Display-based color system

Claim 1

A method for defining an improved perceptually uniform color space for a display device, the improved perceptually uniform color space having coordinates H, V, and C, which are based upon CIELUV coordinates L*, v* and u*, the method comprising the steps of: (a) determining the maximum CIELUV chroma C* uv =(u* 2 +v* 2 ) 1/2 producible by a display device that has a plurality of color-producing primaries, the luminous intensity of the primaries being adjustable between minimum and maximum levels to produce a gamut of colors; (b) establishing a maximum numerical value for the C coordinate; (c) dividing the maximum C value by the determined maximum CIELUV chroma to yield a chroma factor C f ; and (d) defining the improved color space coordinates as: H=arctan (v*/u*)+K, where K=0° for u*>0 and v*>0; K=90° for u*<0 and v*>0; K=180° for u*<0 and v*<0; K=270° for u*>0 and v*<0; V=L*; C=C*.sub.uv (V)(C.sub.f).

Claim 2

A method for defining an improved perceptually uniform color space for a display device, the improved perceptually uniform color space having coordinates H, V, and C, which are based upon CIELUV coordinates L*, v* and u*, the method comprising the steps of: (a) determining the maximum CIELUV chroma C* uv =(u* 2 +v* 2 ) 1/2 producible by a display device that has a plurality of color-producing primaries, the luminous intensity of the primaries being adjustable between minimum and maximum levels to produce a gamut of colors; (b) establishing a maximum numerical value for the C coordinate; (c) dividing the maximum C value by the determined maximum CIELUV chroma to yield a chroma factor C f ; and (d) defining the improved color space coordinates as: H=arctan (v*/u*)+K, where K=0° for u*>0 and v*>0; K=90° for u*<0 and v*>0; K=180° for u*<0 and v*<0; K=270° for u*>0 and v*<0; V=L*; C=C*.sub.uv (V)(C.sub.f).

Claim 6

A method for defining a selected color in terms of a perceptually uniform color space that is described by H, V, and C coordinates, the method comprising the steps of: (a) selecting a color that is defined by a primary intensity vector, which vector denoting the relative values of the luminous intensities of a plurality of primaries, each primary being adjustable to produce a range of luminous intensity levels; (b) generating a matrix for converting the primary intensity vector into corresponding XYZ tristimulus values; (c) multiplying the primary intensity of the selected color by the matrix to yield corresponding tristimulus values X s , Y s , Z s ; (d) computing the CIELUV system coordinates L*, u*, v* that correspond to the tristimulus values X s , Y s and Z s ; (e) computing the H coordinates as H=arctan (v*/u*)+K, where K=0° for u*>0 and v*>0; K=90° for u*<0 and v*>0; K=180° for u*<0 and v*<0; K=270° for u*>0 and v*<0; (f) computing V as V=L*; (g) computing C f as 100/C* uvmax , where C* uvmax is the maximum numerical value of the CIELUV system chroma C* uv producible by the primaries; and (h) computing C as C=(v*.sup.2 +u*.sup.2).sup.1/2 (V)(C.sub.f).

Claim 7

A method for defining a selected color in terms of a perceptually uniform color space that is described by H, V, and C coordinates, the method comprising the steps of: (a) selecting a color that is defined by a primary intensity vector, which vector denoting the relative values of the luminous intensities of a plurality of primaries, each primary being adjustable to produce a range of luminous intensity levels; (b) generating a matrix for converting the primary intensity vector into corresponding XYZ tristimulus values; (c) multiplying the primary intensity of the selected color by the matrix to yield corresponding tristimulus values X s , Y s , Z s ; (d) computing the CIELUV system coordinates L*, u*, v* that correspond to the tristimulus values X s , Y s and Z s ; (e) computing the H coordinates as H=arctan (v*/u*)+K, where K=0° for u*>0 and v*>0; K=90° for u*<0 and v*>0; K=180° for u*<0 and v*<0; K=270° for u*>0 and v*<0; (f) computing V as V=L*; (g) computing C f as 100/C* uvmax , where C* uvmax is the maximum numerical value of the CIELUV system chroma C* uv producible by the primaries; and (h) computing C as C=(v*.sup.2 +u*.sup.2).sup.1/2 (V)(C.sub.f).

Claim 9

A system for defining a color selected from a gamut of colors producible by a color display device in terms of a perceptually uniform color space that is described by H, V and C coordinates, the system comprising: (a) a display device having a plurality of primaries each primary variable between a minimum and maximum luminous intensity level for producing a color that is defined by a primary intensity vector denoting the relative values of the primary intensity levels; (b) input means for receiving and storing data corresponding to the primary intensity vector of the color; (c) processing means for (1) generating a matrix for converting primary intensity vectors into corresponding XYZ tristimulus values; (2) multiplying the primary intensity vector of the color by the matrix to yield the tristimulus values X s , Y s , Z s of the color; (3) determining the L*, u* and v* coordinates of the CIELUV system that correspond to the tristimulus values X s , Y s and Z s ; and (4) computing the H, V and C coordinates as: H=(arctan (v*/u*)+K)-H.sub.0, where K=0° for u*>0 and v*>0; K=90° for u*<0 and v*>0; K=180° for u*<0 and v*<0; K=270° for u*>0 and v*<0; -11°≦H 0 ≦-15°; V=L*; C=(v* 2 +u* 2 ) 1/2 (V)(C f ) where C f =100/C* uvmax , wherein C* uvmax is a maximum numerical value of the CIELUV chroma C* uv producible by the primaries of the display device.

Claim 10

A system for defining a color selected from a gamut of colors producible by a color display device in terms of a perceptually uniform color space that is described by H, V and C coordinates, the system comprising: (a) a display device having a plurality of primaries each primary variable between a minimum and maximum luminous intensity level for producing a color that is defined by a primary intensity vector denoting the relative values of the primary intensity levels; (b) input means for receiving and storing data corresponding to the primary intensity vector of the color; (c) processing means for (1) generating a matrix for converting primary intensity vectors into corresponding XYZ tristimulus values; (2) multiplying the primary intensity vector of the color by the matrix to yield the tristimulus values X s , Y s , Z s of the color; (3) determining the L*, u* and v* coordinates of the CIELUV system that correspond to the tristimulus values X s , Y s and Z s ; and (4) computing the H, V and C coordinates as: H=(arctan (v*/u*)+K)-H.sub.0, where K=0° for u*>0 and v*>0; K=90° for u*<0 and v*>0; K=180° for u*<0 and v*<0; K=270° for u*>0 and v*<0; -11°≦H 0 ≦-15°; V=L*; C=(v* 2 +u* 2 ) 1/2 (V)(C f ) where C f =100/C* uvmax , wherein C* uvmax is a maximum numerical value of the CIELUV chroma C* uv producible by the primaries of the display device.