Patent Publication Number: US-11665307-B2

Title: Background display system

Description:
This application claims priority to German Patent Application 10 2020 119 601.6, filed on Jul. 24, 2020, the disclosure of which is incorporated by reference herein. 
     The invention relates to a background display system for a virtual image recording studio having a background display device which is configured to display a representation of a virtual background behind or above a real physical subject for a recording by means of an associated camera. 
     For example, such a background display system having a background display device can be provided to produce in an image recording studio a virtual background or a virtual environment, before which or in which, a scene to be recorded by means of a camera takes place or a recording can take place. The image recording studio can involve a film studio for recording moving images or a photo studio for recording individual images or still pictures. For this purpose, in particular a three-dimensional background, for example, a landscape or a space, can be displayed on an essentially two-dimensional plane, and an actor can move or position himself or herself as a physically real subject in front of such a background display device such that in the image recording studio almost any number of spaces or landscapes can be re-enacted. Therefore, adding such a background later or separately as in a recording before a Green-Screen, is no longer necessary. 
     The recording of moving image scenes with such a background display device can furthermore facilitate actors to react to events or movements taking place in the background of the subsequent film, since such animation can be represented by means of the background display device and can be directly noticed by the actors. Unlike, for example, with a Green-Screen where the environment is not visible for the actor, the actor can thus experience the background proceedings and adapt to the drama. 
     Such a background display device thus offers the possibility of representing a virtual background for a scene to be recorded which is animated and easily adaptable and therefore facilitates, in particular, with the acting or the gestures. However, a problem arises in the interaction with the associated camera in that the adjustments performed to the camera are based on the mostly occurring representation of a three-dimensional virtual background in two dimensions, which affects differently the image produced by the camera as would be expected by a recording of an actual three-dimensional scene in a three-dimensional environment. In particular, depth-dependent characteristics of the lens connected with the camera can thereby get lost in the image of the representation of the virtual background such that, the image of the representation of the virtual background can deviate from an image of a real background corresponding to the virtual background. 
     Through the choice of qualified and desired depth-dependent effects of the camera lens, especially in view of a bokeh to be generated in the image of the virtual background generated by the camera, can therefore not be realised. The bokeh depicts in particular, the quality of the blurred regions in the image produced by the camera, which is produced by the projection of the incoming light rays onto an image plane and, for example, onto an image sensor disposed there by means of the lens used. For example, the shape of the blurred region as a circle or disc can be determined by the bokeh, whereby these shapes or their sizes can depend, on the one hand, on the distance from the recorded object to the camera, and on the other hand, on the characteristics of the lens used. Since the blurred regions can co-determine the impression of the image produced by the camera, a lens used for a recording can often be chosen just by consideration of the bokeh produced by this lens, whereby the desired bokeh for a recording of the representation of the virtual background often cannot be attained. 
     It is therefore the object of the invention to achieve a background display system which makes it possible to achieve camera effects and/or lens-specific effects in an image of a representation of a virtual background produced by means of an associated camera, and in particular, such effects which would be created by an image of a real background corresponding to the virtual background. 
     This object is achieved by a background display system including the features of claim  1 . 
     The background display system comprises a control device which is configured to control the background display device, wherein the control device comprises a data input for receiving lens data from the associated camera, and wherein the control device is configured to adjust the representation of the virtual background dependence of the received lens data. 
     Since the control device comprises a data input for receiving lens data of the associated camera, camera or lens-specific parameters or settings of the camera for a representation of the virtual background can be considered, so that by adjusting the representation of the virtual background, the optical image of this representation produced or producible by means of the camera can be influenced. The camera, which is intended for recording a scene or an image, can for this purpose be connected to or be connectable with the data input of the control device, and the control device can be configured to receive the lens data wirelessly and/or by a cable from the camera. Accordingly, the camera can also be designed for wireless and/or wired transmission of the lens data. 
     To represent the virtual background, the background display device can constitute, for example, an electronic display with an active pixel matrix and, in particular, can comprise an active illumination apparatus having a plurality of light sources, in particular an LED wall with a plurality of light-emitting diodes or an OLED wall with a plurality of light-emitting diodes which can be controlled individually and/or in groups of adjacent lighting means or arrays of lighting means. As a result, a virtual background, which, in particular, can display a three-dimensional scene, can be represented pictorially by appropriate control of the lighting means on the background display device. Furthermore, the background display device can be configured to generate the representation of the virtual background by means of a rear projection, for which purpose the background display device can comprise, in particular, a partially transparent screen and a projector, in particular, a DLP (digital light processing) projector. 
     The virtual background can be displayed by the background display device, in particular, as a mathematical projection onto an essentially and/or at least partially two-dimensional surface, wherein the background display device can be designed at least partially flat or planar and/or at least partially arched or curved. For example, the background display device or a part of the same intended for displaying the representation of the virtual background, as a background in front of a real subject to be recorded can extend vertically upwards and in an upper section thereof the subject to be recorded is projected arched, in order to be able to present the most complete background possible. 
     In that, the control device is configured to adjust the representation of the virtual background dependent on the received lens data, in particular based on the respective settings of lens parameters or other values that characterize the camera lens used, the effects arising in a theoretical image of a real background, in particular three-dimensional, corresponding to a virtual background can be reproduced in the actual generated image of the representation of the virtual background. For this purpose, the lens data can comprise in particular the lens setting values. Such lens setting values can represent values of variable parameters that can be set for the camera lens. For example, a diaphragm aperture, a focal length and/or a focus value can influence the images generated by means of the camera, so that values of these parameters can be transmitted to the control device as lens data and can be considered when adjusting the representation. Furthermore, the lens data can comprise information on the lens used, which can be designed, in particular, as an interchangeable lens. Also, such information about the lens used, for example, a lens type and/or a serial number, can in addition be used to adjust the representation, in order to be able to reproduce, for example, lens-specific effects, in particular shapes of blurred regions, in the optical image of the representation of the virtual background generated by the camera. In this respect, the lens data can also be referred to as camera lens data. 
     The control device can be designed, for example, as a microprocessor, a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), which is configured to process the received lens data and to generate appropriate commands for adjusting the representation of the virtual background. The control device can have an integrated memory or be connected to a memory, for example, in order to be able to store and access image information and position information of the virtual background. 
     Furthermore, it can be provided for, that the control device comprises a game-engine or is configured to use a game-engine in order to generate the representation of the virtual background. A game-engine can be realised basically as a software in order to generate a representation of an environment, in particular in a computer game taking into account a position, in particular a position of a player. In doing so, the game-engine can access one or more data bases in order to generate the respective environment. Correspondingly, such a game-engine can be used to generate the representation of the virtual background taking into consideration the position of the real subject, in particular an actor, and/or the camera. The representation generated by the game-engine can then be adjusted dependent on the received lens data in order that the optical image generated by the camera approximates a theoretical image of a real background corresponding to the virtual background. Such a game-engine can run, for example, on a microprocessor (in particular, also a multi-core) or a graphics card. 
     For example, the control device can be configured to select from a databank, depending on the received lens data and in particular received information about the lens used or a lens type, a digital filter assigned to the lens and to apply this filter in order to adjust the representation of the virtual background. Furthermore, received lens setting values, for example a focal length or a focusing distance, can be used as parameters in such a digital filter, in order to take into account the setting of the respective lens in the representation of the virtual background. The use of digital filters for adjusting the representation of the virtual background can, for example, also occur by means of a game-engine so long as this is intended for generating the representation of the virtual background. However, it is also possible that such an intended game-engine is provided for only generating the representation without taking into consideration the lens data, while the representation is adjusted by further software modules that do not form part of the game-engine. In addition, the representation can also be generated in other ways, for example by means of models stored in a databank and/or a memory, without the control device comprising of a game-engine. 
     Settings for the parameters of a lens of the associated camera or for the camera can, for example, influence the sharpness of a point or object in an optical image generated by means of the camera. The sharpness with which a respective point or object appears in the image can depend on the distance of the object in question from the camera or its lens, so that objects in a real background corresponding to the virtual background arranged spaced to each other or with different spacing to the camera, would be represented in a theoretical image of this real background with varying sharpness. However, since these objects can be represented by means of the background display device in a plane or at least with a distance to the camera different from the distance of the object in the real background, the objects in the optical image of the representation of the virtual background generated by the camera are imaged mostly having a substantially equal sharpness determined by the distance of the background display device to the camera. The receiving of lens data in particular of lens setting values, allows, for example, the adjusting of the sharpness of the objects already in the representation of the virtual background so as to be able to reach in the optical image of the representation of the virtual background ultimately the same or similar blur as in an image of the real background. By adjusting the representation for all regions of the background display device, in particular a distribution of sharpness comparable with the theoretical image and a comparable bokeh can also be generated. 
     The adjustment of the representation can thus effectively serve to influence and in particular intensify the effects on the optical image of the representation of the virtual background impacted by the associated camera dependent on the lens data and in particular lens adjustment values. Due to the deviation of the geometric conditions of the representation of the virtual background from the conditions in a real background corresponding to the virtual background, the absence of effects or the dampening of such effects can therefore be compensated for. In particular, the deliberate blurred representation of an object or point in the representation of the virtual background can lead to a sharpness or blur of this object or point, caused by the setting of the lens, in the optical image generated by the camera being intensified in such a way that the blur corresponds to or approximates a blur in a theoretical image of a real background corresponding to the virtual background. 
     In order to adjust the representation of the virtual background, it is not necessary that a complete representation of the virtual background has been generated by the background display device before the receiving of lens data or before adjusting the representation. Rather, the adjusting of the representation dependent on the received lens data can, for example, also take place at the beginning of a scene or before a recording when generating the representation, wherein the lens data can be received and the representation in dependence thereof can be generated. Thus, the adjusting of the representation can in principle also take place, or be understood as such, as an integral process during the generation of the representation by means of the background display device. To generate and adjust the representation, the control device can, for example, draw on a model, in particular a three-dimensional model, which can be stored and made available in a non-volatile memory, for example a semiconductor memory. In particular, the control device can draw on a respective model in dependence of the received information about the lens used. Alternatively, or in addition, the control device can draw on a game-engine to generate the representation. 
     Lens data can be transmitted to the control device or received from the control device in real time, for example while a film scene is being recorded, so that the representation can be adjusted, for example, in real time to the changing settings of the lens or camera. For example, the representation of the virtual background can be continuously adjusted while focusing on a real subject, for example an actor&#39;s face, located in front of the background display device, in order to be able to obtain a bokeh in the optical image of the representation of the virtual background generated by the camera which is as close as possible to that expected by a recording of a real background corresponding to the virtual background. 
     Furthermore, it can also be provided for, that positions and/or orientations, for example inclinations or angles, of the lens or of the camera are transmitted to the control device and the control device adjusts the representation of the virtual background dependent on such position data. Movements of the camera can also affect differently the generated image of the representation of the virtual background and a theoretical image when recording a real background corresponding to the virtual background, wherein the control device can, for example, be configured to shift objects of the virtual background depending on the received position data in order to bring their positions in the generated image closer to the expected positions in the theoretical image. 
     As already explained, the background display device can, in particular, be intended to provide a virtual background for a recording of a film scene that is filmed or is to be filmed in the virtual image recording studio. However, it is also possible by means of the background display device to generate a virtual background for a photo shoot, for example in fashion photography, wherein the representation of the virtual background for the photo or still image to be recorded can be adjusted depending on the received lens data. This can make it possible to achieve a realistic bokeh in the optical image of the representation of the virtual background generated by the camera, which is especially aimed at in photography and is conditioned by the choice of lens. 
     Further embodiments of the invention can be taken from the dependent claims, the description and the drawings. 
     In some embodiments, the background display device can comprise a planar active illumination apparatus. In particular, the background display device can comprise an active two-dimensional illumination apparatus, in particular an active pixel matrix. The illumination apparatus can comprise a plurality of lighting means which can be controlled individually and/or in respective groups by the control device in order to be able to generate an image or a representation and to be able to display a virtual background for a recording scene. The lighting means is adjustable in particular with regard to the colour and/or brightness of the light produced, so that by controlling the lighting means, the representation of the virtual background can be actively generated or adapted. As well, the entirety of the lighting means can show a displayed representation of, in particular, the three-dimensional virtual background on, in particular, the two-dimensional surface of the active illumination apparatus. Movements in the virtual background can also be reproduced by adjusting the representation or by a corresponding controlling of the illumination apparatus. As an alternative to an active illumination apparatus with a plurality of lighting means, it can also be provided for, that the background display device is configured to generate the representation of the virtual background by means of a rear projection. 
     In some embodiments, the background display device can be configured to illuminate the real subject. In particular, in addition to generating the representation of the virtual background, the background display device can thus be configured to illuminate the real subject, for example an actor, and operate in addition to other lighting of the virtual image recording studio. In particular, the background display device can extend behind or above the real subject, so that the background display device can be configured to illuminate the real subject from the side and/or from above. 
     Such an illumination of the real subject by means of the background display device makes it possible, for example, to create and record true to detail, effects generated by light sources in a real background corresponding to the virtual background, in particular, when interacting with the real subject. For example, light sources present in the virtual background, such as streetlights or headlights of a passing car in a street scene to be recorded, can directly illuminate an actor, so that the shadow cast by the actor corresponds to the shadow that the actor would cast when illuminated by a real streetlight or a real spotlight. 
     In some embodiments, the background display device can comprise an LED comprising a plurality of individually controllable light-emitting diodes (LED) in a two-dimensional arrangement. In particular, the background display device can be designed as an LED wall with a plurality of light-emitting diodes, wherein the light-emitting diodes can be controlled individually or in groups, in order to generate a representation of a virtual background in an area. By controlling these light-emitting diodes, the display can be adapted by means of the control device, in order to be able to change the virtual background and/or to be able to influence an optical image of the representation of the virtual background, that is generated or can be generated by the camera. Furthermore, the background display device can comprise an OLED wall having a plurality of organic light-emitting diodes (OLED) and/or be designed as an OLED wall. 
     It can be provided for in some embodiments, that the background display device extends in a vertical and/or horizontal orientation. In particular, the background display device can as well extend planar in a vertical and/or horizontal plane or in a curved manner. For example, the background display device can comprise an illumination apparatus, in particular an LED wall, which can extend vertically surrounding a real subject, in order to represent the virtual background in such a way that when the camera is pivoted, the virtual background is also recorded. It is also possible for the background display device to extend in a vertical plane, in order to represent the virtual background in this plane and in particular behind the real subject. Furthermore, the illumination apparatus or the LED wall can, for example, extend in a horizontal plane above the real subject, in order to form or complete the virtual background and/or the illumination of the subject, in this plane or above the subject. In this case, an arched or curved transition can be provided between a vertical and a horizontal section of the background display device. Furthermore, it can be provided for, that the background display device extends, at least in sections, inclined upwards above the real subject. 
     In some embodiments, the control device can be configured to adjust the representation of the virtual background in such a way that an optical image of the representation generated by the camera in accordance with the received lens data approximates a theoretical image that would be generated if a real background corresponding to the virtual background was imaged by means of the assigned camera. 
     In particular, by means of the background display device, a virtual background can be represented which displays a three-dimensional environment for the scene to be recorded. This can therefore deal with, for example, an imitation of a real existing landscape or a real existing space, or fictitious environments can be created. However, a real background that in reality is three-dimensional, and where applicable also in a fictitious reality, can mostly be displayed by the background display device in a projection, in particular in two dimensions, so that in reality, objects or regions of the virtual background that are distant from one another or could be objectionable, are represented on one plane or at least with a distance to each other that deviates from reality. Accordingly, all objects of the virtual background are also recorded by the camera at a distance from the camera that is essentially the same or at least does not correspond to the real distance to the camera. 
     The representation of the virtual background in reality would in particular be a three-dimensional background, by means of the background display device can thus lead to the fact that depth-dependent properties of the lens get lost in an optical image generated by means of the camera. For example, the sharpness of the different regions of the real background in a theoretical image, which the camera would produce when imaging the real background due to its three-dimensionality, depends on the distance between these regions and the camera and, in particular, can change dependent on the lens data or lens setting values, for example, a diaphragm aperture. In order to be able to achieve such effects in the optical image produced or producible by means of the camera, even when recording a scene before the representation of the virtual background, the representation can be adjusted, for example, so as to increase the region of blur in the optical image generated by the camera caused already by a blurred representation. In particular, such a blurring can be generated by combining a number of lighting means of an active illumination apparatus, in particular, a plurality of light emitting diodes to form an area with the same and/or similar colour and/or brightness. 
     For example, the control device can be configured to calculate a theoretical image, i.e. an image of a real background corresponding to a virtual background, in dependence of the received lens data, in order to be able to compare the optical image that can be generated by the camera with this lens data, with the theoretical image. For this purpose, the control device can, for example, draw on a model of the virtual background, which, in particular, can comprise position data for a plurality of (virtual) background regions, from which the distances between these background regions of the virtual background to the (real) background display device onto which the virtual background is displayed, and/or to the camera can be derived. This position data can, in particular, also take into account a curvature of the (real) background display device in a space. The control device can also be configured to calculate the actual producible image of the representation of the virtual background dependent on the lens data in order to be able to compare this image with the theoretical image, for example, using image analysis methods, and to be able to adapt the representation of the virtual background so that the optical image can approximate the theoretical image. 
     Furthermore, it can be provided for, that the control device can access a memory (local or cloud) in which a number of models for generating the representation of the virtual background dependent on the received lens data are stored. These can be obtained beforehand, for example, by simulations or, in particular, when reproducing actual landscapes, experimentally taking pictures of the landscape with different lens setting values, which can be received as lens data by the control device. The control device can thereby be configured to use the respective corresponding model to generate the representation of the virtual background in dependence of the received lens data, in particular lens setting values, and to adjust the representation by changing the model used. 
     Furthermore, respective models for certain lens types and/or respective lenses can also be stored in the memory, so that after receiving information about the lens used or lens data comprising such information, the control device can use a respective assigned model to generate the representation. For example, the received lens data can comprise a lens type and/or a serial number or some other identification of the lens. In particular, a form of blurred regions in an image of a real background corresponding to the virtual background, which can depend on the lens used, can thereby be reproduced in the optical image of the representation of the virtual background actually generated by the camera. In addition to such information about the lens used, the lens data can also comprise respective lens setting values, so that a representation related to the respective lens and adapted to the settings of this lens can be generated. 
     In some embodiments, the lens data can represent parameters that are set in a lens of the associated camera. 
     The lens data can represent set values (lens setting values) of at least one of the following lens parameters of the associated camera: a diaphragm aperture, a focusing distance and/or a focal length of a lens of the associated camera. The diaphragm aperture can in particular relate to an opening width of an iris diaphragm of the lens. In particular, settings of these parameters, depending on the distance between an object and the camera, can affect the sharpness with which the object is imaged in the image generated by the camera, so that the representation of the virtual background, taking into account the values of one or more of these parameters, can be adjusted in order to obtain the most realistic bokeh possible. 
     In some embodiments, it can be provided for, that the control device is configured to receive position data from the associated camera at the data input and to adjust the representation of the virtual background depending on the received position data. For example, such position data can comprise distances or inclinations or angles of the camera or lens relative to the background display device. In order to be able to obtain such position data, the background display system can, for example, comprise a position determining device with auxiliary cameras, which can optically detect the position of the camera intended for recording the scene relative to the background display device and can transmit it to the control device. 
     Also, by taking into account such position data or orientations of the camera when adjusting the representation, an optical image of the representation of the virtual background generated by means of the camera can approximate a theoretical image that would result from a recording of a real background corresponding to the virtual background. For example, when the camera is pivoted, angles to objects displayed by means of the background display device can change differently than would be the case with objects in a real background in which the objects show different distances to the camera. The control device can, for example, be configured to determine such deviations in the representation of the virtual background and to move the objects on the background display device in such a way, that the objects in the optical image generated by means of the camera have an angle corresponding to the angle in the theoretical image or a distance to neighbouring objects are imaged. 
     In some embodiments, the lens data can comprise information about a lens used by the associated camera, wherein the control device can be configured to adjust the representation of the virtual background depending on the received information about the lens used. In particular, the lens can be designed as an interchangeable lens, so that a respective interchangeable lens optimally adapted to the recording to be carried out, can be connected to the camera. Depending on the lens used, lens-specific effects can arise that can have different effects on the optical image of the representation of the virtual background generated by the camera and on a theoretical image that would be generated by the camera when imaging a real background corresponding to the virtual background. In principle, however, cameras with respective permanently assigned lenses can also be provided, so that by transmitting the information, the lens assigned to the respective camera can be registered and can be taken into account when adjusting the representation of the virtual background. 
     Such information about the lens used can, in particular, comprise the lens type or model. The representation of the virtual background can be adjusted in such a way that optical effects caused by the lens type, which would arise in a theoretical imaging of the real background, are imitated in the optical image of the representation of the virtual background generated by the camera. In particular, optical aberrations, in particular distance-dependent optical aberrations, of the lens can be amplified or influenced by adjusting the representation of the virtual background in such a way that these optical aberrations are reflected in an optical image of the representation of the virtual background in the same or approximately the same way as in an image of a real background corresponding to the virtual background. In particular, the control device can access digital filters for this purpose, which correlate with the lens used in order to determine the necessary adjustment of the representation of the virtual background. For example, the control device can be configured to use such digital filters when calculating the theoretical and/or the actual generated image in order to be able to determine a necessary adjustment of the representation of the virtual background. 
     In some embodiments, the information can represent a lens type, an identification of the lens, a shape of an iris diaphragm of the lens (e.g., number of blades or lamellae), an arrangement of cylindrical elements of the lens (in particular, in the case of an anamorphic lens) and/or a coating of an optical element of the lens. In particular, an identification of the lens can comprise a serial number in order to enable an unambiguous determination of the lens used. It can be provided for, that, based on the serial number, the relevant data is read out from a stored databank (local or cloud). In principle, however, only properties of the lens such as the shape of an iris diaphragm or the arrangement of optical elements of the lens can be used to adjust the representation of the virtual background, without directly considering the lens type. 
     In some embodiments, the control device can be configured to adjust the representation of the virtual background in such a way that distance-dependent imaging effects that would arise in a theoretical image, generated by means of the associated camera in accordance with the received lens data, of a real background corresponding to the virtual background are reproduced in the optical image of the representation of the virtual background generated by the camera. 
     In particular, the sharpness with which objects are imaged in the optical image that can be generated by means of the associated camera, can be distance-dependent and depend on the lens data or lens setting values, for example a diaphragm aperture. For example, in reality objects that are far away can be imaged blurred with a wide aperture, while closer objects can be imaged in focus. On the other hand, by reducing the diaphragm aperture, objects that are further away can also be increasingly displayed in focus. 
     Due to this dependency of the sharpness of an object in the optical image on a distance between the object and the camera, differences can occur in an optical image of the representation of the virtual background that can be generated by means of the camera compared to a theoretical image, which would arise in a recording or imaging of a real background. In order to recreate this distance-dependent imaging effect in the optical image that can be generated by the camera, a faraway point in the real background can be displayed blurred in the representation of the virtual background dependent on the received lens data, in order to display this point in the optical image of the representation of the virtual background generated by the camera with a blur corresponding to or approximating the blurring in a theoretical image of the real background. Likewise, for example, brightness values of individual points or regions of the representation of the virtual background can be adjusted dependent on the received lens data, in order to recreate a distance-dependent change in brightness in a theoretical image of the real background that can be generated by means of the camera, for example, by a change in a diaphragm aperture in the optical image of the representation of the virtual background generated by the camera. 
     In some embodiments, the virtual background can represent a three-dimensional scene and the control device can be configured to represent different regions of the three-dimensional scene with different sharpness depending on the received lens data. Since different regions of the three-dimensional scene can be represented with different degrees of sharpness, in particular, a blur gradient can be achieved in the optical image of the representation of the virtual background by means of the camera, which corresponds or approximates a blur gradient in a theoretical image of a real background corresponding to the virtual background. For this purpose, for example, a model of the virtual background can be represented or rendered in sections with different sharpness by means of the background display device. Different regions of the three-dimensional scene can, for example, be divided into different distance regions in relation to the camera or the background display device or into different sharpness regions, whereby the distance regions or sharpness regions for different lens data can be assigned different sharpness or blurriness, with which the virtual background is to be displayed in the representation by means of the background display device. In this way, for example, a distance-dependent blur gradient or a bokeh in the optical image generated by the camera can be approximated to a blur gradient in a theoretical image that would be generated by the camera when imaging the real background or the real three-dimensional scene. 
     In some embodiments, as already mentioned, the control device can be connected to a memory in which the virtual background is stored as a model, wherein the control device can be configured to generate the representation of the virtual background based on the stored model. For example, a model of the background can be stored in the memory, in particular, a semiconductor memory, according to which all objects of the virtual background are sharply represented by the background display device, and the control device can be configured to adapt this model dependent the received lens data, in order to take into account, for example, a changing aperture, and to be able to represent objects more blurred when the diaphragm is opened. Furthermore, the memory can provide, for example, various models of the virtual background, which can be assigned to the respective lens data, for example, a respective lens type or respective lens setting values of the lens, so that the control device can access a respective model dependent on the received lens data and can represent the model by means of the background display device. For example, respective models can be stored for different diaphragm apertures, focal lengths and/or focusing distances or combinations of these parameters. 
     In general, said memory does not have to be arranged locally on the control device. It can also be a storage device accessible via a data network (wired or wireless) (e.g., databank in cloud storage). 
     The stored model of the virtual background can comprise respective image information and respective position information for a plurality of background regions. The image information can comprise, for example, colour and/or brightness information of a respective background region, while the position information can comprise, for example, distances between the background regions and the background display device and/or three-dimensional coordinates of the respective background region, in particular, with respect to one defined origin in the image recording studio or to the background display device. A background region can be formed or displayed, for example, by a single lighting device of an illumination apparatus of the background display device or by a light-emitting diode of an LED wall, while it is also possible for several of such lighting devices to be combined in a common background area. The control device can be configured to adjust or set each of the plurality of background regions individually dependent on the received lens data. 
     In some embodiments, the position information can comprise distances of the background regions from the background display device, wherein the control device can be configured to read out the stored distances and to take them into account when adjusting the representation of the virtual background. The distances can indicate the distance at which a respective region of a real background corresponding to the virtual background would be from the background display device. For example, objects arranged in the virtual background can be assigned to respective background regions. 
     For example, the control device can be configured to determine, at least approximately, distances from the background regions to the camera, from the distances from the background regions to the background display device included in the position information, or to assign to the background regions respective distances to the camera. If a setting is now made to the lens of the camera and a corresponding lens setting value, for example, a diaphragm aperture, is transmitted to the control device, the control device can be configured to determine, based on the distance between the background region and the camera and the received lens data, how the setting of the lens is reflected in a theoretical image of a real background corresponding to the virtual background, in which the background region exhibits the previously determined distance to the camera. Furthermore, the control device can be configured to determine what effect the setting of the lens has on the actual image of the representation of the virtual background generated by the camera, in which the distance from the background regions to the camera corresponds to the distance from the camera to the section of the background display device in which the background region is represented. By comparing the effects in the theoretical image of the real background and in the actual image of the representation of the virtual background generated by the camera, the necessary adjustments to the representation can then be performed in such a way that the background region in the optical image of the representation of the virtual background is imaged by means of the camera in the same or similar way as in the theoretical image when imaging the real background. 
     Furthermore, in some embodiments, the control device can be configured to generate the representation of the virtual background based on the image information stored for the plurality of background regions and to adjust the representation dependent on the position information stored for the plurality of background regions and on the received lens data. The image information can determine a basic model or the representation of the virtual background which, for example, assigns a colour and/or a brightness for each of a plurality of light sources, in particular, light-emitting diodes, an illumination apparatus or an LED wall of the background display device or arrays of such light sources. In particular, the image information can be provided for to generate a completely sharp representation of the virtual background which can be adjusted dependent on the received lens data. It can be provided for that the control device is configured to use a game-engine to generate the representation. 
     In order to be able to reproduce in particular distance-dependent imaging effects that depend on the received lens data by adjusting the representation in an optical image generated by the camera, the stored position information assigned to the plurality of background regions can be used. For example, based on the position information, distances between the background regions and the camera can be determined or assigned in order to determine how and in particular with what sharpness or blurring the background regions would be imaged in a theoretical image of a real background. This makes it possible to represent certain background regions depending on their position and the received lens data, for example, as already blurred by means of the background display device, so that in the optical image of the representation of the virtual background a blurring can be achieved that corresponds to the blurring in a theoretical image of the real background. 
     It can be provided for, that setting instructions for the background display device dependent on the received lens data are stored in the memory, wherein the control device can be configured to control the background display device based on the setting instructions for adjusting the representation of the virtual background. For example, different models can be stored in the memory, based on which the representation of the virtual background can be generated. The models can, for example, be assigned to respective lens data in a look-up table so that the control device can determine the model suitable for the received lens data from the look-up table and can use it to adjust the representation of the virtual background. In particular, setting instructions for each lighting means or for respective groups of lighting means of an illumination apparatus of the background display device, in particular, an LED wall, can be stored. 
     When assigning setting instructions to lens data which comprise at least one lens setting value, it can be provided for, that the control device is configured to interpolate between two setting instructions when the received lens setting value lies between two values, for which, setting instructions are stored in the memory. As an alternative to this, the control device can be configured to use approximately the setting instructions for an adjacent lens setting value. 
     In some embodiments, the control device can have a calculation device which is configured to determine for a plurality of background regions, image parameters of a theoretical image that would be generated if a real background corresponding to the virtual background was imaged by means of the associated camera according to the received lens data, and image parameters of an optical image of the representation of the virtual background that can be generated by means of the associated camera in accordance with the received lens data, wherein the control device can be configured to adjust the representation of the virtual background on the background display device in such a way that the image parameters of the optical image approximate the image parameters of the theoretical image. In particular, the calculation device can be configured to calculate the imaging parameters for the plurality of background regions, which can be stored in the aforementioned memory for the model of the virtual background. The calculation device can be provided, for example, as a microprocessor and/or a CPU and/or a GPU or a part thereof, which is configured to carry out software-based calculation steps or queries. In principle, the control device and the calculation device can be combined in a common unit, while it is also possible that the calculation device is designed as a separate component which is connected to the control device. 
     For example, the calculation device can access position information that is assigned to the respective background regions and based on this position information, can calculate an imaging parameter of the theoretical image for the respective background region dependent on the received lens data. Such an imaging parameter can, for example, be a measure of blurring, for example, a diameter of circles of confusion that arise in the image, or a measure of a brightness with which a respective background region is imaged in the image. Such imaging parameters can, in particular, depend both on the lens data or the lens setting values representing the settings of the lens, for example, a focal length, a focusing distance and/or a diaphragm aperture of the lens of the associated camera, and on the distance from the background regions to the camera, so that the imaging parameters in the theoretical image of the real background and the imaging parameters in the actually generated image of the representation of the virtual background displayed by the background display device, can be distinguished from one another. The calculation device can accordingly be configured to calculate the respective imaging parameters for the imaging of the representation of the virtual background, in particular, taking into account the distance from the background display device to the associated camera. 
     The calculation device and/or the control device can be configured to compare with one another the imaging parameters calculated for the theoretical image and for the optical image actually generated by the camera. Based on such a comparison, the control device can be configured to adjust the representation of the virtual background or the background region on the background display device in such a way that the imaging parameters approximate one another. Thereby, for example, a relationship between the calculated diameters of circles of confusion can be formed for which a respective point is imaged in a background region in the optical image of the representation of the virtual background that can be generated by means of the camera and in the theoretical image of the real background, and a number of light sources of the background display device, reflected by this relationship, can be controlled with the same settings, in order to be able to reproduce in the optical image of the representation of the virtual background circles of confusion expected in the theoretical image. Furthermore, the calculation device can be configured to computationally adapt possible setting instructions for the background display device and to determine the expected imaging parameter in the optical image of the representation of the virtual background that can be generated by the camera, in order to generate a setting instruction in which the imaging parameter approximates as much as possible the imaging parameter of the theoretical image. The setting instructions can relate to, in particular, colour and/or brightness settings of the lighting means of the background display device. 
     Furthermore, the calculation device can be configured to determine a theoretical image that would result from imaging a real background corresponding to the virtual background by means of the camera, and an optical image of the representation of the virtual background by means of the camera in dependence of the lens data, wherein the calculation device and/or the control device can be configured to determine setting instructions for the background display device by comparing the two images. For example, the calculation device can be configured to calculate or simulate the theoretical image and the optical image of the representation of the virtual background for different lens data, in particular different lens setting values, and to adapt the setting instructions for the background display device computationally until the calculated or simulated image of the representation of the virtual background is as close as possible to the theoretical image. For this purpose, for example, the calculation device can use or carry out image analysis methods. The settings determined in this way can then be transmitted to or received by the control device as setting instructions in order to control the background display device. 
     In some embodiments, the calculation device can be configured to calculate the imaging parameters of the optical image and/or the imaging parameters of the theoretical image in dependence of the received lens data. Alternatively, or additionally, the calculation device can be configured to look up in a database, the imaging parameters of the optical image and/or the imaging parameters of the theoretical image in dependence of the received lens data. In particular, for the theoretical image, that would arise from an imaging of a real background corresponding to the virtual background by means of the camera, imaging parameters dependent on the lens data, in particular lens setting values, can be stored in a data base. In addition, imaging parameters for the optical image of the representation of the virtual background that can be generated by the camera in dependence of the received lens data, can be stored in the data base, in particular for different settings of the background display device and for different background regions. As a result, a setting of the background display device can be directly determined for each background region, by which the imaging parameters are as close as possible to one another, and the representation can be adjusted accordingly by the control device. As an alternative to this, the calculation device can be configured to calculate the imaging parameters in dependence of the received lens data, in particular, taking into account the respective position information of the background regions. 
     In some embodiments, the calculation device can be configured to determine setting instructions for the background display device based on the determined imaging parameters of the optical image and the determined imaging parameters of the theoretical image, wherein the control device can be configured to execute the setting instructions for adjusting the representation of the virtual background. In particular, the calculation device can be configured to determine the setting instructions by comparing the imaging parameter of the optical image with the imaging parameter of the theoretical image. For example, the calculation device can calculate as an imaging parameter for a respective background region, a brightness with which the background region is imaged dependent on a diaphragm aperture, which can be transmitted as a lens setting value or with the lens data, and can output a setting instruction so that the background region in question is displayed in the optical image of the representation of the virtual background that can be generated by the camera, with a brightness that corresponds to the brightness of the background region in the theoretical image of a real background corresponding to the virtual background. If, for example, a background region experiences a stronger darkening in the theoretical image than the corresponding background region in the optical image of the representation of the virtual background due to a closing of a diaphragm aperture, this background region can be shown darkened on the background display device in such a way that ultimately results in the same darkening in the optical image of the representation of the virtual background as in the theoretical image. 
     In some embodiments, the calculation device can be configured to determine a measure for a blurring of the background regions in the optical image and in the theoretical image. For example, for this purpose, a diameter of circles of confusion can be determined as a measure of blurring and can be used as an imaging parameter to adjust the representation of the virtual background. 
     Thereby, the calculation device can be configured to determine the measure of the blurring of the background regions in dependence of values of a diaphragm aperture and/or a focal length and/or a focusing distance of the camera. For example, the calculation device can calculate a diameter of circles of confusion based on the diaphragm aperture and position information assigned to respective background regions and use it as an imaging parameter. 
     Furthermore, the calculation device can be configured to determine a depth of field in dependence on values of a diaphragm aperture and/or a focal length and/or a focusing distance. The depth of field indicates a range of distances to the camera in which objects arranged therein are imaged sharply by the camera. By calculating a depth of field, background regions in particular can be determined which in the theoretical image of a real background corresponding to the virtual background in accordance with received lens data, lie in the range of the depth of field and accordingly would be represented sharply in a theoretical image of the real background. For these background regions, the background display device can, in particular, be set in such a way that the background regions are represented with maximum sharpness. Background regions lying outside the depth of field for the received lens data in a real background corresponding to the virtual background can, on the contrary, be represented more blurred in the representation generated by the background display device in order to be able to generate a natural bokeh in the optical image of the representation generated by the camera. For example, the distance of a respective background region from the depth of field or from a front and/or rear hyperfocal plane can determine a blurring to be generated in the representation of the virtual background, so that the depth of field or this distance can form a measure of the blurring. 
     Furthermore, the calculation device can be configured to divide the background regions into respective sharpness regions, wherein the control device can be configured to control the background display device to represent the background regions with a sharpness assigned to a respective sharpness region. For example, the calculation device can be configured to divide the background regions into different sharpness regions depending on a distance from a calculated front and/or rear hyperfocal plane. In dependence of a respective sharpness region which is assigned to a background region, setting instructions for the background display device can thereupon be determined or generated in order to represent the background regions with a respective blurring. For example, a number of adjacent lighting means of the background display device can be assigned to the sharpness regions for this purpose, which are to be operated with the same settings, in particular the same colour and/or brightness, to produce a blurring. In particular, a respective circle of confusion approximating the theoretical image can be generated in the sharpness regions in the optical image of the representation of the virtual background, wherein such circle of confusion can, for example, be randomly distributed in the respective sharpness regions or formed around respective brightest points. For distributing the circles of confusion, for example, information about the lens used or digital filters that correlate with the lens can used. 
     In some embodiments, the calculation device can be configured to determine diameters of circles of confusion in the optical image and in the theoretical image for the background regions in dependence of a diaphragm aperture and/or a focal length and/or a focusing distance. Furthermore, the calculation device can be configured to generate setting instructions for the background display device in such a way that the diameters of the circles of confusion in the optical image approximate the diameters in the theoretical image. In addition, it can be provided for, that the representation is adjusted by the control device in such a way that circles of confusion that form in the theoretical representation of a real background corresponding to the virtual background also arise in the optical image of the representation of the virtual background in order to achieve the most natural possible bokeh of the optical image. For example, the background display device can be controlled for this purpose in such a way that respective brightest points in the virtual background are imaged as circles, which in the optical image have the diameter as expected in the theoretical image. 
     Furthermore, the calculation device can be configured to determine superpositions of circles of confusion in the optical image and in the theoretical image. For this purpose, the calculation device can, in particular, draw on a model of the virtual background stored in a memory and/or transmitted information about a lens connected to the camera, in particular an interchangeable lens, so that when adjusting the representation of the virtual background by means of the background display device, also such lens-specific and/or distance-dependent superimpositions of circles of confusion can be taken into account in order to be able to reproduce as accurately as possible the bokeh in the optical image of the representation of the virtual background. 
     In some embodiments, the calculation device can be configured to determine a measure of a brightness of the background regions in the optical image and in the theoretical image as an image parameter. 
     The calculation device can be configured to determine the measure for the brightness in dependence of a diaphragm aperture, wherein the calculation device can, in particular, be configured to determine a distance-dependent change in brightness in dependence of the diaphragm aperture. For example, the calculation device can determine from a certain distance a portion of emitted light, in particular optically isotropic, which impinges an image sensor of the camera, in dependence of the diaphragm aperture. This portion can be determined, for example, by an opening angle of a cone of rays which, starting out from an object in the representation of the virtual background or in the real background, then passes through the diaphragm aperture. This can make it possible to determine a relationship of the brightness of a background region in the theoretical image to the brightness of the background region in the optical image of the representation of the virtual background, and taking this relationship into consideration, to represent an adjusted background region by means of the background display device. 
     Alternatively, or additionally, in some embodiments it can be provided for, that the calculation device is configured to determine the imaging parameters in dependence of information about a lens connected to the camera. In particular, for this purpose, the camera can be connectable to an interchangeable lens so that it can be determined on the basis of the information, which lens or what type of lens is used in order to adjust accordingly the representation and, for example, to adapt the shapes of blurred regions in the optical image of the representation of the virtual background generated by the camera, to the shapes of those blurred regions in a theoretical image which the camera would generate when imaging a real background corresponding to the virtual background. In particular, dependent on information about the lens type and received lens setting values, the calculation device can look up respective imaging parameters in a databank in order to generate setting instructions for the background display device for adjusting the representation of the virtual background which can be implemented by the control device. 
     The information can include distance-dependent optical aberrations of the interchangeable lens. In particular, such aberrations can comprise shapes of circles of confusion, their diameter and/or diffraction effects. Furthermore, the information can basically comprise any property of the lens and, for example, a shape of an iris diaphragm, in particular, a number of blades or lamellae of the iris diaphragm, a number, an arrangement and/or properties of the cylindrical elements of anamorphic lenses and/or properties of any coatings of the elements of the camera lens, such as the lenses. 
     Furthermore, the calculation device can be configured to access a database with computational instructions for determining setting instructions for the background display device and to determine the setting instructions in dependence on the information based on the computational instructions. For example, digital filters that correlate with the lens type can be stored in such a database, wherein the calculation device can calculate, on the basis of such digital filters, the theoretical image and/or the optical image of the representation of the virtual background, in order to be able to determine or generate setting instructions for the background display device by comparing both of these images. In this case, lens parameter values or lens setting values transmitted as lens data can be applied in such a digital filter, so that, by means of the digital filter, both lens-specific effects, for example, a shape of a blurred region, and the setting of the respective lens can be taken into account. 
     The invention further relates to a recording system with a background display system as disclosed herein and having a camera that comprises a camera lens and that is configured to transmit lens data of the camera lens to the data input of the control device. In particular, the recording system can involve a moving image recording system, so that the camera can be designed as a moving image camera for recording a scene, in particular a film scene. Alternatively, it can also be provided for, that by means of a background display device as described above, a virtual background is represented which serves as a background for a photo recording, so that the camera can also be designed as a photo camera. 
     Since the camera is configured to transmit lens data of the camera lens to the data input of the control device, this lens data can be taken into account when controlling the background display device. In particular, this makes it possible to adjust the representation of the virtual background dependent on the received lens data in such a way, that the optical image generated by the camera approximates a theoretical image that the camera would generate if a real background corresponding to the virtual background were recorded. The representation can, in particular, be adapted in such a way, that a bokeh that appears as natural as possible can be achieved in the optical image of the representation of the virtual background generated by means of the camera. 
     The camera can comprise an image sensor in order to convert incident light into electrical signals and to be able to generate an image. Furthermore, the lens can comprise a lens and/or a lens system in order to be able to guide the light impinging onto the image sensor. The lens can comprise a diaphragm with a diaphragm aperture that can be opened or closed as required in order to be able to adjust the portion of light that reaches the image sensor and a depth of field. Furthermore, it can be provided for, that a focal length or focusing distance of the lens or the lens system is adjustable, for which purpose, for example, one or more lenses of the lens system can be displaced relative to one another. Such adjustments to parameters of the lens can take place, for example, by manually and/or electrically rotating one or more lens rings. 
     In some embodiments, the recording system can comprise a position determining device which is configured to determine a position of the camera relative to the background display device and to transmit corresponding position data to the data input of the control device. For example, for this purpose, the position determining device can comprise auxiliary cameras which optically detect the position of the camera provided for recording a scene relative to the background display device. 
     The position data can also be used to adjust the representation of the virtual background in such a way that the optical image generated by the camera is approximated to a theoretical image of a real background corresponding to the virtual background. In particular, when the camera moves during the recording of a scene or a film scene, objects in the representation of the virtual background can be shifted in such a way, that the position of the objects in the optical image of the representation of the virtual background corresponds to the position of these objects in the theoretical image of the real background. 
     The invention also relates to a method for controlling a background display device, which is configured to display, whether behind or above a real subject, a representation of a virtual background for a recording by means of an associated camera, having the following steps:
         receiving lens data from the associated camera; and   adjusting of the representation of the virtual background in dependence of the received lens data.       

     As already explained above in relation to the background display system and the recording system, such a control of a background display device enables, in particular, a representation of the virtual background generated by the background display device to be adjusted in such a way that an optical image of the representation of the virtual background generated or can be generated by the associated camera, is approximated to a theoretical image which the camera would generate when recording a real background corresponding to the virtual background. In particular, distance-dependent effects can be reproduced in the optical image of the representation of the virtual background. 
     In some embodiments, the method may further comprise the steps of:
         recording a real subject in front of the background display device by means of the associated camera;   acquiring lens data of a camera lens of the associated camera; and   transmission of the lens data to the background display device or to a control device assigned to the background display device.       

     In particular, the lens data can comprise lens setting values or parameter values of the lens. To acquire the lens setting values, the camera can comprise respective sensors, which can be designed, for example, to determine a rotational position of a lens ring for adjusting a diaphragm aperture, a focal length and/or a focusing distance. 
     In some embodiments, the background display device comprises a two-dimensionally extending active illumination apparatus. In turn, the active illumination apparatus enables the representation of the virtual background by way of a plurality of lighting means, in particular, light-emitting diodes or LEDs or to OLEDs, which can be controlled, individually or in respective groups. Furthermore, it is also possible to represent movements in the virtual background, for example, cars driving by during a film scene. 
     In some embodiments, the lens data can represent set values of at least one of the following lens parameters: a diaphragm aperture, a focusing distance and/or a focal length. In particular, these parameters can generate distance-dependent effects in an optical image that can be generated by means of the camera. By considering the lens data when adjusting the representation of the virtual background, these effects can be reproduced in an optical image of this representation by means of the camera in such a way that the effects are similar to those in a theoretical image of a real background corresponding to the virtual background. Furthermore, in some embodiments, the lens data can comprise information about the lens used, in particular, a lens type and/or an identification of the respective lens used, for example, a serial number. As a result, lens-specific effects can also be produced in the optical image of the representation of the virtual background. 
     In some embodiments, the virtual background can represent a three-dimensional scene and different regions of the three-dimensional scene can be represented with different sharpness dependent on the received lens data. In particular, distance values assigned to the respective regions from the background display device and/or the camera, can be taken into account when setting the sharpness in the representation of these regions. 
     It can be provided for, that the representation of the virtual background is adjusted in such a way, that an optical image of the representation of the virtual background that can be generated by means of the associated camera in accordance with the transmitted lens data is approximated to a theoretical image that would be generated if a real background corresponding to the virtual background was imaged by means of the associated camera. In particular, the representation can be adjusted in such a way that distance-dependent effects are reproduced in the optical image of the representation of the virtual background. 
     Distance-dependent effects which arise or can change, in particular, when also changing the lens setting values transmitted as lens data during a recording, do not get lost, for example, due to the display of the virtual background on the background display device which in particular can be configured to be planar and/or two-dimensional, but can be reproduced by adjusting the representation of the virtual background in the optical image generated by the camera. In particular, a bokeh can thereby be generated in the optical image which corresponds to and/or approximates the bokeh which arises in a theoretical image of a real background corresponding to the virtual background. 
     In some embodiments, the representation of the virtual background can be generated based on a model which is read out from a memory. In doing so, the stored model of the virtual background can comprise for a plurality of background regions, a respective image information and a respective position information. In principle, the image information can serve to generate the representation of the virtual background, while the position information can be used together with the received lens data to adjust the representation. 
     Furthermore, in some embodiments, it can be provided for, that diameters of circles of confusion in an optical image of the representation of the virtual background that can be generated by means of the camera, and diameters of circles of confusion in a theoretical image that would be generated if a real background corresponding to the virtual background was imaged by means of the camera, can be determined for a plurality of background regions in dependence of the lens data, wherein the representation of the virtual background can be adjusted in such a way, that the diameters of the circles of confusion in the optical image approximate the diameters of the circles of confusion in the theoretical image. In particular, the diameter of the circles of confusion can serve as a measure of blurring whereby, by generating circles of confusion with the diameter corresponding to the diameter of circles of confusion in the theoretical illustration, in particular, distance-dependent blurring effects can be produced in the optical image of the representation of the virtual background. 
     Furthermore, essentially all steps or a selection of steps can be included in the method, which steps are described above in reference to the control device or the calculation device of the background display system and/or the background display device. 
    
    
     
       The invention is described hereinafter purely by way of example with reference to the embodiments in reference to the drawings. 
         FIG.  1    shows a schematic diagram of a recording system for an image recording studio having a background display system and a camera, 
         FIGS.  2 A and  2 B  show a schematic diagram of a recording carried out by the camera in front of a virtual background generated by a background display device of the background display system, as well as a schematic diagram of a recording in front of a real background corresponding to the virtual background, 
         FIGS.  3 A and  3 B  show a schematic diagram of an optical image that can be generated by the camera when recording the virtual background, as well as a schematic diagram of a theoretical image which would result from a recording of the real background by means of the camera, 
         FIG.  4    shows a further schematic diagram of the recording system to illustrate the adjustment of the representation of the virtual background generated by the background display device in dependence of the received lens data, 
         FIG.  5    shows a schematic diagram of the recording system with an adjusted representation of the virtual background, 
         FIG.  6 A to  6 F  show respective schematic illustrations of a beam path through the camera when recording the virtual background or the real background for different lens setting values transmitted as lens data, 
         FIGS.  7 A and  7 B  show a respective schematic illustration for generating a circle of confusion of the theoretical image corresponding to the real background when recording the virtual background, and 
         FIG.  8 A to  8 F  show respective schematic illustrations for adjusting the representation of the virtual background generated by the background display device in dependence of the determined position data of the camera. 
     
    
    
       FIG.  1    schematically shows a virtual image recording studio  13 , in which a scene, in particular in the form of a moving image recording and/or a photo recording, can be recorded by means of an associated camera  23 . The camera  23  can, in particular, be designed as a moving image camera in order to carry out moving images recordings that can be stored as a series of images  39  generated by the camera  23 . For this purpose, the camera  23  has a lens  59 , which can in particular be designed as an interchangeable lens, which can optionally be connected to a housing of the camera  23 . As a result, a respective lens  59 , optimally adjusted to the environment in the image recording studio  13 , can always be used in order to be able to generate the best possible recordings. In particular, an image sensor  95  can be arranged in the housing of the camera  23  onto which light enters, via a diaphragm aperture B of a diaphragm  97  and guided by means of a lens system or at least one lens  89 , to generate an optical image  39  (see also  FIGS.  6 A to  6 F ). 
     Furthermore, a background display system  11  having a background display device  15  is arranged in the image recording studio  13 , which, together with the camera  23 , is part of a recording system  10 . The background display device  15  comprises an active illumination apparatus  31  configured as an LED wall  33  and is configured to display a representation  19  of a virtual background  21  fora recording by means of the camera  23 . For this purpose, the illumination apparatus  31  or the LED wall  33  comprises a plurality of individually controllable light-emitting diodes  35  which are arranged next to one another in a two-dimensional arrangement. Alternative to this, the active illumination apparatus  31  can comprise, for example, an OLED wall, or the background display device  15  can be configured to generate the representation  19  of the virtual background  21  by means of a rear projection. 
     The representation  19  of the virtual background  21  reflects here, for example, a three-dimensional scene  43  with objects  91 ,  92 ,  93  and  94 , three trees and a path, which can be generated by appropriate control of the light-emitting diodes  35 , in particular, by an appropriate setting of their respective colour and brightness. The three-dimensional scene  43  is projected onto the essentially two-dimensional arrangement of the light-emitting diodes  35  of the illumination apparatus  31 , wherein, in particular, the objects  91 ,  92  and  93  appear at a different distance to the illumination apparatus  31  or the background display device  11 , in order to recreate the three-dimensionality of a real background  20  corresponding to the virtual background  21  (cf. also  FIGS.  2 A and  2 B ). 
     In particular, the representation  19  of the virtual background  21  by way of the background display device  15 , serves to generate a background for a recording of a real subject  17 , for example an actor, in front of which a recording can be made or a film scene can be played. As a result, basically any kind of landscapes, spaces or environments can be created in the image recording studio  13 , in front of, or, in which, a scene, for example, for a movie, is to be filmed. It is also possible, by a time-variable control of the light-emitting diodes  35 , to show movements in the virtual background  21 , for example, a passing car, to which the actor  17  can react in an easy and improved manner compared to a scene in front of a Green-Screen. 
     The background display device  15  extends here essentially in the vertical direction, so that the actor  17  can move in front of the virtual background  21 . However, in order to be able to depict the virtual background  21  more extensively, the background display device  15  can also extend around or above the actor  17 , whereby the background display device  15  above the actor  17  can exhibit, in particular, a horizontal orientation. In order to surround the actor  17  or to be able to generate a transition from the shown vertical orientation to a horizontal orientation, the background display device  15  or the illumination apparatus  31  or the LED wall  33  can also be arched or curved, at least in sections. 
     In addition to representing the virtual background  21 , the background display device  15  can also serve to illuminate the real subject  17  and thereby facilitate, for example, as further studio lighting for the image recording studio  13 . Furthermore, by illuminating the real subject  17  by means of the background display device, the interaction of the real subject  17  or the actor  17  with the light sources present in the virtual background  21 , for example, lanterns or lamps, can be improved, in that, the real subject  17  casts a shadow which corresponds to the light conditions visible in the optical image  39  generated by the camera  23 . 
     While such a background display device  15  can thus offer diverse and convenient possibilities for recording scenes, in particular, moving image recordings in an image recording studio  13  having basically any virtual background  21 , due to the projection of the three-dimensional scene  43  onto the two-dimensional background display device  15 , can result, in particular, in differences between an optical image  39  of the representation  19  of the virtual background  21  generated by the camera  23  and a theoretical image  41 , which the camera  23  would generate by a recording of the real background  20  corresponding to the virtual background  21  (cf.  FIGS.  3 A and  3 B ). 
     As  FIGS.  2 A and  2 B  illustrate, the objects  92  and  93 , projected onto the illumination apparatus  31  in the representation  19  of the virtual background  21 , have respective distances  54  and  53  to the background display device  11  in the real background  20  corresponding to the virtual background  21 , such that the theoretical image  41  of the real background  20  shown in  FIG.  3 B  can differ from the optical image  39  of the virtual background  21  or its representation  19 , as can be seen from the comparison with  FIG.  3 A . In particular, objects  92  and  93  which are further away and also, a part of the object  94  are shown blurred in the theoretical image  41 , while the objects  91 ,  92 ,  93  and  94  are shown completely sharp in the optical image  39 . Settings of the lens  59  or changes in the settings can also affect differently the optical image  39  of the representation  19  of the virtual background  21  and the theoretical image  41  of the real background  20 . 
     For example, a diaphragm aperture B or the opening width of an iris diaphragm of the lens  59  can influence the depth of field  69  of the lens  59 , such that the objects  91 ,  92  and  93  dependent on their distance  53 ,  54  from the camera  23  and dependent on the diaphragm aperture B in the theoretical image  41  of the real background  20  corresponding to the virtual background  21 , can be imaged with varying sharpness  73  (cf.  FIG.  3 B ). If, on the other hand, the camera  23  is set to be focused on the background display device  11 , this distance-dependent imaging effect  37  of a varying sharpness  73  is not reproduced in the optical image  39  of the representation  19  of the virtual background  21 . Rather, all objects  91 ,  92  and  93  are imaged with the same and, here, for example, with full sharpness  73 , with a focus on the background display device  15 , also independent of the diaphragm aperture B (cf.  FIG.  3 A  and  FIGS.  6 A to  6 D ). 
     The sharpness or blur gradients in the theoretical image  41  accompanied with these distance-dependent imaging effects  37  can thus be lost in the optical image  39  which the camera  23  creates of the representation  19  of the virtual background  21 . Such a texture in the sharpness of a background can, however, determine the bokeh of the optical image  39 , whereby the generation of a pleasant and realistic bokeh can be a concern in such a recording and can also determine the choice of the lens  59  which is connected to the camera  23 . In addition, during the recording of a scene, changing the settings of the lens  59 , for example, by opening or closing the aperture  97 , can affect distance dependency and varying sharpness  73  of the objects  91 ,  92 ,  93  and  94  in the theoretical image  41 , whereby the changing bokeh corresponding to the theoretical image  41  of the real background  20  should also be generated as much as possible in the optical image  39  of the virtual background  21  generated by the camera  23 . 
     To address this problem, as shown in  FIG.  4   , the background display system  11  comprises a control device  25  which is connected to the background display device  15  and is configured to control the background display device  15 . Thereby, the control device  25  which can, for example, be designed as a microprocessor, comprises a data input  27  in order to receive lens data  29  transmitted by the camera  23 , and in addition, the control device  25  is configured to adjust the representation  19  of the virtual background  21  dependent on the received lens data  29  (cf. also  FIG.  5   ). 
     The lens data  29  can thereby comprise, in particular, lens setting values or values of parameters of the lens  59  on to which these parameters are set, and/or an information I about the lens  59  used. For example, the lens data  29  can pertain to a diaphragm aperture B, a focusing distance D and/or a focal length F of the lens  59  and represent values to which these parameters of the lens  59  are set or adjusted to. The information I can represent, for example, a lens type, an identification of the lens  59  used such as a serial number, a shape of an iris diaphragm  97  of the lens  59 , the number of blades of the diaphragm  97 , an arrangement or configuration of the cylindrical elements of an anamorphic lens  59  and/or any coatings of the optical elements of the lens  59 , for example, of individual lenses  89 . By taking into account such lens data  29 , the representation  19  of the virtual background  21  can, in particular, be adapted in such a way that the optical image  39  generated by the camera  23  approximates the theoretical image  41 . In particular, different regions of the three-dimensional scene  43  can therefore be represented with different sharpness  73 , in order to recreate in the optical image  39  a blurred gradient of the theoretical image  41 . 
     In order to adapt the representation  19  of the virtual background  21 , the control device  25  is connected to a calculation device  61  and, via the calculation device  61  connected to a memory  45 . As illustrated here, the calculation device  61  can be connected to the control device  25  as a separate unit, for example, as a microprocessor or a CPU. Alternatively, the calculation device  61  can also be integrated into the control device  25 . The control device  25  can also be directly connected to the memory  45 . 
     A model of the virtual background  11  is stored in the memory  45  and based on this, the control device  25  can generate the representation  19  of the virtual background  21  by means of the background display device  15 . The stored model comprises respective image information  49  and respective position information  51  for a plurality of background regions  47 . The position information  51  can comprise, for example, the distances  53  and  54  of the objects  93  and  92  from the background display device  15  (cf.  FIG.  2 B ). 
     In addition, the control device  25  can be configured to generate the representation  19  of the virtual background  21  based on the image information  49  for the background region  47 , and to adjust it taking into consideration the position information  51  and the received lens data  29 . To generate the representation  19 , the control device  25  can use, in particular, a game-engine. For example, the calculation device  61  can be configured to read out the position information  51 , which alternatively or in addition to the above-mentioned distances  53  and  54  can also comprise three-dimensional coordinates of the background regions  47  or of the objects  91 ,  92 ,  93  and  94 , and to generate setting instructions E for the control device  25  in dependence of the received lens data  29 , and which the control device  25  carries out to adjust the representation  19  of the virtual background  21 . For example, the calculation device  61  can organise the respective background regions  47  into respective sharpness regions  70 ,  71  and  72  in dependence of the received lens data  29 , for example, in dependence of the diaphragm aperture B, and by transmitting a setting instruction E cause the control device  25  to represent the background regions  47  with a sharpness  73  corresponding to the respective sharpness regions  70 ,  71  or  72  (cf.  FIG.  5   ). 
     For example, it can be provided for, that the object  93  in the real background  20  that is furthest away from the background display device  15  or the camera  23 , or the background region  47  in which this object  93  is located, is represented blurred by means of the background display device  15 , and also the object  92  spaced from the background display device  15 , cannot be represented completely in focus (cf.  FIG.  5   ). The degree of blurring can depend on the received lens data  29 . For example, the blurring of the objects  92  and  93  in the representation  19  can increase with a largely opened diaphragm  97  and the accompanied small depth of focus  69  and can be reduced with a widely closed diaphragm  97 . Through the blurring of objects  92  and  93 , as well as a part of the object  94 , which are already displayed in the representation  19  of the virtual background  21 , it can be made possible for the optical image  39  of the representation  19  of the virtual background  21  generated by the camera  23  to approximate the theoretical image  41  which the camera  23  would generate when imaging the real background  20  corresponding to the virtual background  21  (cf.  FIGS.  3 A and  3 B ). 
     In order to be able to adjust the background regions  47  by means of the background display device  15  in such a way that the optical image  39  approximates the theoretical image  41 , the memory  45  can have a database  65  in which, for example, assignment tables can be installed which can be directly read out by the calculation device  61  or the control device  25 , and which assigns a respective sharpness region  70 ,  71  or  72  or a corresponding sharpness  73  to the background regions  47  dependent on the received lens data  29 . Therefore, in such a database  65 , in particular, setting instructions E can be stored directly which are assigned to the respective background regions  47  dependent on the received lens data  29  and which the control device  25  can directly implement to adjust the representation  19  of the virtual background  21  or the individual background regions  47 . Furthermore, different models of the virtual background  21  which can be assigned to the respective lens data  29  and, in particular, combinations of lens setting values, can be stored in the database  65  or in the memory  45 , whereby the control device  25 , based on the respective model in dependence of the received lens data  29 , can be configured to generate the representation  19  of the virtual background  21  or to adjust it by a change in the underlying model. 
     As an alternative to reading out such a database  65  or the memory  45 , it can also be provided for, that the calculation device  61  is also configured to computationally determine the setting instructions E for the control device  25  for adjusting the representation  19  of the virtual background  21 . For this purpose, the calculation device  61  can, in particular, be configured to calculate imaging parameters  63  for the optical image  39  which the camera  23  generates from the representation  19  of the virtual background  21 , and imaging parameters  63  for the theoretical image  41 , which the camera  23  would generate when imaging the real background  20 , and to generate the setting instructions E for the control device  25  in such a way that the imaging parameters  63  of the optical image  39  approximate the imaging parameters  63  of the theoretical image  41 . 
       FIGS.  6 A to  6 F  show schematic beam paths through the lens  59  or the camera  23  at an upper point of the most distant object  93  for the representation  19  of the virtual background  21  and for the real background  20 . For illustration purposes, the lens  59  is simplified and is formed or represented with only one lens  89 , which guides incident light onto the image sensor  95 . In principle, however, also more complex lens systems with, for example, several interacting lenses  89  can be provided for. The calculation device  61  can be designed, in particular, to determine imaging parameters  63  on the basis of such considerations or simulations or calculations of such beam paths through the respective lens  59 , and to generate setting instructions E for adjusting the representation  19  of the virtual background  21 . For such simulations, the calculation device  61  can additionally draw on information I about the lens  59  transmitted from the camera  23  to the data input  27  of the control device  25  in order to carry out the simulations, for example, by means of digital filters that correlate with the respective lens type, and to be able to determine lens-specific effects (cf. also  FIG.  4   ). 
     In the example of  FIG.  6 A , a focusing distance D of the lens  59  or its focal length F is selected such that the background display device  15  and thus also the object  93  represented by way of the illumination apparatus  31  or the LED wall  33 , are located within the focus of the camera  23 . The lens  59  comprises the aforementioned diaphragm  97  with an adjustable diaphragm aperture B, through which rays  83 ,  85  and  87  emanating from the object  93  impinges the lens  89  which directs the rays  83 ,  85  and  87  onto the image sensor  95 . Due to the focusing of the camera  23  on the background display device  15 , each point represented on the illumination apparatus  31  and thus also the represented object  93  is sharply imaged as a point  99  on the image sensor  95 . The sharpness  73  of the objects  91 ,  92 ,  93  and  94  in the optical image  39  thus depends essentially on the resolution of the image sensor  95  and the number of light-emitting diodes  35  per unit area which generates the representation  19  of the virtual background  21 . 
     On the other hand, as  FIG.  6 B  shows, the object  93  for the real background  20  corresponding to the virtual background  21  is not within the focus of the camera  23  but has the aforementioned distance  53  to the background display device  15  and therefore to the focus of the Camera  23 . As a result, the rays  83 ,  85  and  87  do not hit the image sensor  95  exactly, but already meet in front of it such that a point of the object  93 , when imaging the real background  20  by means of the camera  23 , is represented as a circle of confusion  75  with a diameter  77  in the theoretical image  41 . 
     For example, the calculation device  61  can be configured to determine for points or background regions  47  represented by one or more light-emitting diodes  35  such circles of confusion  75  for the virtual background  21  as well as the real background  20  corresponding to the virtual background  21 , and to use these as an imaging parameter  63  or as a measure  67  for a blurring. For example, when focusing on the background display device  15 , as in  FIGS.  6 A and  6 B , a plurality of light-emitting diodes  35 , shown as a point  99  or as a circle with a minimum diameter, can be set with the same brightness and colour, to recreate the circle of confusion  75  in the optical image  39  occurring in the theoretical image  41  of the real background  20 . This is illustrated schematically in  FIGS.  7 A and  7 B . For example, a relation between the diameter  77  of the circle of confusion  75  in the theoretical image  41  and the diameter of the point  99  or the circle with minimum diameter in the optical image  39  can be determined, in order to determine the number of light-emitting diodes  35  set identically to recreate the circle of confusion  75  in the optical image  39 . In order to reproduce points, for example the brightest, in the background regions  47  as clear circles of confusion  75 , and to be able to achieve for other regions a realistic blurring gradient, the calculation device  61  can, for example, draw on models of the virtual background  21  stored in the memory  45  or on the information I relating to the lens  59 . 
     As an alternative to such a determining of the diameters  77  of the circles of confusion  75 , the calculation device can also be configured to calculate a depth of field  69  of the lens  59  dependent on the received lens data  29 , in particular the diaphragm aperture B, and taking into account the position information  49  for the background regions  47  can generate setting instructions E for adjusting the representation  19 . For example, distances from background regions  47  to a rear and/or front hyperfocal plane can be used to assign the background regions  47  into respective sharpness regions  70 ,  71  and  72  and to determine corresponding setting instructions E for the control device  25 . In addition, the control device  25  can be configured to control the background display device  15  to represent the background regions  47  or the objects  91 ,  92 ,  93  or  94  arranged within, with a sharpness  73  assigned to the respective sharpness regions  70 ,  71  or  72 . Also, the depth of field  69  or the distances of the objects  91 ,  92 ,  93  and  94  in the real background  20  and in the virtual background  21  to the hyperfocal planes, can thus be used as a measure  67  of the blurring in order to adjust the representation  19  and thereby influence the optical image  39  generated by the camera  23 . 
     Alternatively, or in addition to such imaging parameters  63  such as the diameter  77  of the circles of confusion  75  or the distances to the hyperfocal planes, which can serve as a measure  67  for a blurring of the background regions  47 , the calculation device  61  can also be configured to determine a measure  79  for a brightness of the background regions  47  and is to be considered when determining setting instructions E for the control device  25 . As the comparison between  FIGS.  6 A and  6 B  shows, the difference in the distance between the object  93  and the lens  89  of the lens  59  when imaging the virtual background  21  and when imaging the real background  20 , in addition to the explained blurring effects also leads to the respective angle  81  between the outer rays  83  and  85 , which start from the object  93  and reach the lens  89  and are directed onto the image sensor  95 , differing from one another. Accordingly, the brightness of the object  93  in the optical image  39  of the representation  19  of the virtual background  21  differs from the brightness of the object  93  in the theoretical image  41  of the real background  20  corresponding to the virtual background  21 . This can also be taken into account when adjusting the representation  19  in that, for example, the angle  81  will be considered as an imaging parameter  63  and in the real background objects that are further away, in particular the object  93 , can be represented darker, so that the object  93  can be imaged with a brightness in the optical image  39  of the representation  19  of the virtual background  21  corresponding to or approximating the brightness when imaging the real background  20 . 
       FIGS.  6 C and  6 D  show schematically on the other hand the beam path from a point of the object  93  for a representation by means of the background display device  15  of a virtual background  21  or under the assumption of an imaging of a real background  20 . In comparison to  FIGS.  6 A and  6 B , here the diaphragm aperture B is increased, as a result of which the depth of field  69  is reduced. 
     As  FIG.  6 C  shows, that also with this larger diaphragm aperture B, the object  93  in the representation  19  of the virtual background  21  is imaged sharply onto the image sensor  95  due to the focusing of the camera  23  on the background display device  15 , so that in the optical image  39  only the brightness of the object  93  is increased. On the other hand, since the object  93  in the real background  20  is not positioned at the focusing distance D, the diameter  77  of the circle of confusion  75  registered on the image sensor  95  increases when the diaphragm  97  is opened due to the reduced depth of field  69 . Also, with the diaphragm aperture B accompanied change in the brightness of the object  93 , the optical image  39  differs from the theoretical image  41 , since the angle  81  between the outer rays  83  and  85  do not change in the same way. By an appropriate adjusting of the representation  19  of the virtual background  21 , it is possible to achieve such distance-dependent imaging effects  37  dependent on the received lens data  29 , here for example, the emerging of circles of confusion  75  with a diameter dependent on the diaphragm aperture B, as well as, reproducing the change in brightness in the optical image  39  of the representation  19  of the virtual background  21  generated by the camera  23  and to obtain a natural bokeh corresponding to or approaching the theoretical image  41 . 
     By calculating imaging parameters  63 , for example, the diameters  77  of the circles of confusion  75 , the depth of field  69  or the angle  81  between the rays  83  and  85 , the calculation device  61 , in dependence of the received lens data  29 , for example the diaphragm aperture B, can generate setting instructions E for the control device  25  in order to bring the imaging parameters  63  of the optical image  39  closer to the imaging parameters  63  of the theoretical image  41 . As such, the calculation device  61  can be configured to carry out in real time such calculations and the determination of setting instructions E, such that the representation  19  of the virtual background  21 , for example during a recording of a film scene by means of the camera  23  continually dependent on the received lens data  29  or the changing lens setting values, can be adjusted in order to generate an optical image  39  by means of the camera which is as close as possible to the theoretical image  41  and has a natural and designated bokeh. 
     As an alternative or in addition to the diaphragm aperture B, the lens data  29  can, for example, also relate to the focusing distance D or the focal length F, which can also affect the optical image  39  or the theoretical image  41 . In  FIGS.  6 E and  6 F , the diaphragm aperture B corresponds to those of  FIGS.  6 A and  6 B , whereas the focusing distance D, due to changing the focal length F as viewed from the camera, is positioned in an area in front of the background display device  15 . For example, such a positioning can be provided for so as to focus a face of the actor  17  (cf.  FIGS.  1  to  5   ). 
     Because of this change in the focusing distance D, the background display device  15  in  FIG.  6 E  is also located outside the depth of field  69 , so that a point of the object  93  represented by means of the background display device  15 , is imaged as a circle of confusion  75  on the image sensor  95 . Here too, the diameter  77  of the circle of confusion  75  differs however from that of the circle of confusion  75  in the theoretical image  41  of the point on the object  93  in the real background  20 , as can be seen from the comparison with  FIG.  6 F . Also, here, by adjusting the representation  19  of the virtual background  21  in dependence of the received focal length F or focusing distance D, it can be achieved that the optical image  39  approximates the theoretical image  41 . The calculation device  61  can be configured to perform such calculations for each one of the plurality of background regions  47  in order to enable continual and comprehensive adjustment of the representation  19  of the virtual background  21 . 
     In addition to such settings to the lens  59 , which influence the sharpness  73  or the brightness of the image of one of the objects  91 ,  92 ,  93  and  94 , the position of the camera  23  can also require an adjustment of the representation  19  of the virtual background  21  in order to enable a realistic image  39  by means of the camera  23 . In order to be able to check the position of the camera  23 , the background display system  11  comprises a position determining device  57  which is configured to transmit to the control device  25  position data P relating to the camera (cf.  FIG.  4   ). For this purpose, the position determining device  57  can comprise, for example, auxiliary cameras, not shown, which film the camera  23  and makes it possible to determine its position. 
       FIG.  8 A  shows the camera  23  with an optical axis  101  centrally aligned with the background display device  15 . As such, the representation  19  of the virtual background  21  is generated in such a way that the angles of the objects  91 ,  92  and  93  to the optical axis  101  are equal to the angles of these objects  91 ,  92  and  93  in the real background  20  corresponding to the virtual background  21  (cf.  FIG.  8 B ). If, however, the camera  23  is rotated and, for example, aimed at the actor  17 , the angles of the objects  91 ,  92  and  93  to the optical axis  101  of the camera  23  in the representation  19  of the virtual background  21  and those in the real background  20  change differently, as illustrated in  FIGS.  8 C and  8 D . 
     In order to be able to also correct this effect, the calculation device  61  can be configured to calculate those such angles of the objects  91 ,  92  and  93  for the real background  20  using a model of the virtual background  21  stored in the memory  45 , and to generate setting instructions E for the control device  25  on the basis of which the representation  19  of the virtual background can be adjusted. The control device  25  can in addition be configured to position the objects  91 ,  92  and  93  on the background display device  15 , starting from the original arrangement shown in  FIGS.  8 A and  8 E , in such a way that the arrangement of the objects  91 ,  92  and  93  according to  FIG.  8 F  corresponds to the expected arrangement when recording the real background  20  as shown in  FIG.  8 D . 
     Adjusting the representation  19  of the virtual background  21  in dependence of the received lens data  29  thus makes it possible to generate images  39  by means of such a background display device  15  which correspond to or approximate a realistic or a theoretical image  41  by a recording of the real background  20 . In particular, a realistic texture or a realistic gradient of a distance-dependent blurring in the optical image  39  of the virtual background  21  and a bokeh, corresponding to or approximating the bokeh of the theoretical image  41 , can be achieved. 
     LIST OF REFERENCE NUMBERS 
     
         
           10  recording system 
           11  background display system 
           13  image recording studio 
           15  background display device 
           17  real subject, actor 
           19  representation 
           20  real background 
           21  virtual background 
           23  camera 
           25  control device 
           27  data input 
           29  lens data 
           31  illumination apparatus 
           33  LED wall 
           35 | light-emitting diode 
           37  image effect 
           39  image of the virtual background 
           41  theoretical image 
           43  three-dimensional scene 
           45  memory 
           47  background region 
           49  image information 
           51  position information 
           53  distance 
           54  distance 
           57  position determining device 
           59  camera lens, interchangeable lens 
           61  calculation device 
           63  imaging parameter 
           65  databank 
           67  measure for blurring 
           69  depth of field 
           70  sharpness region 
           71  sharpness region 
           72  sharpness region 
           73  sharpness 
           75  circle of confusion 
           77  diameter 
           79  measure for a brightness 
           81  angle between outer rays 
           83  first outer ray 
           85  second outer ray 
           87  beam 
           89  lens 
           91  first object 
           92  second object 
           93  third object 
           94  fourth object 
           95  image sensor 
           97  aperture 
           99  point 
           101  optical axis 
         B diaphragm aperture 
         D focusing distance 
         E setting instructions 
         F focal length 
         I information 
         P position data