Patent US6766064B1 successfully refreshed from Google Patents.
US6766064B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for performing a contrast based dynamic range management algorithm
Assignee: General Electric Co
•
Filing: 2000-03-10
•
Granted: 2004-07-20
•
Expires: 2020-03-10
Abstract
Abstract A method and apparatus are provided for performing a contrast-based dynamic range management (C-DRM) algorithm. The apparatus comprises an C-DRM processor that performs the C-DRM algorithm of the invention in order to compress an image input to the C-DRM processor down to a desired gray scale range for observation on a display. The C-DRM processor decouples adjustment of image mean values (low frequency) and image contrast values (high frequency), and manages mean and contrast separately. The use of separate mean and contrast modification functions improve on other known compression techniques by providing a more deterministic behavior and reduced complexity, allowing, for example, independent management of negative and positive contrasts. The C-DRM processor can also automatically adapt to the dynamic range of an input image so that the input image thereby applying the minimal compression needed to display the image.
Inventors
- 👤 David Allen Langan
- 👤 Michael Robert Hopple
- 👤 Robert Leland Nevin
- 👤 Jean Lienard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:22
CPC Classifications
G; G06; G06T; G06T5/00; G06T5/90; G06T5/94; G06T2207/00; G06T2207/10; G06T2207/10116
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
169 words
A method of compressing an intensity dynamic range of an input image to a reduced intensity dynamic range of an image display signal, comprising: a) defining plural units of each frame of the input image, each input image unit having a corresponding intensity; b) determining a local mean estimate of the intensity of each of the plural units of the input image; c) processing each local mean estimate, separately and directly, in accordance with: i) a mean modification function to produce a corresponding mean modification processing result, and ii) a contrast function, comprising a contrast modification function, to produce a corresponding contrast modification processing result, wherein the contrast function further multiplies an output of the contrast modification function by a contrast estimate to produce the contrast modification processing result; and d) combining the corresponding mean modification function result and contrast modification function result to produce, for each input image unit intensity, a respective output intensity, within the reduced intensity range, for a corresponding unit of the image display signal.
Claim 2
Independent Claim
169 words
A method of compressing an intensity dynamic range of an input image to a reduced intensity dynamic range of an image display signal, comprising: a) defining plural units of each frame of the input image, each input image unit having a corresponding intensity; b) determining a local mean estimate of the intensity of each of the plural units of the input image; c) processing each local mean estimate, separately and directly, in accordance with: i) a mean modification function to produce a corresponding mean modification processing result, and ii) a contrast function, comprising a contrast modification function, to produce a corresponding contrast modification processing result, wherein the contrast function further multiplies an output of the contrast modification function by a contrast estimate to produce the contrast modification processing result; and d) combining the corresponding mean modification function result and contrast modification function result to produce, for each input image unit intensity, a respective output intensity, within the reduced intensity range, for a corresponding unit of the image display signal.
Claim 3
Dependent Claim
27 words
A method as recited in claim 1 , wherein: each input image unit corresponds to a pixel of the input image as detected by a digital detector.
Claim 4
Dependent Claim
23 words
A method as recited in claim 1 , wherein: each input image unit corresponds to a scan line of an analog image detector.
Claim 5
Dependent Claim
106 words
A method as recited in claim 1 , wherein: the processing of each input image unit intensity, separately and directly, further comprises multiplying the output of the contrast modification function by the mean modification function result and producing the multiplication product as a first combined, corresponding mean modification and contrast modification processing result; and the combining step further comprises combining the combined, corresponding mean modification function processing result and contrast modification function processing result with the mean modification processing result to produce, for each input image unit intensity, the respective output intensity, within the reduced intensity range, for the corresponding unit of the image display signal.
Claim 6
Dependent Claim
152 words
A method as recited in claim 1 , wherein the processing of each input image unit intensity, separately and directly, further comprises: multiplying the mean modification function result by a negative complement of the contrast modification function and producing the multiplication product as a first combined, and corresponding, mean modification function and contrast modification function processing result; and multiplying the contrast modification function by the mean modification function by an inverse of the local mean estimate and by the input image unit intensity and producing the multiplication product as a second combined, and corresponding, mean modification function and contrast modification function processing result; and the combining step further comprises combining the first and second combined, and corresponding, mean modification function and contrast modification function processing results to produce, for each input image unit intensity, a respective output intensity, within the reduced intensity range, for the corresponding unit of the image display signal.
Claim 7
Dependent Claim
80 words
A method as recited in claim 1 , further comprising: determining a contrast estimate as a function of a ratio, of a difference between the intensity of a unit of the input image and the local mean estimate thereof to the local mean estimate; determining a sign of the contrast estimate; and controlling the processing of each local mean estimate by the contrast modification function by employing the sign of the contrast estimate to manage positive and negative contrasts separately.
Claim 8
Dependent Claim
74 words
A method as recited in claim 1 , further comprising: processing the local mean estimate by temporally filtering same and producing a resultant, modified local mean estimate having enhanced dynamic range continuity, substantially independent of rapid changes in the dynamic intensity range of the input image; and controlling the processing of each local mean estimate, including the processing thereof by the mean and contrast modification functions, in accordance with the modified local mean estimate.
Claim 9
Dependent Claim
76 words
A method as recited in claim 7 , further comprising: processing each local mean estimate and the mean and contrast modification function processing results and the output intensity corresponding to each unit of the input image, as respective, multiple bit values; and limiting the number of bits of the output intensity of the corresponding unit of the image display signal to a predetermined number of bits, consistent with display range capabilities of an available display device.
Claim 10
Dependent Claim
85 words
A method as recited in claim 8 , further comprising: performing the processing of each local mean estimate in accordance with the mean and contrast modification functions and the multiplication of the modification results of same for producing multiplication products, in accordance with accessing respective look-up tables from which are produced the corresponding multiplication products and wherein each of the local mean estimate, the mean modification function and the contrast modification function processing results and the respective multiplication products thereof constitute respective, multiple bit values.
Claim 11
Dependent Claim
49 words
A method as recited in claim 9 , further comprising: determining a sign value of the contrast estimate, as a respective, single bit value for each local mean estimate; and combining the sign of a contrast estimate with the local mean estimate for accessing each of the look-up tables.
Claim 12
Dependent Claim
90 words
A method as recited in claim 9 , further comprising: determining a sign of the contrast estimate, as a respective, single bit value for each local mean estimate; forming the local mean estimate as an unsigned number of bits; combining the sign of the contrast estimate with the unsigned number of bits representing the local mean estimate for accessing a first look-up table performing the contrast modification function; and accessing a second look-up table performing the mean modification function using the unsigned number of bits representing the local mean estimate.
Claim 13
Independent Claim
161 words
An apparatus compressing an intensity dynamic range of an input image to a reduced intensity dynamic range of an image display signal, each frame of the input image comprising plural units, the apparatus comprising: a filter determining a local mean estimate of the intensity of each of the plural units of the input image; a computer processing each local mean estimate, separately and directly, in accordance with; a mean modification function to produce a corresponding mean modification processing result, and a contrast function, comprising a contrast modification function, to produce a corresponding contrast modification processing result; and the computer further comprising multiplying an output of the contrast modification function by a contrast estimate to produce the contrast modification processing result; and the computer combining the corresponding mean modification function and contrast modification procession function results to produce, for each input image unit intensity, a respective output intensity, within the reduced intensity range, for a corresponding unit of the image display signal.
Claim 14
Independent Claim
161 words
An apparatus compressing an intensity dynamic range of an input image to a reduced intensity dynamic range of an image display signal, each frame of the input image comprising plural units, the apparatus comprising: a filter determining a local mean estimate of the intensity of each of the plural units of the input image; a computer processing each local mean estimate, separately and directly, in accordance with; a mean modification function to produce a corresponding mean modification processing result, and a contrast function, comprising a contrast modification function, to produce a corresponding contrast modification processing result; and the computer further comprising multiplying an output of the contrast modification function by a contrast estimate to produce the contrast modification processing result; and the computer combining the corresponding mean modification function and contrast modification procession function results to produce, for each input image unit intensity, a respective output intensity, within the reduced intensity range, for a corresponding unit of the image display signal.
Claim 15
Dependent Claim
32 words
An apparatus as recited in claim 12 , further comprising: a digital image detector, each input image unit corresponding to a pixel of the input image as detected by the digital detector.
Claim 16
Dependent Claim
34 words
An apparatus as recited in claim 12 , further comprising: an analog image detector, each input image unit corresponding to a scan line of the input image as detected by the analog image detector.
Claim 17
Dependent Claim
100 words
An apparatus as recited in claim 12 , wherein the processing of each, separately and directly, by the computer further comprises: multiplying the output of the contrast modification function by the mean modification function result and producing the multiplication product as a first combined, corresponding mean modification and contrast modification processing result; and combining the combined, corresponding mean modification function processing result and contrast modification function processing result with the mean modification processing result to produce, for each input image unit intensity, the respective output intensity, within the reduced intensity range, for the corresponding unit of the image display signal.
Claim 18
Dependent Claim
149 words
An apparatus as recited in claim 12 , wherein the processing of each input image unit intensity, separately and directly, by the computer further comprises: multiplying the mean modification function result by a negative complement of the contrast modification function and producing the multiplication product as a first combined, and corresponding, mean modification function and contrast modification function processing result; multiplying the contrast modification function by the mean modification function and by an inverse of the local mean estimate and by the input image unit intensity and producing the multiplication product as a second combined, and corresponding, mean modification function and contrast modification function processing result; and combining the first and second combined, and corresponding, mean modification function and contrast modification function processing results to produce, for each input image unit, a respective output intensity, within the reduced intensity range, for the corresponding unit of the image display signal.
Claim 19
Dependent Claim
86 words
An apparatus as recited in claim 12 , wherein the processing by the computer further comprises: determining a contrast estimate as a function of a ratio, of a difference between the intensity of a unit of the input image and the local mean estimate thereof to the local mean estimate; determining a sign of the contrast estimate; and controlling the processing of each local mean estimate by the contrast modification function by employing the sign of the contrast estimate to manage positive and negative contrasts separately.
Claim 20
Dependent Claim
80 words
An apparatus as recited in claim 12 , wherein the processing by the computer further comprises: processing the local mean estimate by temporally filtering same and producing a resultant, modified local mean estimate having enhanced dynamic range continuity, substantially independent of rapid changes in the dynamic intensity range of the input image; and controlling the processing of each local mean estimate, including the processing thereof by the mean and contrast modification functions, in accordance with the modified local mean estimate.
Claim 21
Dependent Claim
82 words
An apparatus as recited in claim 18 , wherein the processing by the computer further comprises: processing each local mean estimate and the mean and contrast modification function processing results and the output intensity corresponding to each unit of the input image, as respective, multiple bit values; and limiting the number of bits of the output intensity of the corresponding unit of the image display signal to a predetermined number of bits, consistent with display range capabilities of an available display device.
Claim 22
Dependent Claim
91 words
An apparatus as recited in claim 19 , wherein the processing by the computer further comprises: performing the processing of each local mean estimate in accordance with the mean and contrast modification functions and the multiplication of the modification results of same for producing multiplication products, in accordance with accessing respective look-up tables from which are produced the corresponding multiplication products and wherein each of the local mean estimate, the mean modification function and the contrast modification function processing results and the respective multiplication products thereof constitute respective, multiple bit values.
Claim 23
Dependent Claim
55 words
An apparatus as recited in claim 20 , where the processing by the computer further comprises: determining a sign value of the contrast estimate, as a respective, single bit value for each local mean estimate; and combining the sign of a contrast estimate with the local mean estimate for accessing each of the look-up tables.
Claim 24
Dependent Claim
96 words
An apparatus as recited in claim 20 , where the processing by the computer further comprises: determining a sign of the contrast estimate, as a respective, single bit value for each local mean estimate; forming the local mean estimate as an unsigned number of bits; combining the sign of the contrast estimate with the unsigned number of bits representing the local mean estimate for accessing a first look-up table performing the contrast modification function; and accessing a second look-up table performing the mean modification function using the unsigned number of bits representing the local mean estimate.
Claim 25
Independent Claim
178 words
A method of compressing an intensity dynamic range of an input image to a reduced intensity dynamic range of an image display signal, comprising: a) defining plural units of each frame of the input image, each input image unit having a corresponding intensity; b) determining a local mean estimate of the intensity of each of the plural units of the input image; c) processing each local mean estimate, separately and directly, in accordance with: Y=M Y (1+C Y ), where: M Y =F M (M X ), C Y =F C (M X )*C X , and X C =(X−M X )/M X X=input intensity M X =local mean estimate C X =contrast estimate F M ( )=mean modification function F C ( )=contrast modification function Y=C-DRM output intensity M Y =modified local mean C Y =modified contrast; and d) combining the corresponding mean modification function result and contrast modification function result to produce, for each input image unit intensity, a respective output intensity, within the reduced intensity range, for a corresponding unit of the image display signal.
Claim 26
Independent Claim
178 words
A method of compressing an intensity dynamic range of an input image to a reduced intensity dynamic range of an image display signal, comprising: a) defining plural units of each frame of the input image, each input image unit having a corresponding intensity; b) determining a local mean estimate of the intensity of each of the plural units of the input image; c) processing each local mean estimate, separately and directly, in accordance with: Y=M Y (1+C Y ), where: M Y =F M (M X ), C Y =F C (M X )*C X , and X C =(X−M X )/M X X=input intensity M X =local mean estimate C X =contrast estimate F M ( )=mean modification function F C ( )=contrast modification function Y=C-DRM output intensity M Y =modified local mean C Y =modified contrast; and d) combining the corresponding mean modification function result and contrast modification function result to produce, for each input image unit intensity, a respective output intensity, within the reduced intensity range, for a corresponding unit of the image display signal.
Claim 27
Dependent Claim
47 words
A method as recited in claim 23 , wherein: the mean modification function achieves either a linear or a non-linear transformation of the mean component of the image; and the contrast modification function applies a linear gain to the input contrast to the construct the output contrast.
Claim 28
Dependent Claim
35 words
A method as recited in claim 23 , in which the input intensity value (X) of an input pixel is processed by a moving average function to produce the local mean estimate (M X ).
Claim 29
Dependent Claim
37 words
A method as recited in claim 23 , wherein first and second look-up tables respectively perform the contrast modification function and the mean modification function respectively of the equations for determining C Y and C X .
Claim 30
Dependent Claim
37 words
A method as recited in claim 23 , wherein the mean modification function transforms the mean from being linearly related to X-ray counts to being linearly related to an equivalent water thickness represented by the X-ray counts.
Claim 31
Dependent Claim
46 words
A method as recited in claim 23 , wherein the contrast modification function C Y is implemented in compliance with a requirement that F C is monotonically increased in accordance with: F C ( C +1 , Mx )≧ F C ( C,Mx )∀ C, Mx.
Claim 32
Dependent Claim
330 words
A method as recited in claim 23 , further comprising: processing of the equations for determining Y, M Y , C Y and C X to produce the output intensity (Y) in accordance with: Y = CyMy + My , where : Cy = fcCx and fc ( Mx ) = fc Y = fcCxMy + My , where : cx = x - Mx Mx Y = fc ( x - Mx ) ( My / Mx ) + My Y = X fcMy Mx [ x - Mx ( 1 - 1 fc ) ] Y = X ( fxMy Mx ) - Mx ( fcMy Mx ) ( 1 - 1 fc ) My = fm ( Mx ) = fm Y = X ( fcfm Mx ) - Mx ( fcfm My ) ( 1 - 1 fc ) Y = X ( fcfm Mx ) - Mx ( fcfm My - fcfm fcMx ) Y = X ( fcfm Mx ) - Fm ( fc - 1 ) Y = X ( fcfm Mx ) + fm ( 1 - fc ) the contrast modification function processing is performed in a first look-up table which computes: 1 /Mx*Fc ( Scx, Mx )* Fm ( Mx ) the mean modification function processing is performed in a second look-up table which computes: Fm ( Mx )*(1 −Fc ( Scx, Mx )); and the output of the first look-up table is multiplied by the input intensity (X) and the resulting product is added to the output of the second look-up table to produce an output sum; and the output sum is processed by a third look-up table to clip the output to a desired number of bits.
Claim 33
Dependent Claim
17 words
A method as recited in claim 29 , wherein the desired number of bits is eight bits.
Claim 34
Dependent Claim
341 words
A method as recited in claim 23 further comprising processing the equations for determining Y, M Y , C Y and C X to produce the output intensity (Y) in accordance with: Y=CyMy+My , where: Cy=fcCx and fc ( Mx )= fc Y=fcCxMy+My , where: Y = CyMy + My , where : Cy = fcCx and fc ( Mx ) = fc Y = fcCxMy + My , where : cx = x - Mx Mx Y = fc ( x - Mx ) ( My / Mx ) + My Y = X fcMy Mx [ x - Mx ( 1 - 1 fc ) ] Y = X ( fxMy Mx ) - Mx ( fcMy Mx ) ( 1 - 1 fc ) My = fm ( Mx ) = fm Y = X ( fcfm Mx ) - Mx ( fcfm My ) ( 1 - 1 fc ) Y = X ( fcfm Mx ) - Mx ( fcfm My - fcfm fcMx ) Y = X ( fcfm Mx ) - Fm ( fc - 1 ) Y = X ( fcfm Mx ) + fm ( 1 - fc ) the contrast modification function processing is performed in a first look-up table which computes: 1 /Mx*Fc ( Scx, Mx )* Fm ( Mx ) the mean modification function processing is performed in a second look-up table which computes: Fm ( Mx )*(1 −Fc ( Scx, Mx )); and the output of the first look-up table is multiplied by the input intensity (X) and the resulting product is added to the output of the second look-up table to produce an output sum; and the output sum is processed by a third look-up table to clip the output to a desired number of bits.
Claim 35
Dependent Claim
17 words
A method as recited in claim 31 , wherein the desired number of bits is eight bits.
Claim 36
Independent Claim
172 words
An apparatus compressing an intensity dynamic range of an input image to a reduced intensity dynamic range of an image display signal, each frame of the input image comprising plural units, the apparatus comprising: a filter determining a local mean estimate of the intensity of each of the plural units of the input image; a computer processing each local mean estimate, separately and directly, in accordance with: Y=M Y (1+C Y ), where: M Y =F M (M X ), C Y =F C (M X )*C X , and C X =(X−M X )/M X X=input intensity M X =local mean estimate C X =contrast estimate F M ( )=mean modification function F C ( )=contrast modification function Y=C-DRM output intensity M Y =modified local mean C Y =modified contrast; and the computer combining the corresponding mean modification function result and contrast modification function result to produce, for each input image unit intensity, a respective output intensity, within the reduced intensity range, for a corresponding unit of the image display signal.
Claim 37
Independent Claim
172 words
An apparatus compressing an intensity dynamic range of an input image to a reduced intensity dynamic range of an image display signal, each frame of the input image comprising plural units, the apparatus comprising: a filter determining a local mean estimate of the intensity of each of the plural units of the input image; a computer processing each local mean estimate, separately and directly, in accordance with: Y=M Y (1+C Y ), where: M Y =F M (M X ), C Y =F C (M X )*C X , and C X =(X−M X )/M X X=input intensity M X =local mean estimate C X =contrast estimate F M ( )=mean modification function F C ( )=contrast modification function Y=C-DRM output intensity M Y =modified local mean C Y =modified contrast; and the computer combining the corresponding mean modification function result and contrast modification function result to produce, for each input image unit intensity, a respective output intensity, within the reduced intensity range, for a corresponding unit of the image display signal.
Claim 38
Dependent Claim
47 words
An apparatus as recited in claim 33 , wherein: the mean modification function achieves either a linear or a non-linear transformation of the mean component of the image; and the contrast modification function applies a linear gain to the input contrast to the construct the output contrast.
Claim 39
Dependent Claim
35 words
An apparatus as recited in claim 33 , in which the input intensity value (X) of an input pixel is processed by a moving average function to produce the local mean estimate (M X ).
Claim 40
Dependent Claim
37 words
An apparatus as recited in claim 33 , wherein first and second look-up tables respectively perform the contrast modification function and the mean modification function respectively of the equations for determining C Y and C X .
Claim 41
Dependent Claim
37 words
An apparatus as recited in claim 33 , wherein the mean modification function transforms the mean from being linearly related to X-ray counts to being linearly related to an equivalent water thickness represented by the X-ray counts.
Claim 42
Dependent Claim
46 words
An apparatus as recited in claim 33 , wherein the contrast modification function C Y is implemented in compliance with a requirement that F C is monotonically increased in accordance with: F C ( C+ 1 , Mx )≧ F C ( C,Mx )∀ C, Mx.
References Cited (Backward Citations)
US5046118A
Cited
EP0505200A2
Cited
EP0544328A2
Cited
US5450502A
Cited
US5633511A
Cited
EP0780791A2
Cited
US6546124B1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2007-07-20 | 2008-01-19 | 2008-07-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2011-07-20 | 2012-01-19 | 2012-07-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2015-07-20 | 2016-01-19 | 2016-07-20 | $7700.00 | Window Closed / Lapsed |