JPH0351999A - license plate recognition device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a license plate recognition device that processes a still image of a traveling vehicle taken by a television camera to recognize the license plate of the vehicle.

2. Description of the Related Art Conventionally, in this type of license plate recognition device, when static images of moving vehicles taken by a plurality of television cameras are continuously processed, bus usage right arbitration means for connection with a host computer, etc. The priority order of each line is determined according to the connection state of the line. A line with a lower priority level cannot obtain the right to use the bus when a higher request line is using the bus or requesting the use of the bus.

In other words, the right to use the bus is granted to a bus request from a line with a lower priority only when the bus is unused and all higher-order lines have not issued a request for use. .

In addition, in license plate recognition, for example, character recognition of the vehicle type code and character recognition of the usage code, the recognition result will not be valid unless both recognitions are completed.
There is no priority order for each character recognition process.

On the other hand, license plate recognition requires processing all vehicles that are continuously running.

For this reason, plate cutout processing and character recognition processing are performed in a pipeline system. In addition, candidates for plate existing position address information as a result of plate cutting out are sent several times during one imaging session, and as soon as the results are determined, they are sent to character recognition processing. In most cases, the first time is the correct plate location address, but the extraction process is continued as long as there is time, and if there are candidates, they are sent to character recognition processing to improve the accuracy of extraction. For this reason, the bus arbitration system gives priority to the request line from the plate cutting process, and switches to give priority to the request line from the character recognition process when the first plate existing position address is determined.

Problems to be Solved by the Invention However, in the conventional license plate recognition device equipped with the above-mentioned bus right arbitration means, the priority order is fixed, so a request line with a lower priority has to wait a long time to obtain the right to use the bus. I was kept waiting for an hour. Furthermore, due to the limitations of the bus arbitration method, the recognition results are delayed due to waiting for priority order. Additionally, when the previous vehicle passes and the next vehicle is imaged, it is desirable that the plate cutting process be prioritized again, but since the priority could not be switched, the plate cutting process for the next vehicle could not be performed. There wasn't. Furthermore, when attempting to reduce waiting time by using multiple buses, even if a bus is acquired, the memory to be accessed using that bus is in use, so the bus may have to be released after all. This created an issue in terms of bus usage efficiency.

The present invention solves the conventional problems as described above.
Enables priority switching and high-speed bus arbitration control.
It is an object of the present invention to provide a license plate recognition device that can perform the recognition process efficiently.

Means for Solving the Problems The technical means of the present invention for solving the above problems includes an image information storage means having a plurality of image memory cards for storing still images of a running vehicle captured by a plurality of television cameras; A plate cutout image processing calculation means that determines whether or not an image of a license plate is included in the data stored in the image information storage means, and obtains the location address of the license plate if it exists, and the plate cutout image processing means. A character recognition means for recognizing each character in the license plate based on address information of the license plate location by the calculation means, and a plurality of buses capable of reading/writing to each of the image memory cards, each of the above means The present invention is equipped with a control means for outputting a current bus use permission response that is optimal for license plate recognition based on a bus acquisition request to which previous and current memory usage information has been added and the status of the previous bus use permission response. .

action The present invention has the following effects due to the above configuration.

The control means outputs the optimal bus use permission response for the current license plate recognition according to a preset algorithm based on the bus acquisition request with the previous and current memory usage information added and the previous bus use permission response status. do. Therefore, the permission response processing that is most suitable for license plate recognition in response to a bus request is performed in a short time, and when the right to use the bus is obtained, it is possible to reliably access the target memory without any waiting time.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

The figure is a schematic block diagram showing the main parts of a license plate recognition device in one embodiment of the present invention.

The license plate recognition device consists of a plate cutting unit (not shown) (consisting of a plurality of cards that checks the presence of a vehicle license plate from image data and obtains the address of the existing position) and a character recognition unit (not shown) It is equipped with multiple character recognition calculation cards that recognize each character in the license plate from information such as Land Transport Office branch code, vehicle model code, usage code, serial number, etc.

In the figure, l and 2 are bus request latches that latch bus use request lines with used memory information from a plurality of image memory cards (not shown) (storing still image digital data captured by a plurality of television cameras). Department. The information input to the bus request latch units 1 and 2 is as follows:
One image memory card contains four 2-bit information on two lines as shown below.

■No bus request.

■Request to use memory card 1.

■Request to use memory card 2.

■Request to use memory card 3.

3 and 4 are the two buses A and B to the cards to be processed.
This is the authorized output decoding section.

5 is a bus acquisition request code output unit, which inputs the current bus request from the plate cutting unit and the previous bus use permission code, and encodes the current bus request line according to the internally stored priority pattern algorithm. and output it.

Reference numeral 6 denotes a bus acquisition request code output section, which encodes and outputs a request from the character recognition section according to the same built-in algorithm as described above. Reference numeral 7 denotes a bus use permission code output unit 7, which finally outputs a bus acquisition request code for all bus requests according to the stored priority pattern algorithm.

Bus acquisition request latch units 8 and 9 are connected between bus acquisition request code output units 5 and 6 and bus use permission code output unit 7. The bus acquisition request latch section 8 latches the bus acquisition request from the plate cutting section, and the bus acquisition request latch section 9 latches the bus use permission state from the character recognition section. Further, a bus use permission state latch section 10 is connected between the bus use permission code output section 7 and the use permission output decoding sections 3 and 4 for latching the bus use permission state.

In the above configuration, if the outputs of the bus request latch units 1 and 2 change from the current request content to mean a request to one of the four types mentioned above, the bus acquisition request code output unit 5, 6 and the bus use permission code output section 7 determine the priority order at that time, and apply the decoding result to the use permission output decoding sections 3 and 4 via the bus use permission state latch section 10.

The human data of the bus request latch units 1 and 2 has 16 signals for 8 bus request cards, and in addition, has one priority mode signal (PCORCR). The bus request signal is the overall control card output HWRQ l l,12
, HWRQ21, 22, 31, 3 from plate cut section
2, 41 and 42, character recognition card HWRQ51, 5
2, 61, 62, 71, 72, 81 and 82.

The priority mode signal (PCORCR) is PCORCR=O
When (request for plate cutting section)> (request for character recognition section)
and vice versa when PCORCR=1. Further, the output data of the use permission output decoding sections 3 and 4 consists of eight A bus permission signals and eight bus permission signals corresponding to each request. The bus permission signals are HWAAV1, HWBAV2, which are inputs to the overall control card, and HWAAV2 to HWA, which are plate cutting permission signals.
AV8, HWBAV3 which is the permission signal for character recognition card
~ Consists of HWBAV8.

Next, priority processing will be explained.

First, priority control of the plate cutout section card and the character recognition section card is executed in accordance with the priority mode signal (PCORCR). Next, a request from the overall control processing card (HWRQII) is included in the plate cutting group, and its priority is set to the lowest. Next, the priority order of each group is determined by rotating each group according to the level of permission granted at that time. If there is no permission granted, the priority is fixed.

The bus acquisition request code output unit 5 inputs the current bus acquisition request with memory usage information from each card and the previous memory usage status information, and the bus acquisition request code output unit 6 inputs the previous bus usage permission information manually. be done. For each piece of information, the bus use permission code output unit 7 checks whether the memory can be used or not, and if the memory from the requested card is in use, it is excluded from the permission target. This eliminates the need for each processing card on the bus requesting side to check whether memory can be used.

Note that the algorithm of the bus priority method is changed and the new algorithm pattern is output to the bus acquisition request code output units 5 and 6.
and the bus use permission code output unit 7,
It is also possible to adapt to a method suitable for another system.

Effects of the Invention As described above, according to the present invention, there is provided an image information storage means having a plurality of image memory cards for storing still images of a traveling vehicle captured by a plurality of television cameras, and data stored by the image information storage means. A plate cutout image processing calculation means for determining whether or not a license plate image is included in the image, and calculating the existence position address of the license plate if it exists, and a license plate existence position address by the plate extraction image processing calculation means. It has a character recognition means that recognizes each character in the license plate based on the information, and multiple buses that can read/write to each of the above image memory cards, and the memory used previously and this time from each of the above means is The control means outputs the current bus use permission response that is optimal for license plate recognition based on the bus acquisition request to which information is added and the previous bus use permission response status, so that the bus acquisition request in response to the bus input request is Bus arbitration control optimal for plate recognition processing can be performed at high speed. In particular, it is possible to efficiently control multiple buses in response to a large number of bus requests.
It becomes possible to control multiple simultaneous memory accesses using a multi-CPU configuration.

[Brief explanation of drawings]

The figure is a schematic block diagram showing a license plate recognition device in one embodiment of the present invention. 1, 2... Bus request latch unit, 3, 4... Usage permission output decoding unit, 5, 6... Bus acquisition request code output unit, 7... Bus usage permission code output unit, 8, 9 ...
Bus acquisition request latch section, 10... Bus use permission state latch section.

Claims (1)

[Claims] An image information storage means having a plurality of image memory cards for storing still images of a traveling vehicle captured by a plurality of television cameras, and determining whether or not a license plate image is included in data stored by the image information storage means. and a plate cut-out image processing calculation means for determining the location address of the license plate if it exists, and a character that recognizes each character in the license plate based on the license plate location address information by the plate cut-out image processing calculation means. A recognition means and a plurality of buses capable of reading/writing each of the above-mentioned image memory cards are provided, and bus acquisition requests and previous bus usage permissions to which previous and current used memory information are added from each of the above-mentioned means are provided. A license plate recognition device equipped with a control means that outputs a current bus usage permission response that is optimal for license plate recognition based on the response situation.