Patent Publication Number: US-2015062295-A1

Title: Image processing system, transmitting device, receiving device, transmitting method, receiving method, and computer program

Description:
TECHNICAL FIELD 
     The present invention relates to digital broadcasting technology, and in particular to technology for transmitting and receiving a broadcast program in which a 3D program and a 2D program are combined. 
     BACKGROUND ART 
     As the digitisation of television broadcasting progresses, the image quality of broadcast programs is increasing. In recent years, 3D programs have also been broadcast. Currently, 3D programs are encoded in a Side-by-Side format. The Side-by-Side format involves reducing left-view images and right-view images to half-size with respect to the horizontal direction, and combining the images into one to encode the result with the same coding method as a conventional 2D program (e.g., MPEG-2, H.264/MPEG-4AVC, and so on). As such, the Side-by-Side format deteriorates image quality in order to reduce the left-view images and the right-view images. 
     A coding method in which image quality deterioration is unlikely has been proposed as H.264 Multi View Coding (hereinafter, MVC) (see Non-Patent Literature 1). 
     In H.264 MVC, for example, the left-view images are encoded using the conventional coding method applied to 2D programs, namely H.264/MPEG-4AVC, while the right-view images are encoded with reference to the left-view images displayed at the same time-stamp. In H.264 MVC, little image quality deterioration is produced in comparison to the Side-by-Side method, and more effective compression results from encoding the right-view images with reference to the left-view images. 
     Broadcasts combining 2D programs and 3D programs are expected to result from the appearance of this new coding method. 
     CITATION LIST 
     Non-Patent Literature 
     
         
         [Non-Patent Literature 1] 
       
    
     ISO/IEC 14496-10:2009 
     SUMMARY OF INVENTION  
     Technical Problem 
     When 2D programs and 3D programs are combined and the combined programs are broadcast, a reception device must switch between decoding methods with every switch between the 2D programs and the 3D programs. Also, when the reception device is connected to a display device by a High-Definition Multimedia Interface (hereinafter, HDMI) cable, the communication mode used by the HDMI cable must be reset and the transfer rate must be changed with every switch between a 2D program and a 3D program. Resetting the communication mode takes a few seconds, during which the screen of the display device may be blacked out or otherwise unable to normally display the program. 
     For example, when a 3D program is a main feature while a 2D program is a commercial, switching to the commercial may cause the screen to be blacked out such that the first portion of the commercial cannot be displayed. This is a great problem for broadcast stations, whose revenue is obtained by broadcasting commercials. 
     As such, in consideration of the above-described problem, the present disclosure aims to provide a image processing system, a transmission device, a reception device, a transmission method, a transmission method, and a computer program enabling a display device to correctly display a program that has priority, despite 2D programs and 3D programs being combined. 
     Solution to Problem 
     In order to achieve the above-stated aim, an image processing system pertaining to an aspect of the disclosure comprises a transmission device and a reception device, wherein the transmission device includes: a 3D encoder encoding 3D images input thereto to generate a 3D program; a stream generator generating a video stream made up of a plurality of programs, including the 3D program generated by the 3D encoder; a stream transmitter transmitting the video stream; and an information transmitter transmitting information for specifying a priority program among the programs in the video stream; and the reception device includes: an information receiver receiving the information; a stream receiver receiving the video stream; and a decoding processor decoding the video stream, specifying the priority program by using the information, and performing control such that the priority program is output to a channel used for connecting to a display device at a priority program transfer rate equal to a preceding program transfer rate used for a preceding program output immediately before the priority program. 
     Advantageous Effects of Invention 
     According to the above-described configuration, the priority program is output at the same transfer rate as the preceding program, thus removing any need for a communication mode reset between the reception device and the display device. Thus, the display device is able to normally display the priority program. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a system configuration diagram of an image processing system  1 . 
         FIG. 2  is a block diagram illustrating the configuration of a transmission device  10 . 
         FIGS. 3A and 3B  illustrate H.264 and H.264MVC encoding methods. 
         FIG. 4  illustrates the detailed configuration of a 3D encoder  103 . 
         FIG. 5  illustrates the data configuration of additional information  1400 . 
         FIG. 6  illustrates the data configuration of program information  1500 . 
         FIG. 7  is a flowchart of the operations of the transmission device  10 . 
         FIG. 8  is a block diagram illustrating the configurations of a BD recorder  20  and a digital television  30 . 
         FIG. 9  is a block diagram illustrating the configurations of the BD recorder  20  and the digital television  30 . 
         FIG. 10  is a block diagram illustrating the internal configuration of the decoding processor  204 . 
         FIG. 11  illustrates the concepts of the display mode and the transfer rate. 
         FIG. 12  is a flowchart of the operations of the BD recorder  20 . 
         FIG. 13  is a flowchart of the operations of the BD recorder  20  and the digital television  30 . 
         FIG. 14  is a block diagram illustrating the configuration of a transmission device  10   a.    
         FIG. 15  is a flowchart of the operations of the transmission device  10   a.    
         FIG. 16  is a block diagram illustrating the configurations of the BD recorder  20   a  and the digital television  30   a.    
         FIG. 17  is a block diagram illustrating the internal configuration of a decoding processor  204   a  and an HDMI transmitter  205   a.    
         FIG. 18  is a flowchart of the operations of the BD recorder  20   a.    
         FIG. 19  is a flowchart of the operations of the BD recorder  20   a  and the digital television  30   a.    
         FIG. 20  is a block diagram illustrating the configuration of a transmission device  10   b.    
         FIG. 21  is a flowchart of the operations of the transmission device  10   b.    
         FIG. 22  is a block diagram illustrating the configurations of a BD recorder  20   b  and a digital television  30   b.    
         FIG. 23  is a flowchart of the operations of the BD recorder  20   b.    
         FIG. 24  is a system configuration diagram of an image processing system  2 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     1. Embodiment 1 
     An image processing system  1  pertaining to Embodiment 1 is described below, with reference to the accompanying drawings. 
     &lt;1.1 System Overview&gt; 
       FIG. 1  is a system configuration diagram of an image processing system  1 . 
     As shown, the image processing system  1  includes a transmission device  10 , a Blu-ray Disc (hereinafter, BD) recorder  20 , a digital television  30 , an HDMI cable  40 , a remote control  50 , and 3D glasses  60 . The transmission device  10 , the BD recorder  20 , and the digital television  30  are respective examples of a transmission device, a reception device, and a display device, pertaining to the present disclosure. 
     The transmission device  10  is a device installed at a broadcasting station for digital broadcasting. The transmission device  10  encodes a broadcast program made up of a plurality of programs, such as 2D or 3D programs, and transmits the broadcast program over digital broadcast waves. The transmission device  10  also decodes the broadcast program by referencing program information and determining whether or not each program (i.e., the 2D or 3D programs) has priority. When a program has priority, the transmission device generates a priority flag serving as information preventing a receiver from switching between display modes. 
     In the present Embodiment, the term receiver refers to the BD recorder  20  and the digital television  30 . Also, the term display mode may refer to either of a 2D display mode and a 3D display mode, where the 2D display mode indicates a mode in which the receiver displays a 2D program and the 3D display mode indicates a mode in which the receiver displays a 3D program. 
     The BD recorder  20  receives the encoded broadcast program, decodes it, and outputs the result to the digital television  30  via the HDMI cable  40 . Here, the HDMI cable  40  transfers a digital signal in a communication format conforming to the HDMI standard. 
     When outputting the broadcast program to the digital television  30 , the BD recorder  20  makes a determination regarding program priority for the programs in the decoded broadcast program (i.e., the 2D or 3D programs). Then, when a program has priority and the display mode for the priority program differs from the display mode of a preceding program output immediately before, the BD recorder  20  changes the display mode of the priority program. That is, the 2D program may be converted into a 3D program, or the 3D program may be converted into a 2D program. Thus, the display mode is not changed when the priority program is output from the BD recorder  20  to the digital television  30 . 
     The remote control  50  is an input device for inputting various instructions to the BD recorder  20 . The user makes instructions on the remote control  50  in order to select a desired channel and so on, thus being able to input various instructions to the BD recorder  20 . 
     When in the 3D display mode, the digital television  30  outputs a right-view image and a left-view image in alternation. The user is able to view the 3D program stereoscopically by wearing the 3D glasses  60 , which are equipped with liquid crystal shutters. 
     &lt;1-2. Transmission Device  10  Configuration&gt; 
       FIG. 2  is a block diagram illustrating the configuration of the transmission device  10 . As shown, the transmission device  10  includes an input unit  101 , a 2D encoder  102 , a 3D encoder  103 , a priority flag generation unit  104 , a multiplexing unit  105 , and stream transmission unit  106 . 
     The transmission device  10  also includes a processor, Random Access Memory (hereinafter, RAM), Read-Only Memory (hereinafter, ROM), and a hard disk, though none of these are diagrammed. The functional blocks of the transmission device  10  may be realised as a hardware configuration, or as a computer program stored in ROM or on the hard disk and executed by the processor. 
     The input unit  101  receives the broadcast program created by a non-diagrammed program creation device and program information describing a broadcast program configuration. The broadcast program received by the input unit  101  is configured to include a plurality of 2D programs for 2D display and 3D programs for 3D display. 
     Each 2D program includes approximately 60 frames per second (hereinafter also abbreviated fps) of chronologically continuous interlaced images (hereinafter termed 2D source images). The 3D program includes approximately 60 fps of chronologically continuous interlaced images for each of a left view and a right view (hereinafter termed left-view source images and right-view source images). 
     The input unit  101  outputs 2D programs to the 2D encoder  102 , outputs 3D programs to the 3D encoder  103 , and outputs program information to the priority flag generation unit  104 . 
     The 2D encoder  102  receives the 2D program and encodes the received 2D program using a 2D coding method (e.g., H.264). 
     The 3D encoder  103  receives the 3D program and encodes the received 3D program using a 3D coding method (e.g., H.264 MVC). 
     The priority flag generation unit  104  receives the program information and references the received program information to determine whether or not the program currently being processed by the 2D encoder  102  or by the 3D encoder  103  has priority. When the program currently being processed has been found to have priority, the priority flag generation unit  104  outputs a priority flag of one to the multiplexing unit  105 . Likewise, when the program currently being processed has been found not to have priority, the priority flag generation unit  104  outputs a priority flag of zero to the multiplexing unit  105 . The program information is described later. 
     The multiplexing unit  105  receives the 2D program encoded by the 2D encoder  102 , the 3D program encoded by the 3D encoder  103 , and later-described additional information. The multiplexing unit  105  also receives an audio stream from a non-diagrammed audio encoder. 
     The multiplexing unit  105  writes the priority flag received from the priority flag generation unit  104  and the additional information received from the 3D encoder  103  into Program Specific Information (hereinafter, PSI). The multiplexing unit  105  also writes a 3D flag into the PSI, thereby indicating whether each program in the broadcast program is a 2D program or a 3D program. In the present Embodiment, the 3D flag is set to zero to indicate a 2D program and is set to one to indicate a 3D program. 
     The multiplexing unit  105  multiplexes a video stream that includes the encoded 2D program and the encoded 3D program, the audio stream, the PSI, and any other multimedia streams, to generate a transport stream (hereinafter also abbreviated TS). The multiplexing unit  105  outputs the generated transport stream to the stream transmission unit  106 . 
     The stream transmission unit  106  transmits the transport stream generated by the multiplexing unit  105  on digital broadcast waves. 
     The TS  1100  illustrated in  FIG. 2  is a simplified transport stream as transmitted by the stream transmission unit  106 . A 3D program  1102  is a leading program. The 3D program  1102  is followed by 2D program  1104 , 2D program  1106 , and so on, transmitted in order. Priority flag  1101  corresponds to the 3D program  1102 . The priority flag  1101  is set to zero, thus indicating that the 3D program  1102  is a normal program. Priority flag  1103  corresponds to 2D program  1104 . Priority flag  1103  is set to one, thus indicating that 2D program  1104  is a priority program. Priority flag  1105  corresponds to 2D program  1106 . Priority flag  1105  is set to zero, thus indicating that 2D program  1106  is a normal program. 
     &lt;1-3. Coding Method Details&gt; 
     The details of the 2D encoder  102  and the 3D encoder  103  are described next. 
       FIG. 3A  illustrates the frame reference relationships within the encoded stream when the 2D encoder  102  applies the 2D coding method. Here, a frame is a unit of encoding. The stream encoded using the 2D coding method includes I-frames encoded using intra-frame predictive coding without relying on any reference frame, P-frames encoded using inter-frame predictive coding with reference to one previously-processed frame, and B-frames encoded using inter-frame predictive coding with reference to two previously-processed frames simultaneously. As such, the 2D encoder  102  uses a 2D coding method where chronological correlation is employed for inter-frame predictive coding. Examples include H.264/MPEG-4 AVC. 
       FIG. 3B  illustrates the frame reference relationships within the encoded stream when the 3D encoder  103  applies the 3D coding method. The upper row of  FIG. 3B  corresponds to a left-view video stream obtained by encoding the left-view source images. Similarly, the lower row of  FIG. 3B  corresponds to a right-view video stream obtained by encoding the right-view source images. 
     The left-view video stream has the same reference structure as the 2D coding method depicted in  FIG. 3A . 
     The right-view video stream uses compression that applies inter-frame predictive coding using inter-viewpoint correlation, in addition to the inter-frame predictive coding that applies chronological correlations. That is, the frames of the right-view video stream are compressed with reference to frames of the left-view video stream having the same presentation time stamp. 
     A video stream that can be played back individually, such as the left-view video stream, is termed a base view video stream. In contrast, a video stream such as the right-view video stream that is decodable after the base view video stream has been decoded, with reference to the frames making up the base view video stream is termed an additional view stream or a dependent view stream. 
     Next, the details of the encoding process by the 3D encoder  103  are described with reference to  FIG. 4 . 
     An encoder  1302  encodes the left-view source images  1301  and outputs left-view images. The left-view images  1303  are output sequentially by the encoder  1302  and enumerated into an encoded sequence that is the left-view video stream. In the present Embodiment, the left-view video stream corresponds to the base view video stream. 
     As described above, the right-view source images  1304  are encoded using a difference relative to left-view source images having the same time-stamp. As such, a decoding unit  1305  first decodes the encoded left-view images  1303  into decoded left-view images  1306 . Then, in order to increase the compression ratio, an image compressor  1307  compresses the left-view images  1306 , thereby decreasing the resolution and generating reduced images  1308 . The image compressor  1307  also reduces the right-view source images  1304  to generate reduced images  1309 . The image compressor  1307  may compress the left-view images  1306  and the right-view source images  1304  in the vertical direction only, in the horizontal direction only, or in the horizontal and vertical directions. 
     A difference calculator  1310  calculates a difference between the left-view reduced images  1308  and the right-view reduced images  1309 . Encoder  1311  then encodes the calculated difference. The difference  1312  is output sequentially by encoder  1311  and enumerated into an encoded sequence that is the right-view video stream. In the present Embodiment, the right-view video stream corresponds to the additional view video stream. 
     The additional information generation unit  1313  generates additional information describing information such as the reduction factor used by the image compressor  1307 , for each of the base view video stream and the additional view video stream. The additional information is output by the 3D encoder  103  to the multiplexing unit  105  and written into a Program Map Table (hereinafter, PMT) of the PSI by the multiplexing unit  105 . 
     &lt;1-4. Regarding the Additional Information&gt; 
     The following describes the data configuration and usage of the additional information. 
     The decoding process applied to the additional view video stream generated by the 3D encoder  103  is described first. The BD recorder  20  may also perform reversed encoding operations when decoding the additional view video stream. That is, the BD recorder  20  first decodes the encoded difference. Next, the BD recorder  20  reduces the encoded base view video stream and generates reduced images having a lower resolution. Then, reduced decoded images are generated through the addition of the decoded difference to the reduced images. Finally, the BD recorder  20  obtains the right-view images for display by expanding the reduced decoded images. 
     As such, the coding method used by the 3D encoder  103  produces decoded right-view images having a lower resolution than the left-view images. However, given that the user views the left-view images and the right-view images in alternation, the left-view images and the right-view images become fused in the user&#39;s mind, such that the lower resolution of the right-view images is not perceptible. 
     When, as described above, the BD recorder  20  converts a 3D program into a 2D program in order for the display mode of the priority program to match the display mode of the most recent preceding program, the user may experience some discomfort in the event that the left-view images are discarded and the right-view images, having lower resolution, are selected alone for output. As such, an additional information generation unit  1313  generates the additional information such that the appropriate images are selected when the BD recorder  20  converts a 3D program into a 2D program. 
       FIG. 5  illustrates an example of a data configuration for the additional information. The additional information  1400  illustrated by  FIG. 5  includes a base video flag  1401  indicating whether the corresponding stream (i.e., the stream having the additional information  1400  added thereto) is a base view video stream or an additional view video stream, a left-view flag  1402  used when the corresponding stream is an additional view video stream to indicate whether the stream is a left-view video stream or a right-view video stream, a horizontal reduction factor  1403 , a vertical reduction factor  1404 , and a 2D usability flag  1405  indicating whether or not the corresponding stream is usable for output in the 2D display mode. 
     The additional information generation unit  1313  completes the additional information  1400  by writing the values indicated in  FIG. 5  for the base view video stream and the additional view video stream at generation time. 
     When a value such as  50 % is written into the horizontal reduction factor  1403  or into the vertical reduction factor  1404  indicating that reduction occurs, the additional information generation unit  1313  sets the 2D usability flag  140  to FALSE in order to prevent image quality degradation when the BD recorder  20  converts a 3D program into a 2D program. Conversely, when a value such as 100% is written into the horizontal reduction factor  1403  and into the vertical reduction factor  1404  indicating that no reduction occurs, the additional information generation unit  1313  sets the 2D usability flag  1405  to TRUE. 
     When the encoding process depicted in  FIG. 4  is performed, the additional information generation unit  1313  sets the 2D usability flag  1405  of the additional information  1400  associated with the additional view video stream to FALSE. 
     &lt;1-5. Program Information Data Configuration&gt; 
       FIG. 6  illustrates the data configuration of the program information  1500 . The program information  1500  is generated for each broadcast program and describes information pertaining to each program within the broadcast program. For example, the program information  1500  includes a program ID for each program, program content, a priority, and a display mode. 
     The program ID is a number indicating a transmission order for each program. The program content is a field indicating whether the program is a feature or a commercial. The priority is a field indicating whether the program is a normal program or a priority program. As described above, sponsor relationships mean that the broadcast station faces greater problems when commercials are not correctly displayed, than when feature programs are not correctly displayed. As such, in the present Embodiment, the commercials are defined as priority programs and the priority field thereof is accordingly set to Priority. Also, the feature program is defined as a normal program and the priority field thereof is set to Normal. The display mode indicates whether the program is a 2D program or a 3D program. 
     &lt;1-6. Transmission Device  10  Operations&gt; 
       FIG. 7  is a flowchart depicting the operations of the transmission device  10 . 
     The input unit  101  receives a program subject to processing (hereinafter termed a subject program) (step S 1 ). The subject program is a 2D program or a 3D program within the broadcast program. Prior to step S 1 , the input unit  101  receives the program information corresponding to the broadcast program as input, and passes the received program information to the priority flag generation unit  104 . 
     When the subject program input during step S 1  is a 2D program (2D in step S 2 ), the input unit  101  outputs the subject program to the 2D encoder  102 . The 2D encoder  102  then encodes the subject program (step S 3 ). The 2D encoder  102  outputs the encoded 2D program to the multiplexing unit  105 . 
     When the subject program is a 3D program (3D in step S 2 ), the input unit  101  outputs the subject program to the 3D encoder  103 . The 3D encoder  103  then encodes the subject program to generate the base view video stream and the additional view video stream (step S 4 ). The base view video stream and the additional view video stream are hereinafter referred to in combination as an encoded 3D program. 
     Subsequently, the 3D encoder  103  generates additional information for each of the base view video stream and the additional view video stream generated in step S 4  (step S 5 ). The 3D encoder  103  outputs the encoded 3D program and the additional information to the multiplexing unit  105 . 
     The priority flag generation unit  104  references the program information received from the input unit  101  (step S 6 ) and determines whether or not the subject program has priority. Here, the priority flag generation unit  104  is able to identify the subject program using the program ID. The priority flag generation unit  104  extracts the priority corresponding to the program ID of the subject program from the program information. When the priority field is set to Priority, the subject program has priority. When the priority field is set to Normal, the subject program does not have priority. 
     When the subject program has priority (YES in step S 7 ), the priority flag generation unit  104  generates a priority flag of one (step S 8 ) and outputs the results to the multiplexing unit  105 . 
     When the subject program does not have priority (NO in step S 7 ), the priority flag generation unit  104  generates a priority flag of zero (step S 9 ) and outputs the results to the multiplexing unit  105 . 
     The processing of steps S 6  through S 9  may be performed in parallel to steps S 3  and S 4 . 
     The multiplexing unit  105  receives the encoded 2D program, the encoded 3D program, the PSI, the audio stream, and other multimedia streams, and performs multiplexing thereon to generate the transport stream (step S 10 ). 
     The stream transmission unit  106  transmits the transport stream generated by the multiplexing unit  105  on digital broadcast waves (step S 11 ). 
     &lt;1-7. BD Recorder  20  Configuration&gt; 
       FIG. 8  is a block diagram illustrating the configuration of the BD recorder  20  and the digital television  30 . 
     As shown, the BD recorder  20  includes a tuner  201 , a demultiplexer  202 , a control information manager  203 , a decoding processor  204 , and an HDMI transmitter  205 . 
     The BD recorder  20  also includes a processor, RAM, ROM, and a hard disk, none of which are diagrammed. The functional blocks of the BD recorder  20  may be realised as a hardware configuration, or as a computer program stored in ROM or on the hard disk and executed by the processor. 
     The tuner  201  receives and demodulates the digital broadcast wave to obtain the transport stream. 
     The demultiplexer  202  demultiplexes the transport stream, separating out a control information stream, such as the PSI, and streams corresponding to a program selected by the user such as an audio stream and video streams. The demultiplexer  202  outputs the control information stream to the control information manager  203  and outputs the video stream to the decoding processor  204 . 
     The control information manager  203  receives a program selection from the user via the remote control  50 . The control information manager  203  receives the control information stream from the demultiplexer  202 . The control information stream describes stream information (e.g., ID) for designating an elemental steam within the selected program. The control information manager  203  notifies the demultiplexer  202  of the IDs of elemental streams in the selected program, thereby making a request to the demultiplexer  202  to demultiplex the elemental streams having those IDs. The control information manager  203  also extracts a priority flag and additional information corresponding to the selected program from the control information stream, and outputs these to the decoding processor  204 . 
     As shown in  FIG. 10 , the decoding processor  204  includes a 2D/3D determiner  211 , a switcher  212 , a 2D decoder  213 , a 3D decoder  214 , and an output controller  215 . 
     The 2D/3D determiner  211  references the 3D flag in each program in order to sort the programs among the video streams received from the demultiplexer  202  into those for the 2D decoder  213  and those for the 3D decoder by determining whether the programs are 2D or 3D programs. The 2D/3D determiner  211  outputs the programs to the switcher  212  along with determination results. 
     The switcher  212  switches between connecting the 2D/3D determiner  211  to the 2D decoder  213  and to the 3D decoder  214 . Upon receiving a 2D program from the 2D/3D determiner  211 , the switcher  212  connects the 2D/3D determiner  211  to the 2D decoder  213  and outputs the received 2D program to the 2D decoder  213 . Likewise, upon receiving a 3D program from the 2D/3D determiner  211 , the switcher  212  connects the 2D/3D determiner  211  to the 3D decoder  214  and outputs the received 3D program to the 3D decoder  214 . 
     The 2D decoder  213  performs a decoding process according to the coding method used by the 2D encoder  102  of the transmission device  10 . 
     The 3D decoder  214  performs a decoding process according to the coding method used by the 3D encoder  103  of the transmission device  10 . 
     The output controller  215  receives the decoded 2D program from the 2D decoder  213 . The output controller  215  also receives the decoded 3D program from the 3D decoder  214 . The output controller  215  references the values of the priority flag corresponding to each received 2D program and 3D program. When a received program has priority, and the display mode of the priority program differs from the display mode of the preceding program, the output controller  215  changes the display mode of the priority program. That is, the 2D program may be converted into a 3D program, or the 3D program may be converted into a 2D program by the output controller  215 . 
     The HDMI transmitter  205  includes an HDMI connector for connecting the HDMI cable  40 . Upon receiving an output program that includes the 2D and/or 3D programs from the decoding processor  204 , the HDMI transmitter  205  transmits the received output program to the digital television  30  via the HDMI cable  40 . 
     The following describes a change in display mode performed by the output controller  215 , with reference to  FIG. 11 . The horizontal axis of  FIG. 11  represents time. 
     Tier (a) represents the frame rate when a 2D program is being displayed in the 2D display mode. The HDMI cable  40  transfers the frames of the 2D program (labelled 2D) at 60 fps. 
     Tier (b) represents the frame rate when a 3D program is being displayed in the 3D display mode. In order to display the 2D program at the same frame rate as the 2D program, the HDMI cable  40  transmits the left-view frames (labelled L) and the right-view frames (labelled R) making up the 3D program in alternation, at 120 fps. That is, the 3D display mode requires frames to be transferred at twice the frame rate of the 2D display mode. 
     When the 2D program of tier (a) is changed to the 3D display mode, the output controller  215  copies each frame (labelled 2D) making up the 2D program as shown in tier (c), thereby doubling the amount of data, to generate a 3D program without parallax. The HDMI cable  40  transfers the original frames and the copied frames in alternation, at 120 fps. 
     When the 3D program of tier (b) is changed to the 2D display mode, the output controller  215  selects the left-view frames (labelled L) from the 3D program and discards the right-view frames, as shown in tier (d), thus halving the amount of data and generating a 2D program. The HDMI cable  40  transfers the left-view frames at 60 fps. 
     &lt;1-8. Digital Television  30  Configuration&gt; 
     As shown in  FIG. 8 , the digital television  30  includes an HDMI receiver  301 , a video display processor  302 , and a display  303 . 
     The digital television  30  also includes a processor, RAM, ROM, and a hard disk, none of which are diagrammed. The functional blocks of the digital television  30  may be realised as a hardware configuration, or as a computer program stored in ROM or on the hard disk and executed by the processor. 
     The HDMI receiver  301  includes an HDMI connector for connecting the HDMI cable  40 . The HDMI receiver  301  receives the output program transmitted by the HDMI transmitter  205  via the HDMI cable  40 . When a change in display mode occurs in the output program being transmitted and received by the HDMI transmitter  205  and the HDMI receiver  301 , the transmission and reception of the output program is stopped and a communication mode for a control signal is reset in order to change the transfer rate. 
     Upon receiving the output program from the HDMI receiver  301 , the video display processor  302 , which has an internal frame buffer, stores the frames of the output program in the frame buffer. The frame buffer includes a 2D display buffer and a 3D display buffer, where the 3D display buffer further includes a left-view buffer and a right-view buffer. 
     The video display processor  302  stores the frames of the 2D program in the 2D display buffer. The video display processor  302  stores the left-view frame frames of the 3D program in the left-view buffer, and stores the right-view frame of the 3D program in the right-view buffer. 
     When there is a change to the 3D display mode in which a 3D program without parallax is being generated from a 2D program, as in tier (c) of  FIG. 11 , the video display processor  302  stores the original frames in the left-view buffer and stores the copied frames in the right-view buffer. Similarly, when there is a change to the 2D display mode in which a 2D program is generated from a 3D program, as in tier (d) of  FIG. 11 , the video display processor  302  stores the left-view frames in the 2D display buffer. 
     The display  303  is, for example, a liquid crystal display. When in the 2D display mode, the display  303  reads the frames in the 2D display buffer and displays the frames so read at a frequency of 60 Hz. When in the 3D display mode, the display  303  reads the left-view frames and the right-view frames from the respective left-view buffer and right-view buffer in alternation, and displays the frames so read in alternation at a frequency of 120 Hz. 
     &lt;1-9. BD Recorder  20  and Digital Television  30  Operations&gt; 
       FIGS. 12 and 13  are flowcharts of the operations performed by the BD recorder  20  and the digital television  30 . 
     The tuner  201  receives the broadcast program and demodulates it into a TS. The demultiplexer  202  demultiplexes the TS (step S 20 ). The demultiplexer  202  sequentially outputs the demultiplexed video streams (i.e., programs) to the decoding processor  204 . 
     The 2D/3D determiner  211  of the decoding processor  204  references the 3D flag to determine whether or not the program subject to processing (hereinafter also termed a subject program) is a 2D program or a 3D program (step S 21 ). When the 3D flag is set to zero, the subject program is a 2D program. When the 3D flag is set to one, the subject program is a 3D program. 
     When the subject program is a 2D program (2D in step S 22 ), the 2D decoder  213  performs a decoding process (step S 23 ). When the subject program is a 3D program (3D in step S 22 ), the 3D decoder  214  performs a decoding process (step S 24 ). 
     The output controller  215  determines whether or not a change of display mode has occurred between the preceding program and the subject program. For example, a change of display mode occurs when the preceding program is a 2D program and the subject program is a 3D program, and when the preceding program is a 3D program and the subject program is a 2D program. 
     When there is no change in display mode (NO in step S 25 ), the process advances to step S 45 . 
     When a change in display mode occurs (YES in step S 25 ), the output controller  215  references the priority flag of the subject program (step S 26 ) to determine whether or not the subject program has priority. Specifically, the subject program has priority when the priority flag is set to one. Conversely, the subject program does not have priority when the priority flag is set to zero. 
     When the subject program does not have priority (NO in step S 27 ), the process advances to step S 41 . 
     When the subject program has priority (YES in step S 27 ), and is a 2D program (2D in step S 28 ), the output controller  215  copies the original 2D frames in the subject program (step S 29 ) and generates a 2D program without parallax that is playable in the 3D display mode (step S 30 ). Afterward, the process advances to step S 45 . 
     When the subject program has priority (YES in step S 27 ), and is a 3D program (3D in step S 28 ), the output controller  215  references the additional information  1400  associated with the subject program (step S 31 ) and selects one of the left-view frames and the right-view frames (step S 32 ). The output controller  215  selects the left-view frames when flag  1402  indicates the right-view video stream and flag  1405  is set to FALSE within the additional information  1400  associated with the additional view video stream. The output controller  215  outputs only the frames selected in step S 32  to the HDMI transmitter  205  and discards the frames that were not selected, thus generating a 2D program that is playable in the 2D display mode (step S 33 ). Afterward, the process advances to step S 34 . 
     When a change of display mode occurs and the subject program does not have priority, the HDMI transmitter  205  performs a communication mode reset to change the transfer rate (step S 41 ). The HDMI transmitter  205  then transmits a transfer rate change notification to the HDMI receiver  301  of the digital television  30  (step S 42 ). 
     Upon receiving the change notification, the HDMI receiver  301  also performs the communication mode reset to change the transfer rate (step S 43 ). The HDMI receiver  301  then transmits a transfer rate change completion notification to the HDMI transmitter  205  (step S 44 ). 
     Upon receiving the completion notification, the HDMI transmitter  205  outputs the subject program to the HDMI cable  40  (step S 45 ). The HDMI receiver  301  receives the subject program via the HDMI cable  40  (step S 46 ). Upon receiving the subject program from the HDMI receiver  301 , the video display processor  302  outputs the display  303 . The display  303  displays the subject program (step S 47 ). 
     The specific operations performed by the BD recorder  20  upon receiving the TS  1100  described in  FIG. 8  are described next. 
     The decoding processor  204  first decodes 3D program  1102 . This produces a sequence of images such as interval  401  of output program  1600 . The decoding processor  204  then decodes 2D program  1104 . Priority flag  1103  is set to one, thus indicating that 2D program  1104  is a priority program. A change of display mode occurs between 2D program  1104 , being output as-is, and 3D program  1102 , which is the preceding program. The output controller  215  copies the 2D images making up 2D program  1104  and generates a 3D program without parallax. This produces a sequence of images such as interval  402  of output program  1600 . The decoding processor  204  then decodes 2D program  1106 . Priority flag  1105  is set to zero, thus indicating that 2D program  1106  is not a priority program. The 2D program  1106  is then output in the 2D display mode. This produces a sequence of images such as interval  403  of output program  1600 . 
     Intervals  401  and  402  of output program  1600  have the same frame rate. There is thus no need for the HDMI transmitter  205  and the HDMI receiver  301  to perform a communication mode reset. 
     Intervals  402  and  403  of output program  1600  have different frame rates. As such, the HDMI transmitter  205  and the HDMI receiver  301  perform the communication mode reset when the frame rate is changed. Thus, the data transmission process by the HDMI cable  40  is interrupted for a few seconds, and a leading portion of 2D program  1106  may not be displayed on the display  303 . 
     The specific operations performed by the BD recorder  20  upon receiving the TS  1200  described in  FIG. 9  are described next. 
     The decoding processor  204  first decodes 2D program  1202 . This produces a sequence of images such as interval  411  of output program  1700 . The decoding processor  204  then decodes 3D program  1204 . Priority flag  1203  is set to one, thus indicating that 3D program  1204  is a priority program. A change of display mode occurs between 3D program  1204 , being output as-is, and 2D program  1202 , which is the preceding program. The output controller  215  selects the left-view images among the images making up 3D program  1204  and generates a 2D program. This produces a sequence of images such as interval  412  of output program  1700 . The decoding processor  204  then decodes 3D program  1206 . Priority flag  1205  is set to zero, thus indicating that 3D program  1206  is not a priority program. 3D program  1206  is then output in the 3D display mode. This produces a sequence of images such as interval  413  of output program  1700 . 
     Intervals  411  and  412  of output program  1700  have the same frame rate. There is thus no need for the HDMI transmitter  205  and the HDMI receiver  301  to perform a communication mode reset. 
     Intervals  412  and  413  of output program  1700  have different frame rates. As such, the HDMI transmitter  205  and the HDMI receiver  301  perform the communication mode reset when the frame rate is changed. Thus, the data transmission process by the HDMI cable  40  is interrupted for a few seconds, and a leading portion of 3D program  1206  may not be displayed on the display  303 . 
     2. Embodiment 2 
     An image processing system pertaining to Embodiment 2 is described below, with reference to the accompanying drawings. 
     &lt;2.1 System Overview&gt; 
     The image processing system of Embodiment 2 includes a transmission device  10   a,  a BD recorder  20   a,  a digital television  30   a,  a HDMI cable  40 , a remote control  50 , and 3D glasses  60 . 
     In Embodiment 1, described above, the BD recorder  20  functions to convert a 2D program into a 3D program or to convert a 3D program into a 2D program in order to constrain changes in transfer rate occurring in the HDMI cable when a priority program is transmitted. In contrast, Embodiment 2 has the transmission device  10   a  function to convert 2D programs into 3D programs and to convert 3D programs into 2D programs. 
     &lt;2-2. Transmission Device  10   a  Configuration&gt; 
       FIG. 14  is a block diagram illustrating the configuration of the transmission device  10   a.  As shown, the transmission device  10   a  includes an input unit  101 , a controller  120 , a 2D encoder  102 , a 3D encoder  103   a,  a multiplexer  105 , and stream transmitter  106 . The 3D encoder  103   a  also includes a 2D flag generator  130 . Components having the same function as those of the transmission device  10  from Embodiment 1 use the same reference signs thereas. 
     The transmission device  10   a  also includes a processor, RAM, ROM, and a hard disk, none of which are diagrammed. The functional blocks of the transmission device  10   a  may be realised as a hardware configuration, or as a computer program stored in ROM or on the hard disk and executed by the processor. 
     The controller  120  receives a broadcast program that includes a plurality of 2D programs and 3D programs from the input unit  101 , and program information describing the broadcast program. 
     The controller  120  references the program information to specify a priority program, and checks the respective display modes of the specified priority program and a preceding program output immediately prior. When the display modes of the priority program and the preceding program differ, the controller  120  converts a 2D program into a 3D program or converts a 3D program into a 2D program in order to constrain the occurrence of a change in display mode when the receiver displays the priority program. 
     The 2D encoder  102  receives a 2D program from the controller  120  and encodes the received 2D program using a 2D coding method. Here, the 2D program encoded by the 2D encoder  102  includes a 2D program generated by a program creation device, and a 2D program generated from a 3D program by the controller  120 . 
     The 3D encoder  103   a  receives a 3D program from the controller  120  and encodes the received 3D program using a 3D coding method. Here, the 3D program encoded by the 3D encoder  103   a  includes a 3D program generated by a program creation device, and a 3D program generated from a 2D program by the controller  120 . Upon receiving the 3D program from the controller  120 , the 3D encoder  103   a  notifies the controller  120  when the 3D program has no parallax due to having been generated from the 2D program. 
     The 2D flag generator  130  generates a 2D flag indicating whether or not the 3D program encoded by the 3D encoder  103   a  lacks parallax due to having been generated from a 2D program. The 2D flag generator  130  generates a 2D flag reading one when the encoded 3D program lacks parallax due to having been generated from a 2D program. The 2D flag generator  130  generates a 2D flag reading zero when the encoded 3D program has not been generated from a 2D program. The 2D flag is used by the receiver to delete redundant frames. 
     The 3D encoder  103   a  outputs the encoded 3D program to the multiplexer  105  with the 2D flag added thereto. 
     In Embodiment 2 and in the later-described Embodiment 3, the receiver does not perform any processing for converting a 2D program into a 3D program. As such, the 3D encoder  103   a  does not generate additional information  1400 . 
     The TS  2100  illustrated in  FIG. 14  is a simplified transport stream as transmitted by the stream transmitter  106 . A 2D program  2101  is a leading program. The 2D program  2101  is followed by a 3D program  2103 , a 2D program  2105 , and so on, transmitted in order. 2D flag  2102  corresponds to 3D program  2103 . Given that 2D flag  2102  reads one, 3D program  2103  is identified as having originally been a 2D program, converted into a 3D program that has no parallax by the controller  120 . 2D flag  2104  corresponds to 3D program  2105 . Given that 2D flag  2104  reads zero, 3D program  2105  is identified as not being a 2D program converted into a 3D program that has no parallax by the controller  120 . 
     &lt;2-3. Transmission Device  10   a  Operations&gt; 
     The following describes the operations of the transmission device  10   a  with reference to the flowchart of  FIG. 15 . 
     The input unit  101  receives a program subject to processing (hereinafter termed a subject program) (step S 51 ). The subject program is a 2D program or a 3D program within the broadcast program. The input unit  101  passes the received subject program to the controller  120 . Prior to step S 51 , the input unit  101  receives the program information corresponding to the broadcast program as input, and passes the received program information to the controller  120 . 
     Upon receiving the subject program, the controller  120  references the display mode field in the program information to determine whether the subject program is a 2D program or a 3D program. 
     When the subject program is a 2D program (2D in step S 52 ), the controller  120  references the display mode field of the program information to determine whether the preceding program output immediately before the subject program is a 2D program or a 3D program. The controller  120  further determines whether a change in display mode occurs in the receiver, according to the determination results. 
     When the preceding program is a 2D program, no change in display mode occurs in the receiver (NO in step S 53 ). The controller  120  outputs the subject program to the 2D encoder  102  as-is. Afterward, the process advances to step S 60 . 
     When the preceding program is a 3D program, a change in display mode occurs in the receiver (YES in step S 53 ). The controller  120  references the priority field of the program information to determine whether or not the subject program has priority. 
     When the subject program does not have priority (NO in step S 55 ), no problem occurs in the event of a change in display mode. The controller  120  outputs the subject program to the 2D encoder  102 . Afterward, the process advances to step S 60 . 
     When the subject program has priority (YES in step S 55 ), a problem occurs in the event of a change in display mode. The controller  120  copies the 2D images in the subject program (step S 56 ) and generates a 3D program with no parallax that is viewable in the 3D display mode (step S 57 ). The controller  120  outputs the 3D program without parallax to the 3D encoder  103   a.    
     Upon receiving the subject program, the 3D encoder  103   a  then encodes the subject program to generate the base view video stream and the additional view video stream (step S 58 ). Next, the 2D flag generator  130  generates a 2D flag reading one (step S 59 ). The flag is added to the encoded 3D program. The process then continues as explained in steps S 10  and onward of Embodiment 1. 
     The 2D encoder  102  then acquires and encodes the subject program (step S 60 ). The process then continues as explained in steps S 10  and onward of Embodiment 1. 
     When the subject program is a 3D program (3D in step S 52 ), the controller  120  references the display mode field of the program information to determine whether the preceding program output immediately before the subject program is a 2D program or a 3D program. The controller  120  further determines whether a change in display mode occurs in the receiver, according to the determination results. 
     When the preceding program is a 2D program, a change in display mode occurs in the receiver (YES in step S 61 ). The controller  120  references the priority field of the program information to determine whether or not the subject program has priority. 
     When the subject program does not have priority (NO in step S 63 ), no problem occurs in the event of a change in display mode. The controller  120  outputs the subject program to the 3D encoder  102 . Afterward, the process advances to step S 67 . 
     When the subject program has priority (YES in step S 63 ), a problem occurs in the event of a change in display mode. The controller  120  selects the left-view images of the subject program, only, for output to the 2D encoder  102 . 
     The 2D encoder  102  receives the left-view images from the controller  120  and encodes the received left-view images (step S 65 ). The process then continues as explained in steps S 10  and onward of Embodiment 1. 
     When the preceding program is a 3D program, no change in display mode occurs in the receiver (NO in step S 61 ). The controller  120  outputs the subject program to the 3D encoder  103   a  as-is. 
     The 3D encoder  103   a  then encodes the subject program to generate the base view video stream and the additional view video stream (step S 66 ). Next, the 2D flag generator  130  generates a 2D flag reading zero (step S 67 ). The flag is added to the encoded 3D program. The process then continues as explained in steps S 10  and onward of Embodiment 1. 
     &lt;2-4. BD Recorder  20   a  Configuration&gt; 
       FIG. 16  is a block diagram illustrating the configurations of the BD recorder  20   a  and the digital television  30   a.    
     As shown, the BD recorder  20   a  includes a tuner  201 , a demultiplexer  202 , a control information manager  203 , a decoding processor  204   a,  and an HDMI transmitter  205   a.    
     The BD recorder  20   a  also includes a processor, RAM, ROM, and a hard disk, none of which are diagrammed. The functional blocks of the BD recorder  20   a  may be realised as a hardware configuration, or as a computer program stored in ROM or on the hard disk and executed by the processor. 
     The tuner  201 , the demultiplexer  202 , and the control information manager  203  are each configured identically to the corresponding components of Embodiment 1. 
     The following describes the decoding processor  204   a  and the HDMI transmitter  205   a  with reference to  FIG. 17 . As shown in  FIG. 17 , the decoding processor  204   a  includes a 2D/3D determiner  211 , a switcher  212 , a 2D decoder  213 , a 3D decoder  214 , and an output unit  215   a.  The HDMI transmitter  205   a  further includes a redundant flag generator  216 . 
     The 2D/3D determiner  211 , the switcher  212 , the 2D decoder  213 , and the 3D decoder  214  are each configured identically to the corresponding components of Embodiment 1. 
     The output controller  215  of Embodiment 1 may convert a 2D program into a 3D program, or convert a 3D program into a 2D program. However, in Embodiment 2, the transmission device  10   a  has already performed the conversion of the 2D program into a 3D program or of a 3D program into a 2D program. Accordingly, the output unit  215   a  does not function to convert a 2D program decoded by the 2D decoder  213  into a 3D program or to convert a 3D program decoded by the 3D decoder  214  into a 2D program. The output unit  215   a  simply outputs the 2D program received from the 2D decoder  213  and the 3D program received from the 3D decoder  214  to the HDMI transmitter  205   a.    
     The HDMI transmitter  205   a  of Embodiment 2 transmit the decoded frames to the digital television  30   a  connected to the HDMI cable  40 , similarly to the HDMI transmitter  205  of Embodiment 1. Here, when copied frames have been generated from the original 2D images in order to double the frame rate of the 2D program when transmitting frames, the redundant flag generator  216  applies a redundant flag to the redundant frames not required for display on the digital television  30   a.    
     Specifically, the redundant flag generator  216  uses the 2D flag added to the 3D program to distinguish between redundant frames and other frames. The redundant flag generator  216  assigns a redundant flag with a value of one to redundant frames, and assigns a redundant flag with a value of zero to other frames. The redundant flag is, for example stored in a frame header or the like of a format conforming to the HDMI standard, and transmitted to the digital television  30   a.    
     &lt;2-5. Digital Television  30   a  Configuration&gt; 
     As shown in  FIG. 16 , the digital television  30   a  includes an HDMI receiver  301 , a video display processor  302   a,  and a display  303 . 
     The digital television  30   a  also includes a processor, RAM, ROM, and a hard disk, none of which are diagrammed. The functional blocks of the digital television  30   a  may be realised as a hardware configuration, or as a computer program stored in ROM or on the hard disk and executed by the processor. 
     The HDMI receiver  301  and the display  303  are identical to the corresponding components of Embodiment 1. 
     Upon receiving the output program from the HDMI receiver  301 , the video display processor  302   a,  which has an internal frame buffer similar to the video display processor  302  of Embodiment 1, stores the frames of the output program in the frame buffer. 
     In Embodiment 2, a redundant flag is stored in the header of each frame. When the redundant flag of a received frame has a value of one, the video display processor  302   a  deletes the received frame without storing it in the frame buffer, as that frame is a redundant frame not needed for display by the digital television  30   a.    
     &lt;2-6. BD Recorder  20   a  and Digital Television  30   a  Operations&gt; 
       FIGS. 18 and 19  are flowcharts of the operations performed by the BD recorder  20   a  and the digital television  30   a.    
     The tuner  201  receives the broadcast program and demodulates it into a TS. The demultiplexer  202  demultiplexes the TS (step S 70 ). The demultiplexer  202  sequentially outputs the demultiplexed video streams (i.e., programs) to the decoding processor  204 . 
     The 2D/3D determiner  211  of the decoding processor  204   a  references the 3D flag to determine whether or not the program subject to processing (also termed a subject program) is a 2D program or a 3D program (step S 71 ). When the 3D flag is set to zero, the subject program is a 2D program. When the 3D flag is set to one, the subject program is a 3D program. 
     When the subject program is a 2D program (2D in step S 72 ), the 2D decoder  213  performs a decoding process (step S 73 ). Afterward, the process advances to step S 79 . 
     When the subject program is a 3D program (3D in step S 72 ), the 3D decoder  214  performs a decoding process (step S 74 ). Upon receiving the decoded subject program via the output unit  215   a,  the HDMI transmitter  205   a  reads the value of the 2D flag added to the subject program (step S 75 ). 
     When the 2D flag has a value of one (1 in step S 76 ), the subject program is an originally 2D program converted into a 3D program with redundant frames. The HDMI transmitter  205   a  then adds the redundant flag to the frames of the subject program beginning with the first frame, which reads zero, so as to then alternate between values of zero and one (step S 77 ). Afterward, the process advances to step S 79 . 
     When the 2D flag has a value of zero (0 in step S 76 ), the subject program is a 3D program without redundant frames. The HDMI transmitter  205   a  thus adds a redundant flag having a value of zero to all frames of the subject program (step S 78 ). 
     The HDMI transmitter  205   a  determines whether or not a change in display mode occurs. A change of display mode occurs when the preceding program is a 2D program and the subject program is a 3D program, and when the preceding program is a 3D program and the subject program is a 2D program. 
     When there is no change in display mode (NO in step S 79 ), the process advances to step S 84 . 
     When there is a change in display mode (YES in step S 79 ), the HDMI transmitter  205   a  performs a communication mode reset to change the transfer rate (step S 80 ). The HDMI transmitter  205   a  then transmits a transfer rate change notification to the HDMI receiver  301  of the digital television  30   a  (step S 81 ). 
     Upon receiving the change notification, the HDMI receiver  301  also performs the communication mode reset to change the transfer rate (step S 82 ). The HDMI receiver  301  then transmits a transfer rate change completion notification to the HDMI transmitter  205   a  (step S 83 ). 
     Upon receiving the completion notification, the HDMI transmitter  205   a  outputs the subject program to the HDMI cable  40  (step S 84 ). The HDMI receiver  301  receives the subject program via the HDMI cable  40  (step S 85 ). 
     Upon receiving the subject program from the HDMI receiver  301 , the video display processor  302   a  determines whether or not the headers in the frames of the subject program include the redundant flags. When the subject program is a 2D program, the headers in the frames do not include the redundant flags. When the subject program is a 3D program, the headers in the frames include the redundant flags. 
     When the headers do not include the redundant flags (NO in step S 86 ), the video display processor  302   a  stores the subject program in the frame buffer. 
     When the headers include the redundant flags (YES in step S 86 ), the video display processor  302   a  repeats steps S 87  and S 88  for each frame of the subject program. 
     For a redundant flag reading zero, i.e., for a frame that is not redundant, the video display processor  302   a  stores the frame in the frame buffer. For a redundant flag reading one, i.e., for a frame that is redundant, the video display processor  302   a  deletes the frame without storing it in the frame buffer (step S 88 ). 
     The display  303  sequentially displays the frames stored in the frame buffer (step S 89 ). 
     The specific operations performed by the BD recorder  20   a  and the digital television  30   a  upon receiving the TS  2100  described in  FIG. 16  are described next. 
     The TS  2100  includes 3D program  2103  and 3D program  2105 , such that the 3D programs are output to the digital television  30   a  in the stated order. 2D flag  2102  corresponds to 3D program  2103 . 2D flag  2102  reads one, and thus 3D program  2103  is a 3D program without parallax generated from a 2D program in order to constrain the occurrence of a change in display mode given the relationship with the preceding program, namely 3D program  2101  (see  FIG. 14 ). 3D program  2103  includes redundant frames. 2D flag  2104  corresponds to 3D program  2105 . 2D flag  2104  reads zero, and thus 3D program  2105  does not include redundant frames. 
     The HDMI transmitter  205   a  receives the decoded 3D program  2103  from the decoding processor  204   a.  2D flag  2102  reads one, and thus the HDMI transmitter  205   a  assigns redundant flags reading zero and one, in alternation. The 3D program  2103  results as a sequence of images such as interval  421  of output program  2200 . The leading frame has a redundant flag  431  reading zero, and the second frame has a redundant flag  432  reading one. 
     The HDMI transmitter  205   a  then receives the decoded 3D program  2105  from the decoding processor  204   a.  2D flag  2104  reads zero, and thus the HDMI transmitter  205   a  assigns a redundant flags reading zero. The 3D program  2105  results as a sequence of images such as interval  422  of output program  2200 . 
     The video display processor  302   a  receives output program  2200  and deletes the frames having a redundant flag reading one. As a result, the display  303  displays display program  2300  as indicated in  FIG. 16 . Display program  2300  has an interval  441  displayed as a 2D program, at a display frequency of 60 Hz. Another interval  442  is displayed as a 3D program, at a display frequency of 120 Hz. 
     As such, Embodiment 2 has the transmission device  10   a  generate 2D flags enabling the receiver to delete redundant frames. Accordingly, the flickering that occurs when a 3D program without parallax is played back can be prevented. Furthermore, the digital television  30   a  is able to constrain electric power consumption. 
     3. Embodiment 3 
     An image processing system pertaining to Embodiment 3 is described below, with reference to the accompanying drawings. 
     &lt;3.1 System Overview&gt; 
     The image processing system of Embodiment 3 includes a transmission device  10   b,  a BD recorder  20   b,  a digital television  30   b,  a HDMI cable  40 , a remote control  50 , and 3D glasses  60 . 
     In Embodiment 3, much like Embodiment 2 described above, the transmission device  10   a  functions to convert a 2D program into a 3D program or to convert a 3D program into a 2D program in order to constrain changes in transfer rate occurring in the HDMI cable  40  when a priority program is transmitted. The transmission device  10   b  generates 2D flags, much like transmission device  10   a.    
     Furthermore, in Embodiment 3, and much like in the above-described Embodiment 1, the transmission device  10   b  references the program information of the broadcast program to determine whether each program (i.e., 2D programs and 3D programs) therein has priority, and generates a priority flag. However, in Embodiment 3, the usage method of the priority flag differs from that of Embodiment 1. 
     The BD recorder  20   b  generates redundant flags when transmitting HDMI frames to the digital television  30   b,  similarly to BD recorder  20   a  of Embodiment 2. At this point, the BD recorder  20   b  uses the 2D flags and the priority flags to determine the value of the redundant flags. In Embodiment 3, control is performed so as to display a priority program on the digital television  30   b  without deleting redundant frames when the program is a 3D program lacking parallax generated from a 2D program with redundant frames. 
     &lt;3-2. Transmission Device  10   b  Configuration&gt; 
       FIG. 20  is a block diagram illustrating the configuration of the transmission device  10   b.  As shown, the transmission device  10   b  includes an input unit  101 , a controller  120 , a 2D encoder  102 , a 3D encoder  103   a,  a priority flag generator  104 , a multiplexer  105 , and a stream transmitter  106 . The 3D encoder  103   a  also includes a 2D flag generator  130 . 
     Components having the same function as those of the transmission device  10  from Embodiment 1 use the same reference signs thereas. Likewise, components having the same function as those of the transmission device  10   a  from Embodiment 2 use the same reference signs thereas. 
     The transmission device  10   b  also includes a processor, RAM, ROM, and a hard disk, none of which are diagrammed. The functional blocks of the transmission device  10   b  may be realised as a hardware configuration, or as a computer program stored in ROM or on the hard disk and executed by the processor. 
     The TS  3100  illustrated in  FIG. 20  is a simplified transport stream as transmitted by the stream transmitter  106 . A 3D program  3103  is a leading program. The 3D program  3103  is followed by a 3D program  3106 , a 3D program  3109 , and so on, transmitted in order. 
     Priority flag  3101  and 2D flag  3102  correspond to 3D program  3103 . Priority flag  3101  is set to zero, thus indicating that 3D program  3101  is not a priority program. Given that 2D flag  3102  reads zero, 3D program  31015  is identified as not being a 2D program converted into a 3D program by the controller  120 . 
     Priority flag  3104  and 2D flag  3105  correspond to 3D program  3106 . Priority flag  3104  is set to one, thus indicating that 3D program  3106  is a priority program. Given that 2D flag  3105  reads one, 3D program  3106  is identified as having originally been a 2D program, converted into a 3D program by the controller  120 . 
     Priority flag  3107  and 2D flag  3108  correspond to 3D program  3109 . Priority flag  3107  is set to zero, thus indicating that 3D program  3106  is not a priority program. Given that 2D flag  3108  reads one, 3D program  3109  is identified as having originally been a 2D program, converted into a 3D program by the controller  120 . 
     &lt;3-3. Transmission Device  10   b  Operations&gt; 
     The following describes the operations of the transmission device  10   b  with reference to the flowchart of  FIG. 21 . 
     The transmission device  10   b  performs the same processing as the transmission device  10   a  of Embodiment 2 from step S 51  of  FIG. 15  through steps S 59 , S 60 , S 65 , and S 67 . Afterward, the process advances to step S 91  of  FIG. 21 . 
     The priority flag generator  104  references the program information received from the controller  120  (step S 91 ) and determines whether or not the subject program has priority. Here, the priority flag generator  104  is able to identify the subject program using the program ID. The priority flag generator  104  extracts the priority corresponding to the program ID of the subject program from the program information. The priority field reads Priority to indicate that the subject program has priority. The priority field reads Normal to indicate that the subject program does not have priority. 
     When the subject program has priority (YES in step S 92 ), the priority flag generator  104  generates a priority flag of one (step S 93 ) and outputs the results to the multiplexer  105 . 
     When the subject program does not have priority (NO in step S 92 ), the priority flag generator  104  generates a priority flag of zero (step S 93 ) and outputs the results to the multiplexer  105 . 
     The multiplexer  105  receives the encoded 2D program, the encoded 3D program, the PSI, the audio stream, and other multimedia streams, and performs multiplexing thereon to generate the transport stream (step S 95 ). 
     The stream transmitter  106  transmits the transport stream generated by the multiplexer  105  on digital broadcast waves (step S 96 ). 
     &lt;3-4. BD Recorder  20   b  Configuration&gt; 
       FIG. 22  is a block diagram illustrating the configurations of the BD recorder  20   b  and the digital television  30   b.    
     As shown, the BD recorder  20   b  includes a tuner  201 , a demultiplexer  202 , a control information manager  203 , a decoding processor  204   a,  and an HDMI transmitter  205   b.    
     The BD recorder  20   b  also includes a processor, RAM, ROM, and a hard disk, none of which are diagrammed. The functional blocks of the BD recorder  20   b  may be realised as a hardware configuration, or as a computer program stored in ROM or on the hard disk and executed by the processor. 
     The tuner  201 , the demultiplexer  202 , and the control information manager  203  are each configured identically to the corresponding components of Embodiment 1. The decoding processor  204   a  is configured similarly to the corresponding component of Embodiment 2. 
     The HDMI transmitter  205   b  includes a redundant flag generator, similar to Embodiment 2. The redundant flag generator of Embodiment 3 uses the priority flags and the 2D flags when adding the redundant flags to the frames of the 3D program. 
     Specifically, the HDMI transmitter  205   b  is able use the 2D flag to distinguish between redundant frames and other frames. In addition, the HDMI transmitter  205   b  uses the priority flag to specify the priority program. When redundant frames are present in a priority program, the HDMI transmitter  205   b  sets the redundant flags of all frames to zero so as to prevent the redundant frames from being deleted, thus constraining the occurrence of a change in display frequency by the digital television  30   b.    
     &lt;3-5. Digital Television  30   b  Configuration&gt; 
     As shown in  FIG. 22 , the digital television  30   b  includes an HDMI receiver  301 , a video display processor  302   a,  and a display  303 . 
     The digital television  30   b  also includes a processor, RAM, ROM, and a hard disk, none of which are diagrammed. The functional blocks of the digital television  30   b  may be realised as a hardware configuration, or as a computer program stored in ROM or on the hard disk and executed by the processor. 
     The HDMI receiver  301  and the display  303  are identical to the corresponding components of Embodiment 1. The video display processor  302   a  is configured similarly to the corresponding component of Embodiment 2. 
     &lt;3-6. BD Recorder  20   b  and Digital Television  30   b  Operations&gt; 
       FIG. 23  is a flowchart of the operations performed by the BD recorder  20   b  and the digital television  30   b.    
     The tuner  201  receives the broadcast program and demodulates it into a TS. The demultiplexer  202  demultiplexes the TS (step S 100 ). The demultiplexer  202  sequentially outputs the demultiplexed video streams (i.e., programs) to the decoding processor  204   a.    
     The 2D/3D determiner  211  of the decoding processor  204   a  references the 3D flag to determine whether or not the program subject to processing (also termed a subject program) is a 2D program or a 3D program (step S 101 ). When the 3D flag is set to zero, the subject program is a 2D program. When the 3D flag is set to one, the subject program is a 3D program. 
     When the subject program is a 2D program (2D in step S 102 ), the 2D decoder  213  performs a decoding process (step S 103 ). The process then continues as explained in Embodiment 2, advancing to step S 79  of  FIG. 18 . 
     When the subject program is a 3D program (3D in step S 102 ), the 3D decoder  214  performs a decoding process (step S 104 ). 
     Upon receiving the decoded subject program via the output unit  215   a,  the HDMI transmitter  205   b  reads the value of the 2D flag added to the subject program (step S 105 ). When the 2D flag has a value of zero (0 in step S 106 ), the subject program is a 3D program without redundant frames. The process thus advances to step S 109 . 
     When the 2D flag has a value of one (1 in step S 106 ), the subject program is an originally 2D program converted into a 3D program with redundant frames. Next, the HDMI transmitter  205   b  reads the value of the priority flag assigned to the subject program (step S 107 ). 
     When the priority flag has a value of one and the subject program is thus a priority program (YES in step S 108 ), the HDMI transmitter  205   b  adds a redundant flag having a value of zero to each frame of the subject program (step S 109 ). The process then continues as explained in Embodiment 2, advancing to step S 79  of  FIG. 18 . 
     When the priority flag reads zero and the subject program thus does not have priority (NO in step S 108 ), the HDMI transmitter  205   b  adds the redundant flag to the frames of the subject program beginning with the first frame, which reads zero, so as to then alternate between values of zero and one (step S 110 ). The process then continues as explained in Embodiment 2, advancing to step S 79  of  FIG. 18 . 
     The specific operations performed by the BD recorder  20   b  and the digital television  30   b  upon receiving the TS  3100  described in  FIG. 22  are described next. 
     The HDMI transmitter  205   b  then receives the decoded 3D program  3103  from the decoding processor  204   a.  2D flag  3102  reads zero, and thus the HDMI transmitter  205   b  assigns a redundant flags reading zero. The 3D program  3103  results as a sequence of images such as interval  451  of output program  3200 . 
     The HDMI transmitter  205   b  then receives the decoded 3D program  3106  from the decoding processor  204   a.  2D flag  3105  reads one and the priority flag  3104  reads one, and thus the HDMI transmitter  205   b  assigns a redundant flag reading zero. The 3D program  3106  results as a sequence of images such as interval  452  of output program  3200 . 
     The HDMI transmitter  205   b  then receives the decoded 3D program  3109  from the decoding processor  204   a.  2D flag  3108  reads one and the priority flag  3107  reads zero, and thus the HDMI transmitter  205   b  assigns a redundant flags reading zero and one, in alternation. The 3D program  3109  results as a sequence of images such as interval  453  of output program  3200 . 
     The video display processor  302   a  receives output program  3200  and deletes the frames having a redundant flag reading one. As a result, the display  303  displays display program  3300  as indicated in  FIG. 22 . Display program  3300  has an interval  471  displayed as a 3D program, at a display frequency of 120 Hz. Another interval  472  is displayed as a 3D program without parallax, at a display frequency of 120 Hz. A further interval  473  is displayed as a 2D program, at a display frequency of 60 Hz. 
     That is, in Embodiment 3, an interval having priority such as interval  472  does not cause a change in display frequency in the digital television  30   b.  As such, Embodiment 3 constrains any occurrence of the screen blacking out for a moment when changing the display frequency, so as to perfectly display the priority program. 
     4. Other Variations  
     Although the image processing system pertaining to the disclosure has been described in the above Embodiments, other variations on the image processing system are also possible, such as those described below. Of course, no limitation is intended to the image processing system of the above-described Embodiments.
     (1) In the above-described Embodiments, the broadcast program is transmitted by a digital broadcast wave. However, no such limitation is intended. The broadcast program may also perform transmission via a network such as the Internet, and reception and playback may be performed by a digital television, a BD recorder, a personal computer, or any other device.   (2) In Embodiments 2 and 3, the 2D flag may be stored in Supplemental Enhancement Information (hereinafter, SEI) defined in the H.264 standard, in a UserData unit defined in the MPEG2 standard, in additional information of the TS, or in the program information.   (3) In the above-described Embodiments, the priority flag and the 2D flag are transmitted in the same transport stream as the video streams of the broadcast program. However, no such limitation is intended. The priority flag and the 2D flag may also be transmitted through a separate channel, apart from the transport stream of the broadcast program.   (4) In the above-described Embodiments, the display mode of the priority program is changed so as to match the display mode of a preceding program output immediately before the priority program. However, no such limitation is intended. The display mode of the preceding program may instead be changed to match the display mode of the priority program.   

     In Embodiment 1, when the receiver changes the display mode, there is a need for the BD recorder to determine, before outputting the preceding program, whether or not the subsequent program to be output immediately after the preceding program is a priority program. When the subsequent program has priority and the display modes of the preceding program and the priority program differ, the BD recorder converts the preceding program into a 3D program or into a 2D program. 
     In Embodiments 2 and 3, where the transmitter performs the change in display mode, the transmission device references the program information, and when the priority field of the program to be output subsequently after the preceding program is set to Priority, and the display modes of the preceding program and the priority program match, the transmission device converts the preceding program from a 2D program to a 3D program, or from a 3D program to a 2D program. Afterword, the transmission device performs encoding on the preceding program.
     (5) The program information  1500  depicted in  FIG. 6  is an example, only. For instance, the priority field is not required when the transmission device is able to determine whether or not a program has priority by consulting a program content field.   (6) In the above-described Embodiments, one example defines a commercial as a priority program and a feature as a normal program. However, no such limitation is intended. When a program is intended to be displayed correctly without division by the receiver, any such program may be defined as a priority program.   (7) In the above-described Embodiments, an example is given where a normal television broadcast of the 7:00 news includes a feature and commercials, each defined as one program. However, this is intended as an example only. The program may be defined as content in entirety, or as a plurality of pieces of content broadcast in a given time slot. For example, when 3D programs only have a possibility of being broadcast in the morning, then all content broadcast in the morning may be defined as a program for the purposes of the present disclosure.   (8) In the above-described Embodiments, the priority flag and the 2D flag are assigned in program units only. However, this is intended as an example only. The priority flag and the 2D flag may be assigned to every frame, or to every instance a given set of frames, or to every instance of a playback interval of a given length.   (9) In Embodiment 1, above, an additional view video stream typically has a reduced resolution when a 3D program is encoded, and the receiver typically selects the base view video stream when converting the 3D program into a 2D program.   

     However, depending on capture conditions (e.g., angles) at the 3D program production stage, the receiver may be unable to use the base view video stream for converting the 3D program into a 2D program and thus use the additional view video stream of reduced images for 2D display. 
     Also, although the additional view video stream has been reduced, when the values of the horizontal reduction factor  1403  and/or the vertical reduction factor  1404  of the additional information  1400  are sufficiently large, the effect of reduction is negligible. Thus, the transmission device  10  may set the 2D usability flag  1405  of in additional information  1400  of the additional view stream to TRUE. 
     In the above-described Embodiments, the BD recorder  20  uses the base view video stream for 2D display when the 2D usability flag  1405  of in additional information  1400  of the additional view stream is set to FALSE. The BD recorder  20  may use either of the base view video stream and the additional view video stream for 2D display when the 2D usability flag  1405  of in additional information  1400  of the additional view stream is set to TRUE. 
     The BD recorder  20  need not necessarily use the 2D usability flag  1405  of the additional information  1400  to determine whether or not to use the additional view video stream for 2D display. For instance, when images selected using the 2D usability flag  1405  in the 2D display mode alternate between left-view and right-view images over a short interval, the alternation may cause shaking on the screen, which is not beneficial. 
     Once 2D display using the additional view video stream has begun, display may continue to use the additional view video stream independently of the value of the 2D usability flag  1405  in the additional information  1400 . 
     Similarly, once 2D display using the base view video stream has begun, display may continue to use the base view video stream independently of the value of the 2D usability flag  1405  in the additional information  1400 .
     (10) In Embodiment 1, described above, the BD recorder  20  uses the additional information  1400  to select one of the base view video stream and the additional view video stream when performing 2D display of a 3D program.   

     The following process involving the additional information  1400  of the BD recorder  20  may also be used. 
     For example, when the digital television  30  does not have a 3D display function, the BD recorder  20  may use the additional information  1400  assigned to a received 3D program to determine whether to output left-view images or right-view images to the digital television  30 . 
     Also, when the digital television  30  does have a 3D display function but the user has disabled the 3D display function, the BD recorder  20  may use the additional information  1400  assigned to a received 3D program to determine whether to output left-view images or right-view images to the digital television  30 . 
     As such, the BD recorder  20  may use the additional information  1400  to select either of the right-view images and the left-view images.
     (11) In the above-described Embodiments, the BD recorder and the digital television are connected by an HDMI cable. However, this is only intended as an example. The BD recorder and the digital television may also be connected wirelessly, using a digital signal transmission method that conforms to the HDMI standard.   (12) In the above-described Embodiments, the image processing system includes a transmission device, a BD recorder, and a digital television.   

     The following describes a variant image processing system  2  with reference to  FIG. 24 . The image processing system  2  includes a transmission device  10   a,  a digital television  70 , a remote control  50 , and 3D glasses  60 . 
     The transmission device  10   a  is configured similarly to that of Embodiment 2 (see  FIG. 14 ). The digital television  70  includes the tuner  201 , the demultiplexer  202 , the control information manager  203 , the decoding processor  204   a,  the video display processor  302   a,  and the display  303 , each indicated in  FIG. 16 . That is, the digital television  70  combines a reception device and a display device into a single device. The image processing system  2  does not perform any HDMI communication mode reset as no HDMI cable is used to transport the programs. 
     However, when 2D programs and 3D programs are combined, the decoding processor  204   a  of the digital television  70  switches between decoding methods. Switching between decoding methods means that the decoding process is interrupted, and that a delay may occur in the display of programs on the display  303 . 
     The transmission device  10   a  may convert a 2D program into a 3D program, or convert a 3D program into a 2D program, much like Embodiment 2. Accordingly, a change in decoding method is prevented from occurring between a priority program and a preceding program output immediately before the priority program, thereby avoiding any delay in the display of the priority programs by the display  303 .
     (13) In the above-described Embodiments, H.264 MVC is given as an example of a 3D coding method. However, no such limitation is intended. The transmission device may also use a 3D coding method in the Side-by-Side method, where left-view images and right-view images are aligned horizontally, the Top and Bottom methods where left-view images and right-view images are aligned vertically, in the Line Alternative method where the lines within a single picture alternate between left-view images and right-view images, and so on. In such cases, the decoding method used by the receiver may be any method corresponding to the coding method used by the transmission device.   (14) The transmission process, reception process, and display process described in the above Embodiments may be realised as a control program written in program codes of a machine language or a high-level language to be executed by the processor of the transmission device  10 , the BD recorder  20 , and the digital television  30 , or by various circuits connected thereto, and the control program may be written onto a recording medium and delivered or distributed through various communications channels. The recording medium may be an IC card, a hard disk, an optical disc, a floppy disk, ROM, flash memory, and so on. The control program that is delivered and distributed is used by being stored in processor-readable memory, and the various functions described in the above Embodiments are realised by the processor executing the control program. The processor may directly execute the control program, or may execute a compiled or interpreted program based thereon.   (15) The various functional components of the above-described Embodiments (i.e., the input unit  101 , the 2D encoder  102 , the 3D encoder  103 , the priority flag generator  104 , the multiplexer  105 , the stream transmitter  106 , the tuner  201 , the demultiplexer  202 , the control information manager  203 , the decoding processor  204 , the HDMI transmitter  205 , the HDMI receiver  301 , the video display processor  302 , and the display  303 ) may be realised as circuits executing the corresponding functions, or as one or more processors executing a program. The transmission device, the BD recorder, and the digital television of Embodiments 1-3 may also be realised as an IC, an LSI, or another integrated circuit package. Such a package is provided as embedded within each device, such that each device is able to execute the appropriate functions.   (16) The above-described Embodiments and Variations may be freely combined.   

     5. Supplement 
     Various aspects and variations of the image processing system, the transmission device, and the reception device are described below, along with effects thereof.
     (a) An image processing system comprises a transmission device and a reception device, wherein the transmission device includes: a 3D encoder encoding 3D images input thereto to generate a 3D program; a stream generator generating a video stream made up of a plurality of programs, including the 3D program generated by the 3D encoder; a stream transmitter transmitting the video stream; and an information transmitter transmitting information for specifying a priority program among the programs in the video stream; and the reception device includes: an information receiver receiving the information; a stream receiver receiving the video stream; and a decoding processor decoding the video stream, specifying the priority program by using the information, and performing control such that the priority program is output to a channel used for connecting to a display device at a priority program transfer rate equal to a preceding program transfer rate used for a preceding program output immediately before the priority program.   

     According to this configuration, the priority program is output at the same transfer rate as the preceding program, thus removing any need for a communication mode reset between the reception device and the display device. Thus, the display device is able to normally display the priority program.
     (b) Also, the transmission device may further include: an input unit receiving a plurality of programs, each made up of 2D source images or of 3D source images; and a 2D encoder encoding 2D images input thereto with a 2D encoding method to generate a 2D program, the 3D encoder encodes the 3D images input thereto with a 3D encoding method, the stream generator generates the video stream to also include the 2D program generated by the 2D encoder, and the decoding processor equalizes the priority program transfer rate and the preceding program transfer rate by performing, on one of the priority program and the preceding program, a conversion of decoded 2D images into 3D images by doubling data or a conversion of decoded 3D images to 2D images by halving data.   

     According to this configuration, the priority program is output at the same transfer rate as the preceding program despite a 2D program and a 3D program being combined, thus removing any need for a communication mode reset between the reception device and the display device. Thus, the display device is able to normally display the priority program.
     (c) A transmission device comprises: a 3D encoder encoding 3D images input thereto to generate a 3D program; a stream generator generating a video stream made up of a plurality of programs, including the 3D program generated by the 3D encoder; a stream transmitter transmitting the video stream; and an information transmitter transmitting information for specifying a priority program among the programs in the video stream, the priority program being intended for output to a channel used for connecting a reception device corresponding to the transmission device to a display device at a priority program transfer rate equal to a preceding program transfer rate used for a preceding program output immediately before the priority program.   

     According to this configuration, the priority program is output at the same transfer rate as the preceding program by a reception device corresponding to the transmission device, thus removing any need for a communication mode reset between the reception device and the display device. Thus, the display device is able to normally display the priority program.
     (d) Also, the 3D program generated by the 3D encoder includes a left-view video stream and a right-view video stream, one of the left-view video stream and the right-view video stream being a base view video stream and the other being an additional view video stream, the additional view video stream having been generated with reference to the base view video stream, and the 3D encoder includes: an additional information generator generating additional information indicating, in accordance with a reduction factor applied to 3D source images upon generation of the additional view video stream, whether or not the additional view video stream is used when the reception device converts the 3D images into 2D images; and an output unit outputting the additional information in association with the additional view video stream information.   

     According to this configuration, the reception device selects appropriate images by using the additional information when converting 3D images into 2D images.
     (e) A transmission device comprises: a 3D encoder encoding 3D images input thereto to generate a 3D program; a stream generator generating a video stream made up of a plurality of programs, including the 3D program generated by the 3D encoder; and stream transmitter transmitting the video stream, wherein the 3D program generated by the 3D encoder includes a left-view video stream and a right-view video stream, one of the left-view video stream and the right-view video stream being a base view video stream and the other being an additional view video stream, the additional view video stream having been generated with reference to the base view video stream, and the 3D encoder includes: an additional information generator generating additional information indicating, in accordance with a reduction factor applied to 3D source images upon generation of the additional view video stream, whether or not the additional view video stream is used when the reception device converts the 3D images into 2D images; and an output unit outputting the additional information in association with the additional view video stream information.   

     According to this configuration, the reception device selects appropriate images by using the additional information when converting 3D images into 2D images.
     (f) A transmission device comprises: an input unit receiving a plurality of programs, each made up of 2D source images or 3D source images; a 2D encoder encoding 2D images input thereto with a 2D encoding method to generate a 2D program, a 3D encoder encoding 3D images input thereto with a 3D encoding method to generate a 3D program, a controller performing control such that, when the input unit receives a priority program, the priority program is encoded using the same encoding method as a preceding program transmitted immediately before the priority program; stream generator generating a video stream that at least includes the 2D program generated by the 2D encoder or the 3D program generated by the 3D encoder; and a transmission unit transmitting the video stream.   

     According to this configuration, the priority program is output at the same transfer rate as the preceding program despite a 2D program and a 3D program being combined, thus removing any need for a communication mode reset between the reception device and the display device. Thus, the display device is able to normally display the priority program.
     (g) Also, when the priority program is made up of the 2D source images and the preceding program is made up of the 3D source images: the input unit inputs the 3D source images making up the preceding program to the 3D encoder as the 3D images; the controller generates new 3D images from the 2D source images making up the priority program, and inputs the new 3D images to the 3D encoder; and the stream generator generates the video stream so as to include the priority program as the 3D program generated by the 3D encoder and the preceding program, which is another 3D program.   

     According to this configuration, no change in display mode occurs in the receiver as the priority program that is originally in 2D is converted into a 3D program to match the display mode of the preceding program. Accordingly, a state is avoided in which the first portion of a priority program, such as a commercial, is not displayed.
     (h) Further, the controller generates 3D images without parallax by duplicating the 2D source images making up the priority program and inputs the 3D images without parallax to the 3D encoder, and the transmission device further includes an information transmitter transmitting information for specifying a 3D program without parallax generated by the 3D encoder.   

     A 3D program without parallax includes redundant frames that are not necessary for playback. As such, displaying a 3D program without parallax poses a problem of increased electric power consumption by the display device. According to the above configuration, the reception device receives information from the transmission device for specifying a 3D program without parallax, thus enabling an instruction for deleting the redundant frames to be made to the display device. Accordingly, the increased electric power consumption by the display device is constrained.
     (i) In addition, the information transmitter transmits the information to further specify the priority program, among the programs in the video stream, as being intended for display on a display device connected to a reception device corresponding to the transmission device at a priority program display frequency equal to a preceding program display frequency used immediately previously.   

     When the display device switches between the 2D display mode and the 3D display mode, the display frequency must also be changed. The change in display frequency may also cause the screen to be blacked out. According to the above configuration, the reception device receiving the information specifying the priority program from the transmission device is able to make an instruction to the display device such that the priority program is displayed at the same display frequency as the preceding program, thus preventing a change in display frequency by the display device and constraining the screen from being blacked out.
     (j) Furthermore, when the priority program is made up of the 2D source images and the preceding program is made up of the 3D source images: the input unit inputs the 2D source images making up the priority program to the 2D encoder as the 2D images; the controller generates new 2D images from the 3D source images making up the preceding program, and inputs the new 2D images to the 2D encoder; and the video stream generator generates the video stream so as to include the priority program as the 2D program generated by the 2D encoder and the preceding program, which is another 2D program.   

     According to this configuration, no change in display mode occurs in the receiver as the preceding program that is originally in 3D is converted into a 2D program to match the display mode of the priority program. Accordingly, a state is avoided in which the first portion of a priority program, such as a commercial, is not displayed.
     (k) Additionally, when the priority program is made up of the 3D source images and the preceding program is made up of the 2D source images: the input unit inputs the 2D source images making up the preceding program to the 2D encoder as the 2D images; the controller generates new 2D images from the 3D source images making up the priority program, and inputs the new 2D images to the 2D encoder; and the video stream generator generates the video stream so as to include the priority program as the 2D program generated by the 2D encoder and the preceding program, which is another 2D program.   

     According to this configuration, no change in display mode occurs in the receiver as the priority program that is originally in 3D is converted into a 2D program to match the display mode of the preceding program. Accordingly, a state is avoided in which the first portion of a priority program, such as a commercial, is not displayed.
     (l) Further still, when the priority program is made up of the 3D source images and the preceding program is made up of the 2D source images: the input unit inputs the 3D source images making up the priority program to the 3D encoder as the 3D images; the controller generates new 3D images from the 2D source images making up the preceding program, and inputs the new 3D images to the 3D encoder; and the video stream generator generates the video stream so as to include the priority program as the 3D program generated by the 3D encoder and the preceding program, which is another 3D program.   

     According to this configuration, no change in display mode occurs in the receiver as the preceding program that is originally in 2D is converted into a 3D program to match the display mode of the priority program. Accordingly, a state is avoided in which the first portion of a priority program, such as a commercial, is not displayed.
     (m) Yet still, the controller generates 3D images without parallax by duplicating the 2D source images making up the preceding program and inputs the 3D images without parallax to the 3D encoder, and the transmission device further includes an information transmitter transmitting information for specifying a 3D program without parallax generated by the 3D encoder.   

     A 3D program without parallax includes redundant frames that are not necessary for playback. As such, displaying a 3D program without parallax poses a problem of increased electric power consumption by the display device. According to the above configuration, the reception device receives information from the transmission device for specifying a 3D program without parallax, thus enabling an instruction for deleting the redundant frames to be made to the display device. Accordingly, the increased electric power consumption by the display device is constrained.
     (n) Yet further, the information transmitter transmits the information to further specify the priority program, among the programs in the video stream, as being intended for display on a display device connected to a reception device corresponding to the transmission device at a priority program display frequency equal to a preceding program display frequency used immediately previously.   

     When the display device switches between the 2D display mode and the 3D display mode, the display frequency must also be changed. The change in display frequency may also cause the screen to be blacked out. According to the above configuration, the reception device receiving the information specifying the priority program from the transmission device is able to make an instruction to the display device such that the priority program is displayed at the same display frequency as the preceding program, thus preventing a change in display frequency by the display device and constraining the screen from being blacked out.
     (o) A reception device comprises: a stream receiver receiving a video stream made up of a plurality of programs, including a 3D program encoded using a 3D encoding method; an information receiver receiving information for specifying a priority program among the programs in the video stream; and a decoding processor decoding the video stream, using the information to specify the priority program, and performing control such that the priority program is output to a channel used for connecting to a display device at a priority program transfer rate equal to a preceding program transfer rate used by a preceding program output immediately before the priority program.   

     According to this configuration, the priority program is output at the same transfer rate as the preceding program, thus removing any need for a communication mode reset between the reception device and the display device. Thus, the display device is able to normally display the priority program.
     (p) Also, the video stream further includes a 2D program encoded using a 2D encoding method, and the decoding processor equalizes the priority program transfer rate and the preceding program transfer rate by performing, on one of the priority program and the preceding program, a conversion of decoded 2D images into 3D images by doubling data or a conversion of decoded 3D images to 2D images by halving data.   

     According to this configuration, the priority program is output at the same transfer rate as the preceding program despite a 2D program and a 3D program being combined, thus removing any need for a communication mode reset between the reception device and the display device. Thus, the display device is able to normally display the priority program.
     (q) Still, when the priority program is the 2D program and the preceding program is the 3D program, the decoding processor generates 3D images without parallax by duplicating 2D images obtained upon decoding the priority program, and outputs 3D images obtained upon decoding the preceding program and the 3D images without parallax generated by duplication.   

     According to this configuration, no change in display mode occurs in the display device as the priority program that is originally in 2D is converted into a 3D program to match the display mode of the preceding program. Accordingly, a state is avoided in which the first portion of a priority program, such as a commercial, is not displayed.
     (r) Further, an HDMI transmitter transmitting the 2D images and the 3D images obtained upon decoding to the display device, using a communication method conforming to a High-Definition Multimedia Interface (HDMI) standard, wherein the reception device and the display device are connected via a channel conforming to the HDMI standard, and when transmitting the 3D images without parallax, the HDMI transmitter adds a redundant flag indicating that the 3D images are without parallax.   

     A 3D program without parallax includes redundant frames that are not necessary for playback. As such, displaying a 3D program without parallax poses a problem of increased electric power consumption by the display device. The reception device thus enables the display device to delete the redundant frames by transmitting a redundant flag to the display device in a header or the like of the redundant frames. Accordingly, the increased electric power consumption by the display device is constrained.
     (s) In addition, when the priority program is the 2D program and the preceding program is the 3D program, the decoding processor decodes the preceding program and selects one of left-view images and right-view images for output, and outputs 2D images obtained upon decoding the priority program.   

     According to this configuration, no change in display mode occurs in the display device as the preceding program that is originally in 3D is converted into a 2D program to match the display mode of the priority program. Accordingly, a state is avoided in which the first portion of a priority program, such as a commercial, is not displayed.
     (t) Further still, the 3D program includes a left-view video stream and a right-view video stream, one of the left-view video stream and the right-view video stream being a base view video stream and the other being an additional view video stream, the additional view video stream having been generated with reference to the base view video stream, the additional view video stream has additional information indicating whether or not the additional view video stream is usable when the reception device converts the 3D images into the 2D images, according to whether or not reduction has been applied to 3D source images to generate the additional view video stream, and the decoding processor uses the additional information to specify which of the left-view images and the right-view images, obtained upon decoding the preceding program, is selected.   

     When 3D source images are being reduced during a additional view video stream generation, using the additional view video stream images in the 2D display mode is likely to cause image degradation and discomfort for the viewer. Thus, according to the above configuration, the reception device is able to select appropriate images using the additional information when converting a preceding program that is a 3D program into a 2D program to match the display mode of a priority program.
     (u) Additionally, when the preceding program is the 2D program and the priority program is the 3D program, the decoding processor outputs 2D images obtained upon decoding the preceding program, and decodes the priority program and selects one of left-view images and right-view images for output.   

     According to this configuration, no change in display mode occurs in the display device as the priority program that is originally in 3D is converted into a 2D program to match the display mode of the preceding program. Accordingly, a state is avoided in which the first portion of a priority program, such as a commercial, is not displayed.
     (v) In further addition, the 3D program includes a left-view video stream and a right-view video stream, one of the left-view video stream and the right-view video stream being a base view video stream and the other being an additional view video stream, the additional view video stream having been generated with reference to the base view video stream, the additional view video stream has additional information indicating whether or not the additional view video stream is usable when the reception device converts the 3D images into the 2D images, according to whether or not reduction has been applied to 3D source images to generate the additional view video stream, and the decoding processor uses the additional information to specify which of the left-view images and the right-view images, obtained upon decoding the priority program, is selected.   

     When 3D source images are being reduced during a additional view video stream generation, using the additional view video stream images in the 2D display mode is likely to cause image degradation and discomfort for the viewer. Thus, according to the above configuration, the reception device is able to select appropriate images using the additional information when converting a priority program that is a 3D program into a 2D program to match the display mode of a preceding program.
     (w) Yet further, when the priority program is the 3D program and the preceding program is the 2D program, the decoding processor generates 3D images without parallax by duplicating 2D images obtained upon decoding the preceding program, and outputs 3D images obtained upon decoding the priority program and the 3D images without parallax generated by duplication.   

     According to this configuration, no change in display mode occurs in the display device as the preceding program that is originally in 2D is converted into a 3D program to match the display mode of the priority program. Accordingly, a state is avoided in which the first portion of a priority program, such as a commercial, is not displayed.
     (x) In further addition, an HDMI transmitter transmitting the 2D images and the 3D images obtained upon decoding to a display device, using a communication method conforming to an HDMI standard, wherein the reception device and the display device are connected via a channel conforming to the HDMI standard, and when transmitting the 3D images without parallax, the HDMI transmitter adds a redundant flag indicating that the 3D images are without parallax.   

     A 3D program without parallax includes redundant frames that are not necessary for playback. As such, displaying a 3D program without parallax poses a problem of increased electric power consumption by the display device. The reception device thus enables the display device to delete the redundant frames by, for instance, transmitting a redundant flag to the display device in a header or the like of the redundant frames. Accordingly, the increased electric power consumption by the display device is constrained.
     (y) A reception device, comprising: a stream receiver receiving a video stream made up of a plurality of programs, including a 2D program encoded using a 2D encoding method and a 3D program encoded using a 3D encoding method; an information receiver receiving information for specifying a 3D program without parallax; a decoding processor decoding the video stream received by the stream receiver; and an HDMI transmitter transmitting 2D images and 3D images obtained upon decoding to a display device, using a communication method conforming to an HDMI standard, wherein when transmitting 3D images without parallax, the HDMI transmitter adds a redundant flag indicating that the 3D images are without parallax.   

     A 3D program without parallax includes redundant frames that are not necessary for playback. As such, displaying a 3D program without parallax poses a problem of increased electric power consumption by the display device. The reception device thus enables the display device to delete the redundant frames by, for instance, transmitting a redundant flag to the display device in a header or the like of the redundant frames. Accordingly, the increased electric power consumption by the display device is constrained.
     (z) Also, the information receiver also receives information further specifying the priority program, among the programs in the video stream, as being intended for display on the display device connected to the reception device corresponding to a transmission device at a priority program display frequency equal to a preceding program display frequency used immediately previously, and the HDMI transmitter performs control such that the redundant flag is added to the 3D images when the priority program includes the 3D images without parallax.   

     When the display device switches between the 2D display mode and the 3D display mode, the display frequency must also be changed. The change in display frequency may also cause the screen to be blacked out. Thus, the above-described reception device constrains the processing applied to adding the redundant flag to the 3D images, such that no display frequency change occurs in the display device and the screen is constrained from blacking out.
     (A) A reception device, comprising: a stream receiver receiving a video stream encoded using a 3D encoding method; a 3D decoder decoding the video stream; and an output controller converting 3D images obtained upon decoding into 2D images for output, wherein the video stream includes a left-view video stream and a right-view video stream, one of the left-view video stream and the right-view video stream being a base view video stream and the other being an additional view video stream, the additional view video stream having been generated with reference to the base view video stream, the additional view video stream includes additional information indicating, in accordance with a reduction factor applied to 3D source images upon generation of the additional view video stream, whether or not the additional view video stream is used when the reception device converts the 3D images into 2D images; and the output controller uses the additional information to determine whether or not the additional view video stream is used when converting the 3D images into the 2D images.   

     When 3D source images are being reduced during a additional view video stream generation, using the additional view video stream images in the 2D display mode is likely to cause image degradation and discomfort for the viewer. Thus, according to the above configuration, the reception device is able to select appropriate images using the additional information when converting 3D images into 2D images. 
     INDUSTRIAL APPLICABILITY 
     The image processing system pertaining to an aspect of the disclosure is applicable to the industries of manufacturing and selling transmission devices, BD recorders, digital televisions, and the like. The image processing system is also applicable to use as technology enabling a priority program to be displayed normally on a digital television despite 2D and 3D programs being combined. 
     LIST OF REFERENCE SIGNS 
     
         
           1 ,  2  Image processing system 
           10 ,  10   a,    10   b  Transmission device 
           20 , 20   a,    20   b  BD recorder 
           30 ,  30   a,    30   b,    70  Digital television 
           40  HDMI cable 
           50  Remote control 
           60  3D glasses 
           101  Input unit 
           102  2D encoder 
           103 ,  103   a  3D encoder 
           104  Priority flag generator 
           105  Multiplexer 
           106  Stream transmitter 
           120  Controller 
           130  2D flag generator 
           201  Tuner 
           202  Demultiplexer 
           203  Control information manager 
           204 ,  204   a  Decoding processor 
           205 ,  205   a,    205   b  HDMI transmitter 
           211  2D/3D determiner 
           212  Switcher 
           213  2D decoder 
           214  3D decoder 
           215  Output controller 
           215   a  Output unit 
           216  Redundant flag generator 
           301  HDMI receiver 
           302 ,  302   a  Video display processor 
           303  Display