WO2018042283A1 - Procédé de commande de sources d'éclairage, système et produit programme d'ordinateur correspondants - Google Patents

Procédé de commande de sources d'éclairage, système et produit programme d'ordinateur correspondants Download PDF

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Publication number
WO2018042283A1
WO2018042283A1 PCT/IB2017/055033 IB2017055033W WO2018042283A1 WO 2018042283 A1 WO2018042283 A1 WO 2018042283A1 IB 2017055033 W IB2017055033 W IB 2017055033W WO 2018042283 A1 WO2018042283 A1 WO 2018042283A1
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WO
WIPO (PCT)
Prior art keywords
colour
calculating
value
points
acceptance
Prior art date
Application number
PCT/IB2017/055033
Other languages
English (en)
Inventor
Alberto Alfier
Xiaolong Li
Original Assignee
Osram Gmbh
Osram S.P.A. - Societa' Riunite Osram Edison Clerici
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by Osram Gmbh, Osram S.P.A. - Societa' Riunite Osram Edison Clerici filed Critical Osram Gmbh
Publication of WO2018042283A1 publication Critical patent/WO2018042283A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/46—Colour picture communication systems
    • H04N1/56—Processing of colour picture signals
    • H04N1/60—Colour correction or control
    • H04N1/6058—Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut
    • H04N1/6061—Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut involving the consideration or construction of a gamut surface

Definitions

  • the present description relates to the control of lighting sources.
  • One or more embodiments may be applied to the control of electrically-powered light radiation sources, e.g. solid-state light radiation sources such as LED sources.
  • electrically-powered light radiation sources e.g. solid-state light radiation sources such as LED sources.
  • Lighting sources such as solid-state sources may be employed in order to obtain colour points on a gamut area, the possibility being given e.g. to obtain tuneable white colour temperatures.
  • LED sources e.g. LED sources
  • LEDs of different types These LEDs may be embedded in the same package (so-called multi-chip LEDs) or may comprise a plurality of discrete LEDs mounted on a support such as a Printed Circuit Board (PCB) .
  • PCB Printed Circuit Board
  • the available colours define the gamut in a chromatic coordinate system.
  • Each point within the gamut may be obtained by combining the light radiation of a plurality of sources, e.g. LED sources, each having a specific flux value (which may be adjustable e.g. via a dimming action) .
  • HSV Hue- Saturation-Value
  • This system may be defined essentially as a polar coordinate system, wherein the hue value is represented by the angle, the saturation value is given by the radius, and an added parameter is the brightness value, corresponding e.g. to the dimming value .
  • Such a system implements a sort of rearrangement of the geometry of a colour space, e.g. RGB, which may be more intuitive and perceptually relevant than a Cartesian representation.
  • a colour space e.g. RGB
  • a possible practical setup of an HSV system envisages the presence of a linear constant step size change for all the three control factors: in other words, a constant angle step (hue) , a constant distance step (saturation) and a constant dimming step (brightness) .
  • a constant angle step hue
  • a constant distance step saturated
  • a constant dimming step brightness
  • the graph in Figure 1 represents standard variations in chromaticity, shown to a scale which is tenfold the actual scale in the CIE 1931 chromaticity diagram.
  • the movement with a constant angle step may originate, with reference to intrinsically reachable points, resolution values which in most cases may be insufficient.
  • One or more embodiments aim at overcoming the drawbacks described in the foregoing.
  • said object may be achieved by a method having the features set forth in the claims that follow.
  • One or more embodiments may concern a corresponding system for controlling lighting sources (e.g. a system operating according to the DMX (Digital Multiplex) standard, e.g. DMX 256 or DMX 512), as well as a corresponding computer program product loadable into at least one processing device and including software code portions for performing the method according to one or more embodiments, when the product is run on at least one processing device.
  • a corresponding system for controlling lighting sources e.g. a system operating according to the DMX (Digital Multiplex) standard, e.g. DMX 256 or DMX 512
  • DMX Digital Multiplex
  • the reference to said computer program product includes computer-readable media containing instructions for controlling a processing device, in order to coordinate the implementation of the method according to the invention.
  • the reference to "at least one processing device” highlights the possibility of implementing the present invention in a modular and/or distributed form.
  • One or more embodiments may face the problem of the different ways in which the human eye recognizes and distinguishes colours in different areas of a colour space (such as the CIE 1931 colour space, as exemplified in the previous Figure 1, showing the MacAdam ellipses) .
  • a colour space such as the CIE 1931 colour space, as exemplified in the previous Figure 1, showing the MacAdam ellipses
  • One or more embodiments may envisage recalibrating the achievable colour points by varying the angle step which is adopted, e.g. according to an HSV system, by a control device such as a DMX system, having for instance an 8-bit resolution.
  • One or more embodiments may refer, at least conceptually, to the size of the MacAdam ellipse in each colour area, thus using a variable angle resolution which is implementable and acceptable for the various areas of interest.
  • Figure 3 exemplifies, with reference to a chromaticity diagram as shown in Figure 1, some critical aspects which are dealt with in one or more embodiments ,
  • FIG. 4 is a diagram representing the ways of recognizing colours in the human eye
  • Figure 5 which substantially refers to the representation of Figure 3, exemplifies implementation criteria of one or more embodiments
  • FIG. 6 is an exemplary diagram of possible operating criteria of a DMX system
  • FIG. 7 is an exemplary diagram of criteria on which one or more embodiments may be based
  • Figure 8 represents, with the same representation criteria of Figures 3 and 5, the results achievable according to one or more embodiments,
  • FIG. 10 is a block diagram of a DMX system which may be used in one or more embodiments.
  • FIG. 11 is a flow chart exemplifying possible embodiments .
  • Figure 3 exemplifies, with reference to a CIE 1931 chromaticity diagram, a possible mapping of colour points adapted to be achieved in the use of a lighting source including electrically-powered, e.g. solid- state, light radiation sources, e.g. LED sources, adapted to be defined as sources "of different types", meaning that such light radiation sources emit light radiations having different wavelengths or situated about different wavelengths.
  • a lighting source including electrically-powered, e.g. solid- state, light radiation sources, e.g. LED sources, adapted to be defined as sources "of different types", meaning that such light radiation sources emit light radiations having different wavelengths or situated about different wavelengths.
  • Such light radiation sources which may be used e.g. for the generation of a generally white light radiation with adjustable Correlated Colour Temperature (CCT) , are in themselves known in the art, which makes it unnecessary to provide a more detailed description herein .
  • CCT Correlated Colour Temperature
  • one or more light radiation sources of this type may be used in a DMX system (specifically in a so-called DMX “universe”, e.g. a DMX 512 universe), wherein said light radiation sources may be configured "slave” devices LI, L2, L3 (which may be mutually connected in a “daisy chain” configuration, with a so-called terminator T) , adapted to be controlled by a controller M, as shown in the diagram of Figure 10.
  • DMX system specifically in a so-called DMX “universe”, e.g. a DMX 512 universe
  • said light radiation sources may be configured "slave” devices LI, L2, L3 (which may be mutually connected in a “daisy chain” configuration, with a so-called terminator T) , adapted to be controlled by a controller M, as shown in the diagram of Figure 10.
  • the DMX system (originally developed by the Engineering Commission of the United States Institute for theatre Technology - USITT) is the subject of an extensive literature, including regulations, which may be referred to for a general description of the features and the operation of such a system, as well as for the possible implementation of the operating modes described in the following, e.g. referring to the flow chart of Figure 11.
  • the distance between pairs of adjacent points is not the same along the achievable gamut perimeter.
  • Al yellow-green area
  • a similar, although less marked, situation may be found e.g. in the blue-magenta area, denoted as A2 in the same Figure 3.
  • the diagram in Figure 4 exemplifies a possible graph of the SDCM (Standard Deviation of Colour Matching) value, on the y-axis, between adjacent points in the diagram of Figure 3, as a function of the angle value (on the x-axis) .
  • SDCM Standard Deviation of Colour Matching
  • FIG. 5 once again shows the diagram of Figure 3, particular attention being paid to both the yellow-green area Al and the blue-magenta area A2 (without showing the other areas for the sake of simplicity) , highlighting that in the blue-magenta area A2, in addition to the presence of a low number of points covering a rather large space of the gamut, there is also present a rather sharp corner area with a low resolution of colour points.
  • the diagram in Figure 6 shows, always referring to a CCT value amounting to 2500 K (and therefore referring to a representation substantially corresponding to Figures 3 and 5) , the possible functional relationship between the coarse hue regulation value of a DMX system (Hue Coarse DMX, assuming a system with 8-bit resolution) and the corresponding angle value, which is assumed as having a constant increment step value ⁇ .
  • the diagram of Figure 7 exemplifies, by referring directly to the diagram of Figure 4, implementation possibilities of one or more embodiments, wherein the SDCM value (or optionally the value of another metric) for detecting the matching of different colours is treated by acting on the angle increment step value ⁇ , by recalculating the new values of the angular coordinate of the HSV system in order limit SDCM (or another metric) with reference to at least one acceptance threshold, e.g. with reference to a range which is considered acceptable, such as a window of values [SDCM_min, SDCM_max] .
  • Metrics adapted to be used as an alternative to SDCM may be for instance:
  • One or more embodiments may envisage, e.g. at a controller M of a DMX system as schematically shown in Figure 10, the implementation of the steps exemplified in the flow chart of Figure 11.
  • step 10 envisages the identification of the edge region or perimeter E of the gamut area adapted to be implemented by the source (s) LI, L2, L3 included in the lighting system.
  • This step may correspond to the identification of the polygonal path shown in Figure 3.
  • Step 12 in the chart of Figure 11 identifies the possible definition of at least one acceptance threshold for the SDCM (or other) metric, calculated between two consecutive points on the perimeter of the gamut identified in step 10.
  • such threshold may be identified as an acceptance window between two thresholds, respectively a minimum and a maximum threshold, i.e. [SDCM_min, SDCM_max] .
  • only one threshold may be adopted, e.g. an upper threshold, so that the colour points are not too sparse .
  • the available steps e.g. 256 in the 8-bit instance
  • the available steps may be insufficient to perform a re-calibration on the full circle (360°), because the points are concentrated in useless regions.
  • Step 14 identifies the definition of the centre reference point HSV_C, which is used as the origin of the polar system HSV, around which the angular coordinate must be varied through successive variation steps ⁇ (which, according to one or more embodiments, may be made variable and no longer constant) .
  • Step 16 corresponds to the definition of an
  • Step 18 corresponds to identifying a starting colour point (Cx_0, Cy_0) on the gamut of the available sources (e.g. LED sources) : in this respect, see for example the diagram in Figure 5.
  • the available sources e.g. LED sources
  • Step 20 corresponds to calculating a next colour point, e.g. (Cx_i, Cy_i) on the gamut (again, see for example the diagram in Figure 5), which is implemented by moving with an angle step ⁇ as determined in the previous step 16.
  • a next colour point e.g. (Cx_i, Cy_i) on the gamut (again, see for example the diagram in Figure 5)
  • Step 22 corresponds to calculating the metric
  • Step 24 corresponds to a step wherein the SDCM value calculated at step 22 is compared with at least one acceptance threshold (e.g. a window) .
  • at least one acceptance threshold e.g. a window
  • step 24 If the comparison in step 24 yields a positive result (Y) , the angle increment step value ⁇ calculated at step 16 is maintained for calculating a further colour point, which is achieved by using the previously obtained colour point as a (new) starting colour point. If, on the contrary, the comparison at step 24 yields a negative result (N) , indicating that the SDCM value calculated at step 22 is outside the range of acceptable values (exceeding the threshold, i.e. outside window [SDCM_min, SDCM_max] ) , the value ⁇ is re-calculated in order to originate a colour point (step 20), so that the SDCM metric is recalculated in order to yield a positive comparison result in step 24. This sequence may also be iterated in succession, in case of a repetition of negative comparison results in step 24.
  • the re-calculation of the increment step value ⁇ may take into the account the direction in which the calculated metric (e.g. SDCM) value exceeds the acceptance threshold.
  • the calculated metric e.g. SDCM
  • the increment step value ⁇ may be re- calculated, either by increasing or by decreasing it, thus bringing the SDCM value to the acceptance range again .
  • Step 26 involves a comparison, wherein it is checked whether the angular field 0°-360° around centre HSV_C, which must be taken into account, has been wholly explored, by repeating steps 20,22 and 24 until such angular field is completely explored (STOP) .
  • the repetition of steps 20, 22, 24 may be implemented by using, as a starting value for increment ⁇ , the value obtained in the previous step.
  • step 26 when returning from step 26 to step 20, it is in no way mandatory to use the value ⁇ obtained in the previous step: in one or more embodiments, it is possible to re-start with the value ⁇ which has initially been defined at step 16.
  • the identification of the threshold / window of acceptable values [SDCM_min, SDCM_max] may sometimes be too strict, so as not to enable a calculation throughout the 360° angular field with a given resolution.
  • One or more embodiments are adapted to originate a sort of "new mapping" of the colour points, as schematically shown in Figure 8, the possibility being offered (optionally on a 360° angular field) of covering the areas wherein the colour changes are more markedly perceived by the human eye with a number of points sufficient to support a smooth transition, optionally by covering the areas wherein such changes are less perceivable with a lower number of points.
  • the diagram in Figure 8 exemplifies, via a direct comparison with the representations of Figures 3 and 5, that according to one or more embodiments the yellow-green area Al and the blue- magenta area A2 may be covered with a proper number of points .
  • the re-definition of the HSV metric at perimeter E of the gamut area may be beneficial also for the points located within the corresponding polygonal path and positioned at a shorter distance from reference centre HSV, therefore having shorter distances between adjacent points achieved via the consecutive steps of angle increment.
  • the threshold / window of admissible values for the SDCM metric may not have a constant value, as assumed for the diagram in Figure 11; on the contrary, different values are assumed for areas of different colour.
  • more than one mapping angle value may be created for different operating conditions (e.g. as a function of parameters such as e.g. the LED temperature ( s ) , the reference centre point HSV, etc.), the possibility being given of creating different colour points by implementing the same colour control procedure.
  • gamut areas may be used other than the CIE 1931 reference gamut, by using e.g. chromaticity diagrams or colour spaces of different types, e.g. CIE RGB.
  • One or more embodiments may therefore concern a method of calculating colour points in a gamut area (see e.g. Figures 3, 5 and 8) of a colour space for reproduction by a plurality of light radiation sources (e.g. LI, L2, L3) of different colours, wherein said gamut area includes a perimeter (e.g. E) , the method including calculating successive points on said perimeter (E) , with said successive points, having angular coordinate values (Angle) in an HSV system (having e.g. a centre HSV_C) , being representative of respective hue values (Hue Coarse DMX : see for example the diagrams in Figures 6 and 9), wherein the method includes :
  • an acceptance test e.g. 24
  • at least one acceptance threshold e.g. [SDCM_min;, SDCM_max]
  • step 24 Y
  • step 24 N
  • said metric may include the Standard Deviation of Colour Matching (SDCM) metric.
  • SDCM Standard Deviation of Colour Matching
  • One or more embodiments may include using for said acceptance test (24) a window with lower and upper thresholds (e.g. [SDCM_min;, SDCM_max] ) for said metric .
  • lower and upper thresholds e.g. [SDCM_min;, SDCM_max]
  • One or more embodiments may include selecting for said acceptance test different acceptance thresholds in different areas of said colour space.
  • said colour space may be the CIE 1931 colour space.
  • One or more embodiments may concern a control system for controlling a plurality of light radiation sources of different colours for the reproduction of colour points in a gamut area of a colour space, wherein said gamut area includes a perimeter, the system being configured for calculating successive points on said perimeter, with said successive points having, in an HSV system, angular coordinate values which are representative of respective hue values, by operating with the method according to one or more embodiments .
  • One or more embodiments may include a DMX controller .
  • One or more embodiments may include a controller with selectively variable resolution (e.g. 8 bit or more) for calculating the angular coordinate values of said colour points.
  • a controller with selectively variable resolution (e.g. 8 bit or more) for calculating the angular coordinate values of said colour points.
  • One or more embodiments may concern a computer program product, loadable into the memory of at least one processing system and including software code portions for performing the method according to one or more embodiments.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

L'invention porte sur des points de couleur dans une zone de gamme d'un espace de couleur, permettant une reproduction par une pluralité de, par exemple, sources de rayonnement de lumière à DEL (LI, L2, L3) de couleurs différentes, sont identifiées en calculant des points successifs sur le périmètre (E) de la zone de gamme, lesdits points successifs ayant, dans un système HSV (HSV_C), des valeurs de coordonnées angulaires représentatives de valeurs de teinte respectives. Le procédé consiste à : sélectionner une valeur d'étape d'incrément pour ladite coordonnée angulaire, et calculer, à partir d'un point de couleur de départ, un point de couleur suivant sur le périmètre (E) de la zone de gamme, en fonction de la valeur d'étape d'incrément (δ) sélectionnée pour la coordonnée angulaire,-calculer une métrique (par exemple SDCM) indiquant la distance entre le point de couleur de départ et le point de couleur suivant,-appliquer à la métrique calculée un test d'acceptation avec au moins un seuil d'acceptation, et i) si la métrique calculée réussit le test d'acceptation, calculer un autre point de couleur suivant en utilisant ledit point de couleur suivant en tant que nouveau point de couleur de départ, et ii) si la métrique calculée échoue au test d'acceptation, sélectionner une valeur mise à jour pour ladite étape d'incrément d'angle, et recalculer le point de couleur suivant à partir du point de couleur de départ à l'aide de la valeur mise à jour.
PCT/IB2017/055033 2016-09-01 2017-08-21 Procédé de commande de sources d'éclairage, système et produit programme d'ordinateur correspondants WO2018042283A1 (fr)

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IT201600088817 2016-09-01
IT102016000088817 2016-09-01

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060104058A1 (en) * 2004-03-15 2006-05-18 Color Kinetics Incorporated Methods and apparatus for controlled lighting based on a reference gamut
WO2008001290A1 (fr) * 2006-06-27 2008-01-03 Koninklijke Philips Electronics N.V. Système de navigation des couleurs
WO2008068713A2 (fr) * 2006-12-08 2008-06-12 Koninklijke Philips Electronics N.V. Dispositif de génération de lumière avec une couleur variable
WO2013179215A2 (fr) * 2012-05-29 2013-12-05 Koninklijke Philips N.V. Système d'éclairage réglable

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060104058A1 (en) * 2004-03-15 2006-05-18 Color Kinetics Incorporated Methods and apparatus for controlled lighting based on a reference gamut
WO2008001290A1 (fr) * 2006-06-27 2008-01-03 Koninklijke Philips Electronics N.V. Système de navigation des couleurs
WO2008068713A2 (fr) * 2006-12-08 2008-06-12 Koninklijke Philips Electronics N.V. Dispositif de génération de lumière avec une couleur variable
WO2013179215A2 (fr) * 2012-05-29 2013-12-05 Koninklijke Philips N.V. Système d'éclairage réglable

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