JP2006279220A - Multipoint conference system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multipoint conference system for efficiently converting resolution and freely synthesizing video images from a plurality of terminals on one screen. <P>SOLUTION: The plurality of terminals 1-1 to 1-4 are connected to a server 2. The server 2 includes: transmitting/receiving means 8-1 to 8-4; a synthesis control means 9; a synthesizing means 10; and processing means 11-1 to 11-4. The processing means 11-1 to 11-4 receive converted and encoded compression encoding moving pictures from the terminals 1-1 to 1-4, so as to convert the resolution in a code area and perform area extracting processing. The synthesizing means 10 synthesizes the plurality of encoding moving pictures processed by the processing means 11-1 to 11-4, so as to perform synthesis into one encoding moving picture. The synthesized encoding moving picture is transmitted to the terminals 1-1 to 1-4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multipoint conference apparatus that realizes a multipoint video conference, and more particularly to a multipoint conference apparatus that can efficiently perform resolution conversion and combine images from a plurality of terminals.

  There are two types of video conference systems, that is, a mode in which a server exists and a mode in which no server exists. System configuration is easy when there is no server, but it is necessary to connect a new terminal to all other terminals as the number of users increases. Not right.

  On the other hand, in a form in which a server exists, a new terminal only needs to be connected to the server even if the number of users increases, so that a video conference system can be realized with a simple connection regardless of the number of users. For this reason, generally, a video conference system that connects multiple points has a form in which a server exists.

  In a multipoint video conference system in which a server exists, the server not only has the function of retransmitting images from multiple points, but also processes the images from multiple points individually to create an image that matches the connection environment. The function to transmit is required.

  For example, by giving the server the function of compositing multiple images from multiple points, reconstructing them into one image, and transmitting it, the overhead of control information can be reduced, or the bit can be changed according to the line conditions. The rate and frame rate can be converted adaptively. Also, by enlarging only the speaker or encoding only the speaker with high image quality in the composition screen to be transmitted, the video conference can be easily understood and progressed smoothly.

  In a multipoint video conference system where a conventional server exists, a method for selecting an image to be transmitted from a plurality of images received by the server and a plurality of images received by the server are combined and transmitted as one image. There is a method.

  The former method is described in Patent Document 1. In the video conference system described in Patent Document 1, a management table is provided to manage a conference participant's participation mode divided into a dialogue mode and an observer mode, and each user terminal classified into the dialogue mode By transmitting data with different communication loads between each device and the terminal device of each user classified into the observer mode, the remote communication between multiple points can be performed using the current communication infrastructure capacity to the maximum. Realize.

  The latter method is described in Patent Documents 2 and 3. In the multipoint control apparatus described in Patent Document 2, only the intra-frame video data that is intra-frame encoded by extracting the picture header of the video data from the multiplexed data from each video conference terminal is extracted and extracted. Synthesized intra-frame video data. This makes it possible to easily combine and display a plurality of video data.

In the multipoint control apparatus described in Patent Document 3, the encoded bitstream data is decoded into a bitstream having code information including at least motion vector information, and motion by changing the position of the video is converted into motion vector information. After adding the information, the bit stream data of one screen is reconstructed and encoded. As a result, the video position can be efficiently changed and rearranged without degrading the real-time property of the video communication.
Japanese Patent Laid-Open No. 2004-7561 JP 2001-69474 A JP-A-10-262228

  However, in the method of selecting an image to be transmitted from images received by the server as in the video conference system described in Patent Document 1, data such as an image of a person who does not participate in the dialogue is not transmitted. There is a problem that active discussions are hindered because it is necessary to wait for the right to speak.

  In the multipoint control device described in Patent Document 2, since only intra-frame video data is extracted and combined, it is easy to combine a plurality of images. However, since only intra-frame video data is used, it is combined and output. There is a problem that the motion of the image to be played is not smooth.

  In the multipoint control apparatus described in Patent Document 3, the server concatenates the received images and reconstructs one screen image. Therefore, the bit rate of the image transmitted from the server is the bit rate of the received image. Total. Therefore, in a connection environment where the bandwidth is limited, there is a problem that the number of images to be connected as one screen is limited and the composition cannot be freely performed.

  An object of the present invention is to solve the above-mentioned problems and to provide a multipoint conference apparatus that can efficiently combine resolutions and combine images from a plurality of terminals into one screen.

  In order to achieve the above-mentioned object, the present invention provides a conversion code in a multipoint conference apparatus that receives a plurality of pieces of transform-coded information, synthesizes the information into one transform-coded information on a code area, and transmits the information. A plurality of processing means for processing each of a plurality of encoded moving images compressed by the conversion on the code area and a plurality of encoded moving images processed by the plurality of processing means are combined into one code. The basic feature is that it is provided with a synthesizing means for synthesizing it into a synthesized moving image.

  In the present invention, the encoded moving image is processed on the code region without being decoded up to the pixel region (baseband), and is synthesized and combined into one encoded moving image. Thus, since it is not necessary to perform the decoding process and the recompression process, the apparatus configuration can be simplified. Note that it is necessary to prepare the same number of decoding devices as the number of terminals in the process of decoding the encoded moving image to the pixel region.

  Further, by directly manipulating the code information, the time required for processing such as resolution conversion at the time of image synthesis can be shortened, so that the delay associated with the processing can be suppressed and the speed can be increased.

  Furthermore, according to the present invention, not only intra-frame video data but also inter-frame video data can be generated, so that the motion of an image that is synthesized and output can be smoothed.

  Also, by performing resolution conversion simultaneously with the synthesis of a plurality of images, the bit rate of the video to be transmitted can be kept constant regardless of the number of images to be synthesized, so the number of images to be synthesized on one screen can be reduced. It is not limited and can be synthesized freely. In addition, when a plurality of images are transmitted simply by converting the resolution, a synchronization shift occurs between the images, and a process such as elimination of the synchronization shift is necessary for the subsequent synthesis. Since the images are combined and transmitted, there is no problem of synchronization shift between the plurality of images.

  Furthermore, in the process of combining a plurality of images, it is possible to embed arbitrary information in the image boundary portion, and by appropriately selecting the arbitrary information, the compression efficiency can be improved and the convenience of the user at the meeting can be achieved. .

  The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a multipoint conference apparatus according to the present invention. Clients (user terminals; hereinafter simply referred to as terminals) 1-1, 1-2, 1-3,... Are arranged for each user and connected to the server 2 located in the center thereof. .

  Each terminal 1-1, 1-2, 1-3,... Captures and converts a moving image (input moving image) captured by the camera 3-1, 3-2, 3-3,. Encoders 4-1, 4-2, 4-3,... That encode and output compressed encoded moving images, and transmit the compressed encoded moving images to the server 2 via a transmission path. , Receiving the compressed and encoded moving images distributed from the server 2, and decoding the received compressed and encoded moving images to display 6- The decoders 7-1, 7-2, 7-3,... Output to 1,6-2, 6-3,.

  The server 2 receives the compression encoded moving images (input compression encoded moving images) transmitted from the respective terminals 1-1, 1-2, 1-3,. When transmitting / receiving means 8-1, 8-2, 8-3,... For distributing encoded moving images and combining a plurality of input compressed encoded moving images into one compressed encoded moving image, it is used for combining. A combination control means 9 for instructing selection of an input compression-encoded moving image, arrangement in the screen, various effects, and the like. Based on an instruction from the combination control means 9, a plurality of input compression-encoded moving images are compressed by one. A synthesizing unit 10 for synthesizing the encoded moving image, and a processing unit 11-for performing processing necessary for synthesizing by the synthesizing unit 10 such as extraction of a predetermined area from the input compressed encoded moving image and resolution conversion on the code region. 1, 11-2, 11-3,...

  The synthesis control unit 9 instructs the synthesis unit 10 to synthesize a plurality of input compression-coded moving images according to parameters input manually or automatically. This instruction includes selection of an input compression-encoded moving image to be used for synthesis, on-screen arrangement, various effects, and the like. Layout, resolution conversion magnification, cutout, decoration frame (described later), and other effect information are stored as a database, and the information is recalled and instructed to the combining means 10 according to manually or automatically input parameters. You can also.

  The synthesizing unit 10 synthesizes a plurality of input compression-encoded moving images into one compression-encoded moving image on the code area in accordance with an instruction from the synthesis control unit 9. In addition, it instructs the processing means 11-1, 11-2, 11-3,.

  The processing means 11-1, 11-2, 11-3,... Process the input compressed and encoded moving image in accordance with instructions such as extraction of a predetermined area and resolution conversion from the synthesizing means 10. The processing in the processing means 11-1, 11-2, 11-3,... Is performed on the code area by reusing the code information itself or information obtained by variable-length decoding a part thereof, and the input compression code The converted moving image is not completely decoded up to the pixel region.

  Resolution conversion on the code area can be realized by matrix operation with a previously calculated conversion matrix. Specifically, the resolution conversion on the code domain is performed by inputting a set of transform coding coefficients corresponding to the denominator and the number of transform coding coefficients corresponding to the numerator when the magnification is expressed as a rational fraction. Output the pair.

  As a transformation matrix used for resolution transformation, a matrix obtained by combining transformation coding matrices for decoding transformation coding coefficients by the number of denominators, a matrix expressing resolution transformation corresponding to horizontal and vertical directions, and a pixel transformation code. The product of the transform coding matrix to be converted and the matrix combined with the number of numerators is calculated in advance.

  The resolution conversion process itself on the code area can be realized by a matrix operation of a matrix and a conversion matrix in which a high frequency component is forcibly set to 0 for each conversion coding coefficient of an input compression encoded moving image. That is, resolution conversion on the code region can be realized for the low-frequency component of the transform coding coefficient of the input compression-coded moving image. The high frequency component forcibly set to 0 can be controlled by the magnification, and the calculation amount can be suppressed while maintaining the image quality by this operation.

  Further, resolution conversion can be performed on the code region by using the technique previously proposed by the present inventors in Japanese Patent Application No. 2003-372223 (Prior Application 1). FIG. 2 is a functional block diagram of resolution conversion proposed in the prior application 1. The encoding coefficient acquisition unit 21 partially decodes the input compression encoded moving image to acquire the low frequency 4 × 4 DCT component of the 8 × 8 DCT coefficient, and outputs it to the subtractor 22 and the first reduced image generation unit 28. To do.

  The subtracter 22 obtains a difference between the low-frequency 4 × 4 DCT component for one frame acquired by the coding coefficient acquisition unit 21 and the predicted 4 × 4 DCT coefficient for one frame for which motion compensation has been performed, and 4 × for one frame. Prediction error information that is a difference value of 4DCT coefficients is output. The predicted 4 × 4 DCT coefficients for one frame subjected to motion compensation are output from the motion compensation unit 27.

  The quantization unit 23 quantizes the prediction error information obtained by the subtracter 22 and outputs the quantized prediction error information (quantized low frequency 4 × 4 DCT coefficient) to the inverse quantization unit 24 and the basis conversion unit 31. To do. The inverse quantization unit 24 inversely quantizes the quantization prediction error information obtained by the quantization unit 23 and outputs prediction error information including a quantization error.

  The adder 25 adds the prediction error information including the quantization error obtained by the inverse quantization unit 24 and the motion-compensated prediction 4 × 4 DCT coefficient for one frame, and adds a reference 4 × 4 DCT coefficient for one frame. Is output to the frame memory 26. The motion-compensated 27 × 4 DCT coefficients for one frame used here are also output from the motion compensation unit 27 described later.

  The frame memory 26 stores the reference 4 × 4 DCT coefficients for one frame obtained by the adder 25, and the motion compensation unit 27 and the first reference 4 × 4 DCT coefficients as one frame according to the encoding order. 2 to the reduced image generation unit 29.

  The motion compensation unit 27 performs motion compensation on the reference 4 × 4 DCT coefficient for one frame obtained from the frame memory 26 on the 4 × 4 DCT coefficient using the motion vector, and obtains the predicted 4 × 4 DCT coefficient for the previous one frame. This is generated and output to the subtracter 22 and the adder 25.

  The first reduced image generation unit 28 reduces the 2 × 2 DCT coefficients of the low frequency 4 × 4 DCT coefficients for one frame acquired by the coding coefficient acquisition unit 21 by 2 × 2 IDCT including only addition and subtraction. An image is generated, and the reduced image is output to the motion prediction unit 30.

  The second reduced image generating unit 29 generates a reduced image by processing the 2 × 2 DCT coefficients of the low frequency 4 × 4 DCT coefficients for one frame obtained from the frame memory 26 with 2 × 2 IDCT including only addition and subtraction. Then, this reduced image is output to the motion prediction unit 30.

  The motion prediction unit 30 searches for a motion vector between the reduced image obtained by the first reduced image generation unit 28 and the reduced image obtained by the second reduced image generation unit 29, and uses the searched motion vector. The result is output to the motion compensation unit 27.

  The basis conversion unit 31 converts the quantized prediction error information obtained by the quantization unit 23 into 8 × 8 DCT coefficients on the DCT coefficients, and outputs the quantized 8 × 8 DCT coefficients to the variable length coding unit 32. .

  The variable length coding unit 32 performs variable length coding on the quantized 8 × 8 DCT coefficient obtained by the basis conversion unit 31 and the motion vector obtained by the motion compensation unit 30, and outputs the result to the buffer 33.

  The buffer 33 temporarily holds and transmits the data obtained by the variable length encoding unit 32. The rate control unit 34 determines a quantization parameter based on the code amount held in the buffer 33 and controls the amount of information generated from the quantization unit 23.

  In processing such as resolution conversion on the code area, the conversion method can be switched according to whether priority is given to conversion speed or conversion accuracy. In the motion compensation on the code area, the processing load varies depending on the value that the motion information can take. Therefore, when giving priority to the conversion speed, it is preferable to preferentially set the motion information to a value with a small processing load. In order to reduce the processing load, the motion search process can be omitted, and instead, the median value of the motion information of the input compression-coded moving image existing in the processing target region can be used as the motion information of the output compression-coded moving image.

  When extracting or synthesizing an image, if the entire region or only a partial region thereof is cut out without performing resolution conversion, it is only necessary to extract the transform coding coefficient of the corresponding region from the compression-coded moving image. However, if the input compression-coded moving image retains only the residual component and motion information by motion compensation, it may refer to the outside of the region to be cut out, so only the corresponding region is an intra block on the code region. Convert to That is, only a necessary area in the input compression-coded moving image is converted into another format.

  For the process of performing inverse motion compensation on the code domain and converting it into an intra block, for example, the technique previously proposed by the present inventors in Japanese Patent Application No. 2004-5387 (Prior Application 2) can be used. FIG. 3 is a functional block diagram showing this process, and FIG. 4 is an explanatory diagram showing this state.

  In FIG. 3, the code information acquisition unit 35 partially decodes code information of a transform-coded input compression-coded moving image, and performs motion prediction information (motion vector) and quantized prediction error information (difference DCT coefficient). ) To get. The motion vector extracted by the code information acquisition unit 35 is output to the inverse motion compensation unit 37, and the quantized differential DCT coefficient is output to the inverse quantization unit 36.

  The inverse quantization unit 36 inversely quantizes the quantized differential DCT coefficient acquired by the code information acquisition unit 35. The differential DCT coefficient including the quantization error generated by the inverse quantization is output to the inverse motion compensation unit 37.

  The inverse motion compensation unit 37 includes a frame memory, and the difference between the reference DCT coefficient one frame before obtained from the frame memory, the motion vector obtained by the code information obtaining unit 35, and the processing target frame obtained by the inverse quantization unit 36. Inverse motion compensation is performed on the DCT coefficient region using the DCT coefficient (8 × 8 DCT coefficient) to derive the intra DCT coefficient of the processing target frame.

FIG. 4 shows the relationship between the four sets of difference 8 × 8 DCT coefficients generated by the inverse quantization unit 36, that is, macroblocks, and the reference DCT coefficients of the previous frame referred to based on the motion vector. Each of R _{00 to} R ₂₂ is a block of 8 × 8 DCT coefficients.

When reverse motion compensation is performed, four sets of difference 8 × 8 DCT coefficients for one macroblock may straddle up to nine sets of 8 × 8 DCT coefficients R _{00 to} R ₂₂ in the previous frame. Therefore, it is necessary to perform inverse motion compensation of 4 sets of difference 8 × 8 DCT coefficients from the motion vector and 9 sets of reference 8 × 8 DCT coefficients.

  If the horizontal and vertical components of the motion vector are multiples of 8 including 0, one block (DCT coefficient block) overlaps with the block of the previous frame and does not span a plurality of blocks. What is necessary is just to acquire the reference DCT coefficient of a place. In other cases, since it extends over a plurality of blocks, it is necessary to obtain and reconstruct DCT coefficients from those blocks.

  Prior application 2 describes that reverse motion compensation can be performed by using a pre-calculated conversion table even when the horizontal and vertical components of the motion vector are different for each numerical value that can be taken by the motion vector. The conversion table is derived from an arithmetic expression for reverse motion compensation on the pixel region. The method of the prior application 1 can also be used for re-searching motion information in inverse motion compensation on the code domain.

  When synthesizing a plurality of images by the synthesizing means 10 (FIG. 1), the input images obtained by converting the resolution of individual input images at an arbitrary magnification can be arranged so as not to overlap each other. It is also possible to arrange the input images so as to partially overlap each other. Also, it is possible to cut and arrange a part of the input image without converting the resolution.

  For example, in the case of a meeting at four points, it is possible to arrange the four input images so as not to overlap each other by halving the vertical and horizontal directions, or to an arbitrary position of one input image that does not perform resolution conversion. It is also possible to arrange three input images that are 1/8 times vertically and horizontally so as to overlap each other. This can be realized by overwriting the transform coding coefficient. It is also possible to cut out the vertical and horizontal half regions of the four input images from arbitrary positions so as not to overlap.

  If resolution conversion is used in combination, the bit rate of the compressed encoded moving image transmitted by the server 2 can be made smaller than the sum of the bit rates of the received four compressed encoded moving images in any arrangement.

  Furthermore, the arrangement of the images can be changed not only spatially but also temporally as described above. For example, by placing a speaker on a large screen, a noticeable image can be presented with more emphasis.

  When the synthesizing unit 10 synthesizes an input compression-encoded moving image whose resolution has been converted or an input compression-encoded moving image obtained by cutting out a predetermined region, the compression efficiency is increased due to discontinuity at the image boundary. May decrease. In order to improve the compression efficiency, it is possible to embed any information different from the input compression-coded moving image in the image boundary portion in the code area, and reduce the discontinuity at the boundary portion with the arbitrary information. .

  If the above-mentioned arbitrary information is used as a transform coding coefficient coded in advance and the boundary portion is replaced by this, the load on the synthesis process itself can be reduced. Also, arbitrary information can be replaced with only intra frames, and the same transform coding coefficients can be reused for other than intra frames, so that the compression efficiency can be improved. As much as the compression efficiency is improved, it can be directed to improving the image quality and speeding up in other areas.

  As said arbitrary information, the information relevant to a terminal, the information which displays a decoration frame, etc. can be used. It is also possible to change the boundary portion of the image by changing arbitrary information with time. For example, since an attention image can be emphasized and presented to a speaker by adding a flashy decorative frame, not only the compression efficiency is improved and the speed is increased, but also the convenience of the user can be achieved.

  The terminals 1-1, 1-2, 1-3,... Are usually arranged in different environments, and in such a case, the cameras 3-1, 3-2, 3-3,.・ ・ The brightness (brightness), contrast, color tone, etc. of the output image are different. When a plurality of images having different brightness, contrast, color tone, and the like are combined into a single image, there is no overall sense of unity and the image is difficult to see. In order to obtain an image that is uniform and easy to see as a whole, it is preferable to correct the luminance, contrast, color tone, and the like on the code area.

  If there is a difference between the average values of in-screen brightness in multiple input compression-coded moving images, the brightness of each image can be corrected by simply adjusting the DC component of the transform coding coefficient for intra frames. The brightness of the entire synthesized image can be kept constant. When the brightness is reduced in each image, the direct current component is decreased, and when the brightness is increased, the direct current component is increased.

  The contrast correction can be realized by adjusting the AC component of the coding coefficient. When the contrast is weakened, the AC component is decreased, and when it is increased, the AC component is increased.

  It is also possible to obtain an effect of smoothly and continuously synthesizing a plurality of images so as to be semitransparently overlapped. This can be realized by weighted averaging the transform coding coefficients in the boundary portion on the code area.

  It is also possible to emphasize and present only a specific area by operating brightness, contrast, color tone, etc. on the code area. For example, by removing the color difference component from the image other than the speaker, only the speaker can be made a color image and the speaker can be emphasized. The amount of information assigned to the removed color difference component can be assigned to the speaker's image to improve the image quality.

  FIG. 5 is a diagram showing a specific example of a composite image by the combining means 10, and all are examples in which four input images are combined in the case of a meeting at four points. (A) in the figure is an example in which four input images are arranged so as not to overlap each other by ½ times in the vertical and horizontal directions, and (b) in FIG. In this example, the images are arranged so as not to overlap each other, and in the figure (c), the image that is 2/3 times the width and the image that is 1/3 times the height and width are arranged so as not to overlap. FIG. 4D shows an example in which three images that are ¼ times in length and width are arranged so as to overlap at an arbitrary position of one image that is not subjected to resolution conversion. Image superimposition can be realized by overwriting the transform coding coefficient. In these synthesized images, a decorative frame such as a striped pattern or black is added to the image boundary. The striped pattern can be scrolled in the pattern direction by the motion vector.

  FIGS. 5E to 5H are examples of other composite images. As described above, the four images can be combined in various formats, and an arbitrary region can be cut out from the input image and combined. These synthesized images are decorated so as to surround the image boundary and the person of each image.

  Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

It is a block diagram which shows one Embodiment of the multipoint conference apparatus which concerns on this invention. It is a functional block diagram of the resolution conversion process on the code area proposed previously. It is a functional block diagram of the inverse motion compensation and conversion processing to an intra block on the code domain proposed previously. It is explanatory drawing of reverse motion compensation. It is a figure which shows the specific example of the synthesized image by a synthetic | combination means.

Explanation of symbols

1-1 to 1-4 terminal, 2 server, 3-1 to 3-4 camera, 4-1 to 4-4 encoder, 5-1 to 5- 4 ... transceivers, 6-1 to 6-4 ... display. 7-1 to 7-4... Decoder, 8-1 to 8-4 ... transmission / reception means, 9 ... synthesis control means, 10 ... synthesis means, 11-1 to 11-4. Processing means 21, 35: Code information acquisition unit, 22: Subtractor, 23: Quantization unit, 24, 36: Inverse quantization unit, 25: Adder, 26 .. Frame memory 27... Motion compensation unit 28 and 29... Reduced image generation unit 30... Motion prediction unit 31 .. basis conversion unit 32. 33: Buffer, 34: Rate control unit, 37: Reverse motion compensation unit

Claims (11)

In a multipoint conference apparatus that receives a plurality of transform-coded information, combines the information into one transform-coded information on a code area, and transmits the information,
A plurality of processing means for processing each of a plurality of encoded moving images compressed by transform encoding on the code region as an input;
A multipoint conference apparatus comprising: a combining unit that combines a plurality of encoded moving images processed by the plurality of processing units and combines them into one encoded moving image. The multipoint conference apparatus according to claim 1, wherein each of the plurality of processing units includes a processing unit that directly processes and processes code information of an encoded moving image on a code area. The multipoint conference apparatus according to claim 2, wherein the processing unit converts code information of an encoded moving image of only a necessary area into another format. The multipoint conference according to claim 2, wherein the processing unit performs at least one of a resolution conversion process on a code area and a process of extracting a specific area and forming an encoded moving image of a specified size. apparatus. The multipoint conference apparatus according to claim 2, wherein the processing unit switches a processing method according to which of conversion speed and conversion accuracy is prioritized. The multipoint conference apparatus according to claim 1, wherein the synthesizing unit includes a processing unit that directly processes and processes code information of the encoded moving image from the processing unit on a code region. The multiple synthesizing unit according to claim 6, wherein the synthesizing unit is capable of synthesizing a plurality of encoded moving images processed by the processing unit into one encoded moving image with an arbitrary spatial and temporal arrangement. Point conference equipment. The synthesizing unit includes an embedding processing unit capable of embedding arbitrary information in a code area in an image boundary portion when synthesizing a plurality of encoded moving images into one encoded moving image. Item 7. The multipoint conference device according to Item 6. The multipoint conference apparatus according to claim 8, wherein the embedding processing unit can select, as the arbitrary information, information that minimizes the amount of code generated after embedding. The multipoint conference apparatus according to claim 8, wherein the embedding processing unit can operate the arbitrary information on a code area to change in time and space. The multipoint conference apparatus according to claim 6, wherein the synthesizing unit includes a correction processing unit capable of correcting at least one of luminance, contrast, and color tone on a code area.

Images