# US 2003/0165266 A1 · Color conversion apparatus, and color conversion method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2003/0165266 A1 - Document ID: US20030165266A1 - Status: Published application - Kind: A1 - Application number: 10/212,108 - Filed: 2002-08-06 - Published: 2003-09-04 - Earliest claimed: 2002-02-15 - Assignees: Mitsubishi Denki Kabushiki Kaisha - Inventors: Shuichi Kagawa; Hiroaki Sugiura; Mariko Takahashi; Narihiro Matoba - Web page: https://patentgrep.com/patent/US20030165266A1 ## CPC - H04N 1/6058: {Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A method and apparatus for converting color includes converting the hue, lightness, and/or saturation of first color data representing each of plurality of colors forming a color image, to produce second color data corresponding to the first color data. The second color data is converted to third color data suitable for the color space which can be expressed by the image output device used for the output of the color image. Color contraction which is conventionally associated with color conversion that increases lightness or saturation can be prevented. ## Claims ### Claim 1 A color conversion apparatus comprising a second-color-data generating unit for converting a hue, lightness, and/or saturation of first color data representing respective colors forming a color image to generate second color data corresponding to the first color data; and a third-color-data generating unit for generating third color data suitable for the color space which can be expressed by an image output unit used for outputting the color image. ### Claim 2 (depends on 1) The color conversion apparatus as set forth in claim 1, wherein said third-color-data generating unit generates the third color data based on a maximum value of the gradation levels of the respective colors represented by the second color data. ### Claim 3 (depends on 2) The color conversion apparatus as set forth in claim 2, wherein said third color data generating unit reduces the gradation level of each of the colors of the second color data according to the maximum value in excess of a predetermined value. ### Claim 4 (depends on 1) The color conversion apparatus as set forth in claim 1, further comprising a complementary-color-data outputting unit for outputting complementary color data representing the respective complementary colors of a plurality of colors represented by the second color data, wherein said third-color-data generating unit generates the third color data based on the complementary color data. ### Claim 5 (depends on 4) The color conversion apparatus as set forth in claim 4, wherein said third-color-data generating unit generates the third color data based on a maximum value of the gradation levels of the respective complementary colors represented by the complementary color data. ### Claim 6 (depends on 5) The color conversion apparatus as set forth in claim 5, wherein said third-color-data generating unit generates the third color data by reducing the gradation level of each of the complementary colors of the complementary color data according to the maximum value in excess of a predetermined value. ### Claim 7 (depends on 1) The color conversion apparatus as set forth in claim 1, further comprising a ratio calculating unit for calculating a ratio between the hue components of magenta and red, red and yellow, yellow and green, green and cyan, cyan and blue, or blue and magenta, said third-color-data generating unit generates the third color data based on the ratio between the hue components. ### Claim 8 A color conversion apparatus comprising: a first-calculation-term generating unit responsive to first color data representing respective colors of red, green and blue, for generating a first calculation term which is effective for at least one of the hues of red, green, blue, cyan, magenta and yellow; a second-color-data generating unit for generating second color data corresponding to the first color data; and a third-color-data generating unit responsive to the first calculation term, and the second color data, for generating third color data suitable for the color space expressed by the image output unit used for outputting the color image. ### Claim 9 (depends on 8) The color conversion apparatus as set forth in claim 8, wherein said third-color-data generating unit generates the third color data based on a maximum value of the gradation levels of the respective colors represented by the second color data. ### Claim 10 (depends on 9) The color conversion apparatus as set forth in claim 9, wherein said third color data generating unit reduces the gradation level of each of the colors of the second color data according to the maximum value in excess of a predetermined value. ### Claim 11 (depends on 8) The color conversion apparatus as set forth in claim 8, further comprising a second-calculation-term generating unit for generating a second calculation term effective for a predetermined hue included in one of inter-hue zones of red to yellow, yellow to green, green to cyan, cyan to blue, blue to magenta, and magenta to red, based on the first calculation term; wherein said second-color-data generating unit generates the second color data also by multiplying the second calculation term by a predetermined matrix coefficient; the third-color-data generating unit generates the third color data based also on the second color data. ### Claim 12 A color conversion method comprising the steps of: converting a hue, lightness, and/or saturation of first color data representing the respective colors forming a color image to generate second color data corresponding to the first color data; and generating, based on the second color data, third color data suitable for the color space which can be expressed by an image output unit used for outputting the color image. ### Claim 13 (depends on 12) The color conversion method as set forth in claim 12, wherein said step of generating the third color data generates the third color data based on a maximum value of the gradation levels of the respective colors represented by the second color data. ### Claim 14 (depends on 13) The color conversion method as set forth in claim 13, wherein said step of generating the third color data generates the third color data by reducing the gradation level of each of the colors of the second color data according to the maximum value in excess of a predetermined value. ### Claim 15 (depends on 12) The color conversion method as set forth in claim 12, wherein said step of generating the third color data generates the third color data based on the complementary color data representing the respective complementary colors of a plurality of colors represented by the second color data. ### Claim 16 (depends on 15) The color conversion method as set forth in claim 15, wherein said step of generating the third color data generates the third color data based on a maximum value of the gradation levels of the respective complementary colors represented by the complementary color data. ### Claim 17 (depends on 16) The color conversion method as set forth in claim 16, wherein said step of generating the third color data generates the third color data by reducing the gradation level of each of the complementary colors of the complementary color data according to the maximum value in excess of a predetermined value. ### Claim 18 (depends on 12) The color conversion method as set forth in claim 12, further comprising the step of: calculating a ratio between the hue components of magenta and red, red and yellow, yellow and green, green and cyan, cyan and blue, or blue and magenta, wherein said step of generating the third color data generates the third color data based on the ratio between the hue components.