FIELD OF THE INVENTION

This invention relates to indoor lighting.

BACKGROUND OF THE INVENTION

There is more and more awareness in the world about the strong influence the environment has on the wellbeing of people, especially if people spend large amounts of time inside. Various attempts have been made to bring nature inside with artificial views and sky projections, but also using advanced lighting systems which are able to create daylight mimicking effects.

There are many examples of systems which use electronic displays to mimic natural views. The displayed image has a color and brightness at each pixel which matches an image to be displayed.

However, the simple display of an image of an outdoor scene onto a surface, such as displaying an image of the sky onto a ceiling, does not provide a realistic replication of the actual outdoor lighting effect. In particular, it takes no account of the different optical properties of the natural environment through which the light has to travel. Furthermore, a displayed image has limited dynamic range, so that the differences in brightness of a natural scene are not replicated well.

There is therefore a need for a system which can more faithfully mimic realistic outdoor conditions inside a building.

SUMMARY OF THE INVENTION

The invention is defined by the claims.

According to examples in accordance with an aspect of the invention, there is provided an indoor lighting system comprising:

an image generator for generating a multi-region image representing an outdoor scene onto a surface; an array of light sources, wherein each light source is controllable to provide a selected one of a group of lighting effects, the different lighting effects in the group differing by one or more of the directionality, brightness, color and color temperature; and

a controller, wherein the controller is adapted to:

receive information relating to the multi-region image, wherein an image region is associated with each light source; and

control each light source in dependence on the information relating to the associated image region, thereby to complement the lighting effect of the associated image region by replicating natural outdoor lighting conditions which compensate for inadequacies in the multi-region image.

This system controls an array of light sources based on the content of an image of an outdoor scene. Each region of the image is associated with at least one light source. The light sources are controlled to provide different lighting effects, for example there may be a directional lighting effect (e.g. a narrow beam) and a diffuse lighting effect (e.g. a wide beam). In this way, natural lighting conditions may be replicated which correspond to the image, so that the image itself may be complemented or corrected by the light sources. For example, a cloudy sky region results in more diffuse and less directional light, whereas a clear sky region results in more directional and less diffuse light. Thus, the array of light sources may be used to replicate outdoor lighting conditions and thus compensate for inadequacies in the image.

The multi-region image representing an outdoor scene may comprise an occlusion. For example, a cloud in a blue sky occluding natural sunlight, or a tree in a forest occluding natural sunlight. The multi-region image may, by its very nature of being generated by an image generator, cause an incorrect representation of a lighting effect of said occlusion in the outdoor scene. Namely, the artificial lighting effect caused by the image of said occlusion may not correspond to the natural lighting effect as in reality. Thus, the present invention may control each light source, or any light source, in dependence on the information relating to the associated image region, i.e. here e.g. a detected occlusion, so as to complement the artificial lighting effect of the associated image region by replicating a natural outdoor lighting effect (or natural outdoor lighting conditions) which compensate for the incorrect or inadequate in the representation of said occlusion in the outdoor scene of the multi-region image. Said lighting effect of the associated image region, in this application, may be a perceived lighting effect. For example, as perceived by the anatomy of an eye of a human observer.

The invention may be elucidated by an example. For example, an image of a blue sky with a white cloud may be represented on a display, wherein the white colored cloud will have a higher perceived brightness than the blue colored sky. However, in reality, the opposite happens, a cloud in the sky in front of the sun will be blocking sunlight, and hence the cloud will be having a more diffuse lighting condition compared to the surrounding blue sky. Thus said 'natural' lighting conditions are not adequately generated and represented by the 'artificial' image on the display. The present application therefore provides the inventive concept of accompanying the display with an array of light sources, wherein a light source, in dependence whether or not a white cloud or blue sky is present in the image, complements the (artificial) lighting effects of the image by replicating natural outdoor lighting conditions.

Thus, an associated light source compensates the lighting conditions of the image by providing more diffuse light whenever a white cloud is present and less diffuse (e.g. more directional) light in case a blue sky is present.

The light sources may simply be turned off or set to a lower brightness where directional lighting is not desired (i.e. one of the lighting effects may be that the light source is turned down or off). The light sources that remain on may then provide sufficient diffuse light to the other areas in the indoor space. However, the light sources may instead be controllable between two or more on- states with different levels of directionality of the light output, i.e. a directional mode and a scattering mode.

In some examples, the multi-region image does not require complete complementing of the lighting effect, for example at least 50% of the multi-region image. Such a condition may be comprised within the information relating to the multi-region image.

In such cases, the controller may be adapted to control each light source for providing functional lighting.

Said complementing the lighting effect of the associated image region by replicating natural outdoor lighting conditions which compensate for inadequacies in the multi-region image may, in examples, be at least partly complementing and at least partly compensating for inadequacies. A slight compensation or complementing may also be perceived as a light effect more representing the real outdoor scene.

The light sources may for example generate a white light effect which corresponds to lighting conditions associated with the corresponding image segment. The white lighting for example may extend the dynamic range of the image and/or provide directionality. Thus, the light sources may complement lighting effects of the image other than color. The white lighting may have different color temperature (although generally white) or the white lighting may have a single color temperature i.e. using a single type of light source.

Each light source may comprise a downlighting light source.

By "downlighting" light source is meant a light source which provides generally illumination transverse to the multi-region image (on the surface) and generally 'downward' illumination (with respect to the image). Thus, the light sources are adapted to provide output light in a downward direction to provide general illumination to an indoor space. They may e.g. provide light vertically downwardly in case the multi-region image on the surface is horizontal, or in a direction offset from the vertical, or they may have controllable light output direction. Such an offset may for example be at most 30 or 45 degrees of the transverse direction. These light sources are for example discrete units, such as luminaires, and they cover a large area so provide general ambient illumination to the indoor space. They may be mounted on a horizontal surface such as a ceiling, but they may also be wall or post mounted.

The multi-region image may be displayed (by a panel display or a projection display or any other image generation technology) in the indoor space, and the array of light sources complement this image. The multi-region image may be viewed through a window. In this case the image is seen through the window, and the indoor lighting is controlled in dependence on the image (based on image sensing) in order to enhance the lighting effect corresponding to that image.

The multi-region image is for example a real image or simulated image of a sky. The image as processed by the system may be a data file that is stored on a device, or a data file from a system which generates the image or it may be an image captured by a camera.

Thus, the lighting effect generated in the indoor space is based on sky lighting conditions, which may be simulated or real. The sky lighting conditions may relate to the appearance as viewed from the ground, but they may be more general, for example including the appearance as viewed from underwater. The multi-region image may evolve over time, for example being derived from a video image. A first lighting effect may be a directional lighting effect and a second lighting effect may be a diffuse lighting effect. Each light source is thus able to replicate directional lighting of a cloudless sky or diffuse lighting of a cloudy sky.

Each light source may comprise a single lighting element which is controllable to provide the different lighting effects, or each light source may comprise a plurality of lighting elements at least one of which provides a first lighting effect and at least one of which provides a second lighting effect.

The light sources may thus each comprise a single lighting element or a more complex lighting arrangement, to provide the required controllability.

Each downlighting light source may comprise a ceiling-mountable downlighting element. These produce a downlight or daylight effect which is derived from the local conditions of the multi-region image. The light sources are discrete units such as luminaires which are physically separated and in their own separate housings, so that the array may extend across a general illumination area of the ceiling.

The lighting system may thus be ceiling-mounted for providing the general lighting in the indoor space. The lighting effect for example replicates at least some of the characteristics of natural daylight and sky conditions by providing regions of different levels of directionality and scattering in combination with an image of the natural scene e.g. sky.

Each light source may have a controllable color temperature, color, controllable brightness, and/or a controllable light output direction.

A controllable color or direction means the lighting effect can match even more closely the image content of the corresponding image region. The color for example may be controllable between bluish-white (i.e. bright white) and yellowish-white (i.e. natural white), so that the light is generally white with a controllable color temperature.

The controller may be adapted to control the direction in dependence on a real or virtual sun position.

In this way, the directional lighting is controlled so that the lighting effect matches even more closely the natural lighting effect, for a given position of the sun. The directional control may be based on the actual sun position, or it may be based on a virtual sun position. For example a summer's day may be simulated indoors during winter.

The system may, as mentioned before, comprise an image generator for generating the multi-region image onto a surface.

In this way, the system generates the image as well as the corresponding lighting which has a lighting effect at specific locations in dependence on the image. In the case of an image of the sky, the system then replicates both the visual appearance of the sky and the different lighting effects (in terms of directionality and/or brightness and/or color) resulting from natural daylight. The surface is for example the ceiling. However, it may also be a fake window such as a high level (e.g. clerestory) window. The surface may also be a projection wall.

The system may instead simply react to an image which has been generated by an external system.

In one set of examples, the image generator is for example a projector or a display panel arrangement.

In another set of examples, the image generator comprises lighting units, with a lighting unit at each light source, wherein each lighting unit is for delivering light upwardly and the light source is for delivering light downwardly.

In this example, distributed lighting units together form an upward image projector, and these lighting units are at the light sources. Thus, the general lighting and the image generation are combined at the light sources, to provide a compact system. Such an upward image projector may be a high-density LED strip with the functionality to provide an image onto a surface.

In an alternative set of examples, the array of light sources may be integrated with the image generator, wherein the image generator provides the multi-region image in a direction opposite to the illumination direction of the array of light sources. The array of light sources and the image generator may further be accommodated on a grid shaped carrier. Here, opposite refers to emitting light to opposite directions, wherein directionality of light (within the opposite direction) is still preserved. A grid shape may advantageously enable the array of lighting devices and the image-generator without blocking a view to the image, as the image may be generated in the region corresponding to the openings of the grid. The grid shaped carrier may comprise on a first side an image generator comprising a plurality of LED light sources for generating a multi-region image onto the surface, and on an opposite second side the array of light sources. In this way, an advantageously compact lighting system is enabled, wherein an image generator is integrated with the array of light sources.

Furthermore, the grid shaped carrier may comprise a repeating pattern, such as a rectangular mesh, triangular mesh, a hexagonal mesh, a random unstructured mesh pattern or a honeycomb, or a combination thereof, or a combination enabling a complete tessellation of a surface. Further, said grid shaped carrier may be constructed from thin shaped metal. In yet another set of examples, the array of light sources may be in plane with the surface onto which the multi-region image is generated by the image generator. The light sources may for example be integrated in the surface, such as light spots in a ceiling or light spots in a projection screen. Alternatively, the array of light sources may be positioned on an interface of a plurality of display screens adjacent to each other for generating a multi-region image.

The controller may be adapted to receive the multi-region image, and to control all the light sources in dependence on the multi-region image.

This implementation uses a central controller which controls all of the light sources based on the multi-region image.

Alternatively, the controller may comprise a controller portion at each light source, adapted to receive only information relating to the respective image region, and to control the associated light source.

In this implementation, the light source and its associated controller portion may become a standalone component. The controller portion for example comprises a light sensor. In this way, the light source has a light sensor for detecting the local lighting conditions. When the multi-region image is displayed or projected onto a surface, the sensor then detects the local image region to provide control of the light source. This standalone component then does not need any centralized control, as it may react to its local environment. By separately providing a desired image (e.g. of the sky), the light sources automatically control themselves locally to provide the desired lighting effect.

The light sensor may be for sensing at least part of a real or artificial sky image.

Examples in accordance with another aspect of the invention provide an indoor lighting method comprising:

receiving information relating to a multi-region image;

associating each image region with a respective light source of an array of light sources; and

controlling each light source in dependence on the information relating to the associated image region, thereby to provide a selected one of a group of lighting effects, the different lighting effects in the group differing by one or more of the directionality, brightness and color temperature; and thereby to complement the lighting effect of the associated image region by replicating natural outdoor lighting conditions which compensate for inadequacies in the multi-region image, In an aspect of the invention, in a paragraph, there is provided: an indoor lighting system comprising: an image generator for generating a multi-region image representing an outdoor scene onto a surface; an array of light sources (16), wherein each light source is controllable to provide a lighting effect selected from the group of

directionality, brightness, color and color temperature; and a controller (18), wherein the controller is adapted to: receive information relating to the multi-region image, wherein an image region is associated with a light source; and control, in dependence on the information relating to the associated image region, the light source to replicate natural lighting conditions corresponding to the multi-region image, so as to compensate for inadequacies in outdoor lighting conditions represented by the outdoor scene of the multi-region image; or alternatively phrased, control, in dependence on the information relating to the associated image region, the light source to compensate for inadequacies in outdoor lighting conditions represented in the outdoor scene of the multi-region image by replicating natural lighting conditions which correspond to the multi-region image.

In an aspect of the invention, in a paragraph, there is provided: an indoor lighting system comprising: an image generator for generating an image onto a surface, the image representing an outdoor scene and comprising a representation of an outdoor lighting effect; an array of light sources, wherein each light source is controllable to provide a lighting effect; a controller arranged for receiving information relating to a region of the image, wherein the region of the image is associated with a light source; and controlling, based on said information, the light source to compensate for an inadequate representation of said outdoor lighting effect. Said compensation may be performed by either providing directional lighting or diffuse lighting. For example, an occlusion portrayed in the outdoor scene of the image may be complemented by providing diffuse lighting because such an occlusion may block sunlight, which may be inadequately generated by or represented in the image.

In an aspect of the invention, in a paragraph, there is provided: a method for compensating for an inadequacy of a multi-region image representing an outdoor scene, the method being performed by an indoor lighting system comprising an image generator and an array of light sources, the method comprising the steps of: rendering the multi-region image onto a surface by means of the image generator; receiving information relating to the multi- region image; associating an image region of the multi-region image with a light source of the array of light sources; and controlling the light source in dependence of the information so as to complement an inadequate artificial lighting effect of the rendered multi-region image by replicating an adequate natural outdoor lighting effect associated therewith. The embodiments related to the lighting system according to the invention relate mutatis mutandis to the embodiments related to the method according to the invention.

Said inadequacy may be an occlusion, such as a cloud passing through a blue sky, or a leave waving in front of a landscape view, or a white bear walking in front of an ocean view. An occlusion may be any blocking of natural sunlight, e.g. a blocking of natural sunlight by a brightly colored subject, such as white colored.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention will now be described in detail with reference to the accompanying drawings, in which:

Fig. 1 shows an indoor lighting system;

Fig. 2 shows an array of light sources, wherein each light source has a downwardly facing lighting element and an upwardly facing image sensor;

Fig. 3 shows an example of lighting system in which the light sources provide the image generation;

Fig. 4 shows how directional lighting may be provided with the sun at the zenith position;

Fig. 5 shows the angles associated with a sun which is not at the zenith position and shows that light sources which provide a directional light output steered based on the sun position; and

Fig. 6 shows an indoor lighting method.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention provides an indoor lighting system which makes use of an image representing an outdoor scene. Each light source of an array of light sources is able to provide a selected one of a group of lighting effects. Each light source is controlled in dependence on the information relating to the associated image region, thereby to

complement the lighting effect provided by the associated image region.

Figure 1 shows an indoor lighting system. A room 10 has an image 12 of the sky projected onto the ceiling by a projection system 14. The image 12 is a multi-region image, with multiple regions 11, and more generally represents an outdoor scene. The image is multi-region in the sense that it may be considered to be formed as a combination of independent image regions 11, each with their own general color and brightness. The image may be static but preferably it evolves over time, and may for example comprise a video image. The image may be retrieved from a remote storage device, but it may instead be directly streamed from a live outdoor feed of a local or remote camera device.

There is an array of light sources 16, and they are distributed across the area of the ceiling. In Figure 1, these are shown as LED spots, but they may be discrete small downlights or LEDs or LED arrays or light panels or LED strips. Their purpose is to enhance the realism of the image 12, in particular by providing additional lighting effects beyond only the color or brightness of the image on the ceiling. By way of example, the light sources 16 additionally provide control of the directionality of the light provided from the associated region of the ceiling. More generally, each light source 16 is controllable to provide a selected one of a group of lighting effects, the different lighting effects in the group differing by one or more of the directionality, brightness, color and color temperature.

The lighting effects may all be white light effects so that the light sources aim to complement or correct the lighting associated with the multi-region image in respect of parameters other than the color.

Each light source 16 is associated with and located at one region of the image 12. The light source is used to adapt the lighting effect as seen from that region of the image.

A controller 18 receives information relating to the multi-region image and controls each light source in dependence on the information relating to the associated image region, thereby to complement the lighting effect provided by the associated image region.

The light sources 16 are thus controlled to provide different lighting effects, for example a directional lighting effect which replicates direct sunlight and a diffuse lighting effect which replicates lighting from a cloudy part of the sky. The image content may be used to determine the type of sky in each region of the image. In particular, the dominant color of each image region may be used to control the light source, wherein a blue color represents a clear sky, a bright white color represents a bright but cloudy sky, and a grey color content represents an overcast sky.

The light sources may all provide directional lighting. When an individual light source is turned on, a region of the image (representing a region of the sky) appears to generate directional lighting. When turned off, the image itself provide some illumination but also there is diffuse scattered lighting generally in the room from the other light sources. The light sources may all be white light sources. They may have the same color temperature so that only the directionality and brightness is controlled, or they may have controllable color temperature (but generally white) so that the additional lighting has a selectable color temperature, for example matched to the sky color. They may instead have controllable color point so that other (non- white) lighting effects can be created.

The image is only notionally formed of regions, in that one region is associated with one light source. The actual image may be a continuous projected image, or a pixelated display image (but with the pixel size independent of the image region size). The regions may overlap or they may be spaced apart. For example, a light source may be controlled based on only a central part of the image region used to control the light source, or instead the light source may be controlled based on an average or aggregate lighting effect provided by the associated image region. This may be an average or dominant color for example.

The overall system is used to mimic daylight by providing spatial lighting conditions in a room which match the image, for example of the sky. In part of the room where a blue sky image is projected, directional downlight will be created for example a bright warm white directional downlight. In parts of the room where a cloudy sky image is created, no is created or else a low- intensity, neutral white wide beam of light. Different sky colors thus result in different effects, and a dark blue region may even create a different effect to a bright blue region for example.

The example of Figure 1 includes a projection system 14. In this case, the image data used to drive the projection system is also used to control the light sources.

However, the projection system does not need to be part of the system. There may for example be an external system for creating the image. In such a case, the system may include a sensing arrangement for sensing the image, for example the general color within an image region (which has a size corresponding to, or smaller than, or larger than, the area associated with one light source). Other image analysis may also be conducted. For example, sharp shadows in a nature image may indicate that there are sunny outside lighting conditions, whereby the light and direction of the shadow provide further cues on the desired associated lighting conditions. The image region may also be classified or analyzed, for example it may be recognized as a sky with clouds, sea with sunset or starry sky, and associated light settings or scripts can be acquired and activated.

Other image display technologies are also possible. For example, the ceiling may comprise an array of display panels which are tiled together to create the overall image. The tiling may form a grid, and the light sources may be provided along the webs of the grid. They may comprise LEDs so that narrow grid webs may be used between the display panels. Alternatively, display tiles or display panels may be provided which are already equipped with one or multiple light sources in the form of downlighters (in the center, corners or sides of the panel).

In all cases, the light sources may undergo a commissioning step, during which each of the downlighters is associated with a specific region of the image.

The image may be provided across a ceiling or just at (artificial) skylights.

However, the invention is also not limited to ceilings. Figure 1 shows a high level artificial window 20 (e.g. clerestory window) to which an outdoor image is provided. This may again be an image of the sky (as viewed from a shallower angle). A matrix of spotlights can be used to create directional and warm or diffuse and cool lighting effects in the space corresponding with the color of the sky pattern. The spotlight pattern is for example projected on the floor or opposing wall. The angle of the matrix of spotlights may be controllable and change for example as a function of time of day.

As mentioned above, the image may be generated by an external system. Figure 2 shows an array of light sources 16, wherein each light source 16 has a downwardly facing lighting element 16a and an upwardly facing image sensor 16b. The image sensor is used to analyze the local image region of the image 12 which has been projected (or otherwise displayed) above the array of light sources 16.

The light sources then become standalone devices, and this may even avoid the need for a central controller. Each light source then functions as a non-connected, standalone light node. The image sensor 16b may be a light sensor, pixelated sensor or camera device which faces the direction opposite to the light output direction from the lighting element 16a. Depending on what is detected by the sensor, the desired lighting effect is created. The sensors either monitor real-time or artificial sky conditions. In this way, an existing skylight projection system may be supplemented with a daylight mimicking function at the part of a room where it is most appealing. This enables easy configuration and reconfiguration of a daylight mimicking system.

In the examples above, the image generating system and the light sources are implemented by separate systems. Figure 3 shows an example in which the light sources themselves provide the image generation.

Each light source 16 comprises a downwardly facing lighting element 16a and an upwardly facing lighting element 16c. The upwardly facing lighting elements 16c generate the image on the ceiling. The light sources are thus dual- function lighting devices each having an uplighter and a downlighter. The light source array is installed underneath the ceiling, at a distance dependent on uplighting beam angle and the distance between the light sources such that the array of uplighting elements 16c together project a sky- like light projection on the ceiling. The resolution of the image will typically be lower than for a projection system or display panel system.

The downwardly facing lighting elements 16a can either be implemented as a simple collimated, element, or they may each comprise means for directional control of the effects. The elements may be mechanically redirectable, either by hand or motorized, or they may have pixelated control to facilitate various beam widths and directions. In such an arrangement, a pixelated light source and an output lens are used to provide directional control. This has the advantage that changing the beam direction and beam dimensions will not cause any wear of the element. Each element is again associated with a specific region of the image (i.e. the sky image), and is controlled based on the color properties of the sky pattern. The uplighting elements are also controlled to generate the image based on an image data input.

The system may be formed as an open grid structure. The grid is for example a rectangular or square array of grid lines. The grid lines carry lines of LEDs or LED arrays which function as the uplighting elements, which project an image to the ceiling above. An array of light sources (which may all be white) is provided on the opposite side of the grid to provide the effect. The elements are for example at the grid crossings. They create a directional downlight effect. The grid is open such that the ceiling is visible through the openings between the grid lines.

This structure is able to project a sky pattern on an entire ceiling, but the structure can be relatively lightweight. This also makes it much easier to install the structure high up in a room compared to a solution using electronic display panels. An alternative approach is to have one or more wall-mounted linear lighting elements which are arranged to project both a sky pattern upwards and white (directional) light downwards into the room.

Alternatively, in a similar embodiment to the one depicted in figure 3, the array of light sources and the image generator may both be accommodated on a grid shaped carrier (not depicted). This may be a thin sheet metal carrier, alternatively a plastic or composite carrier. The image may be generated in the region corresponding to the openings of the grid. The grid shaped carrier may comprise on a first side an image generator comprising a plurality of LED light sources for generating a multi-region image onto the surface, and on an opposite second side the array of light sources. In figure 3 the plurality of LED light sources for generating a multi-region image onto the surface are equal in number to the array of light sources. However, in the present embodiment (not depicted), the plurality of LED light sources for generating a multi-region image onto the surface are more in number than the amount of light sources in said array of light sources, preferably at least 4 times as much, or at least 10 times as much, for example 30 times as much.

As mentioned above, the light sources may have controllable direction. The beam direction, for all light sources which generate narrow light beams (associated with clear sky image regions), are for example oriented in the same direction. This direction matches the direction of the light from a virtual sun at a certain azimuth and elevation.

Figure 4 shows the lighting effect of the sun at the zenith position, and shows light sources 16 associated with clear sky providing a downward directional light output.

The top part of Figure 5 shows the angles associated with a sun which is not at the zenith position. The zenith is shown as Z, and the sun position shown has elevation E and azimuth A.

The bottom part of Figure 5 shows that the light sources 16 which provide a directional light output are steered to direct light in a direction based on the sun position shown in the top part.

When clouds move out of the way of direct sun beams, sharp shadows suddenly appear. It is known that for many people this effect is able to evoke a feeling of joy. To recreate this, the general lighting may also be able to switch between very diffuse (to mimic the light conditions of daylight for an overcast sky) and highly directional light beams that will create sharp shadows which are associated with sunlight.

This can be implemented for the whole room and is thus not necessarily localized. A possible additional feature is that the sharp beams are created using warm white whereas the diffuse light is cold white, replicating the difference between sunlight and daylight.

The relationship between the image and the provided lighting may be defined rigidly or loosely. Generally, totally clear blue sky will result in directional light output whereas a totally overcast sky will result in cold diffuse light. A dynamic behavior may be provided, for example a fast switching to directional light which very slowly shifts back to diffuse light, even if the image itself has a faster transition back to diffuse light. Thus, dynamic effects may be used which override the direct connection between the mage and the lighting effect. The fast transition to directional light may be used to make people feel good.

Still referring to figure 5, the array of light sources (16) is in plane with the surface onto which the multi-region image is generated.

Figure 6 shows an indoor lighting method. In step 60, information relating to a multi-region image is received. This information may be available because there is a separate image generation system which is part of the overall system, or it may be obtained based on image sensing of an already existing image.

In step 62, each image region is associated with a respective light source of an array of light sources.

Each light source is controlled in step 64 in dependence on the information relating to the associated image region, thereby to provide a selected one of a group of lighting effects, the different lighting effects in the group differing by one or more of the directionality, brightness and color temperature. Each light source may comprise one or more lighting elements.

The examples above are based on an image which represents the sky, and thus has blue and white portions representing clear and cloudy sky conditions. Other color variations may be used both for the generation of the image and for the lighting effect. For example, the image can also relate to an underwater scene, for example the sky as seen from under water. In such a case, a clear sky may correspond to a greenish color. A (virtual) boat (for example a black color) may then block the sun and thus has the same effect as a white cloud in the daylight version. The image may be a sky image on a different (e.g. imagined) planet: for example a clear sky has a pinkish color and clouds are green. The image may thus represent any real or imaginary outdoor scene. Other examples include a rainforest image or a rain forest tree canopy. A bird flying overhead may produce a similar effect to a cloud, namely a region of diffuse light passing overhead.

The invention is of interest generally for indoor spaces in which natural or other outdoor conditions are to be replicated inside, for example in shopping malls, hospitals, offices, lobbies etc.

The invention relates to the creation of a lighting effect based on the content of an image. The image is also displayed in the systems described above. However, the light sources may be controlled based on a captured image, stream or video of sky conditions without the sky image itself being rendered inside the room. Thus, the lighting effect of the outdoor scene is replicated, but not the image of that scene. The image may still be visible however, for example through a window. In this case, the image is still enhanced and complemented, and the natural lighting effect of the scene seen through the window is for example enlarged to cover the full indoor space. The system may be enhanced with additional functionality. For example, the system controller may perform image analysis and thereby detect lighting aspects of the multi-region image which can be improved using the array of light sources. This image analysis may be more involved than the detection of color as in the examples above, but may be based on detection of objects or scenes or other lighting parameters, such as contrast, edge detection etc. In this way, the controller may receive an image, analyze the image and control the array of light sources to create a desired overall lighting effect which is associated with the image content.

The light sources are intended to provide illumination within the indoor space, and for example cover a ceiling area. There should be sufficient light sources to create an image effect over the area. The array of light sources for example extends over an area of at least 5m ² , for example at least 10m ² for example at least 20m ² . There may be at least 10 light sources, for example at least 100 light sources, for example at least 200 light sources.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.