COLOR NAVIGATION SYSTEM
1 Assignment
0 Petitions
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 N̂BR̂BR) differs less than 50% from NH,RG—
-
Citations
19 Claims
-
1-10. -10. (canceled)
-
11. 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 preferably 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 (12, 13, 14, 15, 16)
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
-
15. A color navigation system according to the claim 13, wherein a white point (W) is an arbitrary white point with a correlated color temperature between 2500 K and 6500 K.
-
16. A color navigation system according to the claims 13, 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.
-
17. A method for providing a memory defining discrete color points in a color space, the method comprising the steps of:
-
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 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) preferably 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) preferably 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 (18, 19)
-
Specification