JP2004040594A - Image signal transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a setup for increasing the speed of radio transmission and for supplying images at a high-definition level to a thin-type television, and for transmitting high-definition pictures by radio, since the thin-type television is made large, and the resolution of the thin-type television is improved. <P>SOLUTION: A bit stream is obtained by a number-of-pixels conversion means 103 for converting high-resolution images into a number of pixels in a display device, a plurality of low-resolution image compression means 105-107, and a multiplexing means 108 for the compressed signals for radio transmission. Based on the error rate of the bit stream, a modulation method or the like is determined, separation is made by a separation means 114, decoding is conducted by a plurality of low-resolution image decoding means 115-117, and then an original high-resolution image is restored by a compositing means 118. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a system for compressing and transmitting an image signal, and decoding and displaying the image signal. In particular, the present invention relates to a system for compressing and transmitting a high-resolution image signal using a low-resolution compression unit, and converting the original high-resolution image signal. The present invention relates to a technology that enables decoding and display.
[0002]
[Prior art]
2. Description of the Related Art A system for efficiently transmitting information on a transmission path with a limited transmission rate using an image compression technique such as digital broadcasting has been put into practical use. These are applied not only to digital broadcasting but also to broadband Internet applications and image storage in storage media such as DVDs and HDDs.
[0003]
In this technology, the compression ratio of an image is determined in accordance with a transmission path, a recording speed, and the like. In many cases, an Internet system is operated at an image quality comparable to a VTR, and a storage medium is operated at an image quality equivalent to a standard television. In a broadcasting system represented by BS digital broadcasting, a broadband transmission system can be used, so that image transmission with high-definition image quality is possible, and quality-first services are provided along with high-quality audio. .
[0004]
HDDs, D-VHS, home movies, and the like also employ MPEG-based compression techniques. These are used to record analog broadcasts by compressing and recording using an MPEG codec LSI. We are trying to make it longer. Digital broadcast receivers have been developed and equipped with decoders for decoding high-definition-level compressed images, but these are dedicated to digital broadcast reception and are basically products with only a decoding function.
[0005]
On the other hand, with the development of display technology, PDPs (Plasma Display Panels), large-sized liquid crystal televisions, and the like have been commercialized, and thin televisions are gradually spreading in homes. These products have a feature that they can be placed anywhere in the home because they are thin. Therefore, in many cases, the monitor and the broadcast receiver are provided in separate housings. Among them, there is a product having a TV tuner and an Internet connection function, wirelessly transmitting received screen information and displaying the information on a liquid crystal monitor. Thus, the installation location of the monitor can be selected regardless of the reception environment in the room, and in some cases, the monitor can be carried around.
[0006]
As related prior arts of image transmission, Japanese Patent Application Laid-Open Nos. Hei 10-108175, Hei 6-133286, Hei 8-46961, Hei 9-18878, and Hei 2000-324489 are known. Japanese Patent Laid-Open Publication No. 2000-138911.
[0007]
[Problems to be solved by the invention]
In FIG. 3, reference numeral 301 denotes an information receiving system for receiving and processing information from a television broadcast or the Internet; 302, a broadcast / network receiving unit which receives a television broadcast wave from an antenna or an information signal from a network such as the Internet; A system control unit 303 controls the entire reception processing system 302. An OSD / graphics unit 304 generates a graphic screen or an OSD (on-screen display) screen for a user interface from information received by the broadcast / network receiving unit 302. A generating unit 305 is a synthesizing unit for synthesizing a television image or the like with the graphic screen or OSD screen, 306 is an image compressing unit for compressing the amount of information of an image, 307 is a wireless transmitting unit, and 308 is a transmitting antenna. Reference numeral 309 denotes a display system unit, 310 denotes a system control unit that controls the entire display system unit, 311 a receiving antenna, 312 a wireless receiving unit, 313 an image decoding unit, and 314 a display monitor.
[0008]
In FIG. 3, a display image is created by the OSD / graphics generation unit 304 for Web information and the like obtained from the Internet. The television broadcast wave received from the antenna is demodulated by the broadcast / network receiving unit 302 to generate a video. A user interface screen for television operation is also created by the OSD / graphics generation unit 304, and these are synthesized by the synthesis unit 305 to form an image to be provided to the user. The system shown in FIG. 3 is intended to display this image on a display device at a remote place, and therefore compresses the image to an amount of information that can be transmitted through a wireless transmission path. This is performed by the image compression unit 306, and the compressed signal is transmitted from the antenna 308 via the wireless transmission unit 307. On the other hand, the display system unit 309 decodes the signal received by the antenna 311 in the image decoding unit 313 in accordance with the compression method of the image compression unit 306 to restore the original image information. By displaying this on the monitor 314, a receiving system that does not select the installation location of the display device is established. Normally, the image compression algorithm used in the system of FIG. 3 is an MPEG technology that has been used in digital broadcasting and the like, and among them, MP @ ML (main profile @ main) suitable for compressing / decoding a standard resolution television signal. Level) technology is used. As for wireless technology, a technology capable of transmitting an information amount of about 3 to 6 Mbps obtained by compressing a standard resolution television signal by the MPEG algorithm is available at a low price.
[0009]
By employing the technique of FIG. 3, it is possible to freely carry a thin display, and to use a TV with high interior characteristics such as a wall-mounted type, regardless of the installation location.
[0010]
The example of the display device shown in FIG. 3 is very effective in realizing an application such as a wall-mounted television or a portable television. On the other hand, digital broadcasting has begun to spread, especially BS digital broadcasting, which mainly broadcasts high-definition video. Therefore, in wireless transmission of standard definition television signals, it is necessary to faithfully reproduce and view all contents. It's getting harder.
[0011]
The problem is to replace the MPEG2MP @ ML corresponding to the standard resolution as an image compression algorithm with the technology of the MPEG2 MP @ HL (main profile @ high level) layer used for high definition video of BS digital broadcasting, The transmission can also be realized by using a standard capable of transmitting about 30 Mbps.
[0012]
However, it is only the content compressed on the broadcast station that records the high-definition on the D-VHS, and there is no need to compress the high-definition class image for recording the movie or the analog broadcast on the D-VHS. . For this reason, at present, no high-definition class image compression means for home appliances is provided. Similarly, wireless transmission having a high information transfer rate has a large cost problem.
[0013]
Under such circumstances, an inexpensive mechanism for increasing the speed of wireless transmission and supplying a high-definition image to a flat-screen television has not yet been provided. On the other hand, since the size and the resolution of a flat-screen television are increasing, it is necessary to provide a mechanism for transmitting high-definition video wirelessly at low cost.
[0014]
[Means for Solving the Problems]
The above object can be achieved by inexpensively wirelessly transmitting a high-definition image by adopting a configuration as described in claim 1.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 102 denotes an image generation unit; 103, a pixel number conversion unit for converting the number of pixels of the image from the image generation unit; 104, an image distribution unit for dividing the image; N standard image compression units for compressing images; 108, a multiplexing unit for multiplexing N image-compressed signals into one signal sequence; 109, a radio for transmitting the multiplexed signals as radio signals A signal transmission unit 110 is a transmission antenna, and 111 is a system control unit 1 that controls each unit. The system control unit 1 configures an image information compression transmission unit 100 that compresses an image and transmits it as a wireless signal.
[0016]
Also, 112 is a receiving antenna, 113 is a wireless signal receiving unit, 114 is a separating unit that separates the output signal of the wireless signal receiving unit 113 into a plurality of compressed signals, and 115, 116, and 117 are compressed image signals, respectively. A reference image decoding unit 118, an image synthesis unit 118 for synthesizing signals from the plurality of standard image decoding units, a high-resolution monitor 119 for displaying a synthesized image, and a system control unit 120 for controlling each unit. These constitute the image information decoding and displaying unit 101.
[0017]
In the present embodiment, the image generation unit 102 generates a received television image, an image obtained by combining an OSD signal such as a menu with the received television image, an image of Web information acquired through an Internet connection, and an image of a PC application. The image generated by the image generation unit 102 has a 1920 × 1080 pixel count in a high-definition program in the case of digital broadcasting or the like, and has a high resolution even in a PC application and can display 1600 × 1200 or the like. Here, it is assumed that the resolution of the high resolution monitor 119 is 1280 × 1080. In this case, the pixel number conversion unit 103 converts the number of pixels of the image generation unit 102 into the number of pixels of the high resolution monitor 119 using a filter or the like. The number of divided images in the image distribution unit 104 can be defined based on the converted number of pixels and the number of inputtable pixels of the standard image compression units 105, 106, and 107.
[0018]
FIG. 2 shows an example of dividing an image. FIG. 2A shows the number of pixels of the high resolution monitor 119 as an example in the present embodiment. FIG. 2B shows the number of input pixels of the standard image compression units 105 to 107. FIG. 2C shows how the divided screens overlap each other when four corner images are compressed using four standard image compression units. Generally available image compression LSIs and the like correspond to the standard resolution, and many can compress an image of up to 720 pixels in the horizontal direction and up to 576 pixels in the vertical direction. Therefore, when the four corners of the high-resolution monitor described in the present embodiment are taken out and compressed, there are portions overlapping each other. Image compression is performed by using a macroblock as a unit of a rectangle formed of a specific number of pixels, and since the motion of the image is detected for each macroblock, distortion is likely to occur at the end of the image. In the present embodiment, since the divided images are joined again by the image synthesizing unit 118, if there is a large amount of distortion at the joint, a problem occurs in the quality of the reproduced image. In order to avoid this distortion, a compression method in which the amount of motion vector is adjusted according to the number of overlapping pixels is employed, and the image synthesizing unit 118 determines the macroblock of the divided screen on the side that does not become the end of the image in the overlapping part. Control to extract.
[0019]
The compressed data obtained by the plurality of standard image compression units 105 to 107 can be extracted as a packet called a TS (Transport Stream), for example. The multiplexing unit 108 multiplexes the signals on the time axis to form one bit stream. If the image compressed by the standard image compression unit 105 or the like is, for example, 5 Mbps, four pieces of compressed data are multiplexed to complete a bit stream of 20 Mbps in total. This is a data rate that can be sufficiently transmitted within the standard range of high-speed wireless communication. If it is difficult to use a device for high-speed wireless communication, the multiplexing unit 108 extracts two bit streams obtained by multiplexing two screens, and provides two low-speed wireless transmission units to provide 10 Mbps. Data transfer is also possible.
[0020]
The image information decoding and displaying unit 101 separates the received stream into compressed data corresponding to the plurality of standard image compressing units 105 by the separating unit 114, and supplies the compressed data to the standard image decoding units 115 to 117, respectively. To restore the image. As described above, the image synthesizing unit 118 can restore a high-resolution image without losing quality by extracting data that does not become an end portion in an overlapping portion of the divided images.
[0021]
As described above, in the embodiment of the present invention, a high-definition level image is wirelessly transmitted by using a plurality of generally available inexpensive image compression apparatuses without using an expensive image compression apparatus. It becomes possible to make a wall-mounted television or a movable thin television compatible with high definition.
[0022]
Next, another embodiment of the present invention will be described with reference to FIG. FIG. 4 is an improvement of the image information decoding and display unit 101 of FIG. 1, and the corresponding image information compression transmission unit 100 is the same as that of FIG. In FIG. 4, reference numeral 401 denotes a high-resolution image decoding unit, and the rest is the same as the image information decoding and displaying unit 101. In FIG. 4, the high-resolution image decoding unit 401 is a so-called high-vision-compatible decoding device, and is capable of decoding about four standard-resolution compressed images simultaneously. Accordingly, in the embodiment of the present invention, the four standard resolution compressed data separated by the separation unit 114 are simultaneously input to the high resolution image decoding unit 401 and decoded. The decoded image is processed by the image synthesizing unit 118 in the same manner as described with reference to FIG. 1, and is output as one high-resolution image. When the high-resolution image decoding unit 401 has a graphics processing unit, the operation of the image synthesizing unit 118 can be performed by the graphics processing unit.
[0023]
In the embodiment of the present invention, there is no need to use a plurality of image decoding devices on the side for receiving and displaying wireless signals, which may be advantageous in terms of cost.
[0024]
Next, another embodiment of the present invention will be described. This embodiment will be described with reference to FIG. FIG. 5 is basically the same as the configuration of the image information compression transmission unit 100 of FIG. 1, except that a compression rate control unit 501 for controlling the compression rate of each of the standard image compression units 105 to 107 is added. The plurality of standard image compression units 105 to 107 compress the divided screens respectively, and convert the divided screens into one or a plurality of bit streams by the multiplexing unit 108. In this case, the information rate of the bit stream is designed to be within the information rate that can be transmitted by the wireless transmission unit 109. For example, if a transmission rate of 20 Mbps can be ensured by the wireless transmission unit, four standard image compression units (when N = 4) are set so as to obtain a compressed image at an information rate of 5 Mbps or less. You. In this case, no consideration is given to the ease of compression of each divided screen.
[0025]
In the system provided in the present application, the image generated by the image generation unit 102 is a video that has been compressed / decoded once in the case of, for example, digital broadcasting. Therefore, there is a possibility that the quality of the image is degraded by recompressing in the standard image compression units 105 to 107. This is because an image compression method represented by MPEG has an irreversible property and cannot restore a 100% original image. In order to minimize this deterioration, in FIG. 5, the compression rate control unit 501 is newly used to share information on the degree of difficulty of image compression in the standard image compression units 105 to 107. Assigning a large information rate to the standard image compression unit handling The allocation of the information rate depends on the transmittable information rate of the wireless transmission unit 109. Assuming that the maximum is 20 Mbps as in the above example, in a certain time zone, three of the four standard image compression units have a transmission rate of 4 Mbps. , And the remaining one is compressed at 8 Mbps. Further, since the compression rate control unit 501 has different image compression speeds in the standard image compression units 105 to 107, the compression rate control unit 501 also performs control to insert a timing signal presented on the decoding side to the multiplexing unit 108. Simultaneous image presentation control is enabled.
[0026]
According to the embodiment of the present invention, it is possible to minimize the quality of an image degraded by image compression, and to provide a high-quality system. In addition, in particular, the transmittable rate of the wireless transmission unit 109 is about 10 Mbps, and when multiplexing and transmitting a single bit stream, this is an upper limit information rate for providing high-resolution video. Is considered to greatly affect image quality.
[0027]
FIG. 6 shows another example of the embodiment of the present invention. FIG. 6 is basically an improvement of the image information decoding and displaying unit 101 in the system shown in FIG. 1, and includes a timing control unit 601 for controlling the standard image decoding units 115 to 117 through the image synthesizing unit 118. . When the information rates compressed by the standard image compression units 105 to 107 are different, there is a difference in processing time for decoding by the standard image decoding units 115 to 117. This can be solved by the image synthesizing unit 118 including a buffer memory and temporarily storing and synthesizing the images from the standard image decoding units 115 to 117. However, in order to reduce the memory capacity to be used, the timing control unit Reference numeral 601 denotes a request signal for extracting a part of an image through the image synthesizing unit 118 to the standard decoding units 115 to 117. For example, the image synthesizing unit 118 synthesizes and displays one line at a time. Is possible.
[0028]
According to the embodiment of the present invention, the configuration of the image information decoding display unit 101 can be simplified, and an inexpensive system can be provided.
[0029]
FIG. 7 shows another example of the embodiment of the present invention. FIG. 7 has basically the same configuration as the system shown in FIG. 1, but has a configuration capable of coping with a change in the reception environment between the image information compression / transmission unit 100 and the image information decoding / display unit 101. For example, in the case of a portable television, the reception state changes depending on the physical distance between the wireless transmission unit 109 and the wireless reception unit 113, the use environment of the monitor such as the presence or absence of an obstacle, and the like. Therefore, in consideration of these environments, transmission is performed at a modulation method and a transmission rate of the wireless transmission between the wireless transmission unit 109 and the wireless reception unit 113, or a compression rate in image compression, which are optimal for viewing the high-definition video. Need to be done.
[0030]
In order to determine such a modulation method and a compression rate, the wireless receiving unit 113 or the standard image decoding units 115 to 117 add a function of detecting an error rate, thereby detecting an error rate of received information. Of course, although not shown, a configuration for detecting the error rate may be separately provided. Here, since the object to be transmitted and received is a video, it is not necessary to transmit and receive again even if some error is detected. It is necessary to set in advance up to what error rate is allowed. The system control unit 2 (120) determines a modulation scheme or a compression rate in transmission and reception based on the detected error rate and the allowable error rate. In the determination, the error rate may be detected a plurality of times, and the result may be fed back to approximate the appropriate modulation scheme and compression rate. Then, the determined modulation scheme or compression rate is transmitted from wireless receiving section 113 to wireless transmitting section 109. Here, for convenience, the names of the wireless receiving unit 113 and the wireless transmitting unit 109 are used, but it is sufficient that each has a transmitting and receiving function.
[0031]
Upon receiving information on the modulation method and the compression rate from the system control unit 2 (120), the system control unit 1 (111) instructs the standard image compression units 105 to 107 on the compression rate. Of course, a configuration like the compression rate control unit 501 in FIG. 5 may be provided. Although not shown, the wireless transmission unit 109 can also be instructed on the modulation method.
[0032]
Although the modulation method and the compression rate are determined by the system control unit 2 (120), the system control unit 1 (111) receives necessary information from the system control unit 2 (120), and And the compression rate.
[0033]
The system control unit 1 (111) or the system control unit 2 (120) may control the modulation scheme and the compression rate in the image compression independently, or may control them in association with each other.
[0034]
The embodiments of the present invention can be applied to a transmission / reception system that does not divide an image, and can provide an inexpensive system that can perform stable transmission even in various use environments.
[0035]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, in the system which can freely select an installation place, such as a flat-panel television which is spreading, it can provide low-cost transmission and reception of a high-definition class high-resolution image using wireless communication technology.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of an embodiment of the present invention. FIG. 2 is a diagram illustrating a relationship between the number of pixels of a display unit and the number of pixels of a compression unit. FIG. 3 is a block diagram illustrating an example of an information receiving system. 4 is a block diagram showing another example of the embodiment of the present invention. FIG. 5 is a block diagram showing another example of the embodiment of the present invention. FIG. 6 is a block diagram showing another example of the embodiment of the present invention. FIG. 7 is a block diagram showing another example of the embodiment of the present invention.
100: Image information compression transmission unit, 101: Image information decoding and display unit, 102: Image generation unit, 103: Pixel number conversion unit, 104: Pixel distribution unit, 105, 106, 107: Standard image compression unit, 108: Multiplexing Unit, 109: wireless signal transmitting unit, 110: transmitting antenna, 111: system control unit 1, 112: receiving antenna, 113: wireless signal receiving unit, 114: separating unit, 115, 116, 117: standard image decoding unit, 118 ... Image synthesis unit, 119 ... High resolution monitor, 120 ... System control unit 2, 301 ... Information reception system, 302 ... Broadcast / network reception unit, 303 ... System control unit 1, 304 ... OSD / graphics generation unit, 305 ... Synthesis Unit, 306 image compression unit, 307 wireless transmission unit, 308 transmission antenna, 309 display system, 310 system control unit 2 311 ... receiving antenna, 312 ... wireless reception unit, 313 ... image decoding unit, 314 display monitor, 401 ... high-resolution image decoding unit, 501 ... compression rate control unit, 601 ... timing control section

Claims (9)

Input means for receiving an image signal;
Image compression means for compressing the image signal input at the input means,
Transmitting means for transmitting the image signal compressed by the image compressing means,
Receiving means for receiving the image signal transmitted by the transmitting means,
Decoding means for decoding the compressed image signal received by the receiving means;
Error rate detecting means for detecting an error rate in transmission between the transmitting means and the receiving means,
Control means for controlling a modulation scheme between the transmission means and the reception means or a compression rate in the image compression means, based on the error rate detected by the error rate detection means,
An image signal transmission system comprising: Input means for receiving an image signal;
Dividing means for dividing the image signal input in the input means into a plurality of images,
A plurality of image compression means for compressing the plurality of image signals divided by the division means,
Transmitting means for transmitting a plurality of image signals compressed by the plurality of image compressing means,
Receiving means for receiving the image signal transmitted by the transmitting means,
A plurality of decoding means for decoding a plurality of compressed image signals received by the receiving means,
Combining means for combining images decoded by the plurality of decoding means;
Error rate detecting means for detecting an error rate in transmission between the transmitting means and the receiving means,
Control means for controlling a modulation method between the transmission means and the reception means or a compression rate in the plurality of image compression means, based on the error rate detected by the error rate detection means,
An image signal transmission system comprising: 3. The image signal transmission system according to claim 2, wherein the signals transmitted and received by the transmission unit and the reception unit are obtained by multiplexing a plurality of images compressed by the image compression unit. Pixel number conversion means for converting the number of pixels of the image signal according to the number of pixels of the display device,
The image signal transmission system according to claim 2, wherein the pixel number conversion unit converts the number of pixels of the image signal input by the input unit and outputs the converted signal to the division unit. The image signal transmission system according to claim 2, wherein the divided image signal has a portion that overlaps with an adjacent divided image signal. The image signal transmission system according to claim 5, wherein the synthesizing unit cuts off an end of one of the images and synthesizes an overlapping portion with an adjacent image. 7. The image signal transmission system according to claim 2, wherein one high-resolution decoding unit capable of processing an input image signal is used instead of said plurality of decoding units. 8. The image signal transmission system according to claim 2, wherein said control means controls a compression rate in each image compression means according to an image state of an image signal to be transmitted. 9. The image signal transmission system according to claim 8, further comprising timing control means for controlling decoding timings of said plurality of decoding means when respective compression rates of said plurality of image compression means are different.

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