CN102568081A - Image acquisition and processing method and device of paper money discriminator - Google Patents

Abstract

The invention discloses an image collection and processing method of a banknote authenticator, which comprises a) adopting a line array image sensor to acquire banknote images row by row; The signal is corrected; c) output the corrected digital signal to the digital signal processor for banknote image detection; and d) control the stop and start of the banknote transmission motor when abnormal banknotes are detected; wherein step a) utilizes code The disc signal controls the process of acquiring banknote images. The invention also discloses an image collection and processing device for a banknote authenticator, which includes a line array image sensor for acquiring banknote images line by line, an image digitization module for analog-to-digital conversion and signal correction, and a digital signal for banknote image detection. The processor, the banknote transmission motor used to control the banknote transmission, and the image acquisition control module control the process of acquiring the banknote image by using the code disc signal.

Description

Method and device for image acquisition and processing of banknote authenticator

technical field

The invention relates to an image collection and processing method of a banknote authenticator, and also relates to an image collection and processing device of a banknote authenticator, in particular to an image collection and processing method and device for a banknote authenticator for single-port output banknotes.

Background technique

With the development of the economy, maintaining financial order and the interests of the general public has become more and more important. How to prevent counterfeit money from entering the market has attracted more and more attention from financial management institutions and the general public. It is an effective means to use image processing technology to improve the counterfeit currency identification ability of the banknote authenticator. On September 26, 2010, the state issued the "General Technical Conditions for RMB Counterfeit Banknote Detectors", and in the next few years, all banks' banknote processing equipment will need to have image recognition functions. Banknote authenticators that output banknotes with a single port, such as banknote counters and banknote detectors, have the advantages of small size and low cost, and are welcomed by banks, supermarkets and other units.

In the prior art, the banknote validator with a single port outputting banknotes will shut down when encountering abnormal banknotes, and output the abnormal banknotes. At this time, there will be a following normal or abnormal banknote, which is stuck inside the banknote validator due to the stop of the banknote validator under the condition of incomplete image acquisition. The banknote authenticator of the prior art needs to manually take out the jammed banknote. After starting the banknote validator again, re-insert the banknotes, and carry out the banknote identification operation. This kind of banknote authenticator cannot continue to collect spliced banknote images after restarting when the banknote image collection is incomplete. It needs to take out the banknotes and put them in again to collect the banknote images. The operation is inconvenient and time-consuming.

On the other hand, the linear array image sensor of the banknote validator of the prior art, such as CIS (contact image sensor, contact image sensor) sensor, its characteristic of continuous exposure makes even banknote validator can under the situation that banknote image collection is incomplete After restarting, continue to collect spliced banknote images, but the complete banknote image spliced from this will have obvious light and dark mutations, which will seriously affect the quality of the collected banknote images, and easily cause banknote authenticators to misjudge the banknote images.

Contents of the invention

The technical problem to be solved by the present invention is to propose a banknote authenticator image acquisition and processing method, which can effectively realize the control of banknote image acquisition, and obtain banknote images reliably, completely and with high quality; the present invention also proposes a banknote The image acquisition and processing device of the discriminator, after using this device, there is no need to open the cover to take out the jammed banknotes in the process of banknote identification, and the banknote image acquisition and processing of the jammed banknotes can be continued after restarting, and the image quality is excellent, and there is no sudden change of light and dark , The device is easy to operate, time-saving and fast.

In order to solve the above-mentioned technical problems, the present invention proposes an image acquisition and processing method of a banknote authenticator, including a) using a line array image sensor to acquire banknote images line by line; Correcting the converted digital signal; c) outputting the corrected digital signal to a digital signal processor for banknote image detection; and d) controlling the stop and start of the banknote drive motor when an abnormal banknote is detected; wherein the steps In a), the code disc signal is used to control the process of acquiring banknote images.

In the above method, controlling the process of acquiring banknote images includes: controlling the exposure of the line image sensor; and controlling the acquisition of each line of images.

In the above method, the controlling the exposure of the line image sensor includes: controlling the light emission of the light source; and controlling the photoelectric integration of the line image sensor.

In the above method, the control of the process of acquiring banknote images further includes: when the time interval from the start of exposure to the start of reading the photoelectric integrated charge of this exposure exceeds the set time T, inserting an exposure of the line image sensor , the specific steps include delaying the code wheel signal P0 by n line periods T0 to obtain the code wheel signal Pn (n is an integer >= 1); each code wheel signal Pn triggers the acquisition of a banknote image; and each code wheel signal When P0 arrives, if the time width of the last code wheel signal P0 is greater than the set time T, the photoelectric integration of the line image sensor is turned on, and the light source is turned on to emit light.

In the above method, the code disc signal Pn triggering image acquisition includes the following steps: turn on the photoelectric integration of the line array image sensor; turn on the light source to emit light, wherein the light emitting time is preset; perform analog-to-digital conversion on the banknote image acquired by the line array image sensor ; and correcting the converted digital signal.

In the above method, it also includes at least one of the following methods for adjusting the order of banknote image pixels: when the linear array image sensor is output in segments, the banknote image pixels are sorted; .

In order to implement the above method to solve the above technical problems, the present invention also proposes an image acquisition and processing device for banknote authenticators, including: a line array image sensor for acquiring banknote images line by line, and an image digitization module for analog-to-digital conversion and signal correction , a digital signal processor for banknote image detection, a banknote transmission motor for controlling banknote transmission, and an image acquisition control module for controlling the process of acquiring banknote images using code disc signals.

In the above device, the image acquisition control module includes the following image acquisition control circuit: an image acquisition control circuit for delaying the code disc signal P0 by n lines to obtain the code disc signal Pn (n is an integer >= 1); An image acquisition control circuit for triggering acquisition of a line of banknote images by each code wheel signal Pn; , turn on the photoelectric integration of the line array image sensor and the image acquisition control circuit for turning on the light source to emit light.

In the above device, the code disc signal Pn triggering image acquisition includes the following steps: turn on the photoelectric integration of the line array image sensor; turn on the light source to emit light, wherein the light emitting time is preset; perform analog-to-digital conversion on the banknote image acquired by the line array image sensor ; and correcting the converted digital signal.

The above device also includes at least one of the following banknote image pixel order adjustment circuits: an order adjustment circuit for sorting the pixels when outputting the line array image sensor in segments; Order adjustment circuit for pixel output order.

Beneficial effects: the code disc signal is used to control the process of acquiring banknote images, making the control process more accurate, and more importantly, it has better adaptability and can cope with more situations, such as controlling banknotes when abnormal banknotes are detected The stop and start of the transmission motor, the above-mentioned control method can cope with this situation well.

The process of acquiring banknote images is controlled by the code disc signal, which can cope with the incomplete acquisition of banknote images caused by the sudden stop of the banknote drive motor. After adopting this control method, even after the device is restarted, the jammed banknotes can still be captured and processed with high-quality banknote images without manual removal and re-insertion.

The advantage of controlling the exposure of the line array image sensor and the acquisition of each row of images is that it can avoid the problem of too long exposure time of the line array image sensor, so that the quality of the acquired banknote image can be better and more accurate. Suitable for image detection. After adopting this control method, there will be no obvious light and dark mutations in banknote image acquisition and processing.

The advantage of controlling the light source and photoelectric integration of the line array image sensor is that it can also avoid the problem of too long exposure time of the line array image sensor, so that the image quality of the acquired banknotes can be better and more suitable Do image detection. After adopting this control method, there will be no obvious light and dark mutations in banknote image acquisition and processing.

To sum up, by adopting the image acquisition and processing method of the banknote authenticator proposed by the present invention, the control of banknote image acquisition can be effectively realized, and banknote images can be obtained reliably, completely and with high quality. Using the image collection and processing device of the banknote authenticator proposed by the present invention, after using the device, there is no need to open the cover to take out the jammed banknotes during the banknote identification process, and the jammed banknotes can continue to be image collected and processed after restarting, and the image quality is excellent , There is no sudden change of light and dark, and the device is easy to operate, time-saving and fast.

Description of drawings

Other features and advantages of the invention will become apparent from the following description of preferred embodiments, taken by way of example to explain the principles of the invention, taken in conjunction with the accompanying drawings.

Fig. 1 is a flowchart of an embodiment of the image acquisition processing method in the present invention;

Fig. 2 is a functional block diagram of controlling the process of acquiring banknote images using code disc signals in one embodiment of the present invention;

Fig. 3 is a schematic structural diagram of an embodiment of an image acquisition and processing device in the present invention.

Detailed ways

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings:

Fig. 1 is the flow chart of an embodiment of image acquisition processing method among the present invention, comprises the following steps:

Step 1: Using a line array image sensor to acquire banknote images line by line S108. The line array image sensor can be CIS (contact image sensor, contact image sensor) sensor, CCD (Charge-coupled Device, charge-coupled device) sensor or CMOS (Complementary Metal Oxide Semiconductor, complementary metal oxide semiconductor) sensor. FPGA (Field Programmable Gate Arrayz, field programmable gate array) or CPLD (Complex Programmable Logic Device, complex programmable logic device) can be used to control the exposure, photoelectric integration and output clock and other related signals of the CIS sensor. When obtaining banknote images line by line, the light emitting mode of the light source can be changed according to the line unit, such as white light transmission, white light reflection, infrared transmission, infrared reflection, ultraviolet reflection, various monochromatic light reflection or transmission, etc. The line image sensor captures banknote images with different exposures line by line.

The process of acquiring banknote images is controlled by using the code wheel signal S102. Including controlling the exposure of the line array image sensor S103; and controlling the acquisition of each row of images S104. Controlling the exposure of the line image sensor includes controlling the light emission of the light source S105 and controlling the photoelectric integration of the line image sensor S106. Wherein, controlling the light emission of the light source refers to controlling the light source to start to emit light and to stop emitting light when collecting the image of each row of banknotes. Among them, controlling the photoelectric integration of the line array image sensor refers to controlling the light-sensing start signal of the line-array image sensor, which reads out and clears the charge in the light-sensing unit (pixel) in the line-array image sensor, that is, the light-sensitive signal of the previous line can be read out.

Controlling the process of acquiring banknote images by using the code disc signal is based on the code disc signal corresponding to the banknote transmission. It is mainly adjusted by using the code wheel signal. The code disc is a commonly used incremental angle sensor. It uses photolithography technology to evenly mark lines on the disc. When the disc rotates, the light received by the receiving tube will change brightly and darkly due to the impact of the marking lines, and the output will jump from high to low. Level. Generally, one code wheel signal corresponds to n/m image lines, where m and n are both positive integers. The banknote image line pulse signal can be obtained by frequency multiplication and frequency division of the code disc signal, and the line array image sensor exposure and image acquisition of each line can be started by using the line pulse signal. Since the line pulse signal comes from the code wheel signal, when n/m is equal to 1, it is the code wheel signal itself, so the following code wheel signal generally refers to the line pulse signal obtained by using the code wheel signal.

When the code disc is installed on the motor, when the motor rotates, a pulse signal is output from the photosensitive circuit. That is to say, a pulse signal is output every time the banknote is transported for a certain distance, and the output pulse signal can be converted into the transport distance of the banknote, so that the longitudinal sampling interval of the banknote can be controlled by using the pulse signal output by the code disc.

In order to obtain better image quality, it is necessary to use the code disc signal to control the process of acquiring banknote images during the time period when abnormal banknotes are detected, the banknote drive motor stops and restarts, especially for detected banknotes. Control the process of acquiring banknote images of a normal or abnormal banknote stuck in the transmission motor immediately after the abnormal banknote, thereby controlling the photosensitive time of the line array image sensor, that is, the photoelectric integration time. When the time interval from the start of the exposure to the start of reading the photoelectric integrated charge for this exposure exceeds the set time T, inserting an exposure of the line array image sensor is S107. Generally, the exposure of the line image sensor can be started directly with the code wheel signal, and the readout starts when the next code wheel signal arrives. After turning on the exposure of the line array image sensor, if there is still no readout signal by the set time T, insert an exposure of the line array image sensor before the readout signal, that is, replace the existing exposure with a new exposure, to avoid Banknote image error caused by too long time, Fig. 2 is a functional block diagram of using code disc signal to control the process of acquiring banknote image in one embodiment of the present invention. As shown in Figure 2, the specific steps are as follows:

The code wheel signal P0S202 is delayed by n line periods T0S203 to obtain the code wheel signal PnS204. Among them, the line period T0 is the minimum time required for each line of the line array image sensor to read, n is an integer >= 1, and the size selected by n is related to the banknote scanning speed. If the image of each line of banknotes is transmitted at the current banknote scanning speed The average time of the data is T1, then generally, n=(T1/T0+1), where n is rounded forward. Doing so can avoid the entire line of bright and dark changes in the captured image.

Each of the above Pn signals triggers the acquisition of a line of banknote images, specifically including: turning on the photoelectric integration of the line array image sensor and turning on the light source to emit light, wherein the light emitting time is preset S205; performing analog-to-digital conversion on the banknote image acquired by the line array image sensor S206; And correcting the converted digital signal S207. Wherein said to turn on the photoelectric integration of the line array image sensor is to send a signal SI for the start of integration of the line array image sensor, which is used to end the previous exposure, clear the last photosensitive charge and start the next photosensitive banknote image.

When each code wheel signal P0 arrives S208, if the time width of the last code wheel signal P0 is greater than the set time T S209, turn on the photoelectric integration of the line image sensor and turn on the light source to emit light S210. The light emitting time of the light source is preset.

The signal SI obtained by turning on the photoelectric integration of the line array image sensor is used for the removal of the photosensitive charge of the previous line array image sensor and the start of the next banknote image photosensitive, that is, the photosensitive charge (signal) is not used, because this time The photosensitive time is too long, and the ambient light or dark current interferes greatly, so a new exposure is required.

Step 2: Analog-to-digital conversion S109 of the acquired banknote image, and correction processing S110 on the converted digital signal. Correcting the digital signal is to correct and sort the gray scale of each banknote image pixel collected. Due to uneven illumination, inconsistencies in the photosensitive sensitivity and black level of each photosensitive pixel of the line array image sensor, the collected banknote images will have serious grayscale inconsistencies, and grayscale correction must be performed to obtain correct banknotes image. The above-mentioned grayscale correction refers to performing linear or nonlinear transformation on the collected banknote images. Specifically, the analog output value of the linear image sensor, that is, the acquired banknote image, is corrected after analog-to-digital conversion, so that it can correctly reflect the banknote image information. The specific method is to perform linear or nonlinear transformation compensation on the bright output and dark output of the acquired banknote image output by the line array image sensor after sampling and quantification. If the output value of the linear array image sensor is composed of several segments of the linear array image sensor, each segment of the linear array image sensor will output at the same time, and after digitization, it needs to be sorted so that it can output banknote image information in the order of banknote image pixels. At least one of the following methods for adjusting the order of banknote image pixels is adopted: when segmentally outputting the line array image sensor, sorting the banknote image pixels S114;

Step 3: Output the corrected banknote image to the digital signal processor for banknote image detection S111. The digital signal processor can adopt a dedicated DSP (digital signal processor, digital signal processor) or a general-purpose processor. The banknote image detection method can use existing image recognition methods, such as image matching methods such as grayscale matching and feature matching. The grayscale matching includes using the absolute value of the error and judging the similarity between images; the feature matching includes texture features, shape features, etc., or using corner points, edge points, etc. for matching.

Step 4: When an abnormal banknote is detected, S112 controls the stop of the banknote transmission motor and starts S113. Abnormal banknotes include suspected counterfeit banknotes, damaged, defaced, folded, and too old banknotes that need to be sorted. When abnormal banknotes are detected, the banknote drive motor stops, take out the abnormal banknotes, and start the banknote drive motor again.

FIG. 3 is a schematic structural diagram of an embodiment of an image acquisition and processing device in the present invention. The embodiment includes: a line array image sensor 301 for acquiring banknote images line by line, an image digitization module 302 for analog-to-digital conversion and signal correction, a digital signal processor 303 for banknote image detection, and a system for controlling banknote transmission. The banknote transmission motor 304 and the image acquisition control module 305 that controls the process of acquiring banknote images by using the code disc signal.

Wherein the line array image sensor, in this embodiment the CIS sensor is selected, may be other line array image sensors.

The image acquisition control module uses the code disc signal to control the process of acquiring banknote images, including the exposure control of the line array image sensor and the acquisition control of each row of images. The code disc signal is generated by the code disc photosensitive circuit (including shaping circuit). The image acquisition control module can be realized by circuits such as FPGA or CPLD. The image acquisition control module includes the following image acquisition control circuit: the image acquisition control circuit 306 for obtaining the code disc signal Pn (n being an integer of >= 1) by delaying the code disc signal P0 for n rows; The disc signal Pn triggers the image acquisition control circuit 307 for collecting a line of banknote images; and when each code disc signal P0 arrives, if the time interval to the last code disc signal P0 is greater than the set time T, the line array image is turned on The photoelectric integration of the sensor and the image acquisition control circuit 308 that turns on the light source to emit light.

Image digitization module, including the circuit for realizing analog-to-digital conversion function and signal correction function, the analog-to-digital conversion function can be realized by one or more high-speed ADCs (Analog to Digital Converter, analog-to-digital converter) with more than ten bits, according to the linear array image The number of ADCs is determined by the segmentation of the sensor and the number of channels of the ADC.

The digital signal processor can adopt general digital signal processor DSP (Digital Signal Processing, digital signal processing), as the DSP of TI company (Texas Instruments, Texas Instruments), ADI company (Analog Device Inc, Analog Devices Technology Company), It is more convenient to adopt DSP for video image processing, such as TI's Davinci (Da Vinci) or ADI's Blackfin (black fin) series processors. Digital signal processors can also use other embedded processors, such as x86 (a general term for a microprocessor architecture first developed and manufactured by Intel), ARM (Advanced RISC Machines, Advanced Simple Instruction Set Processor) or MIPS (Microprocessor without interlocked piped stages, microprocessors without internal interlocking piped stages) and other series of processors.

The banknote transmission motor can be implemented by an embedded processor or other circuits, such as processors such as ARM and MIPS, and the processor can also be used in combination with a digital signal processor.

This embodiment also includes a pixel sequence adjustment circuit 309 for sorting the pixels when outputting the line array image sensor in segments. It includes an order adjustment circuit for sorting the pixels when the line array image sensor is output in segments and an order adjustment circuit for adjusting the output order of the pixels when the line array image sensor is reversed left and right. The specific operation is as follows: the line array image sensor outputs data in segments, and input the image acquisition control module composed of FPGA or CPLD through the analog-to-digital conversion of ADC (when using FPGA, the built-in RAM (random access memory, random access memory) can be used to buffer the data, When using a CPLD, it is generally necessary to configure an external RAM), and by controlling the address of writing or reading the RAM, the banknote image output by the pixel order of the line image sensor is obtained.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, various variations or modifications may be made by those skilled in the art within the scope of the appended claims.

Claims (10)

1. An image acquisition processing method of a paper currency discriminator is characterized by comprising the following steps:

a) acquiring a paper money image line by adopting a linear array image sensor;

b) performing analog-to-digital conversion on the acquired banknote image, and performing correction processing on a converted digital signal;

c) outputting the corrected digital signal to a digital signal processor for detecting the image of the paper money; and

d) controlling the stop and start of the paper money transmission motor when detecting abnormal paper money; wherein,

step a) utilizing code wheel signals to control the process of obtaining the paper money image.

2. The image capture processing method of claim 1, wherein said controlling the process of capturing images of the bank notes comprises: controlling the exposure of the line array image sensor; and controlling the acquisition of each line of images.

3. The image processing method of claim 2, wherein the controlling of the line image sensor exposure comprises: controlling the light source to emit light; and controlling the photoelectric integral of the linear array image sensor.

4. The image capture processing method of claim 1, wherein said controlling the process of capturing images of banknotes further comprises: when the time interval from the start of exposure to the start of reading out the photoelectric integrated charges of the exposure exceeds the set time T, inserting the linear array image sensor for exposure once, and the specific steps are that

Delaying a code disc signal P0 for n line periods T0 to obtain a code disc signal Pn (n is an integer which is greater than 1);

each code wheel signal Pn triggers and collects a row of paper money images; and

when each code wheel signal P0 arrives, if the time width of the last code wheel signal P0 is larger than the set time T, the photoelectric integration of the linear array image sensor is started, and the light source is started to emit light.

5. The image acquisition processing method according to claim 4, wherein the trigger acquisition of the banknote image by the code wheel signal Pn comprises the following steps:

starting linear array image sensor photoelectric integration;

starting a light source to emit light, wherein the light emitting time is preset;

performing analog-to-digital conversion on a paper money image acquired by a linear array image sensor; and

and performing correction processing on the converted digital signal.

6. The image capture processing method of claim 1, further comprising at least one of the following banknote image pixel order adjustment methods:

when the linear array image sensor is output in a segmented mode, sorting the image pixels of the paper money; and

and when the line array image sensor is reversely mounted on the left and the right, adjusting the output sequence of the image pixels of the paper money.

7. An image acquisition and processing device of a paper currency discriminator is characterized by comprising: the system comprises a linear array image sensor for acquiring a paper money image line by line, an image digitization module for analog-to-digital conversion and signal correction, a digital signal processor for paper money image detection, a paper money transmission motor for controlling paper money transmission, and an image acquisition control module for controlling the process of acquiring the paper money image by using a code disc signal.

8. The image processing apparatus of claim 7, wherein the image acquisition control module comprises the following image acquisition control circuits:

the image acquisition control circuit is used for delaying the code wheel signal P0 by n lines to obtain a code wheel signal Pn (n is an integer of 1);

the image acquisition control circuit is used for triggering and acquiring a row of paper money images by each code wheel signal Pn; and

and the image acquisition control circuit is used for starting the linear array image sensor photoelectric integration and starting the light source to emit light when each code wheel signal P0 arrives and the time interval to the last code wheel signal P0 is greater than the set time T.

9. The image acquisition processing device according to claim 8, wherein said code wheel signal Pn triggering image acquisition comprises the following steps:

starting linear array image sensor photoelectric integration;

starting a light source to emit light, wherein the light emitting time is preset;

performing analog-to-digital conversion on a paper money image acquired by a linear array image sensor; and

and performing correction processing on the converted digital signal.

10. The image capture processing apparatus of claim 7, further comprising at least one of the following banknote image pixel order adjustment circuits:

the sequence adjusting circuit is used for sequencing the pixels when the linear array image sensor is output in a segmented mode; and

and the sequence adjusting circuit is used for adjusting the output sequence of the pixels when the line array image sensor is reversely arranged on the left and the right.

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