This application claims the priority of Chinese Patent Application No. 201110278160.9, entitled “IDENTIFICATION METHOD FOR VALUABLE FILE AND IDENTIFICATION DEVICE THEREOF”, filed on Sep. 19, 2011 with State Intellectual Property Office of PRC, which is hereby incorporated by reference in its entirety.
The present invention relates to a method and device for distinguishing a value document, and in particular to a method and device for distinguishing a value document by distinguishing an infrared image of the valuable document on a mobile device with an infrared photography function.
Although various bank cards are widely used now, the circulation of cash remains predominant. Some criminals use high-tech means to imitate and forge value documents such as banknotes, causing serious harm to our society. In order to prevent the circulation of imitated value documents such as fake banknotes, there are increasing demands for accuracy and portability of value document distinguishing device. However, nowadays, distinguishing devices with relatively high accuracy mainly include large scale devices such as Banknote-Testing Device and ATM, which have high price and less portability, and therefore the application places of these devices are greatly restricted. In order to solve this problem, some simple devices such as fluorescence pen are emerged on the market; however, these portable devices have difficulties in detecting and distinguishing a value document.
A problem the skilled in the prior art encountered is: if the accuracy of a value document distinguishing device is to be improved, the accuracy for capturing images by the value document distinguishing device must be ensured. For this end, the value document distinguishing device needs to use a stable single light source to capture image, so as to improve the sharpness and reality of a value document image, therefore, the hardware structure and application places of the value document distinguishing device are restricted, and the value document distinguishing device with high accuracy has complex structure, high price and less portability. A value document distinguishing device with simple structure, low price and portability, however, has less accuracy for distinguishing.
Therefore, there is a need for a value document distinguishing device with high accuracy and portability.
An object of the present invention is to provide a value document distinguishing method which is easy to operate and has high accuracy.
An object of the present invention is to provide a value document distinguishing device with high accuracy and portability.
In order to achieve the above objects, the present invention provides a method for distinguishing a value document, and the method includes the following steps:
(1) acquiring an original infrared image, type, denomination and orientation data of a current value document;
(2) obtaining size data and infrared characteristic data of a standard value document corresponding to the current value document from a storage module according to the type, denomination and orientation data of the current value document;
(3) performing calibration process on the original infrared image using image projection transformation technology according to the size data of the standard value document to form a second infrared image, the size of the second infrared image being matched with the size of the standard value document;
(4) obtaining infrared characteristic data of the current value document from the second infrared image, and comparing the obtained infrared characteristic data of the current value document with the infrared characteristic data of the corresponding standard value document, to distinguish whether the current value document is fake; and
(5) outputting a distinguishing result.
Compared with the prior art, in the value document distinguishing method of the present invention, the captured original infrared image is first calibrated using the projection transformation technology; making the original infrared image of the captured current value document match with the size in size data of the stored standard value document template. On one hand, in the present invention it is therefore feasible to directly capture the original infrared image of the current value document using a normal camera device with a infrared filter, without taking an image using a stable signal light source at a site with simple background, and thus the requirement for the original image is low; on the other hand, the original infrared image can be taken from any angle when capturing the original infrared image according to the present invention, and thus the operation is simple; furthermore, according to the present invention, the current value document is distinguished after the captured image is calibrated by the projection calibration module, and thus the accuracy of distinguishing is high.
Preferably, step (1) specifically includes the following steps:
(11) capturing the original infrared image of the current value document; and
(12) obtaining the type, denomination and orientation data of the current value document by way of comparing the original infrared image of the current value document with data stored in the storage module for identification or by way of input from an interactive interface.
Preferably, in step 2, the original infrared image needs to be pre-processed before performing the calibration process on the original infrared image, and step 2 specifically includes the following steps:
(11a) performing image smoothing process on the original infrared image using Gaussian smoothing technology;
(11b) performing recovery process on the original infrared image using image recovery technology of partial differential equation;
(11c) calculating four vertex coordinates of the original infrared image to obtain a value document area; and
(11d) segmenting out the value document area on which the calibration process is to be performed.
After the recovery process, the processed original infrared image is further close to the image of the standard value document, and the accuracy for distinguishing the infrared image is increased. The Gaussian smoothing technology can not only de-noise the infrared image effectively but can also decrease fuzziness in the smoothing process. Image recovery technology of partial differential equation may recover the captured original infrared image to an optimal estimated value. Locating and segmenting process effectively increases the accuracy of infrared image projection calibration.
Preferably, step (3) specifically includes the following steps:
(31) establishing a template according to the size data of the standard value document;
(32) calculating a mapping relationship between the original infrared image and the template by using bilinear equations; and
(33) mapping pixel values of respective points in the original infrared image onto the template according to the mapping relationship, to form a second infrared image.
According to the present invention, using bilinear equations to calculate the mapping relationship, the mapping relationship between coordinates of respective points in the original infrared image and the template can be determined only by finding out four pairs of corresponding points between the original infrared image and the template, taking the four pairs of corresponding points as reference points to establish the bilinear equations, and figuring out eight parameters of the bilinear equations, and thus the computation is simple; performing projection calibration process on the original infrared image according to the mapping relationship may maximally recover the original infrared image, thereby avoiding image distortion. Furthermore, the reference points may be vertexes of the image, or other characteristic points.
Preferably, step (4) specifically includes the following steps:
(41) Obtaining infrared characteristic data from at least one characteristic area in the second infrared image to form first infrared characteristic data, and obtaining infrared characteristic data from a corresponding area in the standard value document to form second infrared characteristic data; and
(42) comparing the first infrared characteristic data and the second infrared characteristic data to obtain a comparison value, determining whether the comparison value meets a set requirement, and determining the current value document is legal if the comparison value meets the set requirement and determining the current value document illegal if the comparison value does not meet the set requirement.
Preferably, the infrared characteristic data includes at least one of the following values: a gradient characteristic value of gray value of the infrared image, an average value of gray value of the infrared image, a variance of gray value of the infrared image.
Preferably, when the infrared characteristic data is the gradient characteristic value of gray value of the infrared image, the determining includes:
(51) calculating a gradient value GΩ(x,y) of gray value of the current value document and a gradient value G0(x,y) of gray value of the corresponding standard value document;
(52) calculating the number Ng of GΩ(x) that meets GΩ(x,y)>THg, calculating the number N0 of G0(x,y) that meets G0(x,y)>THg, where THg is a gradient threshold, 1.0<THg<25.0;
(53) calculating a gradient comparison value N, N=Ng/N0; and
(54) determining the magnitude of the gradient comparison value N, determining that the current value document meets a gradient rule if 0.95≦N≦1.05, or otherwise determining that the current value document does not meet the gradient rule, and then outputting a corresponding gradient legal/illegal signal.
Preferably, when the infrared characteristic data is the average value of gray value of the infrared image, the determining includes:
(61) calculating an average value MΩ of gray value of the current value document and an average value M0 of gray value of the corresponding standard value document;
(62) calculating an average comparison value M, M=Mg/M0; and
(63) determining the magnitude of the comparison value M, determining that the current value document meets an average rule if 0.90≦M≦1.10, or otherwise determining that the current value document does not meet the average rule, and then outputting a corresponding average legal/illegal signal.
Preferably, when the infrared characteristic data is the variance of gray value of the infrared image, the determining includes:
(71) calculating a variance VΩ of gray value of the current value document and a variance V0 of gray value of the corresponding standard value document;
(72) calculating a variance comparison value V, V=Vg/V0; and
(73) determining the magnitude of V, determining that the current value document meets a variance rule if 0.80≦V≦1.25, or otherwise determining that the current value document does not meet the variance rule, and then outputting a corresponding variance legal/illegal signal.
In order to achieve the above objects, the present invention further provides a value document distinguishing device for distinguishing whether a current value document is fake, the device includes:
a collection module for obtaining an original infrared image, type, denomination and orientation data of the current value document;
a storage module for storing size data and infrared characteristic data of a standard value document;
a projection calibration module for performing calibration process on the original infrared image using image projection transformation technology according to the size data of the standard value document to form a second infrared image, the size of the second infrared image being matched with the size of the standard value document;
a process module for obtaining size data and infrared characteristic data of the standard value document corresponding to the current value document from the storage module according to the type, denomination and orientation data of the current value document; obtaining infrared characteristic data of the current value document from the second infrared image, and comparing the obtained infrared characteristic data of the current value document with the infrared characteristic data of the standard value document, to obtain a legal/illegal document signal for the current value document;
an output module for outputting the legal/illegal document signal;
a control module for controlling and coordinating data transfer among respective modules in the value document distinguishing device.
Compared with the prior art, the value document distinguishing device of the present invention is provided with a projection calibration module, which may make the captured infrared image of the current value document has a size consistent with that in size data of a stored standard value document template by using image projection transformation technology. Therefore, on one hand, in the invention, it is feasible to capture the original infrared image that meets the requirement of the present invention only by using a camera device with a infrared filter as a collection module, and the distinguishing device according to the present invention may be directly applied to some simple mobile devices such as mobile phone, web-camera and camera that are provided with infrared shooting function, and thus it is portable and cheap; on the other hand, according to the present invention, the original infrared image can be shot from any angle when capturing the original infrared image of the current value document, calibration may be performed by the projection calibration module if a two-dimensional oblique view is obtained, and thus the operation is simple; furthermore, there must be some errors no matter how stable the collection device in the prior art is and how proper the captured infrared image is, while according to the present invention, the captured image is calibrated by a projection calibration module, and the accuracy of the distinguishing unit is effectively improved, hence the accuracy of distinguishing according to the present invention is improved.
Preferably, the collection module includes:
an infrared camera device for capturing and obtaining the original infrared image of the current value document; and
an interactive interface for collecting and obtaining the type, denomination and orientation data of the current value document inputted from outside.
Preferably, the collection module includes:
an infrared camera device for capturing and obtaining the original infrared image of the current value document; and
a comparison and identification unit for comparing the original infrared image of the current value document with the infrared characteristic data of the standard value document stored in the storage module to obtain the type, denomination and orientation data of the current value document.
Preferably, the value document distinguishing device further includes a pre-process module for pre-processing the original infrared image, the preprocess module includes the following units:
an image de-noise unit for performing image smoothing process on the captured original infrared image;
an image recovery unit for performing recovery process on the original infrared image;
an image locating unit for calculating tour vertex coordinates of the original infrared image to obtain a value document area; and
an image segmentation unit for segmenting out the value documents area on which to the calibration process is to be performed.
Preferably, the projection calibration module includes:
a template process unit for establishing a template using the size data of the standard value document;
a parameter computation unit for calculating a mapping relationship between the original infrared image and the template by using bilinear equations; and
a pixel substitution unit for mapping pixel values of respective points in the original infrared image onto the template according to the mapping relationship, and forming the second infrared image after the calibration process.
According to the present invention, through taking four pairs of corresponding points in the original infrared image and the template as reference points, establishing bilinear equations, and working out eight parameters of the bilinear equations, the mapping relationship between coordinates of respective points in the original infrared image and the template can be determined, and therefore the process is simple and rapid; performing a projection calibration on the original infrared image according to the mapping relationship may make the original infrared image has a size matched with the template size, and thus maximally recover the infrared image and avoid image distortion. The reference points may be vertexes of the image or other characteristic points.
Preferably, the process module includes:
a data selection unit for obtaining the size data and the infrared characteristic data of the standard value document corresponding to the current value document from the storage module according to the type, denomination and orientation data of the current value document; and
a comparison process unit for obtaining the infrared characteristic data of the current value document from the second infrared image, and comparing the obtained infrared characteristic data of the current value document with the infrared characteristic data of the standard value document to obtain a legal/illegal document signal for the current value document.
Preferably, the comparison process unit includes:
a data acquisition unit for obtaining the infrared characteristic data from at least one infrared characteristic area in the second infrared image to form first infrared characteristic data, and obtaining the infrared characteristic data from a corresponding area in the standard value document to form second infrared characteristic data;
a data comparison unit which includes at least one of the following three units:
a fake determination unit for determining whether the current value document is fake according to the gradient legal/illegal signal, the average legal/illegal signal and/or the variance legal/illegal signal, and obtaining the legal/illegal document signal for the current value document.
In order to illustrate the technical contents, structural features, objects to be achieved and effects of the present invention in detail, a detail description will be made in the following in conjunction with embodiments and drawings.
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(1) the infrared camera device 511 acquires the original infrared image P0 of the current value document. The infrared camera device 511 may acquire a two-dimension image of the current value document from any angle, i.e., 0<0θ≦90°, where θ is a shooting angle. The preferable shooting angle of the present invention is θ>60°.
(2) the pre-process module 52 performs pre-process on the captured original infrared image P0, and the specific steps are as follow:
P
U=(P−M
P
D=(P−M
(3) the interactive interface 512 receives the type, denomination and orientation data Pi of the current value document inputted by a user based on prompt information, and the data selection unit 61 obtains attribute characteristic data Sp and infrared characteristic data Si of the standard value document corresponding to the current value document from the storage module 53 according to the type, denomination and orientation data Pi of the current value document.
(4) the projection calibration module 52 is used for performing calibration process on the original infrared image P0 using image projection transformation technology according to the attribute characteristic data Sp of the standard value document to form the second infrared image P2, where the size of the second infrared image P2 is matched with the size in the attribute characteristic data Sp of the standard value document. The specific steps are as follow:
x
1
=s(x0,y0)=c1xO+c2y0+c3x0y0+c4;
y
1
=t(x0,y0)=c5x0+c6y0+c7x0y0+c8;
(5) the comparison process unit 62 obtains the infrared characteristic data of the current value document from the second infrared image P2, compares the obtained characteristic data of the current value document with the infrared characteristic data Si of the standard value document, and obtains a legal/illegal document signal Sd for the current value document. The specific steps are as follow:
I. the data acquisition unit 621 obtains the infrared characteristic data from at least one infrared characteristic area in the second infrared image P2 to form the first infrared characteristic data, and obtains the infrared characteristic data from a corresponding area in the standard value document to from the second infrared characteristic data.
II. the gradient comparison unit 631 calculates a gradient value GΩ(x,y) of gray value of the current value document and a gradient value G0(x,y) of gray value of the corresponding standard value document according to the first characteristic data and the second infrared characteristic data, calculates the number Ng of GΩ(x,y) that meets GΩ(x,y)>THg, calculates the number N0 of G0(x,y) that meets G0 (x,y)>THg, where THg is a gradient threshold, 1.0<THg<25.0; calculates a gradient comparison value N, N=Ng/N0; determines the magnitude of the gradient comparison value N, determines that the current value document meets a gradient rule if 0.95≦N≦1.05, or otherwise determines that the current document does not meet the gradient rule, and outputs a corresponding gradient legal/illegal signal Sd1.
III. the average value comparison unit calculates an average value MΩ of gray value of the current value document and an average value M0 of gray value of the corresponding standard value document according to the first characteristic data and the second infrared characteristic data, calculates an average comparison value M=Mg/M0, determines the magnitude of M, determines that the current value document meets an average rule if 0.90≦M≦1.10, or otherwise determines that the current document does not meet the average rule, and outputs a corresponding average legal/illegal signal Sd2.
IV. the variance comparison unit calculates a variance VΩ of gray value of the current value document and a variance V0 of gray value of the corresponding standard value document according to the first characteristic data and the second infrared characteristic data, calculates a variance comparison value V=Vg/V0, determines the magnitude of V, determines that the current value document meets a variance rule if 0.80≦v≦1.25 or otherwise determines that the current document does not meet the variance rule, and outputs a corresponding variance legal/illegal signal Sd3.
V. the fake determination unit 623 determines whether the current value document is fake according to the gradient legal/illegal signal Sd1, the average legal/illegal signal Sd2 and the variance legal/illegal signal Sd3, and obtains a legal/illegal document signal Sd of the current value document. If the legal/illegal signals Si1, Si2, Si3 are all legal signals, the current value document is a legal document, and a legal document signal is outputted, otherwise, an illegal document signal is outputted.
(6) the output module 56 outputs the legal/illegal document signal Sd inputted by the fake determination unit 623 to a display and/or a warning device, and completes the distinguishing of the current value document.
From the above, a method for distinguishing a value document can be concluded. Referring to
(1) acquiring an original infrared image, type, denomination and orientation data of a current value document;
(2) Obtaining size data and infrared characteristic data of a standard value document corresponding to the current value document from a storage module according to the type, denomination and orientation data of the current value document;
(3) performing calibration process on the original infrared image using image projection transformation technology according to the size data of the standard value document to form a second infrared image, the size of the second infrared image being matched with the size of the standard value document;
(4) obtaining infrared characteristic data of the current value document from the second infrared image, and comparing the obtained infrared characteristic data of the current value document with the infrared characteristic data of the corresponding standard value document, to distinguish whether the current value document is fake; and
(5) outputting a distinguishing result.
Preferably, step (1) specifically includes the following steps:
(11) capturing the original infrared image of the current value document; and
(12) obtaining the type, denomination and orientation data of the current value document by way of comparing the original infrared image of the current value document with data stored in the storage module for identification or by way of inputting from an interactive interface.
Preferably, referring to
(11a) performing image smoothing process on the original infrared image using Gaussian smoothing technology;
(11b) performing recovery process on the original infrared image using image recovery technology of partial differential equation;
(11c) calculating four vertex coordinates of the original infrared image to obtain a value document area; and
(11d) segmenting out the value document area on which the calibration process is to be performed.
Preferably, referring to
(31) establishing a template according to the size data of the standard value document;
(32) calculating a mapping relationship between the original infrared image and the template by using bilinear equations; and
(33) mapping pixel values of respective points in the original infrared image onto the template according to the mapping relationship, to firm a second infrared image.
Preferably, referring to
(41) obtaining infrared characteristic data from at least one characteristic area in the second infrared image to form first infrared characteristic data, and obtaining infrared characteristic data from a corresponding area in the standard value document to form second infrared characteristic data; and
(42) comparing the first infrared characteristic data and the second infrared characteristic data to obtain a comparison value, determining whether the comparison value meets a set requirement, and determining the current value document is legal if the comparison value meets the set requirement and determining the current value document is illegal if the comparison value does not meet the set requirement.
Preferably, the infrared characteristic data includes at least one of the following values: a gradient characteristic value of gray value of the infrared image, an average value of gray value of the infrared image, and a variance of gray value of the infrared image.
Specifically, when the infrared characteristic data is the gradient characteristic value of gray value of the infrared image, the determining includes:
(51) calculating a gradient value GΩ(x,y) of gray value of the current value document and a gradient value G0(x,y) of gray value of the corresponding standard value document;
(52) calculating the number Ng of GΩ(x,y) that meets GΩ(x,y)>THg, calculating the number N0 of G0(x,y) that meets G0(x,y)>THg, wherein THg is a gradient threshold, 1.0<THg<25.0;
(53) calculating a gradient comparison value N, N=Ng/N0; and
(54) determining the magnitude of the gradient comparison value N, determining that the current value document meets a gradient rule if 0.95≦N≦1.05, or otherwise determining that the current value document does not meet the gradient rule, and then outputting a corresponding gradient legal/illegal signal.
Specifically, when the infrared characteristic data is the average value of gray value of the infrared image, the determining includes:
(61) calculating an average value MΩ of gray value of the current value document and an average value M0 of gray value of the corresponding standard value document;
(62) calculating an average comparison value M, M=Mg/M0; and
(63) determining the magnitude of the comparison value determining that the current value document meets an average rule if 0.90≦M≦1.10, or otherwise determining that the current value document does not meet the average rule, and then outputting a corresponding average legal/illegal signal.
Specifically, when the infrared characteristic data is the variance of gray value of the infrared image, the determining includes:
(71) calculating a variance VΩ of gray value of the current value document and a variance V0 of gray value of the corresponding standard value document;
(72) calculating a variance comparison value V, V=Vg/V0; and
(73) determining the magnitude of V, determining that the current value document meets a variance rule if 0.80≦V≦1.25, or otherwise determining that the current value document does not meet the variance rule, and then outputting a corresponding variance legal/illegal signal.
Number | Date | Country | Kind |
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201110278160.9 | Sep 2011 | CN | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CN12/78218 | 7/5/2012 | WO | 00 | 5/8/2013 |