Image transmission system and image transmission method

1. An image transmission system, comprising:

a coaxial cable; and

a plurality of cameras, each of said plurality of cameras including:

an imaging circuit that acquires an image signal by imaging an object,

a coding circuit that generates a coded signal by compression-coding said image signal through one of intra-frame compression or inter-frame compression,

a signal output circuit that outputs said coded signal onto said coaxial cable, and

a synchronous signal generation circuit of a first camera of said plurality of cameras generates a synchronous signal that is transmitted to a second camera of the plurality of cameras, wherein

said second camera outputs said coded signal, obtained through intra-frame compression, onto said coaxial cable after a predetermined time period following receipt of said synchronous signal from said first camera.

2. The image transmission system according to claim 1 , wherein

said first camera of said plurality of cameras further includes a selection signal generation circuit that generates a selection signal for selectively allowing said second camera of said plurality of cameras to output said coded signal obtained through intra-frame compression onto said coaxial cable, and

said second camera includes an output control circuit that controls a signal output in such a manner that said second camera outputs said coded signal, obtained through intra-frame compression, onto said coaxial cable upon receipt of said selection signal from said first camera.

3. The image transmission system according to claim 1 , wherein each camera of said plurality of cameras further includes

an output control circuit that performs output control such that, upon receipt of a selection signal from another camera of said plurality of cameras for selectively allowing a camera of interest to output said coded signal obtained through intra-frame compression onto said coaxial cable, said coded signal obtained through intra-frame compression is output onto said coaxial cable, and

a selection signal generation circuit that generates said selection signal for selectively allowing a third camera of said plurality of cameras to output said coded signal obtained through intra-frame compression onto said coaxial cable.

4. The image transmission system according to claim 1 , wherein each camera of said plurality of cameras further includes

an output detection circuit that detects the output by another camera of said plurality of cameras of said coded signal obtained through intra-frame compression onto said coaxial cable, and

an output control circuit that controls signal output such that when the output by the another camera of said coded signal obtained through intra-frame compression onto said coaxial cable is not detected, said coded signal obtained through intra-frame compression is output onto said coaxial cable.

5. The image transmission system according to claim 1 , wherein

said coded signal generated by said coding circuit includes an I-picture, a P-picture, and a B-picture,

said coding circuit generates said coded signal by compression-coding said image signal in an MPEG format, the MPEG denoting Moving Picture Experts Group, and

a camera of interest outputs either said P-picture or said B-picture onto said coaxial cable when another camera of the plurality of cameras outputs said I-picture onto said coaxial cable.

6. An image transmission method by a first camera of a plurality of cameras in an image transmission system, said image transmission method comprising:

acquiring an image signal by imaging an object;

generating, by a coding circuit, a coded signal by compression-coding said image signal through intra-frame compression or inter-frame compression; and

generating, by a synchronous signal generation circuit, a synchronous signal that is transmitted to a second camera of said plurality of cameras,

wherein said second camera outputs said coded signal, obtained through intra-frame compression, onto said coaxial cable upon elapse of a predetermined time period following receipt of said synchronous signal from said first camera.

7. The image transmission method according to claim 6 , further comprising:

generating, by a selection signal generation circuit, a selection signal for selectively allowing said second camera of said plurality of cameras to output said coded signal obtained through intra-frame compression onto said coaxial cable, wherein

said second camera controls a signal output in such a manner that said second camera outputs said coded signal, obtained through intra-frame compression, onto said coaxial cable upon receipt of said selection signal from said first camera.

8. The image transmission method according to claim 6 , further comprising:

performing, by an output control circuit, an output control such that, upon receipt of a selection signal from another camera of said plurality of cameras for selectively allowing a camera of interest to output said coded signal obtained through intra-frame compression onto said coaxial cable, said coded signal obtained through intra-frame compression is output onto said coaxial cable; and

generating, by a selection signal generation circuit, said selection signal for selectively allowing a third camera of said plurality of cameras to output said coded signal obtained through intra-frame compression onto said coaxial cable.

9. The image transmission method according to claim 6 , further comprising:

detecting, by an output detection circuit, the output by another camera of said plurality of cameras of said coded signal obtained through intra-frame compression onto said coaxial cable; and

controlling, by an output control circuit, said signal output such that when the output by the another camera of said coded signal obtained through intra-frame compression onto said coaxial cable is not detected, said coded signal obtained through intra-frame compression is output onto said coaxial cable.

10. The image transmission method according to claim 6 , wherein

said coded signal generated by said coding circuit includes an I-picture, a P-picture, and a B-picture,

said generating is performed by said coding circuit by compression-coding said image signal in an MPEG format, the MPEG denoting Moving Picture Experts Group, and

outputting of said coded signal by said first camera includes outputting either said P-picture or said B-picture onto said coaxial cable when another camera of the plurality of cameras outputs said I-picture onto said coaxial cable.

11. An apparatus, comprising:

processing circuitry configured to

acquire an image signal;

generate a first coded signal by compression-coding said image signal through intra-frame compression or inter-frame compression; and

generate a synchronous signal that is transmitted to another apparatus, wherein said another apparatus controls a signal output timing according to the synchronous signal such that said another apparatus outputs a second coded signal, obtained through intra-frame compression, upon elapse of a predetermined time period following receipt of said synchronous signal.

12. The apparatus according to claim 11 , wherein the processing circuitry outputs the first coded signal onto a coaxial cable.

13. The apparatus according to claim 12 , wherein

the processing circuitry generates a selection signal for selectively allowing the another apparatus to output said second coded signal obtained through intra-frame compression onto said coaxial cable, and

said another apparatus controls a signal output according to the selection signal such that said another apparatus outputs said second coded signal, obtained through intra-frame compression, onto said coaxial cable upon receipt of said selection signal.

14. The apparatus according to claim 12 , wherein the processing circuitry is further configured to

perform an output control such that, upon receipt of a selection signal from the another apparatus for selectively allowing the processing circuitry to output said first coded signal obtained through intra-frame compression onto said coaxial cable, said first coded signal obtained through intra-frame compression is output onto said coaxial cable; and

generate said selection signal for selectively allowing the another apparatus to output said second coded signal obtained through intra-frame compression onto said coaxial cable.

15. The apparatus according to claim 11 , wherein the processing circuitry is further configured to

detect the output by the another apparatus of said second coded signal obtained through intra-frame compression onto said coaxial cable; and

control said signal output such that when the output by the another apparatus of said second coded signal obtained through intra-frame compression onto said coaxial cable is not detected, said first coded signal obtained through intra-frame compression is output onto said coaxial cable.

16. The apparatus according to claim 11 , wherein

said first coded signal and said second coded signal includes an I-picture, a P-picture, and a B-picture,

said processing circuitry generates the image signal by compression-coding said image signal in an MPEG format, the MPEG denoting Moving Picture Experts Group, and

the processing circuitry outputs said first coded signal by outputting either said P-picture or said B-picture onto said coaxial cable when the another apparatus outputs said I-picture onto said coaxial cable.

17. The image transmission system according to claim 1 , wherein

a camera of interest of said plurality of cameras outputs said coded signal obtained through inter-frame compression, and not obtained through intra-frame compression, onto said coaxial cable when another camera of said plurality of cameras outputs said coded signal obtained through intra-frame compression onto said coaxial cable, and

the camera of interest outputs said coded signal obtained through intra-frame compression, and not through inter-frame compression, onto said coaxial cable when said other camera outputs said coded signal obtained through inter-frame compression onto said coaxial cable.

18. The image transmission system according to claim 1 , wherein said first camera outputs said coded signal, obtained through intra-frame compression, simultaneously with the generation of the synchronous signal.