JPH09214954A - Image transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit a high-resolution input moving image through the use of a low-speed transmission line while switching the image to a low-resolution moving image or a high-resolution still picture corresponding to selection from the reception side. SOLUTION: This system is provided with an encoder part 2 composed of a resolution converting filter 11 for defining the high-resolution moving image as an input signal and providing the low-resolution image from this high- resolution image, an encoder 12 for encoding the output of this converting filter 11, a freezer 13 for freezing the high-resolution image, an encoder 14 for encoding the output of this freezer 13, and a selector 15 for selecting any one of these two encoded outputs corresponding to a request on the reception side. Thus, even through a low-speed transmission line 106, the high-resolution still picture can be transmitted according to the request on the reception side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image transmission system, and more particularly to an image transmission system that compresses and encodes image data for transmission.

[0002]

2. Description of the Related Art As an example of a conventional image transmission system of this type, there is Japanese Patent Laid-Open No. 4-129488. In this technique, an input image, a moving image or a still image is discriminated, and accordingly, adaptively. A technique is disclosed in which the bandwidth of a filter is changed and controlled, the output of this filter is encoded, and the encoded output is sent to a transmission line. By doing so, the amount of generated information can be reduced, and the image quality under a constant transmission rate condition can be greatly improved.

[0003]

SUMMARY OF THE INVENTION In this conventional technique,
When the transmission line is of low speed, moving images and still images cannot be transmitted in high resolution.

An object of the present invention is to provide an image transmission system capable of transmitting a still image with high resolution even on a low speed transmission line.

[0005]

An image transmission system according to the present invention comprises a resolution converting means for converting input moving image data of a predetermined resolution into moving image data of a lower resolution and an output of the resolution converting means. First encoding means for encoding, still image converting means for converting the input moving image data into still image data, second encoding means for encoding the output of the still image converting means, and the first And selecting means for selectively sending the encoded output of the second encoding means to the transmission line according to the selection control signal.

In another image transmission system according to the present invention, first and second decoding means for respectively decoding the respective coded data of the first and second coding means, and reception from the transmission line. An input selecting means for supplying a signal to one of the first and second decoding means according to the selection control signal and an encoded output of the first and second decoding means according to the selection control signal. And an output selecting means for deriving the output.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The operation of the present invention will be described. On the transmission side, one high-resolution moving image can be selectively transmitted to the low-resolution moving image and the high-resolution still image on the transmission line as required, so that even a low-speed transmission line can be transmitted. It becomes possible for the receiving side to receive a high-resolution still image.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an encoding unit, that is, a transmitting side according to an embodiment of the present invention, and FIG. 2 is a block diagram of a decoding unit, that is, a receiving side.

First, referring to FIG. 1, in the encoding unit 1, the high resolution moving image input from the camera 3 to the resolution converter filter 11 via the line 101 is converted into a low resolution moving image by the resolution conversion filter 11. Converted to the line 102
Is input to the moving image encoder 12 via. The encoded output encoded in the encoder 12 is supplied to the selector 15 via the line 103.

The high resolution moving image from the camera 3 supplied to the freeze unit 13 via the line 101 is converted into a still image by the freeze unit 13 and supplied to the still image encoder 14 via the line 104. And is encoded and supplied to the selector 15 via the line 105. In the selector 15, FIG.
One of a moving image coded and a still image coded is selected by the selection control signal supplied via the transmission path 107 from the decoding unit 2 shown in FIG.

Referring to FIG. 2, in the decoding unit 2,
The selector 21 determines whether the coded image supplied via the transmission path 106 is a moving image or a still image according to the selection control signal supplied via the line 208. It is supplied to the moving image decoder 22, and if it is a still image, it is supplied to the still image decoder 23 via the line 204.

The moving picture decoder 22 decodes the supplied encoded moving picture and supplies it to the selector 24 via the line 205. The still image decoder 23 decodes the supplied encoded still image and supplies it to the selector 24 via the line 20.

The selector 24 supplies one of the decoded images to the monitor 4 via the line 207 according to the control signal supplied via the line 208.

FIG. 3 is a diagram showing an example of the resolution conversion filter 11 in the encoding unit 1. The output line 101 from the camera 3 is input to a series circuit of delay elements 51 and 52 for one symbol (one sample of data), and the input and output of the delay element 51 and the output of the delay element 52 are multiplier 53,
At 54 and 55, tap coefficients (eg, 0.25,
0.5 and 0.25), respectively.

The multiplication outputs are added by an adder 56, and a 2: 1 subsample is applied by a sample switch 57. The subsample output is output 102 after resolution conversion.
Will be derived. In the example of FIG. 3, the low-pass filter configuration that halves the bandwidth of the input moving image,
As a result, a high-resolution moving image is transmitted at a low-speed transmission line 106.
Will be converted into a low resolution moving image.

FIG. 4 is a diagram showing an example of the freezer 13, which comprises a frame memory 58. Transmission line 107
When a still image is selected by the selection control signal by, the writing to the frame memory 58 is stopped in response to this selection, and the image of the same frame, that is, the still image is output during the still image selection period. Become.

In FIG. 1, as an example of the encoding system of the moving image encoder 12, the ITU-T H.264 standard is used. The moving picture coding method prescribed in H.261 can be used. Further, as an example of the encoding method of the still image encoder 14, JPEG is used.
(Joint Photographic Expert
t Group) and H.H. H.261 intra-frame coding schemes can be used.

With the above configuration, one high-resolution moving image obtained by the high-resolution camera is switched to either the low-resolution moving image or the high-resolution still image on the receiving side at any time, and the low-speed moving image is displayed. It can be received using the transmission path. For example, a surveillance camera or the like usually does not require a high resolution, but it is possible to pause a moving image and receive a high-resolution still image if necessary.

[0020]

As described above, according to the present invention, a high resolution moving image is converted into a low resolution and encoded, and a high resolution moving image is converted into a still image by a freeze unit. It is possible to send a high-resolution still image when necessary even on a low-speed transmission line, because the encoded data is selectively transmitted by the receiving side selection control. There is.

[Brief description of the drawings]

FIG. 1 is a block diagram of an encoding unit according to an embodiment of the present invention.

FIG. 2 is a block diagram of a decoding unit according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a resolution conversion filter.

FIG. 4 is a diagram showing an example of a freeze unit.

[Explanation of symbols]

 1 Encoding Unit 2 Decoding Unit 3 Camera 4 Monitor 11 Resolution Conversion Filter 12 Moving Image Encoder 13 Freeze Device 14 Still Image Encoder 15, 21, 24 Selector 22 Moving Image Decoder 23 Still Image Decoder

Claims (3)

[Claims] 1. A resolution converting means for converting input moving image data of a predetermined resolution into moving image data of a lower resolution, and a first encoding device for outputting the output of the resolution converting means.
Encoding means, still image converting means for converting the input moving image data into still image data, second encoding means for encoding the output of the still image converting means, and the first and second An image transmission system, comprising: a selection unit that selectively outputs the encoded output of the encoding unit to a transmission line according to a selection control signal. 2. The still image converting means has a frame memory for storing one frame of the input moving image data, and the selection control signal is a signal for selecting an encoded output of the second encoding means. In this case, the image transmission system according to claim 1, wherein the rewriting of the frame memory at that time is stopped thereafter. 3. The first and second decoding means for respectively decoding the encoded data of the first and second encoding means, and the reception signal from the transmission line according to the selection control signal. Input selection means for supplying to one of the first and second decoding means, and output selection means for selectively deriving the encoded outputs of the first and second decoding means according to the selection control signal. The image transmission system according to claim 1 or 2, further comprising: