Abstract:
In a television receiver having Picture-In-Picture (PIP), a controller analyzes the content of a video signal forming a main picture, and automatically adjusts the size and position of a PIP image to correspond to regions of the main picture exhibiting the least amount of motion, texture, and/or a repeating texture. The controller also prevents the PIP image from being positioned over text or faces or other important objects in the main picture.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of The Invention  
           [0002]    The subject invention relates to television receivers having the capability of displaying Picture-In-Picture (PIP).  
           [0003]    2. Description of The Related Art  
           [0004]    PIP is a feature in a television receiver in which the picture from a video signal in a main channel fills the display, while the picture from a video signal in an auxiliary channel is sub-sampled and overlays a portion of the main picture on the display. This enables a user of the television receiver to monitor the video signal from an alternate source, e.g., a television channel from a second tuner, the signal from a video cassette recorder or a video camera, etc.  
           [0005]    However, when displaying the PIP signal, a portion of the main picture is lost. Depending on the content of the main picture, the area occupied by the PIP picture may obscure an important portion of the main picture, for example, in sports, this important portion may be that devoted to displaying the current score, while in a movie, this portion may be that devoted to displaying the faces of the leading characters.  
           [0006]    In order to alleviate this problem, it is known to be able to move the PIP picture to various different positions under control of the user, to reposition the PIP picture such that it does not obscure an important information of the main picture.  
           [0007]    U.S. Pat. No. 6,008,860 discloses circuitry with which the size of the PIP picture may be selectively reduced to further obscure less of the main picture.  
           [0008]    In each of the above arrangements, it is up to the user to determine when such important information is being obscured and to take the corrective action, i.e., reducing the size of the PIP picture or moving the PIP picture, or both.  
         SUMMARY OF THE INVENTION  
         [0009]    It is an object of the present invention to provide a television receiver having a PIP capability in which the size and position of the PIP picture are adjusted automatically in dependence on the content of the main picture.  
           [0010]    The above object is achieved in a television receiver having a picture-in-picture (PIP) functionality, said television receiver comprising a main video path including an input for receiving a main video signal, and a main signal video processing circuit for processing the main video signal in the main video path; an auxiliary video path including an auxiliary input for receiving an auxiliary video signal, and an auxiliary signal video processing circuit for sub-sampling and processing the auxiliary video signal in the auxiliary video path; a display for displaying video signals; and means for selectively applying processed main video signal and the sub-sampled auxiliary video signal to the display such that a picture from the sub-sampled auxiliary video signal overlies a portion of a picture from the main video signal, wherein said selectively applying means comprises means for detecting and analyzing characteristics of the main video signal; and means for changing attributes of the PIP picture in response to said detected and analyzed characteristics of the first video signal.  
           [0011]    Applicants have determined that by analyzing the main video signal, regions in the picture frame may be found which contain relatively unimportant information. These regions may be identified by examining motion and texture, wherein regions having relatively no motion, the least texture, i.e., having a single color, or having a repeated texture, may be candidates for the positioning of the PIP image. Based on the size and positioning of these candidate regions, the size and positioning of the PIP image may be changed to coincide with that of one of the candidate regions.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    With the above objects and advantages in mind as will hereinafter occur, the subject invention will be described with reference to the accompanying drawings, in which:  
         [0013]    [0013]FIG. 1 shows a schematic block diagram of a known television receiver having the PIP function;  
         [0014]    [0014]FIG. 2 shows a schematic block diagram of a television receiver in accordance with the subject invention;  
         [0015]    [0015]FIG. 3 shows a block diagram of a controller for use in the television receiver of FIG. 2; and  
         [0016]    [0016]FIG. 4 shows a flowchart describing the operation of the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    As shown in FIG. 1, a television receiver typically includes an input for receiving television signals. This is shown as an antenna  10  connected to a tuner  12 . One output of the tuner  12  carries an audio portion of the television signal which is applied to an audio signal processing circuit  14  which, in turn, applies the audio signal to an audio amplifier  16  for amplification and then to a loudspeaker  18 . Another output of the tuner  12  carries a video portion of the television signal which is applied to a video signal processing circuit  20  which, in turn, applies the video signal to a matrix circuit  22  for generating the color signals red (R), green (G) and blue (B), which are applied to a display  24 . A controller  26 , which may include a microprocessor, is connected to control inputs of the tuner  12 , the audio signal processing circuit  14 , and the video signal processing circuit  20 , for tuning to the desired television program, and for controlling the audio and video signal processing.  
         [0018]    In the case of Picture-In-Picture (PIP), the television receiver includes an input for an auxiliary television signal, which in this case is shown as a second antenna  28  and a second tuner  30 . A second video signal processing circuit  32  is connected to the output of the tuner  30  and provides a processed video signal to a PIP processor  34 . The PIP processor  34  sub-samples the processed video signal and applies the sub-sampled video signal to one input of a video switch  36  arranged between the video signal processing circuit  20  and the display  24 . The controller  26  is coupled to control inputs of the second tuner  30 , the second video signal processing circuit  32 , the PIP processor  34  and the video switch  36 , for choosing the television program for the PIP, for controlling the processing of the auxiliary video signal, and for controlling the sub-sampling in the PIP processor  34  and the switching of the video switch  36  for controlling the size and position of the PIP image. In this prior art television receiver, if the PIP image obscures an important portion of the main picture, the user must take action, i.e., reduce the size of the PIP image, or move the PIP image to, for example, another of a plurality of pre-assigned regions on the display.  
         [0019]    [0019]FIG. 2 shows a block diagram of the television receiver incorporating the subject invention. It should be apparent that this television receiver is substantially similar to that shown in FIG. 1, with the exception that the video signal from the tuner  12  is additionally applied to the controller  26 ′. The controller  26 ′ includes means for analyzing the content of the video signal for detecting regions of a display resulting from the video image that exhibit the least amount of motion, the least texture, i.e., having a single color, and/or having a repeated texture, i.e., tiles of a texture. This may be done by any known method. For example, U.S. patent application Ser. No. 09/477,084, filed Dec. 30, 1999 (Attorney Docket PHA 23,938), discloses a method of detecting fast motion scenes in a video signal. Once the video signal has been analyzed and the candidate regions identified, the controller  26 ′ performs an algorithm described with reference to FIG. 3.  
         [0020]    [0020]FIG. 3 shows a block diagram of the controller  26 ′ of FIG. 2. In particular, the main video signal from the main tuner  12  is applied to an input  42  of a microprocessor  40 , which applies control signals to the various components in the television receiver via control signal outputs  44 . The microprocessor  40  communicates via a bus  46  with a memory  48 . An object detector  50 , motion detector  52  and texture detector  54  are also coupled to the input  42  for receiving the main video signal, and communicate with the microprocessor  40  via the bus  46 . A timer  56  is additional provided and is also coupled to the bus  46 . A PIP sizer  58 , PIP positioner  60  and PIP transparency adjuster  62  are provided for controlling the attributes of the PIP image, and are connected to the microprocessor  40  via the bus  46 . While separate means have been shown for performing the various functions of the controller  26 ′, it should be understood that these function may be performed by appropriate software programming stored in the memory  48  and operated upon by the microprocessor  40 .  
         [0021]    [0021]FIG. 4 shows a flowchart describing the algorithm performed by the controller  26 ′ in implementing the Smart PIP of the subject invention. In particular, at step  100 , the user turns on the PIP function and the PIP image is displayed at a pre-set size and position. At step  102 , the controller  26 ′ sets a timer to 0. The controller  26 ′, at step  104 , analyzes the main video signal. At step  106 , regions Rn are identified having the least motion, the least texture, and/or a repeated texture. At step  108 , the controller  26 ′ determines whether any regions Rn have been determined. If not, the controller  26 ′, at step  110 , changes the transparency of the PIP image and reverts to step  104 . The transparency of the PIP image is changed such that the main picture is more visible through the PIP image. The changing of the transparency of the PIP image may be performed in one or a plurality of steps.  
         [0022]    If, at step  108 , the controller  26 ′ determines candidate regions Rn, then, at step  112 , the controller  26 ′ determines whether the current position of the PIP image coincides with one of the regions Rn. If so, the controller  26 ′ determines, at step  114 , whether the current PIP size is the same size or smaller than the selected region. If so, the controller  26 ′ reverts back to step  104 , and if not, the controller  26 ′ resizes the PIP image at step  116  and then reverts to step  104 . If, at step  110 , the current PIP position is different from any of the identified regions, the controller  26 ′, at step  118 , attempts to find one of the identified regions which is nearest to the current PIP image position. At step  120  the controller  26 ′ determines whether such a region has been found and, if not, the controller  26 ′ reverts to step  110  and changes the transparency of the PIP image. If such a region is found, the controller  26 ′ checks whether the current value in the timer exceeds a threshold “TIMEOUT” at step  122 . If not, the controller  26 ′ pauses for a predetermined amount of time at step  124  and rechecks the timer value at step  122 . Once the timer value exceeds TIMEOUT, at step  126 , the controller  26 ′ determines whether the PIP size is less than or equal to the size of the nearest region. If so, the controller  26 ′, at step  128 , moves the PIP to the closest region and reverts to step  102 , resetting the timer to 0. If not, the controller  26 ′, at step  130 , resizes the PIP image and, in addition, moves the PIP to the closest region, then reverting to step  102 .  
         [0023]    In implementing the analyzing of the video signal, it may be desired to restrict the potential regions for locating the PIP image such that the image is not placed over text or over faces greater than a particular size or over “important objects.” For example, in a sports broadcast, the current score may be shown in a particular position on the screen and should not be covered by the PIP image. U.S. patent application Ser. No. 09/370,931, filed Aug. 9, 1999 (Attorney Docket No. PHA 23,616) discloses a method and apparatus for detecting such text in a video signal. This may be incorporated in the controller  26 ′ such that any text in the main video signal, i.e., the score in a sporting event, may be detected and is not be overlaid by the PIP image. In, for example, figure skating, it is important not to place the PIP image over the person who is competing. Normally, if there is camera motion (unless the camera is panning), the camera is following an object of interest, i.e., the person. In such cases, the central regions in general are more important than the peripheral regions. Hence, the central regions are less suitable for PIP image overlay.  
         [0024]    Similarly, the article “OMNI-FACE DETECTION FOR VIDEO/IMAGE CONTENT DESCRIPTION” by G. Wei and I. K. Sethi, International Workshop on Multimedia Information Retrieval, ACM Multimedia Conference 2000 (MIR2000), describes a method and apparatus for detecting faces in a video signal. Again, the features of this article may be incorporated into the controller  26 ′ to prevent the controller  26 ′ from positioning the PIP image over the face of the figure skater.  
         [0025]    Up to this point, the subject invention has only addressed the size, positioning and transparency of the PIP image, while the shape of the PIP image has stayed as that of a standard television picture. However, it should be understood that, in addition, The controller  26 ′ may be pre-programmed with alternative shapes for the PIP image, for example, oval, round, trapezoidal, etc. In that event, if, for example, the controller  26 ′ is not able to determine candidate regions, the controller  26 ′ may, instead of or in addition to changing the transparency of the PIP image, change the shape of the PIP image to one of the alternative shapes.  
         [0026]    Numerous alterations and modifications of the structure herein disclosed will present themselves to those skilled in the art. However, it is to be understood that the above described embodiment is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.