Color navigation system
First Claim
1. A memory comprising discrete color points and suitable for use with a color navigation system generating light with a variable color, the color points defined according to three-dimensional CIELAB coordinates hue (H), lightness (L), chroma (C), with predefined intervals Δ
- H between neighboring color points in the hue direction, with predefined intervals Δ
L between neighboring color points in the lightness direction, and with predefined intervals Δ
C between neighboring color points in the chroma direction, respectively;
wherein Δ
L is equidistant over the color space; and
wherein Δ
S is equidistant over the color space, with Δ
C=Δ
S·
L, S indicating saturation;
such that the perceptual color difference Δ
EINV, defined according to the formula;
Δ
EINV=√
{square root over ((Δ
L)2+(fC(H)·
Δ
C)2+(Δ
H)2)}{square root over ((Δ
L)2+(fC(H)·
Δ
C)2+(Δ
H)2)}{square root over ((Δ
L)2+(fC(H)·
Δ
C)2+(Δ
H)2)}is substantially constant over the color space for steps in the L direction and in the S direction;
wherein fC(H) is a proportionality factor between 0 and 1 only depending on hue H;
wherein, for hue values H between a first hue value (H1) corresponding to red and a second hue value (H2) corresponding to green, the proportionality factor fC(H) is equal to 1 and the number of color points in the hue direction in this range is equal to NH,RG;
wherein, for hue values between the second hue value (H2) corresponding to green and a third hue value (H3) corresponding to blue, the proportionality factor fC(H) is set to a constant value fGB such that the number NH,GB(fGB) of color points in the hue direction in this range differs less than 50% from NH,RG, NH,GB(fGB being equal to NH,RG;
wherein, for hue values between the third hue value (H3) and the first hue value (H1), the proportionality factor fC(H) is set to a constant value fBR such that the number NH,BR(fBR) of color points in the hue direction in this range differs less than 50% from NH,RG; and
wherein Δ
H is a function of H such that, for steps in the hue direction along the border of the color space, said perceptual color difference Δ
EINV is substantially constant.
1 Assignment
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Accused Products
Abstract
A system and method for color navigation through a CIELAB color space with coordinates hue (H), lightness (L), chroma (C), with intervals ΔH, ΔL, ΔC such that the perceptual color difference AE1Nv, defined according to the formula: AZW =^{AL)2+{fc(H)−ACf+[AH)2, is constant for steps in direction C and L and for steps in direction H along boundary of color space. fc(H) is a proportionality factor between 0 and 1 depending on hue. For hue values between red (H1) and green (H2), fc(H) =1. For hue values between green (H2) and blue (H3), the proportionality factor fc(H) is set to a constant value foB such that Nκ,GB(fGB) differs less than 50% from NH,RG—For hue values between blue (H3) and red (H1), the proportionality factor fc(H) is set to a constant value fβR such that N^BR^BR) differs less than 50% from NH,RG—.
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Citations
9 Claims
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1. A memory comprising discrete color points and suitable for use with a color navigation system generating light with a variable color, the color points defined according to three-dimensional CIELAB coordinates hue (H), lightness (L), chroma (C), with predefined intervals Δ
- H between neighboring color points in the hue direction, with predefined intervals Δ
L between neighboring color points in the lightness direction, and with predefined intervals Δ
C between neighboring color points in the chroma direction, respectively;wherein Δ
L is equidistant over the color space; andwherein Δ
S is equidistant over the color space, with Δ
C=Δ
S·
L, S indicating saturation;such that the perceptual color difference Δ
EINV, defined according to the formula;
Δ
EINV=√
{square root over ((Δ
L)2+(fC(H)·
Δ
C)2+(Δ
H)2)}{square root over ((Δ
L)2+(fC(H)·
Δ
C)2+(Δ
H)2)}{square root over ((Δ
L)2+(fC(H)·
Δ
C)2+(Δ
H)2)}is substantially constant over the color space for steps in the L direction and in the S direction; wherein fC(H) is a proportionality factor between 0 and 1 only depending on hue H; wherein, for hue values H between a first hue value (H1) corresponding to red and a second hue value (H2) corresponding to green, the proportionality factor fC(H) is equal to 1 and the number of color points in the hue direction in this range is equal to NH,RG; wherein, for hue values between the second hue value (H2) corresponding to green and a third hue value (H3) corresponding to blue, the proportionality factor fC(H) is set to a constant value fGB such that the number NH,GB(fGB) of color points in the hue direction in this range differs less than 50% from NH,RG, NH,GB(fGB being equal to NH,RG; wherein, for hue values between the third hue value (H3) and the first hue value (H1), the proportionality factor fC(H) is set to a constant value fBR such that the number NH,BR(fBR) of color points in the hue direction in this range differs less than 50% from NH,RG; and wherein Δ
H is a function of H such that, for steps in the hue direction along the border of the color space, said perceptual color difference Δ
EINV is substantially constant.- View Dependent Claims (2, 3, 4, 5, 6)
the controller is configured, in response to the user input data and taking into account a current color point, to calculate a target color point based on said steps Δ
H, Δ
L, Δ
C, to take from memory data relating to a color point closest to the target color point, and to generate its color control signals (ξ
1, ξ
2, ξ
3) for the lamp assembly on the basis of these data from memory.
- H between neighboring color points in the hue direction, with predefined intervals Δ
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5. A color navigation system according to the claim 3, wherein a white point (W) is an arbitrary white point with a correlated color temperature between 2500 K and 6500 K.
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6. A color navigation system according to the claims 3, wherein a white point (W) is selected on the blackbody line, described with (xREF,yREF) in CIE1931 space, with the same correlated color temperature as the RGB luminaire with RGB=[1 1 1], i.e. the luminaire at full light output.
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7. A method for providing a memory defining discrete color points in a color space, the method comprising the steps of:
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defining color points according to three-dimensional CIELAB coordinates hue (H), lightness (L), chroma (C), with predefined intervals Δ
H between neighboring color points in the hue direction, with predefined intervals Δ
L between neighboring color points in the lightness direction, and with predefined intervals Δ
C between neighboring color points in the chroma direction, respectively;wherein Δ
L is equidistant over the color space;wherein Δ
S is equidistant over the color space, with Δ
C=Δ
S·
L, S indicating saturation, such that the perceptual color difference Δ
EINV, defined according to the formula;
Δ
EINV=√
{square root over ((Δ
L)2+(fC(H)·
Δ
C)2+(Δ
H)2)}{square root over ((Δ
L)2+(fC(H)·
Δ
C)2+(Δ
H)2)}{square root over ((Δ
L)2+(fC(H)·
Δ
C)2+(Δ
H)2)},is substantially constant over the color space for steps in the L-direction and in the S-direction; wherein fC(H) is a proportionality factor between 0 and 1 only depending on hue H; wherein, for hue values H between a first hue value (H1) corresponding to red and a second hue value (H2) corresponding to green, the proportionality factor fC(H) is equal to 1and the number of color points in the hue direction in this range is equal to NH,RG; wherein, for hue values between the second hue value (H2) corresponding to green and a third hue value (H3) corresponding to blue, the proportionality factor fC(H) is set to a constant value fGB such that the number NH,GB(fGB) of color points in the hue direction in this range differs less than 50% from NH,RG, NH,GB(fGB) being equal to NH,RG; wherein, for hue values between the third hue value (H3) and the first hue value (H1), the proportionality factor fC(H) is set to a constant value fGB such that the number NH,BR(fBR) of color points in the hue direction in this range differs less than 50% from NH,RG, NH,BR(fBR) being equal to NH,RG; and wherein Δ
H is a function of H such that, for steps in the hue direction along the border of the color space, said perceptual color difference Δ
EINV is substantially constant;for each of the color point thusly defined, calculating corresponding color control values (ξ
1, ξ
2, ξ
3) and writing those values into the memory. - View Dependent Claims (8, 9)
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Specification