Abstract:
In a multi-view autostereoscopic display system ( 100 ) a plurality of views ( 120,122,124,126 ) is displayed repeatedly within a plurality of adjacent viewing cones ( 107,111,113 ), where pairs of views among the plurality of views form stereoscopic view pairs. A first set of depth adaptation settings, e.g. baseline and disparity, and at least one further set of depth adaptation settings, e.g. baseline and disparity, are obtained, the at least one further set of depth adaptation settings is different from the first set of depth adaptation settings. The first set of depth adaptation settings is then set for a first subset of views among the plurality of views in all viewing cones. The at least one further set of depth adaptation settings is set for at least one further respective subset of views among said plurality of views in all viewing cones. A simple solution is thereby provided of adapting the system to provide viewers/users with individually adapted depth adaptation settings and thereby providing an enhanced 3D viewing experience to a plurality of simultaneous viewers.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to controlling a multi-view autostereoscopic display system and in particular to controlling depth adaptation settings for a plurality of users of the display system. 
       BACKGROUND 
       [0002]    In traditional two-dimensional (2D) video display systems, one single view is generated and displayed at a 2D display. An extension to 2D video is stereo video, where two views are generated and displayed at a stereo or three-dimensional (3D) display. In such systems, one view is provided for a viewer&#39;s left eye whereas the other view is provided for the viewer&#39;s right eye. In order to separate the views for the left and right eye, respectively, glasses are commonly used which separate the views either in the temporal domain (shutter glasses) or via polarization filtering. Needless to say, from the perspective of the viewer, wearing glasses limits the comfort of 3D viewing. 
         [0003]    3D display systems that are capable of providing a stereo view without the need for specially adapted glasses are so-called autostereoscopic display systems. One class of autostereoscopic display systems is multi-view display systems. In such systems, several slightly different views (typically 9 views, up to 27 views) are displayed in a so called viewing zone or viewing “cone”. Usually, one single viewer will view the display from within such a cone. In this cone two neighboring views builds a stereo view pair. If the viewer moves his head, sequentially different stereo view pairs will be viewed by the viewer. This results in a perceived effect of looking at a 3D scene from different viewing angles. 
         [0004]    In a multi-user multi-view display system these cones are typically repeated several times allowing multiple viewers to look at the display simultaneously perceiving depth impression. In such systems the depth settings, i.e. parameters that are used by the video processing functions in the systems in order to provide the view pairs, are the same for all users. However, the perception of depth is typically different from viewer to viewer, since there are physiological factors that differ from person to person. Whereas some persons are comfortable with a certain depth setting, other persons will get headaches or feel sickness. Therefore, an individual depth adaptation is necessary in order to reach a good 3D experience for a wide range of viewers. However, in today&#39;s multi-user multi-view display systems, individual depth settings are not possible. 
       SUMMARY 
       [0005]    It is an object to obviate at least some of the above disadvantages and therefore there is provided, according to a first aspect, an improved method for controlling a multi-view autostereoscopic display system that comprises a number of operations. A plurality of views is displayed repeatedly within a plurality of adjacent viewing cones, where pairs of views among the plurality of views form stereoscopic view pairs. A first set of depth adaptation settings, e.g. baseline and disparity, and at least one further set of depth adaptation settings, e.g. baseline and disparity, are obtained, the at least one further set of depth adaptation settings is different from the first set of depth adaptation settings. The first set of depth adaptation settings is then set for a first subset of views among the plurality of views in all viewing cones. The at least one further set of depth adaptation settings is set for at least one further respective subset of views among said plurality of views in all viewing cones. 
         [0006]    That is, a simple solution is provided of adapting a multi-user multi-view autostereoscopic display system to provide viewers/users with individually adapted depth adaptation settings and thereby providing an enhanced 3D viewing experience to a plurality of simultaneous viewers. 
         [0007]    A determination can be made of a number of users of the display system, and the number of subsets of views then depends on the determined number of users. Furthermore, embodiments include those where a user input signal is received and a user identifier is determined based on this user input signal. The user identifier is then associated with any one of said sets of depth adaptation settings. 
         [0008]    Such embodiments provide an increased flexibility of adapting the system to different situations involving varying number of viewers/users. 
         [0009]    The obtaining of any one of the sets of depth adaptation settings can comprise receiving a user input signal, determining, based on the user input signal, a user identifier and said any one of said sets of depth adaptation settings, and associating the user identifier with said any one of said sets of depth adaptation settings. 
         [0010]    The reception of the user input signal can comprise reception from any of: a user operated remote control unit, a user gesture recognition unit, a voice recognition unit and a user face recognition unit. 
         [0011]    Any one of the sets of depth adaptation settings can be stored, the storing being associated with said user identifier. 
         [0012]    In other words, such storage can be in the form of a user profile, the contents of which can be retained and from which settings can be obtained at any time. 
         [0013]    Embodiments include those that comprise receiving a user position change indication signal that indicates that a user associated with a user identifier has moved from a first position to a second position. A subset of views corresponding to the first position and a subset of views corresponding to the second position are then determined. A set of depth adaptation settings that have been set for the subset of views corresponding to the first position is then identified, and this identified set of depth adaptation settings is then set, in all viewing cones, for the subset of views that corresponds to the second position. 
         [0014]    That is, such embodiments relate to situations where, when the system detects a change of user position, it adapts the new views with the current settings. 
         [0015]    Embodiments include those that comprise receiving a user position change indication signal that indicates that a user associated with a user identifier has moved from a first position to a second position. A subset of views corresponding to the second position is determined and a set of depth adaptation settings that are associated with the subset of views corresponding to the second position is then calculated, e.g. comprising geometrical calculations involving at least the second position. This calculated set of depth adaptation settings is then set, in all viewing cones, for the subset of views that corresponds to the second position. 
         [0016]    That is, such embodiments relate to situations where, when the system detects a change of user position, it estimate the geometrical situation corresponding to the new position, direction and/or angle of the viewer in relation to the system and adapts the views accordingly. 
         [0017]    The embodiments that comprise reception of a user position change indication signal can comprise reception from any of: a remote control unit, a head tracking unit, a gesture recognition unit and a face recognition unit. 
         [0018]    According to a second aspect, there is provided a computer program product comprising software instructions that, when executed in a processor, performs the method as summarized above. 
         [0019]    According to a third aspect, there is provided a multi-view autostereoscopic display system comprising display circuitry for displaying a plurality of views, the displaying being repeated within a plurality of adjacent viewing cones and where pairs of views among said plurality of views form stereoscopic view pairs. The system further comprises obtaining circuitry for obtaining a first set of depth adaptation settings, obtaining circuitry for obtaining at least one further set of depth adaptation settings, said at least one further set of depth adaptation settings being different from the first set of depth adaptation settings. The system also comprises setting circuitry for setting, in all viewing cones, the first set of depth adaptation settings for a first subset of views among said plurality of views, and setting circuitry for setting, in all viewing cones, the at least one further set of depth adaptation settings for at least one further respective subset of views among said plurality of views. 
         [0020]    The effects and advantages of these further aspects correspond to the effects and advantages as summarized above in connection with the first aspect. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  schematically illustrates a multi-user multi-view display system, 
           [0022]      FIG. 2  is a functional block diagram that schematically illustrates a multi-user multi-view display system, 
           [0023]      FIG. 3  is a flowchart of a first embodiment of a method for controlling a multi-user multi-view display system, 
           [0024]      FIG. 4  is a flowchart of a second embodiment of a method for controlling a multi-user multi-view display system, and 
           [0025]      FIG. 5  is a flowchart of a third embodiment of a method for controlling a multi-user multi-view display system. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0026]      FIG. 1  illustrates schematically a multi-user multi-view display system  100 . The system comprises a 3D display screen  104 , 3D display control circuitry  102 , processing circuitry  106 , memory  108  and input/output (i/o) interface circuitry  110 . The i/o circuitry  110  connects an input signal receiver  112  and a video database  114 . An external video database  118  is also connected to the system  100  via a data communication network  116 , e.g. Internet, via a network connection  115  and the i/o circuitry  110 . The input signal receiver  112  is configured such that it can receive and convey signals to the system  100  from, e.g., a remote control unit that is operated by a viewer. The input signal receiver  112  can also, in some embodiments, be configured such that it can detect and track movement of a viewer, e.g. the head of the viewer, and also recognize facial features or other characteristics of a viewer. Details regarding how signals are received and processed by the signal receiver  112  and other more general operations of the system  100  are known to the skilled person and will not be described in any detail in the present disclosure. However, the actual content and interpretation of signals received in the signal receiver  112  will be described in some detail below. For example, signals received in the signal receiver  112  can comprise information that is interpreted in terms of depth adaptation settings, user identifiers as well as movement of users. 
         [0027]    The system generates a plurality of views, examples of which are views illustrated by arrows  120   a,b ,  122   a,b ,  124   a,b  and  126   a,b , based on video sequence content obtained from, e.g. databases  114  and  118 . The views are pairwise autostereoscopic and hence, as the skilled person will realize, the display screen  104  and the 3D display control circuitry  102  are appropriately configured to generate such view pairs. The views are grouped within viewing cones, an example of which is an angular extent denoted with reference numeral  107  and whose boundary is denoted with reference numeral  109 . Other viewing cones are indicated with reference numerals  111  and  113 . 
         [0028]    A first viewer  128  and a second viewer are located in front of the display screen  104 . As the skilled person will realize, the schematically illustrated situation in  FIG. 1  is a “view from above” and, consequently,  FIG. 1  illustrates a situation where the first viewer  128  is receiving view  120   a  in his left eye and view  120   b  in his right eye. Similarly, the second viewer  130  is receiving views  122   a  and  122   b . Furthermore, as the skilled person will realize, when implementing the system that is schematically illustrated in  FIG. 1 , the number of views are typically larger than the number of views shown. An example of an implemented system will have, e.g., 27 views that are repeated in three to six viewing cones. 
         [0029]    In order to generate views that provide an acceptable depth perception for a viewer, it is necessary, in the 3D display control circuitry  102 , to use appropriate parameters, so-called depth adaptation settings. Depth perception is a combination of multiple factors, both subjective and objective. Each individual user/viewer is different and therefore the 3D/depth perception is different for each person. In order to adapt the depth perception, there are two main parameters: baseline and disparity. Baseline is defined as the distance between the cameras that have generated the views in a view pair, i.e. it is a parameter that affects the actual video capture. It is common to use the expression one, two, three, etc. “baselines”, where “baseline” means here an average distance modeling the eye distance. The more spatially separated the cameras are, the more extreme the depth perception is. However, it is important that cameras capture common parts of the scene so that a stereo pair may be created (otherwise, each eye will receive different information, yielding confusion and sickness in the person). On the other hand, disparity is defined as the separation of two stereo images. In other words, the baseline is in such a case fixed, but the images are “separated”/“shifted” in the processing in the 3D display control circuitry  102  in order to adapt the distance between the images to the perception of the user. 
         [0030]      FIG. 2  illustrates a system  200  similar to the system  100  in  FIG. 1 . However, whereas the system  100  in  FIG. 1  is illustrated from a hardware point of view in terms of processing and other circuitry, the system  200  in  FIG. 2  is illustrated from a point of view of functionality. Hence, the system  200  in  FIG. 2  is a multi-view autostereoscopic display system that comprises display circuitry  201 ,  204  for displaying a plurality of views, the displaying being repeated within a plurality of adjacent viewing cones, and where pairs of views among said plurality of views form stereoscopic view pairs. The system further comprises obtaining circuitry  203  for obtaining a first set of depth adaptation settings and obtaining circuitry  205  for obtaining at least one further set of depth adaptation settings, the at least one further set of depth adaptation settings being different from the first set of depth adaptation settings. Furthermore, the system comprises setting circuitry  207  for setting, in all viewing cones, the first set of depth adaptation settings for a first subset of views among said plurality of views, and setting circuitry  209  for setting, in all viewing cones, the at least one further set of depth adaptation settings for at least one further respective subset of views among said plurality of views. 
         [0031]    Turning now to  FIG. 3 , a flow chart of a method for controlling a multi-view autostereoscopic display system will be described. The method can be realized in a system such as the system  100  in  FIG. 1  as well as in a system such as the system  200  in  FIG. 2 . Typically, the method will be realized in the form of a computer program that is executed in processing circuitry such as the processor  106  in  FIG. 1  or in a combination of different processing circuitry as illustrated in  FIG. 2 . 
         [0032]    The method commences by a plurality of views being displayed in a display step  302 , the displaying being repeated within a plurality of adjacent viewing cones and where pairs of views among the plurality of views form stereoscopic view pairs. 
         [0033]    Although  FIG. 3  may give an impression that the displaying of the views is a “finite” step among other steps in the flow chart, it is to be noted that the displaying of the views continue throughout the flow of the method, as the skilled person will realize. Moreover, a step of determining a number of users of the system can be performed. In such cases, the obtaining steps will be performed in correspondence with the determined number of users. 
         [0034]    In a first and a second obtaining step  304 ,  306  a first set of depth adaptation settings and at least one further set of depth adaptation settings are obtained, respectively, the at least one further set of depth adaptation settings being different from the first set of depth adaptation settings. As the skilled person will realize, the obtaining steps  304 ,  306  can take place in any order and also take place concurrently. In a first setting step  308  the first set of depth adaptation settings is set for a first subset of views among the plurality of views in all viewing cones. In a second setting step  310  the at least one further set of depth adaptation settings is set for at least one further respective subset of views among the plurality of views in all viewing cones. As the skilled person will realize, the setting steps  308 ,  310  can take place in any order and also take place concurrently. 
         [0035]    With reference to  FIG. 1 , the first subset of views are views  120   a,b  and the at least one further subset of views are views  122   a,b . These two subsets of views are repeated in each viewing cone and therefore views  124   a,b  are identical to views  120   a,b  and views  126   a,b  are identical to views  122   a,b  in terms of depth adaptation settings. Although  FIG. 1  illustrates a situation where the first viewer  128  and the second viewer  130  are positioned such that they are viewing respective subset of views  120   a,b  and  122   a,b  within the the same viewing cone  111 , it is of course possible for the second viewer to be positioned such that he, e.g., views the subset of views  126   a,b  having the same depth adaptation settings within viewing cone  113 . 
         [0036]    Turning now to  FIG. 4 , a flow chart of a method for controlling a multi-user multi-view autostereoscopic display system will be described. The method involves two users that provide input to the system in order to individually set depth adaptation settings that provide comfortable 3D viewing conditions. The input from the users can be realized, e.g., by means of a remote control unit operated by way of keystrokes, as well as more advanced detectors such as a gesture recognition unit, a voice recognition unit and a user face recognition unit. The method can be realized in a system such as the system  100  in  FIG. 1  as well as in a system such as the system  200  in  FIG. 2 . 
         [0037]    Specifically, a plurality of views  120 , 122 , 124 , 126  are displayed in a display step  402 , the displaying being repeated within a plurality of adjacent viewing cones  107 , 111 , 113  and where pairs of views among the plurality of views form stereoscopic view pairs. As discussed above in connection with the flow chart in  FIG. 3 , it is to be noted that the displaying of the views continue throughout the flow of the method, as the skilled person will realize. 
         [0038]    In a reception step  404  a first user input signal is received. Based on the received first user input signal, a first user identifier and a first set of depth adaptation settings are determined in a determination step  406 , whereupon the first user identifier is associated, in an association step  408 , with the first set of depth adaptation settings. In a setting step  410  the first set of depth adaptation settings is set for a first subset of views  120   a,b  and  124   a,b  among the plurality of views in all viewing cones. 
         [0039]    Corresponding steps are performed in relation to the second user. That is, in a reception step  412  a second user input signal is received. Based on the received second user input signal, a second user identifier and a second set of depth adaptation settings are determined in a determination step  414 , whereupon the second user identifier is associated, in an association step  416 , with the second set of depth adaptation settings. In a setting step  410  the second set of depth adaptation settings is set for a second subset of views  122   a,b  and  126   a,b  among the plurality of views in all viewing cones. 
         [0040]    A step of storing any of the sets of depth adaptation settings can be performed in connection with the sequence in  FIG. 4 . Such a storing step can associate each user with a set of settings and thereby define a so-called user profile. Such a user profile can be retained for as long as needed and settings can be obtained from such a user profile when required. 
         [0041]      FIG. 5  is a flow chart that illustrates embodiments where depth adaptation settings are set in situations where a user moves from a first position to a second position in front of a display system such as the display system  100  in  FIG. 1  and the system in  FIG. 2 . As in the previous examples, a plurality of views are displayed in a display step  502 , the displaying being repeated within a plurality of adjacent viewing cones and where pairs of views among the plurality of views form stereoscopic view pairs. As discussed above in connection with the flow chart in  FIGS. 3 and 4 , it is to be noted that the displaying of the views continue throughout the flow of the method, as the skilled person will realize. 
         [0042]    A user identifier is determined in an identification step  504  and user position change indication signal is received in a position change detection step  506 . These two steps can be seen as a single step in that reception of a user position change indication signal can include the user identifier. The skilled person will, when realizing the method, decide on an exact structure and content of this user position change indication signal. The user may supply the position change indication signal by means of a remote control unit or the position change indication signal may originate from processing in a head tracking unit, a gesture recognition unit or a face recognition unit. 
         [0043]    Using the information obtained in the identification step  504  and the position change detection step  506  the method then determines and decides, in a determination step  508  and a decision step  510 , how to control the depth adaptation settings for the user that has moved to a new position in front of the display system. A first alternative is that it is the desire of the user that the current depth adaptation settings shall “follow” the user when moving from the first to the second position. In such cases, the determination step  508  comprises determining a subset of views corresponding to the first position and determining a subset of views corresponding to the second position. The set of depth adaptation settings that have been set for the subset of views corresponding to the first position is then identified in an identification step  512 . These first position depth adaptation settings are then set, in a setting step  516 , in all viewing cones for the subset of views corresponding to the second position. 
         [0044]    A second alternative is that it is the desire of the user that the depth adaptation settings shall be “adjusted” or “re-calculated” when moving from the first to the second position. That is, the settings are adjusted to be appropriate for the second position at which the user is located. In such cases, the determination step  508  comprises determining a subset of views corresponding to the second position and a calculation is made, in a calculation step  514 , of a set of depth adaptation settings that are associated with the subset of views corresponding to the second position. Typically, geometrical calculations are involved. These calculated second position depth adaptation settings are then set, in the setting step  516 , in all viewing cones for the subset of views corresponding to the second position.