Patent Publication Number: US-2012038744-A1

Title: Automatic 3d content detection

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Provisional Application Ser. No. 61/373,710 filed Aug. 13, 2010, which is fully incorporated herein by reference. 
    
    
     FIELD 
     The subject matter described herein relates generally to three-dimensional (3D) video display and, more particularly, to systems and methods to automatically detect 3D content in a video program signal and switch to 3D format video signal processing and display. 
     BACKGROUND 
     Three-dimensional (3D) video display is done by presenting separate images to each of the viewer&#39;s eyes. One example of a 3D video display implementation in television, referred to as time-multiplexed 3D display technology using shutter glasses. In time-multiplexed 3D display implementation, different images are sent to the viewer&#39;s right and left eyes. Images within a video signal are coded as right and left pairs of images, which are decoded separately by the television for display. The images are staggered in time with the right image being rendered on the display screen of the television followed by the left image being rendered on the display screen of the television. The television typically provides a synchronization signal to a pair of LCD shutter glasses worn by the viewer(s). The shutter glasses include left and right shutter lenses. The shutter glasses selectively block and pass the light in coordination with the synchronization signal. Thus the viewer&#39;s right eye only sees the right image rendered on the screen, and the left eye only sees the left image rendered on the screen. From the information received from the two eyes, and the difference between them, the viewer&#39;s brain reconstructs a 3D representation of the object being shown. 
     In order for a 3D video program to be properly displayed by the television the viewer must manually place the television in 3D processing and display mode by navigating the television setup menus. If the viewer forgets how to or is unable to navigate the television&#39;s setup menus, the 3D video program signal will not be properly processed and displayed by the television. 
     Therefore, it would be desirable to provide systems and methods that facilitate automatic detection of 3D content in a video program signal and, based on the detection of 3D content, automatically switching the display mode of the television to 3D video display. 
     SUMMARY 
     Embodiments described herein are directed to improved systems and methods that facilitate automatic detection of 3D content in a video program signal and, based on the detection of 3D content, automatic switching of the program signal processing and display mode of the television to 3D format. In a preferred embodiment, a television configured to enable automatic 3D video content detection and viewing includes a control system comprising a central processing unit (CPU) and on screen display (OSD) controller coupled to the CPU for processing and displaying the program signal in the proper format such as standard video or 3D fast format. The CPU preferably comprises non-volatile memory coupled to a logic unit which includes integrated circuits, processors, and software stored in memory and executable on the processors, and a 3D detection module configured to detect whether an input video program signal S p  contains 3D video content. Depending on the determination of the 3D detection module, the logic unit will automatically instructs the OSD controller to process and display the program signal S p  in standard or 3D format. The 3D detection module, which preferably comprises a signal parser, motion vector and histogram detectors and comparators, and a correlation detector, parses frames of an input video program signal S p  into first and second images and determines the level of correlation between the first and second images by motion vector and histogram information from the images. If the input signal is interlace, the detection can be done on either a frame-by-frame or a field-by-field basis. 
     Other objects, systems, methods, features, and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of this invention, and be protected by the accompanying claims. It will be understood that the particular methods and apparatus are shown by way of illustration only and not as limitations. As will be understood by those skilled in the art, the principles and features explained herein may be employed in various and numerous embodiments. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The details of the invention, both as to its structure and operation, may be gleaned in part by study of the accompanying figures, in which like reference numerals refer to like parts. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely. 
         FIG. 1  is a schematic diagram of a television system. 
         FIG. 2  is a schematic diagram of a 3D detection module. 
         FIG. 3  is a chart showing the Histogram of the left and right images of a video program signal frame. 
         FIG. 4  is a diagram showing the motion vectors of the left and right images of successive video program signal frames. 
         FIG. 5  is a chart illustrating 3D detection threshold setting. 
         FIG. 6  is a chart illustrating 3D detection threshold setting. 
     
    
    
     It should be noted that elements of similar structures or functions are generally represented by like reference numerals for illustrative purpose throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the preferred embodiments. 
     DETAILED DESCRIPTION 
     Embodiments, described herein are directed to improved methods and systems that facilitate automatic detection of 3D content in a video program signal and, based on the detection of 3D content, automatically switching the processing and display mode of the television to 3D format. The left and right images (or top and bottom images) of a video program signal in 3D format, which are created by two cameras for left and right eye viewing (or by computer graphics), are very similar except for the camera angle from which imaged object is shot. Thus, the level of correlation between the left and right images can be used to detect whether the video program signal S p  is in 3D format. 
     In a preferred embodiment, frames of an input video program signal S p  are parsed into first and second images, such as left and right images, top and bottom images, or the like, and the correlation of the first and second images are determined by motion vector information and histogram information. If, based on the level of correlation between the first and second images, it is determined that the video program signal includes 3D content, the television automatically switches the video processing and display mode to 3D format without the need for viewer or user input. 
     Turning to figures, the embodiments provided herein are described in detail. In a preferred embodiment, as depicted in  FIG. 1 , a television  100  configured to enable automatic 3D video content detection and 3D video processing and display includes a control system comprising a central processing unit (CPU)  102  and an on screen display (OSD) controller  104 . The OSD controller  104  controls the format in which a program signal is processed and displayed. The television further includes an audio-video output unit  110  coupled to the OSD controller  104 . The audio-video output unit  110  preferably includes a video display  112  for displaying the images or video component of a program signal S p  and a speaker  114  for outputting the audio program signal S p  or the audio component of the program signal S p  associated with the video component of program signal S p . 
     The CPU  102  preferably comprises non-volatile memory  106  coupled to a logic unit  108  which includes integrated circuits, processors, and software stored in memory  106  and executable on the processors. The logic unit  108  includes a 3D detection module  120  configured to detect whether an input video program signal S p  contains 3D video content. Depending on the determination of the 3D detection module  120 , the logic unit  108  will automatically instruct the OSD controller  104  to process and display the program signal S p  in standard or 3D format. If instructed to process and display the program signal S p  in 3D format, the OSD controller  104  will separately decode right and left pairs of images (or top and bottom pairs of images) within the input video program signal S p  and display the images on the video display  112  in a manner readily understood by one of skill in the art. 
     Turning to  FIG. 2 , the 3D detection module  120  includes a signal parser  124  which parses the frames  122  of an input video program signal S p  into a left image  126  and a right image  128  to be analyzed to determine the level of correlation between the left and right images  126  and  128  of the video frame  122 . The left and right images  126  and  128  output from the parser  124  are fed into left and right motion vector detectors  130  and  134  to retrieve motion vector information from the left and right images  126  and  128 . If the input signal S p  is interlace, the detection and comparison can be done on either a frame-by-frame or field-by-field basis. 
     An example of motion vector information detected by the left and right image motion vector detectors  130  and  134  is illustrated in  FIG. 4 . A motion vector comparator  138  compares the motion vector output received from the left and right image motion vector detectors  130  and  134 . The motion vector comparator  138  compares each point of vector data between the left and right images  126  and  128 . If a first vector  150  of the left image  126  is within a certain range or threshold value of a first vector  152  of the right image  128 , i.e., the angle and distances of the vectors  150  and  152  are within a certain range or threshold value of one another, then the first vectors  150  and  152  of the left and right images  126  and  128  are considered to be equal vectors. 
     Motion vector detection and comparison does not work, however, when the frame comprises a freeze frame or still image. 
     Similarly, the left and right images  126  and  128  are fed into left and right histogram detectors  132  and  134  to retrieve histogram information from the left and right images  126  and  128 . An example of histogram information detected by the left and right image histogram detectors  130  and  134  is illustrated in  FIG. 3 . The histogram information can be, e.g., luminance and/or color within the intensity domain. 
     A histogram comparator  140  compares the histogram output received from the left and right histogram detectors  132  and  134  for each segment of the left and right images  126  and  128  in, e.g., the intensity domain. The histogram comparator  140  compares a ratio of histogram data between segments  1 ,  2 ,  3 , . . . , n of the left and right images  126  and  128 . If the ratio between corresponding segments of the left and right images is within a certain range or threshold value, the corresponding segments of the left and right images  126  and  128  are considered to be equal. 
     A correlation detector  142  uses the information output from the motion vector comparator  138  and the histogram comparator  140  to determine if the content of the program signal S p  is in 3D format or not. The correlation detector  142  evaluates the number of equal vectors and equal segments of the left and right images  126  and  128  and if the number of equal vectors and/or equal segments are above a threshold number of equal vectors and/or equal segments, the content of the program signal S p  is considered to be in 3D format. 
       FIGS. 5 and 6  provide examples of evaluation thresholds for 3D format detection.  FIG. 5  illustrates a “wide” detection threshold wherein if a threshold for either the number of equal vectors or equal segments is reached, the content of the program signal S p  is considered to be in 3D format regardless of the corresponding number of equal vectors or equal segments.  FIG. 6 , however, illustrates a more “conservative” detection threshold in which a threshold number of equal vectors and equal segments must both be reached in order for the program signal S p  to be considered to be in 3D format. 
     If the correlation detector  142  determines the content of the program signal S p  to be in 3D format, the logic unit  102  automatically instructs the OSD controller  104  to process and display the program signal S p  in 3D format. 
     The particular examples set forth herein are instructional and should not be interpreted as limitations on the applications to which those of ordinary skill are able to apply the systems and methods described herein. Modifications and other uses are available to those skilled in the art which are encompassed within the spirit of the invention as defined by the scope of the appended claims.