EP0423653A2
Expired / Lapsed
EP
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Method and apparatus for compensating for color in color images
Assignee: Panasonic Holdings Corp
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Filing: 1990-10-12
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Granted: —
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Expires: 2010-10-12
Abstract
Abstract The present invention relates to a method and an apparatus for compensating for color in color images for use in an image processing field which is employed for three dimension computer graphics and so on. Conventionally, a color compensation method for color images for use in this field has not made any compensation between a lightness of a texture itself representing a pattern on the surface of an object and an intensity of the surface of the object derived by an intensity calculation when an image is generated, so that the generated image has been extremely unnatural. The present invention performs a color compensation for color images by making a luminance of texture data coincident with an intensity derived by an intensity calculation. Also, a lightness compensation is performed for a color image according to a display scene. From measuring results of color changes of plural colors in a uniform color space, a color change of arbitrary texture data under a chromatic color light source is represented and compensated for.
Inventors
- 👤 Kazutaka Nishio
- 👤 Kenji Nishimura
- 👤 Toshiya Naka
- 👤 Yoshimori Nakase
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 10:44
CPC Classifications
G; G06; G06T; G06T15/00; G06T15/50; G06T15/506
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
198 words
A method for compensating for color in color images in a combination comprising a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of the surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of the intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion (6) unit for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue: said method being characterized by calculating a luminance of said object from a ratio of the intensity of said object to said maximum intensity, both calculated by said intensity processing unit, a reflectance of said attribute data of said object, and a luminance of a standard white.
Claim 2
Independent Claim
198 words
A method for compensating for color in color images in a combination comprising a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of the surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of the intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion (6) unit for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue: said method being characterized by calculating a luminance of said object from a ratio of the intensity of said object to said maximum intensity, both calculated by said intensity processing unit, a reflectance of said attribute data of said object, and a luminance of a standard white.
Claim 3
Independent Claim
230 words
A method for compensating for color in color images in a combination comprising a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue: said method being characterized by calculating a lightness of a surface irradiated with a chromatic color reference light, when it is derived from a lightness of said surface irradiated with an achromatic color reference light, by a mapping representative of a displacement amount of an arbitrary color in a color space, said mapping being calculated based upon chromaticity coordinates of a standard white and a standard color patch when they are irradiated with said achromatic and chromatic color reference lights.
Claim 4
Independent Claim
230 words
A method for compensating for color in color images in a combination comprising a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue: said method being characterized by calculating a lightness of a surface irradiated with a chromatic color reference light, when it is derived from a lightness of said surface irradiated with an achromatic color reference light, by a mapping representative of a displacement amount of an arbitrary color in a color space, said mapping being calculated based upon chromaticity coordinates of a standard white and a standard color patch when they are irradiated with said achromatic and chromatic color reference lights.
Claim 5
Independent Claim
215 words
A method for compensating for color in color images in a combination comprising a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue: said method being characterized by changing, for changing lightness of said color image data, its saturation in proportion to a lightness changing rate within a range in which said lightness of the color image data does not exceed a lightness value of a standard white when irradiated with a chromatic color reference light, or by decreasing its saturation in proportion to the lightness changing rate.
Claim 6
Independent Claim
215 words
A method for compensating for color in color images in a combination comprising a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue: said method being characterized by changing, for changing lightness of said color image data, its saturation in proportion to a lightness changing rate within a range in which said lightness of the color image data does not exceed a lightness value of a standard white when irradiated with a chromatic color reference light, or by decreasing its saturation in proportion to the lightness changing rate.
Claim 7
Independent Claim
202 words
A method for compensating for color in color images in a combination comprising a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue: said method being characterized by calculating, for compensating for a display luminance range of an output image, a display luminance of said display (7) from a maximum display luminance and a minimum display luminance of said display (7), a median value of the display luminance and a luminance of color image data.
Claim 8
Independent Claim
202 words
A method for compensating for color in color images in a combination comprising a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue: said method being characterized by calculating, for compensating for a display luminance range of an output image, a display luminance of said display (7) from a maximum display luminance and a minimum display luminance of said display (7), a median value of the display luminance and a luminance of color image data.
Claim 9
Independent Claim
195 words
An apparatus for compensating for color in color images comprising: a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of the surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue; and a luminance calculation unit (3) for calculating a luminance of said object from a ratio of the intensity of said object to said maximum intensity, both calculated by said intensity processing unit, a reflectance of said attribute data of said object, and a luminance of a standard white.
Claim 10
Independent Claim
195 words
An apparatus for compensating for color in color images comprising: a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of the surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue; and a luminance calculation unit (3) for calculating a luminance of said object from a ratio of the intensity of said object to said maximum intensity, both calculated by said intensity processing unit, a reflectance of said attribute data of said object, and a luminance of a standard white.
Claim 11
Independent Claim
197 words
An apparatus for compensating for color in color images comprising: a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue, and a color space mapping unit (4) for calculating a mapping representative of a displacement amount of an arbitrary color in a color space on the basis of chromaticity coordinates of a standard white and a standard color patch when they are irradiated with said achromatic and chromatic color reference lights.
Claim 12
Independent Claim
197 words
An apparatus for compensating for color in color images comprising: a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue, and a color space mapping unit (4) for calculating a mapping representative of a displacement amount of an arbitrary color in a color space on the basis of chromaticity coordinates of a standard white and a standard color patch when they are irradiated with said achromatic and chromatic color reference lights.
Claim 13
Independent Claim
214 words
An apparatus for compensating for color in color images comprising: a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue; and a color compensation unit (5) for changing lightness of said color image data by changing its saturation in proportion to a lightness changing rate within a range in which said lightness of the color image data does not exceed a lightness value of a standard white when irradiated with a chromatic color reference light, or by decreasing its saturation in proportion to the lightness changing rate.
Claim 14
Independent Claim
214 words
An apparatus for compensating for color in color images comprising: a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of a surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of said surface of said object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by the use of said lightness, said saturation and said hue; and a color compensation unit (5) for changing lightness of said color image data by changing its saturation in proportion to a lightness changing rate within a range in which said lightness of the color image data does not exceed a lightness value of a standard white when irradiated with a chromatic color reference light, or by decreasing its saturation in proportion to the lightness changing rate.
Claim 15
Independent Claim
173 words
An apparatus for compensating for color in color images comprising: a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of the surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of the intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of the surface of the object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by compensating for said lightness, saturation and hue with a maximum display luminance and a minimum display luminance of said display (7), a median value of the display luminance and a luminance of color image data.
Claim 16
Independent Claim
173 words
An apparatus for compensating for color in color images comprising: a color conversion unit (1) for performing a color conversion on color image data to calculate a luminance, a lightness, a saturation and a hue; an intensity processing unit (2) for calculating an intensity of the surface of an object, a maximum intensity thereof, a maximum intensity of a display scene, a minimum intensity of said display scene, and a median value of the intensity of said display scene by the use of shape data representative of a shape of said object, light source data representative of a position and light emitting characteristics of a light source and attribute data representative of optical property of the surface of the object; and a display luminance conversion unit (6) for converting to a display luminance of a display (7) by compensating for said lightness, saturation and hue with a maximum display luminance and a minimum display luminance of said display (7), a median value of the display luminance and a luminance of color image data.
References Cited (Backward Citations)
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