JP2006121578A - Image transmission system, image transmitting apparatus, image receiving apparatus and image transmitting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image transmission system wherein transmission efficiency can be improved by suppressing increase in the amount of transmission data with delay correction of camera operation. <P>SOLUTION: An image transmitting apparatus 200 includes an image encoding unit 101 for performing compression encoding on an image photographed by a camera 110 with a compression rate that is different for each region, and a transmission unit 102. An image receiving apparatus 300 includes a transmission unit 152, an image decoding unit 154, a remote control unit 154, and an image display control unit 155 for correcting the display range of an image. The image encoding unit 101 sets the compression rate of the image vicinity higher three times in comparison with that of the image center. Thus, while camera operation is not performed, the amount of all the transmission data in 50% is used for actual display in the center. Even while panning to right is performed, the amount of all the transmission data in 33% is used to actual display. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image transmission system, an image transmission device, an image reception device, and an image transmission method for transmitting an image taken by a camera.

  Conventionally, a remote monitoring system is known as an example of an image transmission system that transmits an image captured by this type of camera. In the remote monitoring system, when video is encoded and transmitted to the network as a packet, video delay occurs at the receiving terminal due to fluctuations in the arrival time of image data in the network. When an operation such as panning or tilting is performed from the receiving terminal to the camera on the transmitting terminal side, the greater the delay of this video transmission, the later the operation result is reflected in the received video, and the operability decreases.

  A conventional remote monitoring system includes an image compression encoding unit that compresses and encodes an image captured by a camera to generate image data, an image expansion unit that expands the compression encoded image data, and an instruction frame necessary for operation. An instruction frame generation unit is generated, an image composition unit that synthesizes an image with the instruction frame, and an operation information analysis unit that analyzes operation information (see Patent Document 1). In this remote monitoring system, the operation information and the display delay of the image are analyzed, and the expected movement position is presented on the delayed screen, thereby suppressing the decrease in operability.

  In addition, a method is known in which a range wider than the display range is captured and transmitted in advance, and the display range is corrected on the receiving side so that no delay occurs (see Patent Document 2). In this method, in addition to the appearance that no delay occurs, the designated area is always displayed at the center of the screen.

JP 2002-165212 A Japanese Patent Laid-Open No. 2002-185556

  However, in the conventional image transmission system as described above, when the display range is corrected on the receiving side, the larger the delay, the larger the photographing range that must be photographed, which increases the amount of transmission data. There was a situation. Further, when the camera operation is not performed, there is a situation in which a lot of transmitted data is wasted without being displayed, and transmission efficiency is lowered.

  The present invention has been made in view of the above circumstances, and an image transmission system, an image transmission device, and an image reception device capable of suppressing an increase in the amount of transmission data associated with camera operation delay correction and improving transmission efficiency. It is another object of the present invention to provide an image transmission method.

An image transmission system according to the present invention is an image transmission system for transmitting an image captured by a camera, wherein the image encoding means generates the image data by compressing and encoding the image at a different compression ratio for each region; and Image transmitting means for transmitting the image data generated by the image encoding means, image receiving means for receiving the transmitted image data, image decoding means for decoding the received image data, and the decoding Display means for displaying the processed image data.
As a result, it is possible to suppress an increase in the amount of transmission data that accompanies camera operation delay correction and to improve transmission efficiency.

Further, as one aspect of the present invention, in the above-described image transmission system, when displaying a predetermined display range by the display unit among the operation unit that operates the camera and the decoded image data, Image display control means for correcting the display range so that there is no transmission delay of the image data in the appearance of display on the display means when the camera is operated is provided.
As a result, even if a camera operation is performed, it is possible to make it appear that there is no apparent delay in transmission of image data, and it is possible to suppress deterioration in image quality.

According to another aspect of the present invention, in the image transmission system described above, the image encoding unit divides the image into a plurality of regions in a lattice shape, and at least one region located in a central portion is a peripheral portion. It is assumed that compression encoding is performed at a compression rate lower than that of the area located in the area.
As a result, the smaller the operation amount of the camera, the more image data with a lower compression ratio at the center is displayed, so that the amount of data used for display increases and image quality deterioration can be reduced.

Also, as one aspect of the present invention, in the image transmission system described above, the image encoding unit sets a compression rate for each region in accordance with the operation content of the camera.
Thus, according to the camera operation, for example, by reducing the compression rate of the region where the display range is corrected and setting the compression rate of other regions high, the image quality can be improved while suppressing the amount of transmission data. It becomes possible to plan.

An image transmission apparatus according to the present invention is used in an image transmission system that transmits an image captured by a camera, and transmits image data to an image reception apparatus. The image transmission apparatus has a different compression ratio for each region. Image encoding means for generating image data by compression encoding, image transmission means for transmitting image data generated by the image encoding means, and camera control means for controlling the operation of the camera according to an operation instruction It is to be prepared.
As a result, it is possible to suppress an increase in the amount of transmission data that accompanies camera operation delay correction and to improve transmission efficiency.

An image receiving apparatus according to the present invention is used in an image transmission system for transmitting an image captured by a camera, and receives image data from an image transmitting apparatus. The image receiving apparatus has a different compression ratio for each region. Image receiving means for receiving image data generated by compression encoding from the image transmitting apparatus, image decoding means for decoding the received image data, and display means for displaying the decoded image data Is provided.
As a result, it is possible to suppress an increase in the amount of transmission data that accompanies camera operation delay correction and to improve transmission efficiency.

The image transmission method of the present invention is an image transmission method for transmitting an image captured by a camera, wherein the image encoding step generates the image data by compressing and encoding the image at a different compression ratio for each region; and An image transmission step for transmitting the generated image data, an image reception step for receiving the transmitted image data, an image decoding step for decoding the received image data, and the decoded image data And a display step for displaying.
As a result, it is possible to suppress an increase in the amount of transmission data that accompanies camera operation delay correction and to improve transmission efficiency.

  According to the present invention, it is possible to provide an image transmission system, an image transmission device, an image reception device, and an image transmission method capable of suppressing an increase in the amount of transmission data associated with camera operation delay correction and improving transmission efficiency. .

  In the present embodiment, a configuration example of an image transmission system applied to a remote monitoring system is shown.

  FIG. 1 is a block diagram showing a configuration of a remote monitoring system according to an embodiment of the present invention. The remote monitoring system 100 includes a camera 110, a monitor 111 corresponding to an example of a display unit, an image transmission device 200, an image reception device 300, and a dedicated line 400 connecting them.

  The image transmission apparatus 200 includes an image encoding unit 101 corresponding to an example of an image encoding unit that compresses and encodes an image captured by the camera 110 at a different compression rate for each region, and the compressed and encoded image data. The transmission unit 102 corresponds to an example of an image transmission unit that transmits to the image reception device 300 and receives an operation instruction from the image reception device 300. The operation instruction received by the image transmission device 200 is transmitted from the transmission unit 102 to the camera 110. The camera 110 includes a camera control unit 115 that corresponds to an example of a camera control unit that performs a camera control operation that changes a shooting range such as pan, tilt, zoom in, and zoom out, and performs pan, tilt, and the like in accordance with received operation instructions. Perform the operation.

  On the other hand, the image receiving apparatus 300 receives the compressed and encoded image data from the image transmitting apparatus 200 and also transmits a transmission unit 152 corresponding to an example of an image receiving unit that transmits an operation instruction to the image transmitting apparatus 200. An image decoding unit 153 corresponding to an example of an image decoding unit that decodes the image data, a remote operation unit 154 corresponding to an example of an operation instruction unit for remotely operating the camera, and a monitor after correcting the display range of the image 111 has an image display control unit 155 corresponding to an example of an image display control unit that makes it appear that no delay occurs when displayed on the screen 111. Specifically, when a predetermined display range of the decoded image data is displayed on the monitor 111, when the camera is operated, the camera operation is performed so that an apparent transmission delay of the image data does not occur. Accordingly, the position of the display range is changed.

  The image encoding unit 101 may add a difference to the compression rate for each area by using encoding that divides the screen into a plurality of small areas such as MPEG and JPEG. You may use the encoding which supports (Region Of Interest). The image decoding unit 103 decodes the image data encoded by the image encoding unit 101.

  The remote operation unit 154 includes means for measuring a mechanical position in order to detect a camera operation by the user. As the means for measuring, for example, a means for detecting the amount of movement of the stick, pressing of the button or the amount of movement may be used, or pressing of a virtual operation button or the like displayed on the Web browser or the control monitor. The movement may be interpreted and output.

  The operation of the remote monitoring system having the above configuration will be described. FIG. 2 is a diagram showing how to correct the display range of the image in the pan operation of the remote monitoring system of this embodiment. When the image captured by the camera 110 is encoded by the image encoding unit 101 in the image transmission device 200 and transmitted to the transmission unit 152 in the image reception device 300 via the dedicated line 400 by the transmission unit 102, Decoded by the image decoding unit 103.

  When the remote operation unit 154 detects a camera operation by the user, the remote operation unit 154 outputs an operation signal (operation instruction) for the camera 110 to the transmission unit 152 and notifies the image display control unit 155 of the operation content. The operation instruction input to the transmission unit 152 is transmitted to the transmission unit 102 in the image transmission apparatus 200 via the dedicated line 400 as described above. As described above, the image display control unit 105 corrects the image display range so that transmission delay of image data does not occur. Specifically, in FIG. 2, at time T <b> 0 when panning is started in the right direction, the captured image includes captured portions 1 to 5. At the next photographing time T1, photographing portions 2 to 6 are included. Similarly, at the next photographing time point T2, photographing portions 3 to 7 are included. At the time point T3 when the panning is stopped, the photographing parts 4 to 8 are included. Thereafter, at the photographing time point T4, the panning operation is stopped, so that the photographing portions 4 to 8 remain.

  On the other hand, at the time point T0, among the shooting parts 1 to 5 included in the received image, the shooting parts 2 to 4 located in the center are displayed. At the subsequent time point T1, since transmission delay occurs, a captured image at the pan start time point T0 is obtained as a received image, and the captured portions 3 to 5 are corrected to be in the display range. At the subsequent time point T2, the captured image at the capturing time point T1 is obtained as a received image, and the captured portions 4 to 6 are corrected to be in the display range. At the subsequent time T3, the captured image at the capturing time T2 is obtained as the received image, and the captured portions 5 to 7 are corrected to be in the display range. At the subsequent time point T4, since the pan operation is stopped, the captured image captured at the capturing time point T3 is obtained as the received image, and correction is performed so that the captured portions 5 to 7 located in the center are within the display range.

  In this way, an image can be displayed so that there is no delay with respect to the start of the pan operation. Although FIG. 2 shows a pan operation, the same processing can be performed in camera operations such as tilt, zoom in, and zoom out operations.

  FIG. 3 is a diagram showing a bandwidth allocated when the compression rate for each region when encoding is performed by the image encoding unit 101 of the present embodiment is equal. In this embodiment, the range (display range) actually displayed on the monitor 111 in the received image data is set to 25%, and the captured image is divided into 16 areas to set the compression rate. It was. The numbers in each area represent the bandwidth to be assigned, and the larger the number, the lower the compression rate. FIG. 3A shows bandwidth allocation when the compression rate of image data is set evenly. In FIG. 3B, when the camera operation is not performed, the central portion is the display range. In FIG. 3C, when the camera is operated and panning in the right direction, the right side portion is the display range. In either case, that is, regardless of whether or not the camera is operated, 25% of the total transmission data amount is actually used for display, and the remaining 75% is used for delay correction of the camera operation.

  FIG. 4 is a diagram showing a bandwidth allocated when the compression rate for each region when encoding is performed by the image encoding unit 101 of the present embodiment is set high in the peripheral portion of the image. FIG. 4A shows band allocation in the case where the compression ratio of the peripheral portion of the image is set to be three times higher than that of the central portion. In FIG. 4B, when the camera operation is not performed, the center portion is the display range. In this case, 50% of the total transmission data amount can be used for actual display. In FIG. 4C, when there is a camera operation and panning in the right direction, the right side portion is the display range. Even when the camera is operated, 33% of the total transmission data amount can be used for actual display. The smaller the operation amount, the larger the amount of data used for display and the less the deterioration of image quality. Note that methods other than those described above may be used for setting the region dividing method and compression rate.

  As described above, according to the remote monitoring system of the present embodiment, by compressing and encoding an image at a different compression rate for each region, an increase in the amount of transmission data associated with delay correction of camera operation is suppressed, and transmission efficiency is improved. Can be improved.

  The above is the description of the embodiments of the present invention. However, the present invention is not limited to the configurations of these embodiments, and the functions shown in the claims or the functions of the configurations of the embodiments are included. Any configuration that can be achieved is applicable.

  For example, in the above-described embodiment, the image transmission device and the image reception device are connected via a dedicated line, but may be connected via a network such as the Internet instead of the dedicated line. Further, in the above embodiment, the image captured by the camera is divided into 4 × 4 grid-like regions, and the four regions located in the central portion are 1 / compared to the 12 regions located in the peripheral portion. Although compression encoding is performed at a compression rate as low as 3, the method of dividing an image region and setting the compression rate for each region are not limited to this. For example, the image may be divided into 8 × 8 grid-like regions, or may be divided into regions surrounded by a plurality of concentric circles. Further, the compression rate setting may be changed according to the camera operation. That is, in accordance with the camera operation, the compression rate of the region where the display range is corrected is set low, and the compression rate of other regions is set high. For example, in the case of a pan operation, the upper and lower regions of the image do not contribute to the display, so the compression rate of these regions may be increased and the compression rate of the left and right regions may be decreased. In the case of a tilt operation, the left and right areas of the image do not contribute to the display, so the compression ratios of these areas may be increased and the compression ratios of the upper and lower areas may be decreased. Thereby, it is possible to improve the image quality while suppressing the amount of transmission data.

  The present invention has an effect of suppressing an increase in the amount of transmission data associated with delay correction of camera operation and improving transmission efficiency, and an image transmission system for transmitting an image photographed by a camera, an image This is useful for a transmission device, an image reception device, an image transmission method, and the like.

The block diagram which shows the structure of the remote monitoring system which concerns on embodiment of this invention The figure which shows how to correct | amend the display range of the image in pan operation of the remote monitoring system of this embodiment The figure which shows the zone | band allocated when the compression rate for every area | region at the time of encoding by the image encoding part of this embodiment is set equally. The figure which shows the zone | band allocated when the compression rate for every area | region at the time of encoding by the image encoding part of this embodiment is set high in an image peripheral part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Remote monitoring system 101 Image encoding part 102,152 Transmission part 110 Camera 111 Monitor 153 Image decoding part 154 Remote operation part 155 Image display control part 200 Image transmission apparatus 300 Image reception apparatus

Claims (7)

An image transmission system for transmitting an image captured by a camera,
Image encoding means for generating image data by compressing and encoding the image at a different compression ratio for each region;
Image transmitting means for transmitting the image data generated by the image encoding means;
Image receiving means for receiving the transmitted image data;
Image decoding means for decoding the received image data;
An image transmission system comprising: display means for displaying the decoded image data. The image transmission system according to claim 1,
Operation instruction means for instructing operation of the camera;
When displaying the predetermined display range by the display means in the decoded image data, when the camera is operated, the transmission of the image data is not delayed due to the appearance of the display on the display means. An image transmission system comprising: an image display control unit that corrects the display range. The image transmission system according to claim 1 or 2,
The image encoding means divides the image into a plurality of areas in a grid pattern, and compresses and encodes at least one area located in the central part at a lower compression rate than the area located in the peripheral part. . The image transmission system according to claim 2,
The image encoding system is an image transmission system in which the compression rate for each region is set in accordance with the operation content of the camera. An image transmission device that is used in an image transmission system that transmits an image captured by a camera and transmits image data to an image reception device,
Image encoding means for generating image data by compressing and encoding the image at a different compression ratio for each region;
Image transmitting means for transmitting the image data generated by the image encoding means;
An image transmission device comprising: camera control means for controlling the operation of the camera in accordance with an operation instruction. An image receiving device that is used in an image transmission system that transmits an image captured by a camera and receives image data from an image transmitting device,
Image receiving means for receiving, from the image transmitting apparatus, image data generated by compressing and encoding the image at a different compression ratio for each region;
Image decoding means for decoding the received image data;
An image receiving apparatus comprising: display means for displaying the decoded image data. An image transmission method for transmitting an image captured by a camera,
An image encoding step of generating image data by compressing and encoding the image at a different compression ratio for each region;
An image transmission step of transmitting the generated image data;
An image receiving step of receiving the transmitted image data;
An image decoding step for decoding the received image data;
A display step of displaying the decoded image data.

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