputs image pixels; and an image processor for enhancing a digital image comprising image pixels, wherein said image processor, constructs a histogram of pixel values from at least part of said image pixels, forms an inverse histogram from said histogram, forms a cumulative inverse histogram from said inverse histogram, derives an inverse histogram-based pixel mapping function from said cumulative inverse histogram, and applies the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 49
Dependent Claim
84 words
A portable radio communication device comprising: an input which inputs image pixels; and an image processor for enhancing a digital image comprising image pixels, wherein said image processor, constructs a histogram of pixel values from at least part of said image pixels, forms an inverse histogram from said histogram, forms a cumulative inverse histogram from said inverse histogram, derives an inverse histogram-based pixel mapping function from said cumulative inverse histogram, and applies the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 50
Dependent Claim
83 words
An image processor for enhancing a digital image which includes a plurality of image pixels, comprising: an input which inputs said image pixels; and a processor which constructs a histogram of pixel values from at least part of said image pixels, forms an inverse histogram from said histogram, forms a cumulative inverse histogram from said inverse histogram, derives an inverse histogram-based pixel mapping function from said cumulative inverse histogram, and applies the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 51
Dependent Claim
83 words
An image processor for enhancing a digital image which includes a plurality of image pixels, comprising: an input which inputs said image pixels; and a processor which constructs a histogram of pixel values from at least part of said image pixels, forms an inverse histogram from said histogram, forms a cumulative inverse histogram from said inverse histogram, derives an inverse histogram-based pixel mapping function from said cumulative inverse histogram, and applies the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 52
Dependent Claim
21 words
An image processor according to claim 46 , wherein said processor forms a modified histogram from said histogram of pixel values.
Claim 53
Dependent Claim
20 words
An image processor according to claim 46 , wherein said processor forms a modified inverse histogram from said inverse histogram.
Claim 54
Dependent Claim
22 words
An image processor according to claim 46 , wherein said processor forms a modified cumulative inverse histogram from said cumulative inverse histogram.
Claim 55
Dependent Claim
40 words
An image processor according to claim 46 , wherein the inverse histogram-based pixel mapping function is arranged to decrease the contrast of the digital image for image pixels that have values with a frequency of occurrence exceeding a pre-determined amount.
Claim 56
Dependent Claim
40 words
An image processor according to claim 50 , wherein the inverse histogram-based pixel mapping function is arranged to increase the contrast of the digital image for image pixels having values with a frequency of occurrence less than said predetermined amount.
Claim 57
Dependent Claim
52 words
An image processor according to claim 46 , wherein said processor constructs said histogram of pixel values by, defining a set of pixel value ranges, and for each pixel value range, counting the number of image pixels from said at least part of said image pixels that have values within that range.
Claim 58
Dependent Claim
75 words
An image processor according to claim 52 , wherein said processor forms said inverse histogram from said histogram by identifying a pixel value range having a maximum number of image pixels for each pixel value range, subtracting the number of image pixels within that range from said maximum number, thus forming a modified value for each pixel value range, and storing the value thus obtained in a corresponding pixel value range of the inverse histogram.
Claim 59
Dependent Claim
66 words
An image processor according to claim 52 , wherein said processor forms said inverse histogram from said histogram by defining a reference value, for each pixel value range, subtracting the number of image pixels within that range from said reference value, thus forming a modified value for each pixel value range, storing the value thus obtained in a corresponding pixel value range of the inverse histogram.
Claim 60
Dependent Claim
84 words
An image processor according to claim 52 , wherein said processor forms said inverse histogram from said histogram by identifying a pixel value range having a maximum number of image pixels defining a reference value greater than said maximum number, for each pixel value range, subtracting the number of image pixels within that range from said reference value, thus forming a modified value for each pixel value range, and storing the value thus obtained in a corresponding pixel value range of the inverse histogram.
Claim 61
Dependent Claim
60 words
An image processor according to claim 53 , 54 or 55 , wherein said processor forms said cumulative inverse histogram by adding to the modified value for each pixel value range, the modified values for all pixel value ranges comprising smaller pixel values and storing the value thus obtained in a corresponding pixel value range of the cumulative inverse histogram.
Claim 62
Dependent Claim
36 words
An image processor according to claim 56 , wherein said processor derives said inverse histogram-based pixel mapping function from said cumulative inverse histogram using the value of each pixel value range of said cumulative inverse histogram.
Claim 63
Dependent Claim
34 words
An image processor according to claim 56 , wherein said processor derives said inverse histogram-based pixel mapping function from said cumulative inverse histogram by interpolating between pixel value ranges of said cumulative inverse histogram.
Claim 64
Dependent Claim
22 words
An image processor according to claim 46 , wherein said processor constructs said histogram from all image pixels of said digital image.
Claim 65
Dependent Claim
25 words
An image processor according to claim 46 , wherein said processor constructs said histogram from a part of the image pixels of said digital image.
Claim 66
Dependent Claim
84 words
An image processor for enhancing a digital image which includes a plurality of image pixels, comprising: an input which inputs said pixels; and a processor which constructs a histogram of pixel values from at least part of image pixel values of said image pixels, form a cumulative histogram from said histogram, derives a mapping function from the cumulative histogram, forms an inverse histogram-based pixel mapping function from said mapping function, and applies the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 67
Dependent Claim
84 words
An image processor for enhancing a digital image which includes a plurality of image pixels, comprising: an input which inputs said pixels; and a processor which constructs a histogram of pixel values from at least part of image pixel values of said image pixels, form a cumulative histogram from said histogram, derives a mapping function from the cumulative histogram, forms an inverse histogram-based pixel mapping function from said mapping function, and applies the inverse histogram-based pixel mapping function to a set of image pixels.
Claim 68
Dependent Claim
21 words
An image processor according to claim 61 , wherein said processor forms a modified histogram from said histogram of pixel values.
Claim 69
Dependent Claim
20 words
An image processor according to claim 61 , wherein said processor forms a modified cumulative histogram from said cumulative histogram.
Claim 70
Dependent Claim
20 words
An image processor according to claim 61 , wherein said processor forms a modified mapping function from said mapping function.
Claim 71
Dependent Claim
26 words
An image processor according to claim 61 , wherein said processor forms a modified inverse histogram-based pixel mapping function from said inverse histogram-based pixel mapping function.
Claim 72
Dependent Claim
40 words
An image processor according to claim 61 , wherein the inverse histogram-based pixel mapping function is arranged to decrease the contrast of the digital image for image pixels that have values with a frequency of occurrence exceeding a pre-determined amount.
Claim 73
Dependent Claim
40 words
An image processor according to claim 66 , wherein the inverse histogram-based pixel mapping function is arranged to increase the contrast of the digital image for image pixels having values with a frequency of occurrence less than said predetermined amount.
Claim 74
Dependent Claim
55 words
An image processor according to claim 61 , wherein said processor forms the inverse histogram-based pixel mapping function from said mapping function by differentiating said mapping function to form a differentiated mapping function, finding the maximum value of said differentiated mapping function subtracting said maximum value from said differentiated mapping function and integrating the result.
Claim 75
Dependent Claim
52 words
An image processor according to claim 61 , wherein said processor constructs said histogram of pixel values by defining a set of pixel value ranges, and for each pixel value range, counting the number of image pixels from said at least part of said image pixels that have values within that range.
Claim 76
Dependent Claim
42 words
An image processor according to claim 69 , wherein said processor forms said cumulative histogram by adding to the number of image pixels within each pixel value range, the number of image pixels in all pixel value ranges comprising smaller pixel values.
Claim 77
Dependent Claim
34 words
An image processor according to claim 70 , wherein said processor derives said mapping function from said cumulative histogram using the number of image pixels within each pixel value range of said cumulative histogram.
Claim 78
Dependent Claim
29 words
An image processor according to claim 70 , wherein said processor derives said mapping function from said cumulative histogram by interpolating between pixel value ranges of said cumulative histogram.
Claim 79
Dependent Claim
22 words
An image processor according to claim 61 , wherein said processor constructs said histogram from all image pixels of said digital image.
Claim 80
Dependent Claim
25 words
An image processor according to claim 61 , wherein said processor constructs said histogram from a part of the image pixels of said digital image.
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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) | 2009-03-27 | 2009-09-26 | 2010-03-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2013-03-27 | 2013-09-26 | 2014-03-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2017-03-27 | 2017-09-26 | 2018-03-28 | $7700.00 | Window Closed / Lapsed |