COLOR CONTROL IN LIGHT FIXTURE WITH SUBTRACTIVE COLOR MIXING SYSTEM AND ADDITIONAL FILTER

Abstract

A method for controlling a subtractive color mixing system in a light fixture, comprising a light source, the subtractive color mixing system comprising a plurality of subtractive color filters, and an additional filter. The method is for emitting light having a target color upon having traversed the additional filter, such as upon having traversed the subtractive color mixing system and the additional filter and optionally being emitted from the light fixture. The method comprising receiving target information indicative of, such as defining, the target color, calculating a target control setpoint for each subtractive color filter within the plurality of subtractive color filters based on the target information, and calibration data, which for a plurality of sets of calibration control setpoints is indicative of an emitted color, controlling each of the subtractive color filters according to each calculated target control setpoint for each of the subtractive color filters.

Claims

1. A method for controlling a subtractive color mixing system in a light fixture, wherein the light fixture comprises: a light source, and the subtractive color mixing system, which comprises a plurality of subtractive color filters, and an additional filter, and wherein the method is for emitting light having a target color upon having traversed the additional filter, such as upon having traversed the subtractive color mixing system and the additional filter and optionally being emitted from the light fixture, said method comprising: receiving target information indicative of, such as defining, the target color, calculating a target control setpoint for each subtractive color filter within the plurality of subtractive color filters based on: the target information, and calibration data, which for a plurality of sets of calibration control setpoints is indicative of an emitted color, and controlling each of the subtractive color filters according to each calculated target control setpoint for each of the subtractive color filters.

2. The method of claim 1, wherein for one or more or all of the sets of calibration control setpoints, the emitted color, such as the emitted color of the calibration data, is defined by light having traversed the additional filter, such as light having traversed the subtractive color mixing system and the additional filter and optionally being emitted from the light fixture.

3. The method of claim 1, wherein for one or more or all of the sets of calibration control setpoints, the emitted color, such as the emitted color of the calibration data, is based on light not having traversed the additional filter, such as light having traversed the subtractive color mixing system and not having traversed the additional filter.

4. The method of claim 1, wherein: for a plurality of the sets of calibration control setpoints, the emitted color, such as the emitted color of the calibration data, is based on light not having traversed the additional filter, such as light having traversed the subtractive color mixing system and not having traversed the additional filter, and for one or more of the sets of calibration control setpoints, the emitted color, such as the emitted color of the calibration data, is defined by light having traversed the additional filter, such as light having traversed the subtractive color mixing system and the additional filter and optionally being emitted from the light fixture.

5. The method of claim 1, wherein: for a plurality of the sets of calibration control setpoints, the emitted color, such as the emitted color of the calibration data, is based on light having traversed the subtractive color mixing system and not having traversed the additional filter, and for one or more of the sets of calibration control setpoints, the emitted color, such as the emitted color of the calibration data, is defined by light having traversed the additional filter and not having traversed the subtractive color mixing system, and optionally being emitted from the light fixture.

6. The method of claim 1, wherein the calibration data comprises a number N of sets of calibration control setpoints being 2 or more, such as 3 or more, such as 4 or more, such as 5 or more, such as 6 or more, such as 8 or more, such as 10 or more, such as 30 or more, such as 100 or more, such as 200 or more, such as 300 or more, such as 500 or more, such as 750 or more, such as 1000 or more.

7. The method of claim 6, wherein the plurality of sets of calibration control setpoints comprises a set of calibration control setpoints, where each calibration control setpoint corresponds to substantially zero, such as zero, subtraction of light by a corresponding subtractive color filter.

8. The method of claim 6, wherein the plurality of sets of calibration control setpoints comprises, for each of a plurality of subtractive color filters, a set of calibration control setpoints wherein: the calibration control setpoint for the subtractive color filter corresponds to non-zero, such as substantial, subtraction of light, and the calibration control setpoint for all other subtractive color filters within the plurality of subtractive color filters corresponds to substantially zero, such as zero, subtraction of light.

9. The method of claim 6, wherein the plurality of sets of calibration control setpoints comprises, one or more sets of mixed calibration control setpoints wherein: a plurality, such as comprising of two or consisting of two, of calibration control setpoints each corresponds to non-zero, such as substantial, subtraction of light.

10. The method of claim 6, wherein: the plurality of sets of calibration control setpoints comprises a plurality of mixed calibration control setpoints; a plurality, such as comprising of two or consisting of two, of calibration control setpoints each corresponds to non-zero, such as substantial, subtraction of light; and corresponding colors of light emitted from the light fixture according to the plurality of sets of mixed calibration control setpoints have different distances in a color space, such as the CIE 1931 color space, with respect to a color for which each setpoint corresponds to substantially zero, such as zero, subtraction of light by a corresponding subtractive color filter.

11. The method of claim 1, wherein for one or more or all of the sets of calibration control setpoints, the emitted color, such as the emitted color of the calibration data, is defined by light having traversed the subtractive color mixing system and/or the additional filter, and originating from the light source.

12. The method of claim 1, wherein the method is for emitting light having a target color upon having traversed the subtractive color mixing system and the additional filter and optionally being emitted from the light fixture.

13. A light fixture system, comprising: a light fixture comprising: a light source, a subtractive color mixing system, wherein the subtractive color mixing system comprises a plurality of subtractive color filters and a transducer for controlling the subtractive color filters upon receipt of target control setpoints, and an additional filter, and a control device arranged for: receiving target information indicative of, such as defining, a target color, such as said target color being representative of a desired color of light upon having traversed the additional filter, such as upon having traversed the subtractive color mixing system and the additional filter and optionally being emitted from the light fixture, calculating a target control setpoint for each subtractive color filter within the plurality of subtractive color filters based on: the target information, and calibration data, which for a plurality of sets of calibration control setpoints is indicative of an emitted color, and outputting calculated target control setpoints enabling controlling each of the subtractive color filters according to each calculated target control setpoint for each of the subtractive color filters; wherein the control device is operationally connected to the subtractive color mixing system and arranged for controlling the subtractive color mixing system by outputting calculated target control setpoints to the transducer controlling respective subtractive color filters.

14. The light fixture system of claim 13, wherein the additional filter is selected as any of the following: a color-temperature-compensation (CTC) filter, such as a color-to-orange (CTO) filter, such as a quantitatively adjustable color-to-orange (CTO) filter, or a color-to-blue (CTB) filter, such as a quantitatively adjustable color-to-blue (CTB) filter, a color-rendering index (CRI) enhancement filter, or a color filter.

15. The light fixture system of claim 13, wherein the additional filter is adjustable, such as qualitatively adjustable, such as quantitatively adjustable, and wherein the control device is arranged for outputting target control setpoints based on a setting of the additional filter.

16. The light fixture system of claim 13, further comprising: a second light fixture comprising: a second light source, a second subtractive color mixing system, wherein the second subtractive color mixing system comprises a plurality of second subtractive color filters and a second transducer for controlling the second subtractive color filters upon receipt of target control setpoints, and a second additional filter, and a second control device arranged for: receiving target information indicative of, such as defining, a target color, such as said target color being representative of a desired color of light upon having traversed the second additional filter, such as upon having traversed the second subtractive color mixing system and the second additional filter and optionally being emitted from the second light fixture, calculating a target control setpoint for each second subtractive color filter within the plurality of second subtractive color filters based on: the target information, and calibration data, which for a plurality of sets of calibration control setpoints is indicative of an emitted color, and outputting calculated target control setpoints enabling controlling each of the second subtractive color filters according to each calculated target control setpoint for each of the second subtractive color filters, wherein the second control device is operationally connected to the second subtractive color mixing system and arranged for controlling the second subtractive color mixing system by outputting calculated target control setpoints to the second transducer controlling respective second subtractive color filters, wherein a change in target control setpoints is present upon a change in a setting of the additional filter of the control device is different from a setting of the second additional filter of the second control device.

17. The light fixture system of claim 16, wherein a difference or standard deviation in a color of light upon having traversed the subtractive color mixing system and the additional filter, is smaller than it would have been in the absence of the additional filter.

18. A method of manufacturing a light fixture system comprising: a light fixture comprising: a light source, a subtractive color mixing system, wherein the subtractive color mixing system comprises a plurality of subtractive color filters and a transducer for controlling the subtractive color filters upon receipt of target control setpoints, and an additional filter, and a control device arranged for: receiving target information indicative of, such as defining, a target color, such as said target color being representative of a desired color of light upon having traversed the additional filter, such as upon having traversed the subtractive color mixing system and the additional filter and optionally being emitted from the light fixture, calculating a target control setpoint for each subtractive color filter within the plurality of subtractive color filters based on: the target information, and calibration data, which for a plurality of sets of calibration control setpoints is indicative of an emitted color, and outputting calculated target control setpoints enabling controlling each of the subtractive color filters according to each calculated target control setpoint for each of the subtractive color filters; wherein the control device is operationally connected to the subtractive color mixing system and arranged for controlling the subtractive color mixing system by outputting calculated target control setpoints to the transducer controlling respective subtractive color filters; wherein the method comprises: obtaining, such as measuring or calculating, error information regarding a color difference between a desired color, and a color of light emitted from the light fixture or a part thereof upon having traversed the additional filter, and arranging the control device so that calculating a target control setpoint for each subtractive color filter within the plurality of subtractive color filters is based on said error information.

19. The method of manufacturing of claim 18, wherein the method further comprises: obtaining the calibration data wherein for a plurality of the sets of calibration control setpoints, the emitted color, such as the emitted color of the calibration data, is based on light not having traversed the additional filter, and wherein obtaining the error information comprises measuring the color of light emitted from the light fixture or a part thereof upon having traversed the additional filter, and wherein arranging the control device so that calculating a target control setpoint for each subtractive color filter within the plurality of subtractive color filters based on said error information comprises arranging the control device to calculate a target control setpoint for each subtractive color filter within the plurality of subtractive color filters which negates the color difference.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0175] The first, second, third, fourth and fifth aspect according to the disclosure will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present disclosure and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

[0176] FIG. 1 shows a flow-chart of a method according to the disclosure;

[0177] FIG. 2 illustrates a structural diagram of an illumination device;

[0178] FIG. 3 illustrates a structural diagram of a moving head light fixture;

[0179] FIG. 4 shows a triangulated point set of color points in a calibration data set;

[0180] FIG. 5 shows an overview of a light fixture system; and

[0181] FIG. 6 illustrates color adjustment during manufacture of a light fixture system.

DETAILED DESCRIPTION

[0182] FIG. 1 shows a flow-chart of a method 100 according to the disclosure for controlling a subtractive color mixing system in a light fixture, wherein [0183] the light fixture comprises [0184] a light source, [0185] the subtractive color mixing system, which comprises a plurality of subtractive color filters, and [0186] an additional filter,

[0187] and wherein the method is for emitting light having a target color upon having traversed the additional filter, such as upon having traversed the subtractive color mixing system and the additional filter and optionally being emitted from the light fixture, said method comprising: [0188] receiving (102) target information indicative of, such as defining, the target color, [0189] calculating (104) a target control setpoint for each subtractive color filter within the plurality of subtractive color filters based on: [0190] the target information, and [0191] calibration data, which for a plurality of sets of calibration control setpoints is indicative of an emitted color, and [0192] controlling (106) each of the subtractive color filters according to each calculated target control setpoint for each of the subtractive color filters.

[0193] FIG. 2 illustrates a structural diagram of an illumination device 200 (wherein “illumination device” and “light fixture” may be used interchangeably throughout the present application). The illumination device comprises a cooling module 201 comprising a plurality of LEDs 103 (which could in an alternative embodiment be one or more discharge bulbs), a light collector 241, an optical gate 242 and an optical projecting and zoom system 243. The cooling module is arranged in the bottom part of a lamp housing 248 of the illumination device and the other components are arranged inside the lamp housing 248. The lamp housing 248 can be provided with a number of openings 250. The light collector 241 is adapted to collect light from the LEDs 103 and to convert the collected light into a plurality of light beams 245 (dotted lines) propagating along an optical axis 247 (dash-dotted line). The light collector can be embodied as any optical means capable of collecting at least a part of the light emitted by the LEDs and convert the collected light to a light beams. In the illustrated embodiment the light collector comprises a number of lenslets each collecting light from one of the LEDs and converting the light into a corresponding light beam. However it is noticed that the light collector also can be embodied a single optical lens, a Fresnel lens, a number of TIR lenses (total reflection lenses), a number of light rods or combinations thereof. It is understood that light beams propagating along the optical axis contain rays of light propagating at an angle, e.g. an angle less that 45 degrees to the optical axis. The light collector may be configured to fill the optical the gate 242 with light from the light sources 103 so that the area, i.e. the aperture, of the gate 242 is illuminated with a uniform intensity or optimized for max output. The gate 242 is arranged along the optical axis 247. The optical projecting system 243 may be configured to collect at least a part of the light beams transmitted through the gate 242 and to image the optical gate at a distance along the optical axis. For example, the optical projecting system 243 may be configured to image the gate 242 onto some object such as a screen, e.g. a screen on a concert stage. A certain image, e.g. some opaque pattern provided on a transparent window, an open pattern in a non-transparent material, or imaging object such as GOBOs known in the field of entertainment lighting, may be contained within the gate 242 so that that the illuminated image can be imaged by the optical projecting system. Accordingly, the illumination device 200 may be used for entertainment lighting. In the illustrated embodiment the light is directed along the optical axis 247 by the light collector 241 and passes through a number of light effects before exiting the illumination device through a front lens 243a. The light effects can for instance be any light effects known in the art of intelligent/entertainments lighting for instance, a CMY subtractive color mixing system 251, color filters 253, gobos 255, animation effects 257, iris effects 259, a focus lens group 243c, zoom lens group 243b, prism effect 261, framing effects (not shown), or any other light effects known in the art. The mentioned light effects only serves to illustrate the principles of an illuminating device for entertainment lighting and the person skilled in the art of entertainment lighting will be able to construct other variations with additional are less light effects. Further it is noticed that the order and positions of the light effects can be changed.

[0194] It is understood that in the embodiment depicted in FIG. 2, the each of the color filters 253 may take the place at the additional filter. In an alternative embodiment, color filters 253 may be replaced with or supplemented with one or more of CTC filter(s), such as a CTB filter and/or a CTO filter, or a CRI enhancement filter.

[0195] FIG. 3 illustrates a structural diagram of a moving head light fixture 302 comprising a head 200 rotatable connected to a yoke 363 where the yoke is rotatable connected to a base 365. The head is substantially identical to the illumination device shown in FIG. 2 and substantial identical features are labeled with the same reference numbers as in FIG. 2 and will not be described further. The moving head light fixture comprises pan rotating means for rotating the yoke in relation to the base, for instance by rotating a pan shaft 367 connected to the yoke and arranged in a bearing (not shown) in the base). A pan motor 369 is connected to the shaft 367 through a pan belt 371 and is configured to rotate the shaft and yoke in relation to the base through the pan belt. The moving head light fixture comprises tilt rotating means for rotating the head in relation to the yoke, for instance by rotating a tilt shaft 373 connected to the head and arranged in a bearing (not shown) in the yoke). A tilt motor 375 is connected to the tilt shaft 373 through a tilt belt 377 and is configured to rotate the shaft and head in relation to the yoke through the tilt belt. The skilled person will realize that the pan and tilt rotation means can be constructed in many different ways using mechanical components such as motors, shafts, gears, cables, chains, transmission systems, bearings etc. Alternatively it is noticed that it also is possible to arrange the pan motor in the base and/or arrange the tilt motor in the head. The space 379 between the yoke and the bottom part of the head is limited as the moving head light fixture is designed to be as small as possible. As known in the prior art the moving head light fixture receives electrical power 381 from an external power supply (not shown). The electrical power is received by an internal power supply 383 which adapts and distributes electrical power through internal power lines (not shown) to the subsystems of the moving head. The internal power system can be constructed in many different ways for instance by connecting all subsystems to the same power line. The skilled person will however realize that some of the subsystems in the moving head need different kind of power and that a ground line also can be used. The light source will for instance in most applications need a different kind of power than step motors and driver circuits. The light fixture comprises also a controller 385 which controls the components (other subsystems) in the light fixture based on an input signal 387 indicative light effect parameters, position parameters and other parameters related to the moving head lighting fixture. The controller receives the input signal from a light controller (not shown) as known in the art of intelligent and entertainment lighting for instance by using a standard protocol like DMX, ArtNET, RDM etc. Typically the light effect parameter is indicative of at least one light effect parameter related to the different light effects in the light system. The controller 385 is adapted to send commands and instructions to the different subsystems of the moving head through internal communication lines (not shown). The internal communication system can be based on a various type of communications networks/systems. The moving head can also comprise user input means enabling a user to interact directly with the moving head instead of using a light controller to communicate with the moving head. The user input means 389 can for instance be bottoms, joysticks, touch pads, keyboard, mouse etc. The user input means can also be supported by a display 391 enabling the user to interact with the moving head through a menu system shown on the display using the user input means. The display device and user input means can in one embodiment also be integrated as a touch screen.

[0196] FIG. 4 shows a triangulated point set 400 (of color points in a calibration data set) in a CIE 1931 color space with a plurality of points of a set of calibration data, each point being representative of a color of light emitted from a (one of four) light fixtures (the light fixtures being named Fixture 1018, Fixture 1016, Fixture 1017 and Fixture 1012, cf., the legend in the figure) when each subtractive color filter in the light fixture is controlled according to a respectice calibration control setpoint. The figure also shows the black body line 420 as a full drawn line. The achievable color gamut is defined by the outer edges of the measured points, shown as a thick fully drawn line 422.

[0197] Furthermore, point set mesh generation within the color space has been carried out for one fixture (Fixture 1012) based on the calibration data, such as wherein calibration data points form vertices, wherein the point set mesh generation is a point set triangulation.

[0198] For example, the subtractive color mixing system may comprise three color filters, and the point mesh generation is triangulation wherein any mesh polygon comprise vertices which have no more than two filters inserted in the optical path. FIG. 4 depicts such embodiment, wherein a subtractive CMY (cyan, magenta, yellow) color mixing system has been calibrated (for four light fixtures) to give the depicted point sets, which have been triangulated. The calibration data of FIG. 4 comprises for each combination of two filters in the set of three filters (i.e., three combinations) any combination of 5 possible setting for each filter, i.e., the plurality of sets of calibration control setpoints comprises 75 sets (i.e., 3 combinations of two filters with 5 times 5 settings for each combination of filters, i.e., 3×5{circumflex over ( )}2 sets). FIG. 4 shows the no-filter calibration control setpoint 402 where each calibration control setpoint corresponds to substantially zero, such as zero, subtraction of light by the corresponding subtractive color filter, which is effectively the color of the lamp of the light fixture, which in the present example lies on or near the black body line 420. The calibration data of FIG. 4 also comprises, for each of a plurality of subtractive color filters, sets of calibration control setpoins where the calibration controll setpoint for the subtractive color filter corresponds to non-zero, such as substantial, subtraction of light, and the calibration control setpoint for all other subtractive color filters within the plurality of subtractive color filters corresponds to substantially zero, such as zero, subtraction of light, such as sets of calibration control setpoints with only one color filter fully inserted (such as inserted to the maximum extent possible in the specific implementation) in the optical path, such as the yellow-filter calibration control setpoint 404 (with only the yellow filter fully inserted), the cyan-filter calibration control setpoint 406 (with only the cyan filter fully inserted) and the magenta-filter calibration control setpoint 408 (with only the magenta filter fully inserted). Each dotted line 410a, 410b, 410c shows, respectively, a line in the color space corresponding to gradually increasing (away from the no-filter calibration control setpoint 402) insertion of a single color filter. FIG. 4 also shows color points corresponding to sets of mixed calibration control setpoints wherein a plurality of calibration control setpoints each corresponds to non-zero, such as substantial, subtraction of light, for example a first color point 414 and a second color point 416. Furthermore, the corresponding colors i.e., cf., first color point 414 and second color point 416, of light emitted from the light fixture according to the plurality of sets of mixed calibration control setpoints have different distances in a color space with respect to a color (cf., the no-filter color point 402) for which each setpoint corresponds to substantially zero, such as zero, subtraction of light by the corresponding subtractive color filter. In other words, the first color point 414 is closer to color point 402 compared to color point 416. Still further, for the sets of mixed calibration control setpoints with corresponding emitted colors at different distances in a color space, the same two calibration control setpoints are non-zero (such as for these two calibration control setpoints, the same two filters are inserted in the optical path), such as where only these two control calibration setpoints are non-zero, such as wherein the two corresponding color points 414, 416 are between the same two dotted lines, such as lines 410a, 410b.

[0199] FIG. 4 also shows an exemplary target color, as indicated by star 418, which is not coinciding with a color of a set of calibration control setpoints (such as the star not coinciding with any rounded marker, but is rather within the triangles or on the edges between the rounded markers, and in this example being placed entirely within a triangle in the triangulated mesh).

[0200] According to an embodiment, calculating a target control setpoint for each subtractive color filter within the plurality of subtractive color filters based on the target information and calibration data which for a plurality of sets of calibration control setpoints is indicative of an emitted color, may comprise identifying the set of calibration control setpoints with a corresponding color being closest to the target color and setting the target control setpoint for each color filter as equal to the corresponding calibration control setpoint of said (nearest) set of calibration control setpoints. This may be advantageous for its simplicity (e.g., renders point mesh generation superfluous) and may in particular work well for high-resolution calibration data (such as calibration data with a high number of calibration control setpoints, which colors which are well-distributed in color space) and/or where requirements for (exact) color reproduction is relatively relaxed. In a further embodiment, calculating a target control setpoint for each subtractive color filter within the plurality of subtractive color filters based on the target information and calibration data which for a plurality of sets of calibration control setpoints is indicative of an emitted color, may comprise identifying the (plurality of) sets of calibration control setpoints with a corresponding color being closest (or nearest) to the target color and setting the target control setpoint for each color filter based on said (nearest) sets of calibration control setpoints, such as by relying on nearest-neighbour interpolation.

[0201] According to another embodiment, calculating a target control setpoint for each subtractive color filter within the plurality of subtractive color filters may comprise determining a mesh polygon (after point mesh generation), such as the smallest mesh polygon, comprising the target color, such as by optionally repeatedly applying a method for determining if the target color is within a mesh polygon. Once the (smallest) mesh polygon comprising the target color has been identified, the target control setpoints are identified by interpolating, such as performing linear triangle interpolation within the mesh polygon based on the vertices of the mesh polygon, so as to achieve target control setpoints. For example, each vertice may be associated with three scalar values, corresponding to the calibration control setpoint for each filter, and the a linear triangle interpolation may be carried out for the calibration control setpoint for each filter resulting in a set of target control setpoints with a target control setpoint for each filter.

[0202] According to a still further embodiment, the set of target control setpoints may be obtained by any means, e.g., non-linear interpolation, taking multiple points on either side into account, extrapolation by multiple points, etc.

[0203] FIG. 5 shows an overview of a light fixture system 500, such as a calibration setup, said light fixture system comprising a light fixture 506 comprising a light source, a subtractive color mixing system, wherein the subtractive color mixing system comprises a transducer for controlling the subtractive color filters upon receipt of target control setpoints, and a control device 502, wherein the control device is operationally connected to the subtractive color mixing system and arranged for controlling the subtractive color mixing system by outputting calculated target control setpoints to the transducer controlling respective subtractive color filters. In more detail, a controlling device 502 sets and submits consecutively—via an interface 504, e.g., a USB-to-DMX interface (which is a serial digital interface adapter to connect a computer to one or more fixtures)—to a light fixture 506 sets of control setpoints for controlling each color filter of a subtractive color mixing system of the light fixture 506, whereupon the light fixture emits light 508 accordingly, and a light measuring device, which in the presently depicted embodiment is exemplified by an integrating sphere 510 comprising a color meter or a spectrometer and wherein optionally the emitted light (from the light fixture) is emitted to the color meter or the spectrometer via the integrating sphere, is arranged for receiving light 508 emitted from the a lighting fixture. Software is thus used to control the lighting fixture 506 (through an interface 504) and measurement equipment such that the light spectrum is measured for a number of different configurations of the subtractive color filters. The measurements may form calibration measurements, are sent from the integrating sphere 510 to the controlling device 502, which can then determine colors and triangulate a color space accordingly. Subsequently, the controlling device can utilize the the calibration data to (e.g., via a color engine algorithm) to determine one or more control setpoints that produces one or more target colors.

[0204] FIG. 6 illustrates steps for adjusting color during manufacture of a a light fixture system, such as the light fixture system according to the third aspect. In some embodiments, the steps enable the control device to calculate target control setpoints for the purpose of enabling emitting light having a desired color 602 after having traversed the subtractive color system and the additional filter), which in FIG. 6 is illustrated in the context of a color space 600, such as a CIE color space. As shown, the steps include: [0205] obtaining calibration data wherein for a plurality of the sets of calibration control setpoints, the emitted color, such as the emitted color of the calibration data, is based on light having traversed the subtractive color mixing system and not having traversed the additional filter, [0206] determining starting control setpoints describing a color 604, such as without any of the subtractive color filters traversed, [0207] measuring a color of light 606 (where the additional filter changes the color of light 604 to the color of light 606 as indicated by dashed arrow 608, which due to production tolerances could be anywhere within a relatively large color area 610) emitted from the light fixture or a part thereof upon having traversed the additional filter and not having traversed the subtractive color mixing system, [0208] determining an error information as an error vector 612, between [0209] the desired color 602, and [0210] the color of light 606, emitted from the light fixture or a part thereof upon having traversed the additional filter and not having traversed the subtractive color mixing system, [0211] arranging the control device to calculate a target control setpoint for each subtractive color filter within the plurality of subtractive color filters which negates the error vector, such as said target control setpoint bring the color 604 to the color 614 (as indicated by the arrow 616), which will be advantageous due to the additional filter then bringing the color, to the desired color 602 (as indicated by the arrow 618).

[0212] Although the present disclosure has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present disclosure is set out by the accompanying claim set. In the context of the claims, the terms “comprising” or “comprises” do not exclude other possible elements or steps. Also, the mentioning of references such as “a” or “an” etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the disclosure. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.