WO2005027513A1

WO2005027513A1 - Method and system for capture of the multi-channel image signal implementing improved agc function

Info

Publication number: WO2005027513A1
Application number: PCT/KR2004/001844
Authority: WO
Inventors: Hyung Joo Kim; Jae Sool Shim; Joong Bum Yoon; Seung Il Cheong
Original assignee: Udp Co., Ltd.
Priority date: 2003-09-18
Filing date: 2004-07-23
Publication date: 2005-03-24
Also published as: KR100426655B1

Abstract

The present invention relates to a method and system for capturing of the multichannel image signal. More particularly, the present invention relates to a method and system for capturing of the multi-channel image signal, wherein the method and system can capture analog image signals which are input from a plurality of channels and have different magnitudes, convert the same into digital image signals having a certain magnitude, and prevent a decrease in speed (frame rate) when capturing. The present invention provides a system for capturing of the multi-channel analog image signal comprising a multiplexer for receiving a plurality of analog image signals from a plurality of channels respectively and outputting the same selectively; a standard signal output unit for measuring the magnitude of the analog image signal corresponding to each channel, determining gain required for outputting the predetermined aimed magnitude from the measured magnitude, and storing a value of a digital standard signal corresponding to the gain according to each channel; a digital/analog converting unit for searching the value of the digital standard signal corresponding to the channel determined according to a predetermined capturing order among the stored values of digital standard signals and generating an analog standard signal corresponding to the searched value of the digital standard signal; and an image signal capturing unit for amplifying the analog image signal corresponding to the channel determined according to a predetermined capturing order input from the multiplexer by using the generated analog standard signal and converting the amplified analog image signal into a digital image signal.

Description

METHOD AND SYSTEM FOR CAPTURE OF THE MULTI-CHANNEL IMAGE SIGNAL IMPLEMENTING IMPROVED AGC FUNCTION

Technical Field The present invention relates to a method and system for capturing of the multichannel image signal. More particularly, the present invention relates to a method and system for capturing of the multi-channel image signal, wherein the method and system can capture analog image signals which are input from a plurality of channels and have different magnitudes, convert the same into digital image signals having a certain magnitude, and prevent a decrease in speed (frame rate) when capturing.

Background Art Generally, the conventional system for capturing of the multi-channel image signal receives analog image signals photographed by using a CCD (Charge Couple Device) camera from a plurality of channels, converts the input analog image signals into digital image signals, and then stores the converted digital image signals using an image processing board. FIG. 1 is a drawing for explaining the conventional system for capturing of the multi-channel image signal 100. The system for capturing of the multi-channel image signal 100 receives analog image signals photographed by cameras 111, 112, 113 for each channel and captures the analog image signals whereby the system generates digital image signals. However, since the system for capturing of the multi-channel image signal 100 captures a plurality of analog image signals with one image signal capturing device (not shown), the system uses a method of capturing an analog image signal corresponding to each channel according to a predetermined capturing order. For example, the system uses a method of capturing a first analog image signal (a second and a third analog image signal not captured at this state), whereafter a second analog image signal, and finally a third analog image signal. Accordingly, there is a problem that a digital image signal digitalized and output by the system for capturing of the multi-channel image signal 100 has a decreased frame rate in comparison with the original first to third analog image signals, whereby image information is lost. Accordingly, it is required the method for capturing analog image signals input from the multi-channels with maintaining the frame rate of each analog image signal to the maximum. In the meantime, while analog image signals input from each camera 111, 112, 113 are being transmitted to the system for capturing of the multi-channel analog image signal 100, the magnitudes thereof diminish. Accordingly, in case the camera 111 is in a remoter location than the camera 112, since it is longer diminishing time until an analog image signal is input into the system for capturing of the multi-channel analog image signal 100, the magnitude of the second analog image signal is bigger than the magnitude of the first analog image signal for analog image signals input into the system for capturing of the multi-channel analog image signal 100. Furthermore, in case of the camera 113 in a remoter location than the camera 111, there is a case to install an amplifier in the middle of the camera 113 and the system for capturing of the multi-channel analog image signal 100 and amplify the third analog image signal in order to prevent the magnitude of the analog image signal from over-diminishing. In this case, there are many cases that the magnitudes of analog image signals input from a plurality of channels are different by channel, e.g., the magnitude of the third analog image signal is rather bigger than the magnitudes of the first and the second analog image signals. In this case, if the first to the third analog image signals are converted into the first to the third digital image signals by amplifying the analog image signals with the same gain, there is a problem that brightness of each screen corresponding to each image signal is different. Accordingly, although the system for capturing of the multichannel analog image signal 100 captures each analog image signal in the same way, it is necessary to regulate each gain thereof respectively in order for a user to have appropriate brightness of screen displaying the converted digital analog image signals. In other words, if it is too big the magnitude of the digital image signal after capturing, the screen is displayed too brightly, and if it is too small the magnitude of the digital image signal, the screen is displayed too dark. Therefore, in order to get the optimum brightness of screen, the analog image signal should be amplified by deciding gain according to the magnitude thereof before capturing. For example, in case that while the magnitude of an analog image signal for achieving the optimum brightness of screen is 1, the magnitude of a first analog image signal is 0.5, the magnitude of a second analog image signal is 1.1 and the magnitude of a third analog image signal is 1.5, each analog image signal should be amplified two times, 10/11 times, and 2/3 times. For this, the conventional system for capturing of the multi-channel analog image signal 100 is comprised as shown in FIG. 2. FIG. 2 is a block diagram illustrating a system for capturing of the multi-channel analog image signal 200 corresponding to the system 100. A multiplexer 201 receives a first to a third analog image signals from each channel and outputs the same selectively, an AGC (Automatic Gain Control) device 202 measures the magnitude of the output analog image signal whereby the device determines gain thereof and amplifies the output analog image signal according to the gain thereof. AGC function means the function of outputting a signal having a certain magnitude regardless of the magnitude of the input signal and an AGC device means the device of implementing AGC function. For example, in case that the certain magnitude is 1 as aforementioned, the measured magnitude of the first analog image signal is 0.5 and gain according thereto is 2. An image signal capturing device 203 captures the first analog signal whose magnitude is amplified to 1 by the AGC device 202 whereby the device 203 can obtain a first digital image signal having the magnitude of 1. In the mean time, although FIG. 2 illustrates the AGC device 202 and the image signal capturing device 203 as separate devices, generally the image signal capturing device 203 having the AGC device 202 built-in, the AGC device 202 is manufactured and sold. An indicating device 204 displays the first digital image signal output from the image signal capturing device 203, and there are some cases that the first digital image signal is not displayed on the indicating device 204 but transmitted to a computer in a remote location (not shown) to be stored or displayed. The system for capturing of the multi-channel analog image signal 200 is not to receive one analog image signal from one channel and convert the same into a digital image signal, but to receive a plurality of image signals from a plurality of channels and capture each analog image signal channel by channel according to a predetermined capturing order. However, whenever the conventional AGC device 202 captures the analog image signal corresponding to each channel, the device 202 requires the adaptation time which is from the time that the device 202 measures the magnitude of the analog image signal corresponding to one channel, decides gain thereof and amplifies the same to the time that the device 202 measures the magnitude of an analog image signal to be captured corresponding to next channel, decides gain thereof and amplifies the same (i.e. until the device 202 adapts to a new analog image signal). Accordingly, in the prior art, due to the above adaptation time, there are problems that users of the system for capturing of the multi-channel analog image signal 100 have no choice but to selectively use a method of decreasing capturing speed (deterioration of image quality) in order to use the AGC device 202 or a method of capturing at the aimed frame rate (failure for regulating the brightness of screen) although the AGC device 202 cannot act normally. In the meantime, although there is used the relative magnitude of an image signal for convenient explanations in the present specification, IRE unit (a unit named after (the Institute of Radio Engineers): lIRE is 0.00714V since the magnitude from the maximum point of the image signal to the minimum point thereof should be IV) is used to indicate the magnitude of the image signal. In the present specification, the magnitude of the image signal not having a separate unit means the relative magnitude which is used for convenient explanations.

Detailed Description of the Invention Technical Question The present invention is conceived in order to solve the aforementioned problems in the prior art and an object of the present invention is to provide a system and method for capturing of the multi-channel analog image signal which can implement AGC function without decreasing capturing speed (a frame rate).

Technical Solutions In order to achieve the object and to solve the aforementioned problems in the prior art, a system for capturing of the multi-channel analog image signal according to the present invention comprises a multiplexer for receiving a plurality of analog image signals from a plurality of channels respectively and outputting the same selectively; a standard signal output unit for measuring the magnitude of the analog image signal corresponding to each channel, determining gain required for outputting the predetermined aimed magnitude from the measured magnitude, and storing a value of a digital standard signal corresponding to the gain according to each channel; a digital/analog converting unit for searching value of the digital standard signal corresponding to the channel determined according to predetermined capturing order among the stored values of digital standard signals and generating an analog standard signal corresponding to the searched value of the digital standard signal; and an image signal capturing unit for amplifying the analog image signal corresponding to the channel determined according to a predetermined capturing order input from the multiplexer by using the generated analog standard signal and converting the amplified analog image signal into a digital image signal. According to an aspect of the present invention, the analog image signals comprise image signals of the blanking area and image signals of active area and the standard signal output unit measures the magnitudes of the analog image signals respectively based on image signals of the blanking area. Furthermore, the present invention provides a method for capturing of the multi-channel analog image signal comprising the steps of receiving a plurality of analog image signals from a plurality of channels respectively; measuring the magnitude of the analog image signal corresponding to each channel respectively; outputting value of a digital standard signal corresponding to each channel respectively based on the measured magnitude and storing the values; generating an analog standard signal based on value of the digital standard signal corresponding to the channel determined according to a predetermined capturing order; and amplifying the analog image signal corresponding to the channel determined according to the capturing order by using the generated analog standard value and converting the amplified analog image signal into a digital image signal. Furthermore, the present invention provides computer-readable recording media recording a program for implementing the method above.

Brief Description of the Drawings FIG. 1 is a drawing for explaining a system for capturing of the multi-channel image signal according to the prior art. FIG. 2 is a block diagram illustrating a system for capturing of the multichannel image signal according to the prior art. FIG. 3 is a block diagram illustrating a system for capturing of the multichannel analog image signal according to an embodiment of the present invention. FIG. 4 is a drawing illustrating one example of data stored in a standard signal output unit in one embodiment of the present invention. FIG. 5 is a drawing for explaining an organization of analog image signals in an embodiment of the present invention. FIG. 6 is a drawing illustrating one line of signals belonging to the active video area of analog image signals in an embodiment of the present invention. FIG. 7 is a drawing illustrating one line of signals belonging to the blanking area of analog image signals. FIG. 8 is a flowchart illustrating a method for capturing of an analog image signal according to another embodiment of the present invention. FIG. 9 is an internal diagram of a general-purpose computer which can be used in a system for capturing of the multi-channel image signal according to an embodiment of the present invention.

Best Mode for Carrying out the Invention Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 is a block diagram illustrating a system for capturing of the multi- channel analog image signal according to the present embodiment. A system 300 comprises a multiplexer 301, a standard signal output unit 302, a digital/analog converting unit 303 and an image signal capturing unit 304. The multiplexer 301 receives a plurality of analog image signals from a plurality of channels respectively and outputs at least one analog image signal among the input analog image signals selectively, and the output analog image signal is input into the image signal capturing unit 304. The standard signal output unit 302 measures the magnitude of each analog image signal input in the image signal capturing unit 304 respectively, outputs a value of a digital standard signal corresponding to each channel respectively based on the measured magnitude and then stores the output value. The value of the digital standard signal is used in order to determine gain in the process of converting the analog image signal into the digital image signal in the image signal capturing unit 304, which is mentioned later. As shown in FIG. 3, there are explained cases that a first to a third analog image signals are input respectively from three channels, i.e., a first to a third channels for examples. In case the magnitude of each of analog image signal input into the multiplexer 301 is 0.5 (a first analog image signal), 1.1 (a second analog image signal), 1.5 (a third analog image signal) and the desired magnitude of the digital image signal after capturing is 1, i.e., the aimed magnitude is 1, each gain is 2, 10/11, and 2/3. Since the desired magnitude of the digital image signal after capturing (hereinafter, 'aimed magnitude') is 1, the standard signal output unit 302 decides the value of the digital standard signal as the same value of the gain, outputs value of each digital standard signal corresponding to each channel as 2, 10/11, and 2/3 respectively, and store the same. Accordingly, data as shown in FIG. 4 are stored in the standard signal output unit 302. The image signal capturing unit 304 captures the first to the third analog image signals according to a predetermined capturing order. Since the image signal capturing unit 304 can capture only one analog image signal at one moment, it should be determined that in what order a plurality of analog image signals input from a plurality of channels are to be captured. It is defined that the order determined in this way is a "capturing order." For example, this capturing order may enable each corresponding analog image signal to be captured in order of the first channel, the second channel and the third channel. According to the embodiment, this capturing order may be determined at random by a user or according to predetermined algorism for increasing the capturing speed, etc. The digital/analog converting unit 303 searches the value of the digital standard signal corresponding to the channel determined according to the capturing order among the stored values of digital standard signals, and generates the analog standard signal based on the searched value of the digital standard signal. In the aforementioned example, in case the analog image signal corresponding to the first channel is captured in the image signal capturing unit 304, since the analog image signal corresponding to the second channel should be captured according to the capturing order, the digital/analog converting unit 303 searches the value of the digital standard signal corresponding to the second channel in the standard signal output unit 302 and generates the analog standard signal (substantially, conversion of the value of the digital standard signal into the analog standard signal) based on the searched value of the digital standard signal (' 10/11' as shown in FIG. 4). The image signal capturing unit 304 having captured the first analog image signal captures the second analog image signal according to the capturing order and converts the captured second analog image signal into a second digital image signal. At this time, the image signal capturing unit 304 converts the second analog image signal into the digital image signal wherein the magnitude of the second analog image signal after amplifying is to be 1 based on the analog standard signal. Furthermore, according to another embodiment of the present invention, there can be established a predetermined error range for the desired magnitude of the image signal. For example, in case that the desired magnitude of the analog image signal is 1 and an error range within 1% is set and in case that the magnitude of the input analog image signal is between 0.09 and 1.1 , the gain thereof can be 1. Furthermore, in case the magnitude thereof is between 0.09 and 1.1 at the result of amplification according to the gain output by the standard signal output unit 302, the image signal capturing unit 304 can decide that the analog image signal has been normally amplified and convert the amplified analog image signal into the digital image signal. The digital analog image signal output after the conversion is transmitted to a computer system such as PC 305, etc, and then stored or displayed according to uses thereof. As aforementioned, since it is possible to enable the magnitude of each digital image signal after capturing to be within a certain or predetermined error range by using the values of digital standard signals stored for each channel, if each digital image signal is displayed, the brightness of screen is uniformalized to suitable brightness for a user's use. Furthermore, in the prior art, in case of capturing analog image signals by changing one chamiel into another channel according to a channel order, adaptation time is necessary since it is needed to measure the magnitude of a new analog image signal, determine the gain thereof, and then amplify the same whenever the event happens. However, in case of the system for capturing of the multi-channel analog image signal 300 according to the present embodiment, if the system 300 determines the value of the digital standard signal corresponding to each channel just once, the system 300 does not need to repeat measurement of the magnitude and decision of gain whenever changing one channel into another channel. Therefore, the aforementioned adaptation time is not necessary. Accordingly, the system for capturing of the multi-channel analog image signal 300 can capture the multi-channel analog image signal at the same speed as that of before implementing AGC function, with regulating the brightness of screen to the optimum. For example, generally, in case of regulating the screen by using the conventional AGG device included in an image capturing device, it was impossible to support 30 [fps]. However, in case of using the system for capturing of the multichannel analog image signal 300 according to the present embodiment, it is possible to support frame rate of 30 [fps]. In the mean time, analog image signals comprise each frame. Each frame comprises the blanking area and the active video area as shown in FIG. 5. In FIG. 5, the vertical axis is time and the horizontal axis is one line of analog image signals. Furthermore, FIG 6 is a drawing illustrating one line of signals belonging to the active video area among analog image signals and FIG. 7 is a drawing illustrating one line of signals belonging to the blanking area among analog image signals. There is no video data included in signals belonging to the blanking area.

Therefore, there is no area having the shape as marked by dotted lines 601 of FIG 6, and period having the certain magnitude 'a' is longer than the signals belonging to the active video area as showed in FIG. 7. Accordingly, the system for capturing of the multi-channel analog image signal 300 according to another embodiment of the present invention measures the magnitude of the analog image signal by measuring the magnitude of the area marked by the solid line 703 of FIG 7 among the signals belonging to the blanking area. It is also possible to measure the magnitude of the analog image signal by measuring the magnitude of the area marked by the solid line 602 of FIG. 6. However, in the aspect that signals are unstable in many cases because the continuing section is short, it is preferable to measure the magnitude by using signals belonging to the blanking area. Hereinafter, a method for capturing of the multi-channel analog image signal according to another embodiment of the present invention will be described in detail. The method for capture of an analog image signal can be implemented by the system for capturing of an analog image signal as shown in FIG. 3. FIG. 8 is a flowchart illustrating the method for capturing of an analog image signal according to the present embodiment. The system for capturing of an analog image signal receives a plurality of analog image signals from a plurality of channels in the step of 801. The system for capturing of an analog image signal measures the magnitude of each analog image signal respectively in the step of 802, and outputs values of digital standard signals respectively based on the measured magnitude and stores the output values for each channel in the step of 803. Values of digital standard signals stored like above have a data structure as shown in FIG. 4. The system for capturing of an analog image signal captures a plurality of analog image signals corresponding to a plurality of channels according to a predetermined capturing order and decides analog image signals of the channel to be captured according to the capturing order in the step of 804. The system for capturing of an analog image signal generates the analog standard signal based on value of the digital standard signal corresponding to the channel to be captured in the step of 805 and after amplifying the analog image signal of the channel to be captured by using the analog standard signal, converts the amplified analog image signal into the digital image signal in the step of 806. Like above, since the gain (associated with the value of the digital standard signal) according to the magnitude of the analog image signal corresponding to each channel is predetermined and the corresponding analog image signal is captured according to the gain whenever the corresponding analog image signal is captured, there is no need of a period adapting to analog image signals of another channel every time (the period of time necessary for measuring the magnitude of the analog image signal and determining the gain thereof). Therefore, it is sharply reduced the period necessary for implementing AGC function. Accordingly, there is provided the method for capturing of the multi-channel analog image signal which can implement AGC function without decreasing a frame rate. In this embodiment, it is preferable to measure the magnitude of each analog image signal by using image signals belonging to the blanking area as the aforementioned embodiment. Furthermore, the present invention provides computer-readable media for implementing the system for capturing of the multi-channel analog image signal. The media may also include, alone or in combination with the program instructions, data files, data structures, tables, and the like. The media and program instructions may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well known and available to those having skill in the computer software arts. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROM disks; magneto-optical media such as floptical disks; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory devices (ROM) and random access memory (RAM). The media may also be a transmission medium such as optical or metallic lines, wave guides, etc. including a carrier wave transmitting signals specifying the program instructions, data structures, etc. Examples of program instructions include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. FIG. 9 is an internal diagram of a general-purpose computer system which can be adopted in the aforementioned system for capturing of multi-channel image signal. The computer system 900 includes any number of processors 901 (also referred to as central processing units, or CPUs) that are coupled to storage devices including primary storage (typically a random access memory, or "RAM 902 "), primary storage (typically a read only memory, or "ROM 903"). As is well known in the art, ROM 903 acts to transfer data and instructions uni-directionally to the CPU and RAM 902 is used typically to transfer data and instructions in a bi-directional manner. Both of these primary storage devices may include any suitable type of the computer-readable media described above. A mass storage device 904 is also coupled bi-directionally to CPU and provides additional data storage capacity and may include any of the computer-readable media described above. The mass storage device 904 may be used to store programs, data and the like and is typically a secondary storage medium such as a hard disk that is slower than primary storage. A specific mass storage device such as a CD-ROM 906 may also pass data uni-directionally to the CPU. Processor 901 is also coupled to an interface 905 that includes one or more input/output devices such as such as video monitors, track balls, mice, keyboards, microphones, touch-sensitive displays, transducer card readers, magnetic or paper tape readers, tablets, styluses, voice or handwriting recognizers, or other well-known input devices such as, of course, other computers. Finally, processor 901 optionally may be coupled to a computer or telecommunications network using a network connection as shown generally at 907. With such a network connection, it is contemplated that the CPU might receive information from the network, or might output information to the network in the course of performing the above-described method steps. The above-described devices and materials will be familiar to those of skill in the computer hardware and software arts.

Industrial Applicability According to the present invention, there is provided a system and method for capturing of the multi-channel analog image signal which can implement AGC function, wherein the system and method measures the magnitude of each analog image signal received from a plurality of channels respectively, pre-determines gain corresponding to each analog image signal based on the measured magnitude, captures the corresponding analog image signal by amplifying the same according to the pre-determined gain, whenever capturing the analog image signal whereby the system and method does not decrease capturing speed (a frame rate). Furthermore, in case of measuring the magnitude according to the present invention, there is an effect that it is possible to measure the magnitude of the analog image signal more correctly and stably by measuring the magnitude using signals belonging to the blanking area among analog image signals.

Claims

1. A system for capturing of the multi-channel analog image signal, the system comprising: a multiplexer for receiving a plurality of analog image signals from a plurality of channels respectively and outputting the same selectively; a standard signal output unit for measuring the magnitude of the analog image signal corresponding to each channel, determining gain required for outputting the predetermined aimed magnitude from the measured magnitude, and storing a value of a digital standard signal corresponding to said gain for each channel; a digital/analog converting unit for searching the value of the digital standard signal corresponding to the channel determined according to a predetermined capturing order among the stored values of digital standard signals and generating an analog standard signal corresponding to the searched value of the digital standard signal; and an image signal capturing unit for amplifying the analog image signal corresponding to the channel determined according to the capturing order input from the multiplexer by using the generated analog standard signal and converting the amplified analog image signal into a digital image signal.

2. The system as claimed in claim 1, further comprising: the analog image signals including image signals of the blanking area and image signals of active area; and the standard signal output unit measuring the magnitude of the analog image signal respectively based on the image signals of the blanking area.

3. A method for capturing of the multi-channel analog image signal, comprising the steps of: receiving a plurality of analog image signals from a plurality of channels respectively; measuring the magnitude of the analog image signal corresponding to each channel respectively; determining gain required for outputting the predetermined aimed magnitude from the measured magnitude; storing a value of a digital standard signal corresponding to the determined gain in a predetermined storage unit for each channel; searching the value of the digital standard signal corresponding to the channel determined according to a predetermined capturing order among the storage units.; generating an analog standard signal corresponding to the searched value of the digital standard signal; and amplifying the analog image signal corresponding to the channel determined according to said capturing order by using the generated analog standard signal and converting the amplified analog into a digital image signal.

4. A computer readable recording medium recording a program for implementing the method of claim 3.