WO2015188592A1 - 一种图像校准方法及装置 - Google Patents

一种图像校准方法及装置 Download PDF

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WO2015188592A1
WO2015188592A1 PCT/CN2014/091874 CN2014091874W WO2015188592A1 WO 2015188592 A1 WO2015188592 A1 WO 2015188592A1 CN 2014091874 W CN2014091874 W CN 2014091874W WO 2015188592 A1 WO2015188592 A1 WO 2015188592A1
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image
image data
exposure time
lighting parameter
strong
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PCT/CN2014/091874
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English (en)
French (fr)
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王倩文
梁添才
刘梦涛
张翼飞
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广州广电运通金融电子股份有限公司
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Priority to EP14894715.3A priority Critical patent/EP3157238A4/en
Priority to US14/917,238 priority patent/US9866727B2/en
Priority to AU2014397243A priority patent/AU2014397243B2/en
Publication of WO2015188592A1 publication Critical patent/WO2015188592A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/409—Edge or detail enhancement; Noise or error suppression
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/00002—Diagnosis, testing or measuring; Detecting, analysing or monitoring not otherwise provided for
    • H04N1/00026—Methods therefor
    • H04N1/00045—Methods therefor using a reference pattern designed for the purpose, e.g. a test chart
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/401—Compensating positionally unequal response of the pick-up or reproducing head
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/407—Control or modification of tonal gradation or of extreme levels, e.g. background level
    • H04N1/4076—Control or modification of tonal gradation or of extreme levels, e.g. background level dependent on references outside the picture
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/70—Circuitry for compensating brightness variation in the scene

Definitions

  • Embodiments of the present invention relate to the field of image processing, and in particular, to an image calibration method and apparatus.
  • a scanner device such as an optical image sensor is often used to scan a sheet medium such as paper, banknotes, and a check, to generate image data of the sheet medium, and to perform high-speed recognition and processing of the machine by an information processing device such as a CPU.
  • an information processing device such as a CPU.
  • a scanner device such as an optical image sensor
  • the image sensor is an array of CMOS photosensitive elements made up of hundreds or even thousands of silicon wafers, one photosensitive element Is a pixel, there is an amplifier at each pixel position, and the electrical characteristics of the plurality of photosensitive devices and the amplifying circuit have a large inconsistency with each other, thereby causing the image sensor to scan the paper of uniform color brightness (ie, Under the same uniform radiation input, the voltages outputted by the respective photosensitive devices and the amplifying circuit are different in size, so that the image brightness data formed in the image processing device is also different, so that the image produces an uneven brightness and brightness, which seriously affects the image quality. Thereby affecting the image recognition result.
  • the commonly used calibration method is to use some standard gray paper (the gray scale uniformity of standard gray paper) to calibrate, that is, to record the standard gray paper of different gradations for each photosensitive unit (the gray scale of standard gray paper) Uniform), through the same lighting parameters, the formed image data, linearly fit the actual grayscale paper with the standard grayscale, and find the grayscale calibration curve of each photosensitive unit.
  • some standard gray paper the gray scale uniformity of standard gray paper
  • gray standard papers cannot guarantee the uniformity of the standard gray scale in production, and will cause gray scale changes and long service life as the use and storage process.
  • the standard of the gray standard paper used as the calibration reference causes the calibration effect to be different; in addition, due to the limitation of the number of times the gray scale calibration paper is used, it can generally only be used three to five times, that is, it needs to be replaced, resulting in the calibration cost. Higher.
  • the embodiment of the invention provides an image calibration method and device, and calculates a deviation compensation coefficient of each pixel according to the image data generated by the strong and weak lighting parameters, and uses the deviation compensation coefficient to calibrate each of the image sensing unit acquisition and output.
  • the data of the image pixels can thus eliminate the influence of the inconsistency of each photosensitive element of the image sensing unit on the gray level of the image, thereby improving the effect of image recognition of the document medium.
  • S3 Calculate the image data after the calibration of the sheet medium according to the strong lighting parameter, the weak lighting parameter, and the image data.
  • the step S1 includes:
  • the obtaining the strong lighting parameters of each photosensitive unit at a short exposure time comprises:
  • the image data IHi and the gradation value GrayH are stored.
  • the obtaining the weak lighting parameters of each photosensitive unit at a short exposure time comprises:
  • the image data ILi and the gradation value GrayL are stored.
  • the image data tH is 60 us, and the gradation value GrayH is 200.
  • the image data ILi is 10 us, and the gradation value GrayL is 20.
  • the step S3 includes:
  • step S2 The image data obtained in step S2 is recorded as Xi, and the image data after calibration is recorded as Xi'.
  • X i ' GrayL+(GrayH-GrayL)*(X i -IL i )/(IH i -IL i ).
  • step S1 and before step S3 the method further includes:
  • a first obtaining unit configured to acquire a strong lighting parameter of each photosensitive unit at a long exposure time and a weak lighting parameter at a short exposure time
  • a second acquiring unit configured to acquire image data of the sheet medium
  • a calculating unit configured to calculate image data of the sheet medium after calibration according to the strong lighting parameter, the weak lighting parameter, and the image data.
  • the device also includes:
  • the storage unit is configured to store the strong lighting parameters and the weak lighting parameters.
  • An image sensing unit configured to collect image information of the medium
  • a storage unit configured to store the image information and control parameters and image processing parameters of the image sensing unit
  • control processing unit configured to control the image calibration device, and calculate a deviation compensation coefficient according to the control parameter and the image processing parameter, and use the deviation compensation coefficient to calibrate data of each image pixel that is output by the image sensing unit.
  • a strong lighting parameter of each photosensitive unit at a long exposure time and a weak lighting parameter at a short exposure time are acquired; then image data of the sheet medium is acquired; The strong lighting parameter, the weak lighting parameter, and the image data are used to calculate image data after calibration of the sheet medium.
  • the method for calculating the deviation compensation coefficient of each pixel by using the image data generated according to the strong and weak lighting parameters, and using the deviation compensation coefficient to calibrate the data of each image pixel collected and output by the image sensing unit the embodiment of the present invention
  • the image calibration method and device can eliminate the influence of the inconsistency of each photosensitive element of the image sensing unit on the image gray scale, thereby improving the image recognition effect of the document medium.
  • FIG. 1 is a flow chart of a first embodiment of an image calibration method according to the present invention.
  • FIG. 2 is a flow chart of a second embodiment of an image calibration method according to the present invention.
  • FIG. 3 is a schematic structural view of a first embodiment of an image calibration apparatus according to the present invention.
  • FIG. 4 is a schematic structural view of a second embodiment of an image calibration apparatus according to the present invention.
  • FIG. 5 is a schematic structural diagram of an image sensing unit in an embodiment of an image calibration apparatus according to the present invention.
  • Fig. 6 is a structural schematic view showing the application of the image calibrating apparatus of the present invention to the identification of banknotes.
  • the embodiment of the invention provides an image calibration method and device, and calculates a deviation compensation coefficient of each pixel according to the image data generated by the strong and weak lighting parameters, and uses the deviation compensation coefficient to calibrate each of the image sensing unit acquisition and output.
  • the data of the image pixels can thus eliminate the influence of the inconsistency of each photosensitive element of the image sensing unit on the gray level of the image, thereby improving the effect of image recognition of the document medium.
  • a first embodiment of an image calibration method in an embodiment of the present invention includes:
  • the calibration coefficient of the image data can be obtained by the strong light-lighting parameter of the photosensitive unit at a long exposure time and the weak light-lighting parameter at a short exposure time, so that the strong light-lighting parameter of each photosensitive unit at a long exposure time can be first obtained and is short. Weak lighting parameters for exposure time.
  • the above-mentioned sheet medium is a sheet medium to be scanned and read.
  • S3 Calculate the image data after the calibration of the sheet medium according to the strong lighting parameter, the weak lighting parameter and the image data.
  • the calibration coefficient of the image data can be calculated according to the strong lighting parameter, the weak lighting parameter and the image data, and the image data after the sheet medium calibration can be calculated according to the calibration coefficient and the image data obtained in step S2.
  • the strong lighting parameters of each photosensitive unit at a long exposure time and the weak lighting parameters at a short exposure time are acquired; then the image data of the sheet medium is obtained; finally, according to the strong lighting parameters, the weak lighting
  • the parameter and image data are used to calculate the image data after the sheet medium is calibrated.
  • the method for calculating the deviation compensation coefficient of each pixel by using the image data generated according to the strong and weak lighting parameters, and using the deviation compensation coefficient to calibrate the data of each image pixel collected and output by the image sensing unit the embodiment of the present invention
  • the image calibration method can eliminate the influence of the inconsistency of each photosensitive element of the image sensing unit on the image gray scale, thereby improving the image recognition effect of the document medium.
  • the second embodiment of the image calibration method of the present invention includes:
  • the calibration coefficient of the image data can be obtained by the strong light-lighting parameter of the photosensitive unit at a long exposure time and the weak light-lighting parameter at a short exposure time, so that the strong light-lighting parameter of each photosensitive unit at a long exposure time can be first obtained and is short. Weak lighting parameters for exposure time.
  • the above specific process of obtaining the strong lighting parameters of each photosensitive unit at a long exposure time and the weak lighting parameters at a short exposure time may include: obtaining a strong lighting parameter of each photosensitive unit at a long exposure time; acquiring each photosensitive light The weak lighting parameters of the unit at short exposure times. It should be noted that the order of obtaining data of the strong lighting parameters and the weak lighting parameters is not limited, and may be set according to actual needs.
  • the obtaining of the strong lighting parameters of each photosensitive unit at a short exposure time includes: long exposure of the gray channel plate for tH time; recording the image data IHi obtained by the long exposure and the corresponding gray value GrayH; stores image data IHi and gray value GrayH.
  • the image data tH may be specifically 60 us, and the gray value GrayH may be 200.
  • the weak lighting parameters for obtaining each photosensitive unit at a short exposure time include: short exposure of the gray channel plate for tL time; recording the image data ILi obtained by the long exposure and the corresponding gray value GrayL; and the image data ILi and Gray value GrayL storage.
  • the image data ILi may be 10us, and the gray value GrayL may be 20.
  • the obtained strong lighting parameters and weak lighting parameters can be stored.
  • the image data of the sheet medium can be acquired after storing the strong lighting parameters of each photosensitive unit for a long exposure time and the weak lighting parameters for a short exposure time.
  • the above-mentioned sheet medium is a sheet medium to be scanned and read.
  • the calibration coefficient of the image data can be calculated according to the strong lighting parameter, the weak lighting parameter and the image data, and the image data after the sheet medium calibration can be calculated according to the calibration coefficient and the image data obtained in step 203.
  • step 204 may include: reading image data IHi, gray value GrayH, image data ILi, and gray value GrayL; recording image data obtained in step 203 as Xi, and calibrated image data as Xi′, then
  • X i ' GrayL+(GrayH-GrayL)*(X i -IL i )/(IH i -IL i ).
  • the image data Xi' after the sheet medium calibration can be obtained.
  • the strong lighting parameters of each photosensitive unit at a long exposure time and the weak lighting parameters at a short exposure time are acquired; then the image data of the sheet medium is obtained; finally, according to the strong lighting parameters, the weak lighting
  • the parameter and image data are used to calculate the image data after the sheet medium is calibrated.
  • the method for calculating the deviation compensation coefficient of each pixel by using the image data generated according to the strong and weak lighting parameters, and using the deviation compensation coefficient to calibrate the data of each image pixel collected and output by the image sensing unit the embodiment of the present invention
  • the image calibration method can eliminate the influence of the inconsistency of each photosensitive element of the image sensing unit on the image gray scale, thereby improving the image recognition of the document medium. Effect.
  • the second embodiment of the image calibration method of the banknote of the present invention is described in detail above.
  • the first embodiment of the image calibration apparatus of the present invention is described below.
  • the image calibration apparatus in the embodiment of the present invention is described.
  • An embodiment includes:
  • a first obtaining unit 301 configured to acquire a strong lighting parameter of each photosensitive unit at a long exposure time and a weak lighting parameter at a short exposure time;
  • a second acquiring unit 302 configured to acquire image data of a sheet medium
  • the calculating unit 303 is configured to calculate the image data after the sheet medium calibration according to the strong lighting parameter, the weak lighting parameter, and the image data.
  • the device also includes:
  • the storage unit 304 is configured to store the strong lighting parameters and the weak lighting parameters.
  • the first embodiment of the image calibration apparatus of the present invention is an embodiment corresponding to the first embodiment and the second embodiment of the image calibration method of the present invention, and therefore has the first embodiment and the second embodiment of the image calibration method of the present invention. The characteristics are not repeated here.
  • the image calibration device can eliminate the influence of the inconsistency of each photosensitive element of the image sensing unit on the image gray scale, thereby improving the image recognition effect of the document medium.
  • the first embodiment of the image calibration apparatus of the banknote of the present invention has been described in detail above, and in particular, the second embodiment of the image calibration apparatus of the present invention is described below. Referring to FIG. 4 to FIG. 6, the image of the embodiment of the present invention is shown.
  • the second embodiment of the calibration device comprises:
  • the image sensing unit 401 is configured to collect image information of the medium
  • the storage unit 402 is configured to store image information and control parameters and image processing parameters of the image sensing unit;
  • the control processing unit 403 is configured to control the image calibration device, and calculate the deviation compensation coefficient according to the control parameter and the image processing parameter, and calibrate the data of each image pixel output by the image sensing unit with the deviation compensation coefficient.
  • the image sensing unit 401 collects the number of verification images according to the control parameters. According to, for example, a strong lighting parameter and a weak lighting parameter, and collecting image information of the medium; then the storage unit 402 can store the verification image data and the image processing parameter for subsequent calling; finally, the control processing unit 403 processes the image according to the control parameter and the image.
  • the parameter calculates the deviation compensation coefficient, and uses the deviation compensation coefficient to calibrate the data of each image pixel collected by the image sensing unit.
  • the banknote discriminating device may include a sensor module, a sensor control module, an image processing module, a CPU, a memory, and a communication control module, wherein the sensor module includes a plurality of sensors for collecting banknote data; and sensor control The module is configured to control the image sensor, and send the collected data to the image processing module for processing; the image processing module is configured to process the collected banknote data, and the processing in the embodiment of the invention is to calibrate the banknote data;
  • the banknote data and the calibrated banknote data may be stored by a memory, for example, by a non-volatile memory; the banknote authentication device may be connected to the main control module through the communication control module, so that the main control module calls the data in the memory. . See Figure 6 for the sensor module above.
  • the method for calculating the deviation compensation coefficient of each pixel by using the image data generated according to the strong and weak lighting parameters, and using the deviation compensation coefficient to calibrate the data of each image pixel collected and output by the image sensing unit the embodiment of the present invention
  • the image calibration method can eliminate the influence of the inconsistency of each photosensitive element of the image sensing unit on the image gray scale, thereby improving the image recognition effect of the document medium.

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Abstract

一种图像校准方法及装置，根据强弱打光参数产生的图像数据计算每一像素的偏差补偿系数，并利用该偏差补偿系数去校准图像传感单元采集输出的每个图像像素的数据，因此能够消除图像传感单元每个感光元件不一致性对图像灰度造成的影响，从而提高了文档介质图像识别的效果。本发明实施例的方法包括：S1：获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；S2：获取薄片介质的图像数据；S3：根据所述强打光参数、弱打光参数及所述图像数据计算所述薄片介质校准后的图像数据。

Description

一种图像校准方法及装置
本申请要求2014年06月13日提交中国专利局、申请号为201410264151.8、发明名称为“一种图像校准方法及装置”的发明专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明实施例涉及图像处理领域，具体涉及一种图像校准方法及装置。
背景技术
在金融机关或企业团体中，经常会使用光学图像传感器等扫描仪装置，扫描例如纸张，钞票、支票等薄片介质，生成薄片介质的图像数据，并由CPU等信息处理设备进行机器高速识别和处理，从而实现帐票等文档处理业务的信息化，高效化。
在使用光学图像传感器等扫描仪装置扫描例如纸张，钞票、支票等薄片介质，由于图像传感器是由数百个甚至上千个硅晶片制成的CMOS感光元件多段拼接而成的阵列，一个感光元件就是一个像素，在每一个像素位置都有一个放大器，这多个感光器件和放大电路的电气特性相互之间存在较大的不一致性，因此造成图像传感器在扫描颜色亮度均一的纸张时(即在同一均匀辐射输入下)，各个感光器件和放大电路输出的电压有大小的不同，从而在图像处理装置中形成的图像亮度数据也不同，使图像产生亮度明暗不均的区域，严重影响图像质量，从而影响图像识别结果。
而目前常用的校准方式，是利用一些标准灰度纸(标准灰度纸的灰度均一)进行校准，即通过记录各个感光单元对于不同灰度的标准灰度纸(标准灰度纸的灰度均一)，通过相同的打光参数，形成的图像数据，对实际的灰度纸与标准灰度进行线性拟合，求出每个感光单元的灰度校准曲线。
但这些灰度标准纸，生产中无法保障其标准灰度均一，而且会随着使用、存放过程，会产生灰度变化，使用寿命不长等因素。这样，一方面作为校准基准的灰度标准纸的不标准，导致校准效果存在差异；另外，也由于灰度校准纸使用次数限制，一般只能使用三到五次，即需要更换，导致校准成本较高。
发明内容
本发明实施例提供了一种图像校准方法及装置，根据强弱打光参数产生的图像数据计算每一像素的偏差补偿系数，并利用该偏差补偿系数去校准图像传感单元采集输出的每个图像像素的数据，因此能够消除图像传感单元每个感光元件不一致性对图像灰度造成的影响，从而提高了文档介质图像识别的效果。
本发明实施例提供的图像校准方法，包括：
S1：获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；
S2：获取薄片介质的图像数据；
S3：根据所述强打光参数、弱打光参数及所述图像数据计算所述薄片介质校准后的图像数据。
优选的，
所述步骤S1包括：
S11：获取每个感光单元在长曝光时间的强打光参数；
S12：获取每个感光单元在短曝光时间的弱打光参数；
或
S11：获取每个感光单元在短曝光时间的弱打光参数；
S12：获取每个感光单元在长曝光时间的强打光参数。
优选的，
所述获取每个感光单元在短曝光时间的强打光参数包括：
对灰度通道板进行tH时间的长曝光；
记录长曝光得到的图像数据IHi及对应的灰度值GrayH；
将所述图像数据IHi及所述灰度值GrayH存储。
优选的，
所述获取每个感光单元在短曝光时间的弱打光参数包括：
对灰度通道板进行tL时间的短曝光；
记录长曝光得到的图像数据ILi及对应的灰度值GrayL；
将所述图像数据ILi及所述灰度值GrayL存储。
优选的，
所述图像数据tH为60us，所述灰度值GrayH为200。
所述图像数据ILi为10us，所述灰度值GrayL为20。
优选的，
所述步骤S3包括：
读取所述图像数据IHi、所述灰度值GrayH、所述图像数据ILi及所述灰度值GrayL；
将步骤S2得到的图像数据记为Xi，校准后的图像数据记为Xi′，則
Xi'＝GrayL+(GrayH-GrayL)*(Xi-ILi)/(IHi-ILi)。
优选的，
步骤S1之后及步骤S3之前还包括：
存储所述强打光参数及所述弱打光参数。
本发明实施例提供的图像校准装置，包括：
第一获取单元，用于获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；
第二获取单元，用于获取薄片介质的图像数据；
计算单元，用于根据所述强打光参数、弱打光参数及所述图像数据计算所述薄片介质校准后的图像数据。
优选的，
所述装置还包括：
存储单元，用于存储强打光参数及弱打光参数。
本发明实施例提供的图像校准装置，包括：
图像传感单元，用于采集介质的图像信息；
存储单元，用于存储所述图像信息以及所述图像传感单元的控制参数和图像处理参数；
控制处理单元，用于控制图像校准装置，且根据所述控制参数和所述图像处理参数计算偏差补偿系数，并用所述偏差补偿系数校准图像传感单元采集输出的每个图像像素的数据。
本发明实施例中，首先获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；然后获取薄片介质的图像数据；最后根据 所述强打光参数、弱打光参数及所述图像数据计算所述薄片介质校准后的图像数据。通过采用了根据强弱打光参数产生的图像数据计算每一像素的偏差补偿系数，并利用该偏差补偿系数去校准图像传感单元采集输出的每个图像像素的数据的方式，本发明实施例的图像校准方法及装置能够消除图像传感单元每个感光元件不一致性对图像灰度造成的影响，从而提高了文档介质图像识别的效果。
附图说明
图1为本发明图像校准方法第一实施例流程图；
图2为本发明图像校准方法第二实施例流程图；
图3为本发明图像校准装置第一实施例结构示意图；
图4为本发明图像校准装置第二实施例结构示意图；
图5为本发明图像校准装置实施例中图像传感单元的结构示意图；
图6为本发明图像校准装置应用于纸币鉴别中的结构示意图。
具体实施方式
本发明实施例提供了一种图像校准方法及装置，根据强弱打光参数产生的图像数据计算每一像素的偏差补偿系数，并利用该偏差补偿系数去校准图像传感单元采集输出的每个图像像素的数据，因此能够消除图像传感单元每个感光元件不一致性对图像灰度造成的影响，从而提高了文档介质图像识别的效果。
请参阅图1，本发明实施例中图像校准方法第一实施例包括：
S1：获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；
通过感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数可以获得图像数据的校准系数，因此可以首先获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数。
S2：获取薄片介质的图像数据；
获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打 光参数之后，可以获取薄片介质的图像数据。上述的薄片介质为待扫描读取的薄片介质。
S3：根据强打光参数、弱打光参数及图像数据计算薄片介质校准后的图像数据。
根据强打光参数、弱打光参数及图像数据可以计算得到图像数据的校准系数，根据校准系数及步骤S2得到的图像数据可以计算得到薄片介质校准后的图像数据。
本发明实施例中，首先获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；然后获取薄片介质的图像数据；最后根据强打光参数、弱打光参数及图像数据计算薄片介质校准后的图像数据。通过采用了根据强弱打光参数产生的图像数据计算每一像素的偏差补偿系数，并利用该偏差补偿系数去校准图像传感单元采集输出的每个图像像素的数据的方式，本发明实施例的图像校准方法能够消除图像传感单元每个感光元件不一致性对图像灰度造成的影响，从而提高了文档介质图像识别的效果。
上面简单介绍了本发明图像校准方法的第一实施例，下面对本发明图像校准方法的第二实施例进行详细的描述，请参阅图2，本发明实施例中图像校准方法第二实施例包括：
201：获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；
通过感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数可以获得图像数据的校准系数，因此可以首先获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数。
上述获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数的具体过程可以包括：获取每个感光单元在长曝光时间的强打光参数；获取每个感光单元在短曝光时间的弱打光参数。需要说明的是，强打光参数及弱打光参数的获取数据的先后顺序不做限定，可以根据实际需求进行设定。
其中获取每个感光单元在短曝光时间的强打光参数包括：对灰度通道板进行tH时间的长曝光；记录长曝光得到的图像数据IHi及对应的灰度值 GrayH；将图像数据IHi及灰度值GrayH存储。上述图像数据tH具体可以为60us，灰度值GrayH具体可以为200。
其中获取每个感光单元在短曝光时间的弱打光参数包括：对灰度通道板进行tL时间的短曝光；记录长曝光得到的图像数据ILi及对应的灰度值GrayL；将图像数据ILi及灰度值GrayL存储。上述图像数据ILi具体可以为10us，灰度值GrayL具体可以为20。
202：存储强打光参数及弱打光参数；
完成步骤201之后，可以将获取得到的强打光参数及弱打光参数进行存储。
203：获取薄片介质的图像数据；
存储每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数之后，可以获取薄片介质的图像数据。上述的薄片介质为待扫描读取的薄片介质。
204：根据强打光参数、弱打光参数及图像数据计算薄片介质校准后的图像数据。
根据强打光参数、弱打光参数及图像数据可以计算得到图像数据的校准系数，根据校准系数及步骤203得到的图像数据可以计算得到薄片介质校准后的图像数据。
步骤204的具体过程可以包括：读取图像数据IHi、灰度值GrayH、图像数据ILi及灰度值GrayL；将步骤203得到的图像数据记为Xi，校准后的图像数据记为Xi′，則
Xi'＝GrayL+(GrayH-GrayL)*(Xi-ILi)/(IHi-ILi)。
根据上述的公式，可以得到薄片介质校准后的图像数据Xi′。
本发明实施例中，首先获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；然后获取薄片介质的图像数据；最后根据强打光参数、弱打光参数及图像数据计算薄片介质校准后的图像数据。通过采用了根据强弱打光参数产生的图像数据计算每一像素的偏差补偿系数，并利用该偏差补偿系数去校准图像传感单元采集输出的每个图像像素的数据的方式，本发明实施例的图像校准方法能够消除图像传感单元每个感光元件不一致性对图像灰度造成的影响，从而提高了文档介质图像识别 的效果。
上面对本发明钞票的图像校准方法的第二实施例作了详细描述，特别是对的过程，下面介绍本发明图像校准装置第一实施例，请参阅图3，本发明实施例中图像校准装置第一实施例包括：
第一获取单元301，用于获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；
第二获取单元302，用于获取薄片介质的图像数据；
计算单元303，用于根据强打光参数、弱打光参数及图像数据计算薄片介质校准后的图像数据。
优选的，
装置还包括：
存储单元304，用于存储强打光参数及弱打光参数。
本发明图像校准装置第一实施例是与本发明图像校准方法第一实施例及第二实施例相对应的实施例，因此也具有本发明图像校准方法第一实施例及第二实施例所具有的特点，在此处不再累述。
通过采用了根据强弱打光参数产生的图像数据计算每一像素的偏差补偿系数，并利用该偏差补偿系数去校准图像传感单元采集输出的每个图像像素的数据的方式，本发明实施例的图像校准装置能够消除图像传感单元每个感光元件不一致性对图像灰度造成的影响，从而提高了文档介质图像识别的效果。
上面对本发明钞票的图像校准装置的第一实施例作了详细描述，特别是对的过程，下面介绍本发明图像校准装置第二实施例，请参阅图4至图6，本发明实施例中图像校准装置第二实施例包括：
图像传感单元401，用于采集介质的图像信息；
存储单元402，用于存储图像信息以及图像传感单元的控制参数和图像处理参数；
控制处理单元403，用于控制图像校准装置，且根据控制参数和图像处理参数计算偏差补偿系数，并用偏差补偿系数校准图像传感单元采集输出的每个图像像素的数据。
本发明实施例中，图像传感单元401会根据控制参数采集校验图像数 据，例如强打光参数和弱打光参数，并采集介质的图像信息；接着存储单元402可以存储校验图像数据及图像处理参数，以便后续调用；最后控制处理单元403根据控制参数和图像处理参数计算偏差补偿系数，并用偏差补偿系数校准图像传感单元采集输出的每个图像像素的数据。
下面以一个具体实例来说明本发明实施例各部件的工作过程：
请参阅图5，在纸币鉴别中，纸币鉴别装置可以包括传感器模块、传感器控制模块、图像处理模块、CPU、存储器及通信控制模块，其中传感器模块包括若干个传感器，用于采集纸币数据；传感器控制模块用于控制上述的图像传感器，并将采集数据发送至图像处理模块进行处理；图像处理模块用于对采集到的纸币数据进行处理，在本发明实施例中的处理为对纸币数据进行校准；上述的纸币数据及校准后的纸币数据可以由存储器进行存储，例如可以由非易失性存储器进行存储；纸币鉴别装置可以通过通信控制模块与主控模块相连，以便主控模块调用存储器里的数据。上述的传感器模块请参阅图6。
通过采用了根据强弱打光参数产生的图像数据计算每一像素的偏差补偿系数，并利用该偏差补偿系数去校准图像传感单元采集输出的每个图像像素的数据的方式，本发明实施例的图像校准方法能够消除图像传感单元每个感光元件不一致性对图像灰度造成的影响，从而提高了文档介质图像识别的效果。
本领域普通技术人员可以理解实现上述实施例方法中的全部或部分步骤是可以通过程序来指令相关的硬件完成，其中的程序可以存储于一种计算机可读存储介质中，上述提到的存储介质可以是只读存储器，磁盘或光盘等。
以上对本发明所提供的一种图像校准方法及装置进行了详细介绍，对于本领域的一般技术人员，依据本发明实施例的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本发明的限制。

Claims (10)

  1. 一种图像校准方法，其特征在于，包括：
    S1：获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；
    S2：获取薄片介质的图像数据；
    S3：根据所述强打光参数、弱打光参数及所述图像数据计算所述薄片介质校准后的图像数据。
  2. 根据权利要求1所述的图像校准方法，其特征在于，所述步骤S1包括：
    S11：获取每个感光单元在长曝光时间的强打光参数；
    S12：获取每个感光单元在短曝光时间的弱打光参数；
    或
    S11：获取每个感光单元在短曝光时间的弱打光参数；
    S12：获取每个感光单元在长曝光时间的强打光参数。
  3. 根据权利要求2所述的图像校准方法，其特征在于，所述获取每个感光单元在短曝光时间的强打光参数包括：
    对灰度通道板进行tH时间的长曝光；
    记录长曝光得到的图像数据IHi及对应的灰度值GrayH；
    将所述图像数据IHi及所述灰度值GrayH存储。
  4. 根据权利要求3所述的图像校准方法，其特征在于，所述获取每个感光单元在短曝光时间的弱打光参数包括：
    对灰度通道板进行tL时间的短曝光；
    记录长曝光得到的图像数据ILi及对应的灰度值GrayL；
    将所述图像数据ILi及所述灰度值GrayL存储。
  5. 根据权利要求4所述的图像校准方法，其特征在于，
    所述图像数据tH为60us，所述灰度值GrayH为200。
    所述图像数据ILi为10us，所述灰度值GrayL为20。
  6. 根据权利要求4或5所述的图像校准方法，其特征在于，所述步骤S3包括：
    读取所述图像数据IHi、所述灰度值GrayH、所述图像数据ILi及所述 灰度值GrayL；
    将步骤S2得到的图像数据记为Xi，校准后的图像数据记为Xi′，則
    Xi'＝GrayL+(GrayH-GrayL)*(Xi-ILi)/(IHi-ILi)。
  7. 根据权利要求4或5所述的图像校准方法，其特征在于，步骤S1之后及步骤S3之前还包括：
    存储所述强打光参数及所述弱打光参数。
  8. 一种图像校准装置，其特征在于，包括：
    第一获取单元，用于获取每个感光单元在长曝光时间的强打光参数及在短曝光时间的弱打光参数；
    第二获取单元，用于获取薄片介质的图像数据；
    计算单元，用于根据所述强打光参数、弱打光参数及所述图像数据计算所述薄片介质校准后的图像数据。
  9. 根据权利要求8所述的图像校准装置，其特征在于，所述装置还包括：
    存储单元，用于存储强打光参数及弱打光参数。
  10. 一种图像校准装置，其特征在于，包括：
    图像传感单元，用于采集介质的图像信息；
    存储单元，用于存储所述图像信息以及所述图像传感单元的控制参数和图像处理参数；
    控制处理单元，用于控制图像校准装置，且根据所述控制参数和所述图像处理参数计算偏差补偿系数，并用所述偏差补偿系数校准图像传感单元采集输出的每个图像像素的数据。
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