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EP0781036A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Colour correction with consideration of the scene illuminant

Assignee: HP Inc
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Filing: 1996-11-12
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Granted: —
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Expires: 2016-11-12
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Abstract

Abstract A color image editing system and method uses sensor responses in an image capture device to estimate and separate illuminant and surface reflectance in a scene. The system uses the estimated surface reflectances, along with a desired illuminant SPD, to calculate the corresponding XYZ values. To render the images on an imaging device , the XYZ values are converted into device-dependent display or printer values. The image data may be manipulated in a manner that is intuitive to humans, such as correcting the image data according to changes in lighting and surface color. An image capture device, such as a scanner or digital camera, represents a scene as image data that is resolved as device-dependent channels, such as RGB. For each channel, the spectral reflectances of the surfaces within the scene are described reflectance functions that are independnt of the lighting function that describes the illuminant spectral power distribution (SPD). Display operators can independently adjust the surface and lighting functions.

Inventors

  • 👤 Joyce E. Farrell

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-01 11:49
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/56; H04N1/60; H04N1/6083; H04N1/6086; H04N1/603

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 78 words
A method for characterizing a scene as surfaces and illuminants comprising the steps of: measuring an illuminant spectral signature of a capturing device 110; capturing the scene as an array of pixel values 150; characterizing a scene transfer function by combining the illuminant spectral signature with a device signature of the capturing device 130; and characterizing a scene signature by describing illumination and surfaces corresponding to the array of pixel values according to the scene transfer function 160.
Claim 2
Dependent Claim 24 words
A method for characterizing a scene as surfaces and illuminants as defined in claim 1 further comprising the step of rendering the scene 190.
Claim 3
Dependent Claim 54 words
A method for characterizing a scene as surfaces and illuminants, as defined in claim 2, wherein the step of rendering further comprises the steps of: customizing the scene signature to describe the surfaces in the scene 160; customizing the scene signature according to an effective illuminant level 170; and rendering the scene signature 190.
Claim 4
Dependent Claim 31 words
A method for characterizing a scene as surfaces and illuminants, as defined in claim 1, wherein the step of capturing the scene comprises the step of scanning a rendered image 110.
Claim 5
Dependent Claim 45 words
A method for characterizing a scene as surfaces and illuminants, as defined in claim 3, wherein the step of customizing the scene signature to describe the surfaces in the scene further comprises the step of characterizing the scene signature according to a look-up table 195.
Claim 6
Dependent Claim 53 words
A method for characterizing a scene as surfaces and illuminants, as defined in claim 3, wherein the step of customizing the scene signature to describe the surfaces in the scene further comprises the step of rendering the scene surface matrix according to a transfer function that corresponds to a display device signature 193.
Claim 7
Dependent Claim 25 words
A method for characterizing a scene as surfaces and illuminants, as defined in claim 1, further comprising the step of capturing the device signature 130.
Claim 8
Dependent Claim 31 words
A method for characterizing a scene as surfaces and illuminants, as defined in claim 1, further comprising the step of modeling a set of surfaces as a surface spectral signature 180.
Claim 9
Dependent Claim 62 words
A method for characterizing a scene as surfaces and illuminants, as defined in claim 8, wherein the step of modeling a set of surfaces further comprises the steps of: scanning a rendered scene 110; generating an array of pixels that corresponds to the rendered scene 200; and determining a scene signature according to the array of pixels and the device signature 230.

References Cited (Backward Citations)

US4574319A Cited
US4970584A Cited
US5144498A Cited
WO1992004803A1 Cited
EP0531891A2 Cited
EP0624028A1 Cited

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