EP0626782A2
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Method and apparatus for convex interpolation for color calibration
Assignee: Eastman Kodak Co
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Filing: 1994-05-25
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Granted: —
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Expires: 2014-05-25
Abstract
Abstract A convex interpolation apparatus and method to map source color signals in a n-dimensional color space to target color signals in a m-dimensional color space includes finding a set of sample signals in the source color space whose convex hull encloses the given signal; determining the coefficients needed to express the given signal as a convex combination of the set of sample signals; and interpolating the source signal to obtain a target signal in the target color space by using the coefficients and the sample signals is the target color space that correspond to the sample signals selected in the source color space. The sample signals in both color spaces can be lattice points or non-lattice points. A method and apparatus are also provided which can not only determine if a point is enclosed by a convex hull of a set of points in a n-dimensional space, but also simultaneously derive the coefficients needed to express the given point as a convex combination of the set of points.
Inventors
- 👤 Shijie J. C/O Eastman Kodak Company Wan
- 👤 Rodney L. C/O Eastman Kodak Company Miller
- 👤 James R. C/O Eastman Kodak Company Sullivan
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:54
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/56; H04N1/60; H04N1/6058; H04N1/6016; H04N1/6019
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
65 words
A method of converting a color signal from a device independent color space to a device dependent color space for an output device, comprising the steps of: (a) performing a convex interpolation of the color signal in the device independent color space to produce a converted color signal in the device dependent color space; and (b) displaying the converted color signal using the output device.
Claim 2
Dependent Claim
81 words
A method as recited in claim 1, wherein step (a) comprises the steps of: (a1) determining whether a set of color signals in the independent color space, which have a known relationship to corresponding signals in the dependent color space, form a convex hull that encloses the color signal; (a2) determining interpolation coefficients if the convex hull encloses the color signal; and (a3) performing a convex interpolation using the coefficients and the corresponding color signals to produce the converted color signal.
Claim 3
Dependent Claim
49 words
A method as recited in claim 2, wherein step (a1) comprises the steps of: (i) performing a convex inclusion procedure on the set of signals; and (ii) adding a next nearest signal to the set if the convex hull does not enclose the color signal performing step (i) again.
Claim 4
Dependent Claim
68 words
A method as recited in claim 3, wherein step (i) comprises the steps of: (A) adding unit vector signals to the set; and (B) minimizing a sum of dimensional weights subject to signal weight times the corresponding signal summing to the color signal, the sum of the dimensional weights and signal weights equaling one and the dimensional and signal weights all being greater than or equal to zero.
Claim 5
Independent Claim
43 words
A method of performing a conversion, comprising the steps of: (a) determining nearest signals in the first space whose convex hull encloses a signal to be interpolated; and (b) performing a convex interpolation with second space signals corresponding to the first space signals.
Claim 6
Independent Claim
58 words
A method of converting a color signal from a device independent color space to a device dependent color space, comprising: (a) creating an inverse look-up table using a look-up table and backward convex interpolation; and (b) converting the color signal from the device independent space to the device dependent space by forward interpolation using the inverse look-up table.
Claim 7
Independent Claim
57 words
A method of converting a first signal, comprising: (a) performing an interpolation of the first signal from an n dimensional vector space to an m dimensional vector space to produce an interpolated second signal, where n and m are positive integers that need not be equal; and (b) using the interpolated signal to drive an output device.
Claim 8
Independent Claim
89 words
A method of interpolation a color signal, comprising the steps of: (a) finding a first set of sample signals in a source color space whose convex hull encloses the color signal; (b) determining coefficients which express the color signal as a convex combination of the first set of sample signals; and (c) interpolating the color signal to obtain a target signal in a target color space using the coefficients and a second set of sample signals in the target color space corresponding to the first set of sample signals.
Claim 9
Independent Claim
55 words
An apparatus, comprising: an output device for reproducing a color image responsive to image data in an output device color space; and a computer connected to said output device and performing a convex interpolation conversion of the image data from a device independent space to the output device color space and driving said output device.
Claim 10
Dependent Claim
69 words
An apparatus as recited in claim 9, wherein said computer comprises: enclosure means for determining whether a set of signals in the device independent space form a convex hull enclosing the image data; determination means for determining interpolation coefficients when the convex hull encloses the image data; and interpolation means for performing an interpolation using the coefficients and second signals in the device color space corresponding to the set.
References Cited (Backward Citations)
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