Display-based color system

Claim 1

A method for defining an improved perceptually uniform color space for a display device, wherein the display device 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, 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 the display device; (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* uv (V) (C f ).

Claim 2

A method for defining an improved perceptually uniform color space for a display device, wherein the display device 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, 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 the display device; (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* uv (V) (C f ).

Claim 6

A method for transforming a selected color into a perceptually uniform color space described by H, V, and C coordinates, wherein the selected color is comprised of a combination of display device primaries, the luminous intensity of each primary being variable between a minimum and maximum level, the selected color being definable by a primary intensity vector denoting the relative values of the primary intensities, the method comprising the steps of: (a) generating a matrix for converting primary intensity vectors into corresponding XYZ tristimulus values; (b) multiplying the primary intensity vector of the selected color by the matrix to yield corresponding tristimulus values X s , Y s , Z s ; (c) computing the L*, u*, v* coordinates of the CIELUV system that correspond to the tristimulus values X s , Y s and Z s ; (d) computing the H coordinate 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; (e) computing V as V = L*; and (f) computing C as C = (v*² + u*²) 1/2 (V) (C f ) wherein C f is a factor for establishing a maximum numerical value for C producible by the display device.

Claim 7

A method for transforming a selected color into a perceptually uniform color space described by H, V, and C coordinates, wherein the selected color is comprised of a combination of display device primaries, the luminous intensity of each primary being variable between a minimum and maximum level, the selected color being definable by a primary intensity vector denoting the relative values of the primary intensities, the method comprising the steps of: (a) generating a matrix for converting primary intensity vectors into corresponding XYZ tristimulus values; (b) multiplying the primary intensity vector of the selected color by the matrix to yield corresponding tristimulus values X s , Y s , Z s ; (c) computing the L*, u*, v* coordinates of the CIELUV system that correspond to the tristimulus values X s , Y s and Z s ; (d) computing the H coordinate 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; (e) computing V as V = L*; and (f) computing C as C = (v*² + u*²) 1/2 (V) (C f ) wherein C f is a factor for establishing a maximum numerical value for C producible by the display device.

Claim 10

A method for transforming a selected color in a color space having H, V and C coordinates based upon CIELUV coordinates L*, u* and v* and defined as: H = arctan (v*/u*) + K)-H₀, 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° ≦ H₀ ≦ -15° V = L* C = (v*²+u*²) 1/2 (V) (C f ) wherein C f is a factor for establishing a maximum numerical value for C producible by the display device, into the corresponding primary luminous intensity levels of a display device having a plurality of primaries, the method comprising the steps of: (a) receiving for a selected color an H, V and C coordinate; (b) converting the H, V and C coordinates of the selected color into a tristimulus vector comprising tristimulus values X s , Y s and Z s corresponding to the selected color; (c) generating a matrix for converting tristimulus vectors into corresponding primary luminous intensity vectors that denote relative intensity levels of the display device primaries; and (d) multiplying the tristimulus vector of the selected color by the matrix to convert the tristimulus vector of the selected color into a selected primary luminous intensity vector, the selected primary intensity vector denoting the relative luminous levels of the primaries for displaying the selected color on the display device.

Claim 11

A method for transforming a selected color in a color space having H, V and C coordinates based upon CIELUV coordinates L*, u* and v* and defined as: H = arctan (v*/u*) + K)-H₀, 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° ≦ H₀ ≦ -15° V = L* C = (v*²+u*²) 1/2 (V) (C f ) wherein C f is a factor for establishing a maximum numerical value for C producible by the display device, into the corresponding primary luminous intensity levels of a display device having a plurality of primaries, the method comprising the steps of: (a) receiving for a selected color an H, V and C coordinate; (b) converting the H, V and C coordinates of the selected color into a tristimulus vector comprising tristimulus values X s , Y s and Z s corresponding to the selected color; (c) generating a matrix for converting tristimulus vectors into corresponding primary luminous intensity vectors that denote relative intensity levels of the display device primaries; and (d) multiplying the tristimulus vector of the selected color by the matrix to convert the tristimulus vector of the selected color into a selected primary luminous intensity vector, the selected primary intensity vector denoting the relative luminous levels of the primaries for displaying the selected color on the display device.

Claim 12

A method for transforming a selected color in a color space having H, V and C coordinates based upon CIELUV coordinates L*, u* and v* and defined as: H = arctan (v*/u*) + K)-H₀, 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° ≦ H₀ ≦ -15° V = L* C = (v*²+u*²) 1/2 (V) (C f ) wherein C f is a factor for establishing a maximum numerical value for C producible by the display device, into the corresponding primary intensity levels of a CRT display device having red, green and blue primaries, the method comprising the steps of: (a) receiving for a selected color an H, V and C coordinate; (b) converting the H, V and C coordinates of the selected color into a tristimulus vector comprising tristimulus values X s , Y s , and Z s corresponding to the selected color; (c) generating an XYZ-to-RGB matrix for converting tristimulus vectors into rgb intensity vectors denoting relative intensity levels of the three primaries corresponding to the tristimulus vector from which it is converted; and (d) multiplying the tristimulus vector of the selected color by the XYZ-to-RGB matrix to convert the tristimulus vector of the selected color into a selected rgb intensity vector, the selected rgb intensity vector denoting the relative luminous level of the red, green and blue primaries necessary for displaying the selected color on the display device.

Claim 13

A method for transforming a selected color in a color space having H, V and C coordinates based upon CIELUV coordinates L*, u* and v* and defined as: H = arctan (v*/u*) + K)-H₀, 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° ≦ H₀ ≦ -15° V = L* C = (v*²+u*²) 1/2 (V) (C f ) wherein C f is a factor for establishing a maximum numerical value for C producible by the display device, into the corresponding primary intensity levels of a CRT display device having red, green and blue primaries, the method comprising the steps of: (a) receiving for a selected color an H, V and C coordinate; (b) converting the H, V and C coordinates of the selected color into a tristimulus vector comprising tristimulus values X s , Y s , and Z s corresponding to the selected color; (c) generating an XYZ-to-RGB matrix for converting tristimulus vectors into rgb intensity vectors denoting relative intensity levels of the three primaries corresponding to the tristimulus vector from which it is converted; and (d) multiplying the tristimulus vector of the selected color by the XYZ-to-RGB matrix to convert the tristimulus vector of the selected color into a selected rgb intensity vector, the selected rgb intensity vector denoting the relative luminous level of the red, green and blue primaries necessary for displaying the selected color on the display device.