CN115629507A

CN115629507A - Method for identifying authenticity of handwriting and patterns of file

Info

Publication number: CN115629507A
Application number: CN202211386368.7A
Authority: CN
Inventors: 徐期林; 孙威; 周永芳; 张海山; 黄旭; 丘欢欢
Original assignee: Guangdong Nantian Judicial Appraisal Firm
Current assignee: Guangdong Nantian Judicial Appraisal Firm
Priority date: 2022-11-07
Filing date: 2022-11-07
Publication date: 2023-01-20
Anticipated expiration: 2042-11-07
Also published as: CN115629507B

Abstract

The invention discloses a method for identifying the authenticity of a document handwriting and a pattern, which utilizes a white light source to irradiate detected bodies with the same color on a carrier; in the white light, part of light with the wavelength is absorbed by the detected body, and the rest of light with the wavelength is reflected by the detected body; the light reflected by the detected body passes through the filter structure to filter part of the light with wavelengths, and the rest of the light with wavelengths is captured by a photographic device (including a video camera, a camera and the like); when the colors of all parts of the detected object image acquired by the photographing device are consistent, judging that all parts of the detected object are not necessarily tampered; when the local color of the image of the object acquired by the imaging device is different, the relevant parts of the object are judged to be different, and the object is judged to have been tampered. The method for identifying the authenticity of the document handwriting and the pattern has the advantages of simple adopted equipment, low use cost and wide applicable range of the detected object.

Description

Method for identifying authenticity of document handwriting and pattern

Technical Field

The invention relates to the field of file authenticity identification, in particular to a method for identifying authenticity of a file handwriting and a pattern.

Background

The falsified (stained) files are general names of various falsified files formed by adopting various means on the basis of original real files and various contaminated and damaged stained files. In the field of document inspection of judicial identification, the inspection of the documents is generally carried out by using a microscope direct observation method, namely observation and judgment under a 10-200 times-volume visual microscope. However, the conventional method is unreliable and is very easy to make misjudgment.

In addition, some methods are also used for inspection by infrared photography, etc., which has great limitation in practical application process, and many metamerism phenomena cannot be identified.

Disclosure of Invention

The invention aims to provide a method for identifying authenticity of writing and patterns of a document, which adopts simple equipment, has low use cost and wide applicable detected object range.

In order to achieve the above object, the present invention provides a method for identifying authenticity of document handwriting and pattern, wherein a white light source is used to irradiate the detected object with the same color on each part of a carrier; light with a part of wavelengths in the white light is absorbed by the detected body, and light with the other wavelengths is reflected by the detected body; the light reflected by the detected body passes through the filter structure to filter part of the light with the wavelength, and the light with the other wavelengths is captured by the photographic device; when the colors of all parts of the image of the detected object acquired by the photographic device are consistent, the detected object is judged not to be falsified; when the color of the part of the image of the object obtained by the imaging device is different, the relevant parts of the object are judged to be different, and the object is falsified.

As a further improvement of the invention, when the colors of the part of the image of the detected object obtained by the photographing device are consistent, whether the local colors of the image of the detected object have differences can be continuously observed by adjusting the filtering range of the structure of the filtering sheet.

As a further improvement of the invention, the white light source is an LED lamp, a fluorescent lamp, sunlight and the like.

As a further improvement of the present invention, the filter structure includes at least two filters sequentially arranged along the optical path.

As a further improvement of the invention, the filter structure comprises 1 filter.

As a further improvement of the invention, the optical filter comprises three pieces, namely an LP450 optical filter, a blue light optical filter and a green light optical filter; obtaining a light transmission range with a light transmission rate-wavelength curve diagram showing double wave peaks, double wave troughs and long wave flux through the combined action of the three optical filters; when the colors of the parts of the image of the object obtained by the photographing device fall in different sections in the light transmission range and show different color differences, the relative parts of the object are judged to be different, and the object is tampered.

As a further improvement of the present invention, the subject is ink.

Advantageous effects

Compared with the prior art, the method for identifying the authenticity of the document handwriting and the pattern has the advantages that:

1. the white light source is easy to obtain and low in cost.

2. The operation environment requirement is low, and the operation can be carried out in a dark indoor lamplight environment in the daytime or in a dark environment.

3. The method can also be used for identifying the authenticity of some detected objects which cannot be detected by infrared rays, makes up for the defects of the identification method and has wider usable range.

4. The method is easy to popularize and apply in the basic level.

The invention will become more apparent from the following description when taken in conjunction with the accompanying drawings, which illustrate embodiments of the invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a method for authenticating the authenticity of writing and patterns of a document;

FIG. 2 is a photograph of a subject under a white light source for various black ink writing;

FIG. 3 is a photograph showing the actual photographing effect of various black ink handwriting subjects on the photographing apparatus;

FIG. 4 is a photograph showing the actual shooting effect of various black ink handwriting subjects by using a VSC8000 text analyzer;

FIG. 5 is a graph showing transmittance-wavelength curves of an LP450 filter;

FIG. 6 is a graph showing a transmittance-wavelength curve of a blue filter;

FIG. 7 is a graph showing transmittance vs. wavelength curves for a green filter;

FIG. 8 is a schematic diagram showing three filters in the same transmittance-wavelength curve;

fig. 9 is a graph showing transmittance-wavelength curves of three stacked filters.

Detailed Description

Embodiments of the present invention will now be described with reference to the accompanying drawings.

Examples

Referring to fig. 1, in a method for authenticating a document writing or a pattern, a white light source is used to irradiate a test object 6 having the same color on a support 5. Some of the white light having a wavelength is absorbed by the subject 6, and the rest of the white light having a wavelength is reflected by the subject 6. The light reflected by the subject 6 is filtered by the filter structure 4 for a part of the wavelengths, and the rest of the wavelengths are captured by the imaging device 3. When the colors of the respective parts of the image of the subject 6 acquired by the imaging device 3 match, it is determined that the subject 6 is not necessarily falsified. When the image of the subject 6 acquired by the imaging device 3 has a local color difference, it is determined that the subject has been tampered with because the portions of the subject are different. The photographing device may be a video camera, a still camera, or the like. In this embodiment, the white light source is an LED lamp 1.

When the colors of all parts of the image of the object 6 acquired by the photographing device 3 are consistent, whether the local colors of the image of the object 6 are different or not can be continuously observed by adjusting the filtering range of the filter structure 4.

Filter structure 4 can adopt 1 piece of filter, also can adopt the multi-disc filter. In this embodiment, the filter structure 4 includes at least two filters sequentially arranged along the light path. The optical filter can adopt a blue band-pass and long-wave-pass optical filter, a green band-pass and long-wave-pass optical filter and a 430nm or above long-wave-pass optical filter according to requirements, and the optical filters can be used independently or in a superposition combination mode. As shown in fig. 1, the filter is a multi-sheet filter and is used in a stacked combination.

The subject 6 is ink. The object 6 may be various ink marks formed on a document, such as characters written by a sign pen, printed characters, stamp prints formed by stamping, or the like, or patterns formed on a document by using a pigment. The carrier 5 may be paper, a certificate, a card, a canvas, etc.

In the specific implementation, 1 blue band-pass and long wave-pass filter, a green band-pass and long wave-pass filter, or each wavelength long wave-pass filter of 430nm or more are additionally arranged in front of the lens of the photographic device 2 according to requirements, or filters with different specifications are additionally arranged, the color temperature of the photographic device is adjusted to 3000K to 5000K, and the color saturation is adjusted to more than 60%. In daytime indoors or in dark environments, the subject 6 is illuminated with a low power LED light source, such as a 5 watt LED flashlight. After focusing the image device 2 clearly, images with different absorption and reflection of each part of the object 6 can be shot and recorded.

In this embodiment, the optical filter includes three pieces, which are an LP450 optical filter, a blue optical filter, and a green optical filter. The LP450 optical filter, the blue optical filter and the green optical filter are sequentially arranged along the light path. Through the combined action of the three optical filters, a light transmission range 7 with a light transmission rate-wavelength curve diagram of double peaks, double troughs and long wavelength pass is obtained, as shown in fig. 9. The partial light transmittance of wave crest and long wave pass is high, and the partial light transmittance of wave trough is low.

When the colors of the respective portions of the image of the object 6 acquired by the imaging device 3 fall in different regions in the light transmission range 7 and the colors displayed on the imaging device 3 are different, it is determined that the respective portions of the object 6 are different and the object 6 has been tampered with.

As shown in fig. 2, the subject of various black ink writings actually takes an effect photograph under a white light source. As shown in fig. 3, the images are photographs showing the actual photographing effect of the objects with different black ink writings on the photographing device 2 after the reflected light is filtered by the filter structure 4. After the optical filter, the color of the

samples

1001021048 and 1001888067 are obviously different, and the color of the

samples

1301027009 and 1001027002 are also obviously different, which shows that the handwriting is formed by using different inks, as shown in fig. 3. Fig. 4 is a picture of the effect of the VSC8000 document analyzer (one of the most advanced document analyzers in the world) actually taken under infrared (830 nm wavelength) irradiation for various black ink handwriting subjects, and it can be seen that there is no significant difference between the

sample numbers

1301027009 and 1001027002. Therefore, the method can also play a role in identifying authenticity aiming at some detected objects which cannot be detected by infrared rays, not only makes up for the defects of the identification method, but also has wider usable range, low identification cost, low energy consumption and simple operation.

The present invention has been described in connection with the preferred embodiments, but the present invention is not limited to the embodiments disclosed above, and is intended to cover various modifications, equivalent combinations, which are made in accordance with the spirit of the present invention.

Claims

1. A method for identifying authenticity of writing and pattern of document is characterized in that a white light source is used to irradiate a detected body (6) with same color on a carrier (5); in the white light, a part of light with wavelengths is absorbed by the detected body (6), and the rest of light with wavelengths is reflected by the detected body (6); the light reflected by the detected body (6) passes through the filter structure (4) to filter part of the light with wavelengths, and the rest of the light with wavelengths is captured by the photographic device (3); when the colors of all parts of the image of the object (6) acquired by the imaging device (3) are consistent, the object (6) is judged not to be tampered; when the image of the object (6) acquired by the imaging device (3) has a local color difference, it is determined that the respective parts of the object (6) are different and the object (6) has been tampered with.

2. The method for verifying authenticity of a document writing and a pattern according to claim 1, wherein when the colors of the parts of the image of the subject (6) obtained by the photographing device (3) are consistent, whether the local colors of the image of the subject (6) are different is continuously observed by adjusting the filtering range of the filter structure (4).

3. The method for authenticating the authenticity of the writing and the design of a document according to claim 1 or 2, wherein the white light source is an LED lamp (1).

4. A method as claimed in claim 1, characterized in that the filter structure (4) comprises at least two filters arranged in succession along the light path.

5. The method of claim 4, wherein the optical filter comprises three filters, which are respectively an LP450 filter, a blue filter, and a green filter; obtaining a light transmission range (7) with a light transmission rate-wavelength curve diagram of double wave peaks, double wave troughs and long wave flux through the combined action of the three optical filters; when the reflected light of each part of the image of the object (6) acquired by the imaging device (3) is in different sections in the light transmission range (7) and different color differences are generated, the relative parts of the object (6) are judged to be different, and the object (6) is tampered.

6. A method of authenticating documents or documents according to claim 1, wherein said filter structure (4) comprises 1 filter.

7. A method of authenticating documents according to claim 1, wherein said test object (6) is ink.

8. The method of claim 1 or 2, wherein the wavelength response range of the photographic device is from visible light to near infrared light of 400nm or more, the color temperature range is from 2000K to 7000K, and the color saturation is from 60% to 100%.