GB2535384A

GB2535384A - Lighting system

Info

Publication number: GB2535384A
Application number: GB1608488.1A
Authority: GB
Inventors: Allen Gammons Roderick; Christoph Winter Jan; Aaron Gammons Roderick
Original assignee: Rotolight Ltd
Current assignee: Rotolight Ltd
Priority date: 2011-09-08
Filing date: 2012-09-07
Publication date: 2016-08-17
Anticipated expiration: 2032-09-07
Also published as: GB2494537B; GB201608489D0; GB2535384B; GB201216033D0; GB2494537A; GB201608488D0; GB2535385A; GB2535385B; GB201115546D0

Abstract

A controller for controlling a lighting device comprises means for storing lighting settings corresponding to a lighting scene and means for controlling transitioning or cross fades between lighting settings, wherein said transitioning occurs over a user-defined time period (e.g. between 1 second and 5 seconds). A method of controlling a lighting device is also disclosed.

Description

Intellectual Property Office Application No. GII1608488.1 RTM Date:8 June 2016 The following terms are registered trade marks and should be read as such wherever they occur in this document: i Phone iPad Bluetooth Zigbee Wi-Fi Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo Lighting system This invention relates to a lighting system. This invention also relates to a method of controlling a lighting device, and to a corresponding apparatus.

Broadly, according to one aspect of the invention, there is provided a lighting system, which comprises a portable device for measuring lighting conditions in an environment in which the device is locatable, means for transmitting data relating to said measurement to a lighting device, and means for controlling said lighting device in dependence on said data thereby to emulate said lighting conditions.

According to another aspect of the invention, there is provided a lighting system, which comprises a portable device having means for measuring the colour temperature relating to lighting conditions in an environment in which the device is locatable, means for transmitting data relating to said measurement to a lighting device, and means for controlling said lighting device in dependence on said data thereby to emulate said lighting conditions.

Preferably, the measuring means is adapted to measure any colour of light within the visible spectrum.

Preferably, the measuring means is adapted to measure the colour temperature of the visible light in said environment.

Preferably, the measuring means is adapted to measure white light within the rage of 1,700 Kelvin to 9,300 Kelvin, and preferably within the range of 2,000 Kelvin to 8,000 Kelvin, and more preferably within the range of 2,600 Kelvin to 7,200 Kelvin.

Preferably, the measuring means is adapted to measure the different colour components of the light in the environment.

Preferably, the measuring means is adapted to measure the RGB colour components of the light. -2 -

Preferably, the portable device is in the form of one or more of the following: a portable computer, such as a notebook, laptop or tablet computing device; a personal digital assistant (PDA); and a smartphone.

Preferably, portable device comprises a camera, preferably a digital camera.

Preferably, the measuring means measures the colour temperature using the camera.

Preferably, the camera comprises an image sensor.

Preferably, the image sensor is in the form of a CCD (charge-coupled device) or CMOS (complementary metal-oxide-semiconductor) sensor.

Preferably, the camera is provided with image and/or light enhancement functionality, and wherein the measuring means is adapted to modify at least some of this functionality during the measurement thereby to capture the raw data as sensed by the image sensor of the camera.

Preferably, the measuring means is adapted to disable at least some of this functionality 20 during measurement.

Preferably, the measuring means is adapted to disable Auto White Balance functionality of the camera thereby to enable raw lighting conditions to be captured.

Preferably, the measuring means is adapted to alter the operation of the Auto White Balance functionality of the camera during measurement.

Preferably, the measuring means is adapted to lock the operation of the Auto White Balance functionality relative to a given correlated colour temperature (CCT) reading.

Preferably, the system further comprises means for determining an actual CCT using known RGB values related to the given CCT reading.

Preferably, the actual CCT is determined via a predetermined look-up table. -3 -

Preferably, the actual CCT is determined via a transformation function.

Preferably, a measurement is taken based on an average of the values of the image data captured within a particular window of the image sensor.

Preferably, the measuring means is adapted to measure light intensity.

Preferably, the system further comprises a processor for comparing the measurement with a set of reference data values, optionally in the form of a lookup table, to determine a closest possible match between the actual measurement and a particular data value, and preferably wherein the processor is adapted to use interpolation during this matching process.

Preferably, the system further comprises means for calibrating the measuring means, optionally during a setup procedure.

Preferably, the system further comprises means for storing said measured lighting conditions, for subsequent recall and/or transmission.

Preferably, the portable device is adapted to receive data relating to measured lighting conditions, optionally from a similar such portable device, optionally for onward transmission to a lighting device.

Preferably, the portable device is adapted to download data relating measured lighting conditions for subsequent recall and/or transmission to a lighting device.

Preferably, the portable device is connectable to a communications network, and preferably to at least one or more of the following types of communication networks: a mobile phone network; a wireless LAN; and a Wi-Fi network.

Preferably, the portable device is adapted to transmit details relating to the device itself along with the data.

Preferably, transmission occurs over a secure channel. -4 -

Preferably, the portable device is adapted to selectively control (wirelessly) a plurality of lighting devices connectable to the system.

Preferably, the portable device further comprises a digital multiplex controller, and preferable a DMX512 controller, and more preferably wherein the controller is implemented in software.

Preferably, the lighting device is in the form or a low power light, preferably a light-emitting diode (LED) (panel) light, optionally comprising an LED array including LEDs of differing power and/or colour, or optionally a cluster of LEDs.

According to a further aspect of the invention, there is provided a method of controlling a lighting device, which comprises measuring the colour temperature relating to the lighting conditions in a particular environment using a portable device, transmitting data relating to said measured lighting conditions to a lighting device, and controlling said lighting device in dependence on said data thereby to emulate said lighting conditions.

According to another aspect of the invention, there is provided an apparatus for controlling a lighting device, the apparatus comprising means for measuring the colour temperature relating to the lighting conditions in an environment in which the apparatus is locatable, and means for transmitting data relating to said measurement to a lighting device thereby to control the light produced by said lighting device to emulate said lighting conditions.

Preferably, the apparatus is in the form of a portable computing device including a camera, and wherein the measuring means is adapted to use the camera to measure the colour temperature.

According to a further aspect of the invention, there is provided a lighting system, which comprises a (portable) device having stored thereon data relating to particular lighting conditions, means for transmitting said data to a lighting device, and means for controlling said lighting device in dependence on said data thereby to emulate said lighting conditions. -5 -

Preferably, the data includes a library of lighting condition data values, preferably including at least one or more of the following types: stock industry standard lighting data values; measured lighting data values; downloaded lighting data values; and user created lighting data values.

According to another aspect of the invention, there is provided a system for (remotely) controlling a light source, the system comprising: a user device; a receiving device; light controlling circuitry; wherein the user device is adapted to (wirelessly) transmit light reading measurements to the receiving device; wherein the receiving device is adapted to transmit said received light reading measurements to the light controlling circuitry; and wherein the light controlling circuitry modifies the intensity and/or colour of the light in dependence on the received light reading measurements.

Various aspects or examples of the present invention provide the following advantages and/or functionality: -The ability to match artificial light to ambient light during an interview, film recording, or photo shoot - Recalling a certain previously measured light colour / intensity of an outdoor shooting to reproduce that in a studio In an example, the camera of a mobile device (e.g. iPhone) is used as a measuring device for live / remote control adjustment and/or recall of previously stored light or colour measurements to adjust the colour or intensity of a source of illumination. This is achieved by using a (digital) camera as a measuring device (colorimeter / photometer) in which RGB (red/green/blue) values are captured and then transformed into CIE XYZ values (Standardized Colour Values by the Commission International d'Eclairage) which can be used to calculate the actual Correlated Colour Temperature (CCT) which is the basic metric used to match the colour of white light or the XYZ values to the colours of coloured light.

Further features are characterised by the appended claims. -6 -

It is envisaged that aspects of the system, portable device, method, and/or user interface described herein may be implemented in software running on a computer such as a personal computer or laptop, smartphone, or tablet, and it is to be appreciated that inventive aspects may therefore reside in the software running on such devices.

Other aspects of this system, portable device and/or method may be implemented in software running on various interconnected servers, and it is to be appreciated that inventive aspects may therefore reside in the software running on such servers.

The invention extends to any novel aspects or features described and/or illustrated herein.

The invention extends to methods and/or apparatus substantially as herein described 15 with reference to the accompanying drawings.

The invention also provides a computer program and a computer program product for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein, and a computer readable medium having stored thereon a program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.

The invention also provides a signal embodying a computer program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein, a method of transmitting such a signal, and a computer product having an operating system which supports a computer program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.

Any apparatus feature as described herein may also be provided as a method feature, and vice versa. As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure, such as a suitably programmed processor and associated memory. -7 -

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. Furthermore, any, some and/or all features in one aspect and/or example can be applied to any, some and/or all features in any other aspect and/or example, in any appropriate combination.

It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently.

Furthermore, features implemented in hardware may generally be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly.

These and other aspects of the present invention will become apparent from the following exemplary embodiments that are described with reference to the following figures in which: Figure 1 shows a schematic representation of a lighting control system; Figure 2 shows a schematic of an alternative example of the lighting control system of Figure 1; Figure 3 shows schematic hardware diagram of the lighting control system of Figures 1 or 2; Figure 4 shows the steps in a lighting control process; Figure 5 shows the state of a signal at different stages of the lighting control process of Figure 4; Figure 6 shows an example screenshot of the opening screen of an application used to control the system of Figure 1; Figure 7 shows an example screenshot of a 'Library' view of the application; Figure 8 shows an example screenshot of a manual lighting control page of the application; Figure 9 shows an example screenshot of the screen presented to the user upon selecting a light from the screen of Figure 8; Figure 10 shows an example screenshot of a DMX-style cross fader; Figure 11 shows an example 'scene page'; -8 -Figure 12 shows a front view of an example light array; Figure 13 shows a rear view of an example light array; Figure 14 shows an alternative lighting control process to that shown in Figure 4; Figure 15 (a) shows example black body radiation spectra for different correlated colour temperatures; Figure 15(b) is a schematic diagram of an auto white balance process; Figure 16(a) is a flow chart of an example method for calibrating a lighting control process; Figure 16(b) shows example light measurements captured using the method shown in Figure 16(a); and Figure 17 shows a schematic representation of a further example of a lighting control system.

In overview, a system is provided in which a portable communication device (such as an iPhone, iPad, tablet, PC, mobiles, PDAs and other electronic devices) is adapted to measure and 'capture' any colour of light within the visible spectrum. The portable device is then able to process this captured reading via a set of data tables and then transmit the closest found match remotely/wirelessly (to include Bluetooth, Wi-Fi wireless chip, 3G, 4G, infra red, DMX or other wireless type) to one or multiple stage, professional photographic or video/film and TV lights which would in turn accurately replicate this correlated colour temperature/characteristic of light. This would be achieved by mixing 2, 3, 4 or more 'colours' or temperatures of Light Emitting Diodes (LEDs), Light Emitting Polymers (LEPs) or other technologies on the aforementioned stage, photographic, video/ film and TV lights to create the desired colour temperature.

Figure 1 shows a schematic diagram of a lighting control system. The system comprises a portable mobile user device 100, a lighting device in the form of a lighting array 102 and a light controlling device 103.

The user device 100 may comprise a camera, or other light sensing means in order to take this measurement. The user device 100 may be a smartphone or tablet PC for example. Ideally, this measurement will contain information on the colour (Kelvin) and other properties of the sensed light. This information is stored on the user device 100, shown by data 106. -9 -

This data 106 is then processed, for example, by being calibrated and interpolated to determine the closest match which the light source can replicate, and then transmitted wirelessly to the light controlling device 103. The calibration step comprises modifying the measurement depending on the type of sensor used to take the reading, for example an iPhone may have different sensitivities over different wavelengths to an iPad. This step may occur when setting up the system on the user device 100, and/or each time a measurement is taken. The interpolation step comprises analysing the measurement and comparing certain features to that of a number of saved samples (for example in a lookup table). The wireless transmission may be via Wi-Fi, Bluetooth, Zigbee or any other wireless transmission means. The data is modulated onto a signal before transmission, as depicted by 106'. This signal is received by a light controlling device 103 which processes the signal 106' and determines the electrical signal that it needs to send to the lighting array 102 in order to replicate the light conditions as contained in signal 106'. This electrical signal is dependent on the lighting array 102. In one example, the sensor and light array calibration information is known to the device 100 and a calibrated signal is transmitted to the light controlling device 103. In another example, the type of sensor used is encoded into the signal 106' by the user device 100, and the information on the type of lighting array 102 can either be hard-coded into the light controlling circuitry, input manually, or also encoded in the signal 106'. For example, the signal could comprise the measurement (data) and information on the sensor and type of light (metadata). The light controlling device 103 then sends the calibrated and interpolated signal to the lighting array 102, which produces light with substantially the same properties as that of the measured light.

The light array 102 in one example comprises an array of different types of LEDs, preferably red, green, blue and white LEDs. The array may be a panel, flood light, a cluster or any other arrangement of LEDs. This provides the ability for the array to produce light of any visible colour by varying the relative intensities of the different LEDs. An LED array is advantageous for this reason compared to filament (incandescent), halogen or other types of lighting, and also generally require significantly less power to produce the same intensity of light.

One use for the system shown in Figure 1 is where a user device 100 has taken a light measurement (at an outdoor scene for example) which needs to be replicated by using a lighting array 102.

-10 -It is envisaged that the user device 100 is typically a mobile device such as an iPhone or iPad, with a downloaded application (app) adapted to provide the functionality and user interface for the lighting control. It is envisaged that a single user device 100 can control a number of different light arrays 102 using a single application. In certain examples, the light controlling device 103 and the lighting array 102 are provided in as a single unit.

Figure 2 shows the system of Figure 1, but incorporating an intermediate device 108. This intermediate device 108 effectively acts as a router, passing on the data 106 received from the user device 100 on to the lighting controller. This provides further functionality, in particular: i) If user device 100 used to sample the light is not, for example, within Wi-Fi range of the light array, it can send the data on to another similar mobile device, which can then control the light array, so mobile networks are used; and ii) If there are a number of light arrays 102, the intermediate device 108 acts as a hub'.

It is also possible to use this system along with a pre-existing light control system, such as a DMX (Digital Multiplexer), or PC, thereby to provide enhanced functionality.

Examples of possible intermediate devices 108 are: another user device (such as smartphone or tablet PC), a wireless router, a PC or DMX.

Figure 3 shows a schematic diagram of the hardware of the lighting system. The user device 100 comprises a light sensor 300, a processor 302 and associated memory 304, a modulator and multiplexer 306 and a transmitter/receiver 308. As discussed above, the light sensor 300 may be a digital camera, or another light sensing device. When the sensor is a digital camera, all image correction settings, such as auto white balance, are turned off before taking the measurement. This is to ensure that the image corresponds exactly to the light incident on the Charged Couple Device (CCD) in the camera. The light sensor 300 measures the light colour of a particular scene and stores this in memory 304. Ideally, this is a standardised scene, such as a white card exposed to the ambient light, held at a predefined distance, so that consistent measurements can be made. Alternatively, the user device 100 may receive the light measurement from another such user device. The user device may also have a number of pre-loaded or saved light measurements stored in memory 304.

The memory 304 also includes information such as the type of light sensor 300 used to measure the particular scene. This may be hard-coded into the user device 100, stored after a calibration process, or passed to the memory 304 along with the light measurement from an external source. The memory may also include data on the type of light array 102 it is able to transmit to. The light measurement, along with associated metadata is then converted into a signal, using processor 302. The data is modulated onto a carrier wave, which may be multiplexed to transfer separate pieces of information. The signal is then transmitted by transmitter/receiver 308 via an aerial and received by receiver/transmitter 310 in the light controlling device 103. The signal is demodulated (and de-multiplexed) and the original data is passed to memory 314. This data is then converted into an electrical signal using processor 316 and the signal is passed to light controlling circuitry 104. This calculates the correct relative light intensities and colour levels for the particular light array 102 that it is connected to in order to replicate the light conditions sent from the user device 100.

In one example, the transmission of the data 106 between the user device 100 and the light controller 103 may be secure to prevent malicious or unauthorised use of the system. In one example, this consists of the user device 100 'pairing' with a particular light array 102 by inputting the light's serial number or a system-wide PIN into the user device 100. This serial number or PIN is used to ensure only an authorised user device can control the light array 102.

After the transmission process, the light controlling device 103 may send a confirmation signal back to the user device 100, confirming the settings received so as to enable the user device 100 to check that the correct settings have been received by the lighting array 102.

Figure 4 illustrates the process followed by the system in order to replicate light levels from a measurement taken by a user device 100. Step 51 is to take the light level/colour measurement. This could be by using an in-built camera or light meter in the user device 100. This reading is then calibrated and interpolated in step S2. There are a number of options for this step. The device 100 contains information relating to the properties of the light sensor. This information can be used to create a standardised measurement which is subsequently prepared for transmission as described above. Alternatively, the information regarding the type of light sensor may be simply added to the transmission as metadata, and a calibrated measurement generated at a later stage. This option may be preferable if the processing speed of the user device 100 is low compared to that of the light controlling device 103, and/or the transmission network has a high bandwidth. Preferably, the calibration of both the light sensor 300 and of the light array 102 is done at the user device 100 to minimise the data transmitted. The data being transmitted is thus effectively a command to the light array 102.

The data (and metadata) is then transmitted in step S3. This data is modulated onto a carrier signal and transmitted via a transmitter as described above. The signal is then received in step S4. The dotted line 400 between steps S3 and S4 indicates where the process moves from the user device 100 to the light controlling device 103. The light controlling device 103 then converts this to an electrical signal in step S5 before sending the electrical signal to the light array 102 in step S6.

Figure 5 shows the state of the information relating to the lighting levels at various points in the process described above, along with the hardware/software provided to change the state. The information starts off as a light level/colour measurement 500. This is then turned into a calibrated and interpolated measurement 504 using a lookup table 502. Lookup table 502 contains information relating to different types of sensor, and how the measurements differ from a standard sensor. This lookup table may also contain data regarding the light arrays to which the user device 100 is 'paired', so that a fully calibrated signal can be generated. The table 504 lists the signal needed for each element of the light array 102 to produce all available light settings. The lookup table 502 may be locally stored on the user device 100, or stored remotely on a server which the user device 100 has access to. In a simple example, the lookup table contains just the information relating to the light sensor in the user device 100 itself and is only queried at set up, with all future measurements using this initial calibration. The calibrated and interpolated measurement is then modulated onto a carrier wave by modulator 510 to form modulated signal 508. This signal is received by light controlling device 103, demodulated 512 back into the calibrated measurement 504. This signal is then converted into an electrical signal 516. Lookup table 514 may be present to calibrate the -13 -signal if one or both steps of calibrating the sensor and light array have not been performed by the user device 100. Electrical signal 516 is generated and sent to the light array 102 which produces a light output 518.

In an example, there is provided a system which enables a user communication device (such as a smartphone, tablet, PC, mobile, PDA and other user device) to measure and store any colour of light within the visible spectrum. The user device then processes this captured reading, referencing a set of data tables, and then transmits the closest found match wirelessly (for example via Bluetooth, Wi-Fi wireless chip, 3G, 4G, infra red, DMX) to a light array which would in turn accurately replicate this colour temperature and characteristic of light. This is achieved by mixing 2, 3, 4 or more 'colours' or temperatures of Light Emitting Diodes (LEDs), Light Emitting Polymers (LEPs) or other light emitting devices to create the desired colour temperature.

The system is calibrated with a unique algorithm to each individual user device to ensure accuracy of colour capture and replication whatever the portable device used may be.

The user device is able to store and recall unlimited presets which include industry standard Correlated Colour Temperatures (CCTs) -specifically 5600K Daylight and 3200 Kelvin tungsten or recall previously captured Correlated Colour Temperature (CCT) measurements from a 'user library'. The CCT is the temperature of the Planckian radiator whose perceived colour most closely resembles that of a given stimulus at the same brightness and under specified viewing conditions.

This operation may be controlled via the use of a pre-loaded application, 'app', alternatively or additionally, computer software may be used.

The colour temperature of a light source is the temperature that a black body would be at when it radiates a comparable spectrum, or peak wavelength. This is measured in Kelvin 30 (K).

An example of where this system would be particularly useful is when the light illuminated on an object must match the ambient light so that the whole scene has uniform lighting. In an interview situation, for example, there may be ambient light and a light on the subject. If the light does not match the ambient light, it is likely that different -14 -areas of the shot will be in different lighting. This will result in the colour and white balance calibration of the camera being incorrect in some areas, leading to blueing or oranging of white objects in areas of different lighting. The system described herein aims to overcome this and other problems.

Another application where the system described herein could be utilised is in generating specific colours of light for aesthetic reasons. For example mood lighting by an LED array in a hotel, restaurant or home could be tailored to match particular conditions that a lighting designer has seen elsewhere. This could also be applied in the workplace, where studies have shown that workforce productivity can be affected by colour of light.

Figures 6-11 show example screenshots of an 'app' used to control the system described above. In the following description, the appearance and controls will be described in relation to an app on a user device such as a smartphone, but can equally be applied to any other interface device, such as a PC.

Figure 6 shows an example screenshot of the opening interface screen shot of an app used to control the system. Four functions are displayed here, although in reality, many more functions are indeed available. Sample button 600, when selected, activates the light sensor (e.g. camera), and displays a sample image detected by the CCD of the camera in target area 602. This is a blurred, or averaged image of the target image, so that a measurement of the colour conditions can be captured. In one example, the pixel values over the entire sample image are averaged and used as the reading. The device 100 determines the colour temperature of this image by analysing the spectrum and displays this in box 604. The system can either run in 'white mode', where it detects white light between 2800K to 6900K for example, or in 'ROB mode' returning the RGB colour components of the light.

In one example, the device 100 measures some characteristic components of the spectrum of the sample (for example peak wavelength, peak intensity, discrete wavelength measurements) derives the spectrum that is incident on the sample object, and then compares these to standard illuminates to determine the Correlated Colour Temperature. A standard illuminant is a published spectrum which corresponds to a particular type and temperature of lighting. Standard illuminants (such as Standard Illuminat A and D65) are black body spectra (at 2856K and 6774K respectively); others, -15 -such as Standard Illuminats B, C and D are daylight simulators and differ slightly from a black body curve. This comparison may produce a more accurate representation of likely lighting conditions compared to assuming black-body radiation. Two standard illuminates that are often used are 'daylight' at 5600K and 'tungsten' at 3200K.

It is important to note that rather than the properties of the image itself being returned, it is the properties of the light incident on the sample object (i.e. white card) that is returned. This can be derived from the light received from the sample object, if given sufficient information about the sample object. It is also worth noting that this derivation produces more accurate results for certain sample objects over others (for example white rather than black card).

This measurement can then be transmitted to the lighting array by pressing the transmit' button 606.

Other functionality provided on this screen is a store button 608 which enables a measurement to be stored, and a recall button 610 which enables a previously taken measurement, or library measurement to be recalled from memory.

Figure 7 shows an example screenshot of the Library'. This is an area in which pre-saved and/or downloaded measurements can be recalled, compared and transmitted. Pre-saved measurements, stock readings and other readings such as purchased libraries (e.g. a library of specific Lee Filter ®, Colour FX ®, Rosco ®, Co Tech ®, settings) can be loaded for subsequent transmission or adjustment. It is envisaged that a user can access, purchase and download a range of settings which correspond to commercially available filters into their personal library. Thus, the user can use the present system to replace, or replicate prior systems which have been using gel filters over tungsten lights for example.

Figure 8 shows an example screenshot of a lighting control page of the app. A number of lights are shown which have been 'paired' with the user device 100. These lights can be controlled separately or together by using the group button 800. Each light has their current colour temperature shown along side, and a button to find out more info' about the particular light. As described above, the user device can pair with a number of lights, -16 -thereby forming an 'ad-hoc' network of lights. In one example, there is no need for a central router or hub to facilitate this network.

Figure 9 shows an example screenshot of the screen presented to the user upon selecting a light (or number of lights) from the previous screen. There is a switch 900 to turn the light on and off, a rotatable button 902 to alter the colour temperature of the light (shown in box 904). This can also be entered manually. The brightness of the light can also be adjusted by moving control 906.

In one example, the app works via a web interface, two web pages being accessible. The first page would contain variables such as brightness and colour (as shown in Figure 9). By altering these values the app can control the light array 102.

The second page, accessible using the 'more info' button, contains 'factory set-up' information such as the type of light array 102, characteristics of LEDs fitted, serial number, etc. These values will never need to be changed by customers.

Figure 10 shows an example screenshot of a DMX-style cross fader. This screen allows the user to adjust the light levels of a number of different light arrays. The channels correspond to different light arrays (e.g. White -5600K), or a number of channels may correspond to a single light array with RGB controls (see channels 2, 3 and 4 of Figure 10). The user can select the channels they wish to appear on the DMX and adjust their levels, or turn them off completely. On pressing 'select', a display of all the parameters of that given light array is displayed.

Figure 11 shows an example 'scene page' where a user can programme transitions between different saved lighting levels. The user can place different scenes into the placeholders (1-17 shown) and set the transition time between the scenes (1s-5s shown).

The system, portable communication device, and/or software application (app) preferably have at least some of the following features: * Control brightness of the light array.

* Control colour temperature on bi-colour lights.

* Control multiple devices simultaneously, like a DMX desk.

-17 - * Recall multiple named 'scenes'.

* Control cross fades between scenes.

* Manual fade up and fade down.

* Have a graphic of a representation of fader controller desk.

* Powering up the light with the encoder button depressed will put it into 'firmware update mode'.

* Bootstrap system allows for firmware update even if previous update failed. Since this is a Wi-Fi data transfer, with error correction / data checksum bit built in to the transfer handshake protocol.

* The serial number of the lighting array identifies whether device is single colour (e.g. tungsten or Daylight) or three colour and the app will automatically send correct firmware.

* Firmware update (tungsten / daylight / bi-colour and later tricolour with colour library).

* DMX style fader control over brightness & white balance (to include RGB plus white control with colour library).

* 128 scene store/ recall with embedded cross fade, fade up, fade down.

* Colour library for tricolour plus white.

* Built in colorimeter mini app to automatically detect and set 'auto white balance' and display colour in Kelvin (if colour is not in range of 2800-6300K then it says out of range error').

* The DMX fader page is preferably for one light at a time (with all parameters and scene / library access on one page), and further a second version with multiple faders which allows for scene recall and fader grouping for commanding multiple sets of lights individually from each other.

* A page is provided where you enter the serials of the lights to be controlled, assign fader channels to them, assign lights to groups.

* Device app is optimised for both iPhone and iPad in the first instance and 3rd party products also.

* Addressability and control of lamp brightness and colour temperature.

* Firmware updates are transmitted via the Wi-Fi interface as they are released.

Figures 12 and 13 show an example light array 102 in the form of a light panel which is adapted for use in the system as described above. Figure 12 shows the front of the light -18 - 102. In this example, there is provided an array of LEDs 1202 in a circular arrangement, around which a hexagonal series of 'barn doors' 1200 are arranged. These act to shield areas in which light should not be directed, reducing unwanted shadows and reflections. Barn doors 1200 can be pivoted about an axis that lies on the plane of the light to alter the direction and extent of the light. The barn doors 1200 can also be removed, so that a number of such lights can be tessellated together to form a large array. LED array 1202 contains a number of different LED lights of varying colours, for example at least two of white, red, green and blue. Preferably, there are a number of different colour white LEDs in the array 1202.

Figure 13 shows the rear view of the example light array 102. Display 1300 shows the colour temperature that the light array 102 is currently set to. This can be altered manually by way of rotatable button 1302. Light controlling circuitry 104, light controlling device 103 (Figures 1 and 2), power input, battery and DMX input/output (not shown) are accessible from the rear of the light 102.

Alternatives and modifications Figure 14 shows an alternative process to that shown in Figure 4. As in Figure 4, the process starts with a light measurement being taken in S1. This measurement is calibrated and interpolated as described above in relation to Figure 4 and is transmitted in step S3 then received by the light controlling device 103 in step S4. This is then converted to an electrical signal S5 and sent to the light array S6, also as in Figure 4. The next step is for the user device 100 to measure the local light levels, once the light array is operational in step S7. This is to determine whether the colour of the light has changed by having the lights turned on, which could lead to calibration errors. This measurement is compared to the original measurement in step S6, and step S7 determines whether they are within an acceptable range of one-another. If they are not, the electrical signal is adjusted S7 in dependence on the disparity and the signal is sent to the light array at step S6. This process continues until the two signals are within an acceptable range of one-another, when the process can end. This feedback loop ensures that the generated light matches the ambient light to a high degree of accuracy.

This feedback process shown by Figure 14 can also be utilised to act as an intensity matching process. In this case, the intensity of the light is measured at S1 at the time of -19 -measuring the colour. These measurements are then transmitted and received as above, and a light source is activated in dependence on the colour measurement. Another measurement of the intensity is then taken at the same distance at which it was previously taken, and this new measurement is compared to the original intensity measurement. The electrical signal sent to the light array is then modified in dependence on the disparity between these measurements until the original intensity has been matched. In a particularly advantageous example, both intensity and colour are hence matched.

In some examples, it is not possible to turn off or disable certain built-in enhancement functionality of the camera of the portable device 100, such as the 'Auto White Balance' (AWB) enhancement functionality. In this case, the taw' RGB values for the received light are not readily available. This is illustrated in Figures 15(a) and (b). Figure 15(a) shows various black body spectra for three different colour temperatures 2700K, 5000K and 7000K. Superimposed on this is the section of visible light, where blue is on the left of the box, green in the centre and red on the right.

The relative RGB components 1500 of light as reflected from a test card at correlated colour temperatures 2700K, 5000K and 7000K indicated by reflectance numerals 1502, 1504 and 1506 shown in Figure 15(b). A digital camera which employs AWB enhancement will correct the RGB values of the detected light signal to [1,1,1] 1508 as this represents 'white' in RGB space. Thus, regardless of the actual CCT, when white' is detected by the camera, the RGB values will be [1,1,1] It is thus not possible to determine the CCT from these 'corrected' RGB values.

Accordingly, as illustrated in Figures 16(a), 16(b) and 17, a transformation function or look-up table is employed to determine the actual CCT from the detected corrected' RGB values. . The transformation function or look-up table is determined in the following way. A standard illuminant (e.g. a 5000K light) is used to illuminate a test card as shown in step S1 of Figure 16(a). A light level reading is taken of this test card which is then used as a reference level in step S2. The AWB is then locked' to this value in step S3. In one example, this involves storing the settings used by the AWB algorithm for that reading and then using those settings for all future readings. Future readings are thus relative to a '5000K white' reading. The CCT of each future reading can be determined from this relative reading by means of a look-up table in step S5 which converts relative -20 -RGB values to CCT values. The look-up table may be specific to the camera in question as the relative RGB values produced by the locked' AWB algorithm may depend on the software and hardware being used.

Figure 16(b) shows the RGB readings produced with a 'locked' AWB. The 5000K measurement 1604 results in a RGB reading of [1,1,1]. The 2700K reading 1602 gives a higher relative Red (R) reading and the 7000K measurement results in a higher Blue (B) and lower Green (G) reading. The triplet [R,G,B] combined with the known raw 5000K reading 1600 uniquely defines a particular CCT and thus the lighting temperature of an illuminated test card can be accurately determined in this manner. The measured RGB values 1602, 1606 can be converted into CCTs by combining them with the known RGB values 1600 for the standard illuminant.ln this way the raw RGB values (1500) are determined. These are then used to look up the most likely CCT in a pre-stored look-up table. This look-up table is pre-loaded onto the app on the device 100, or is downloaded to the device 100. It is calculated by determining the RGB values from a black body spectrum or by determining these values by calibrating an identical camera with a number of different standard illuminants. This second option may be preferable if the camera's response to different CCTs is non-linear.

Figure 17 illustrates schematically the various hardware and software modules used to implement the system in this example where AWB functionality cannot be disabled. Figure 17 illustrates both the initial calibration phase and the system in operation. The calibration process uses a standard illuminant 1700 illuminating a test card. This is detected by a camera 1704. The camera includes a filter such as a Bayer-pattern filter 1706 to separate the raw RGB components 1708 of the light. The light is then incident on a sensor 1710 which produces the sensed components RGB_i indicated by reference numeral 1712. An ideal sensor would not alter these raw values 1710. These values are then sent to an Auto White Balance (AWB)' module 1714 which produces RGB_awb values 1716 which are the values 1508 shown in Figure 15(b).

These values are subsequnrtly turned into triplets [X,Y,Z] by the RGB to XYZ module 1718. The RGB raw values for the standard illuminant 1700 are stored in a control system 1722, which is employed by XYZ recalibration module 1724 to feed back to the RGB to XYZ module 1718. Other factors such as exposure time, aperture and ISO speed 1726 may be used by recalibration unit 1724. Further measurements are taken using the -21 -same AWB settings as for the standard illuminant. These settings are stored for use during operation. In operation, these settings are passed to a controller 1730 to lock the AWB settings in the camera 1704 via a controller 1732.

The recalibrated XYZ values are extracted from the look-up table 1720 to determine the most likely CCT which is then passed to light controller 1734 which transmit an appropriate control signal to control the light source 1736.

In one example, the 5000K standard illuminant is provided by the same light source that is used to simulate the lighting conditions.

A person skilled in the art would appreciate that any suitable calibration CCT can be used, and the the use of a 5000K standard illuminant is merely exemplary.

It will be appreciated that particular aspects of any of the examples described above can be combined in various ways.

It will be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

Claims

-22 -Claims 1. A controller for controlling a lighting device, the controller comprising: means for storing lighting settings corresponding to a lighting scene; means for transitioning between lighting settings; wherein said transition occurs over a user-defined time period.
2. A controller according to claim 1 further comprising means for storing lighting settings corresponding to a plurality of lighting scenes.
3. A controller according to claim 2 further comprising means for storing transitions between a plurality of lighting scenes.
4. A controller according to any preceding claim wherein said lighting settings comprise colour temperature.
5. A controller according to any preceding claim wherein said lighting settings comprise brightness.
6. A controller according to any preceding claim wherein said means for transitioning comprises means to cross-fade between lighting settings.
7. A controller according to any preceding claim comprising means for transmitting said lighting settings to a lighting device.
8. A controller according to claim 7 wherein means for wirelessly transmitting said lighting settings to a lighting device.
9. A controller according to any preceding claim further comprising means for receiving user input.
10. A controller according to claim 9 wherein said user input comprises the time period over which said transition occurs.
11. A controller according to any of claims 9 to 10 wherein said user input comprises a colour temperature.

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12. A controller according to any of claims 9 to 11 wherein said user input comprises a brightness.
13.A method of controlling a lighting device, the method comprising: storing lighting settings corresponding to a lighting effect; recalling said lighting settings; transitioning between lighting settings.
14. A method according to claim 13 comprising receiving user input relating to the timing of said transitions between lighting settings.
15. A method according to claim 14 wherein receiving user input comprises wirelessly receiving user input.