RU2682423C1 - Laser cleaning of paper based documents - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to methods of processing materials using laser technology and can be used to clean the surface of historical documents on a paper basis in the process of restoration by the action of laser radiation on its surface, whereby areas of the document containing printing ink and ink are excluded from the processing area, which allows preserving the graphic and text information on them. Method is proposed for cleaning the surface of historical documents on a paper basis by means of high-precision laser scanning of their surface, in which areas with typographical ink and ink, that is, text and graphic images are excluded from the treatment area. Technical implementation of this method involves the use of high-precision scanning laser systems, similar to the scanning systems used for laser marking and engraving. Proposed method includes the creation of a mask image, which will be used to clean the document, as well as the selection of output laser parameters. Mask image is loaded into a computer program to control the operation of the scanning system, after which mutual precise orientation of the working area of the laser system with the cleaned area on the document surface is performed.EFFECT: method allows cleaning of historical documents on a paper basis with preservation of the graphic and text information available on them.1 cl, 4 dwg

Description

The invention relates to the field of laser technology, and more particularly to methods for the restoration of paper-based documents using lasers, and can be used to clean the surface of documents.

Traditional chemical and mechanical methods for cleaning paper-based documents are known, using scalpels, erasers, scrapers, and also chemical reagents (GOST 7.48-2002. Preservation of documents. Minsk: Interstate Council for Standardization, Metrology and Certification, 2002); (Sysoltseva V.N. Restoration of a rare document from the collection of Grand Duke Konstantin Nikolaevich - the book of D.P. Shelekhov “People's Leadership in Agriculture” (1838) // Bulletin of the Far Eastern State Scientific Library. 2013, issue (No. 1) 58. S. 23-28.); (Golysheva E.V. Restoration of a book monument of the 17th century / Bulletin of the Far Eastern State Scientific Library. 2004, issue (No. 3) 24. P. 113-117). Such methods are characterized by the danger of their use for the state of preservation of the document itself, which is unacceptable when restoring documents of high historical and informational value.

The use of mechanical methods adversely affects the properties of the mechanical strength of the substrate. The use of chemical solvents leads to their uncontrolled effect on the substrate and adjacent areas of the surface of the document, which entails the loss of the primary properties of the object.

There is also a method of cleaning the surface of works of art and paper documents using laser radiation (Laser cleaning of handwritten and printed documents from pollution / A.A. Galushkin, M.D. Gerashchenko, L.G. Levashova, V.A. Parfenov, T. S. Tkachenko // Proceedings of the Laboratory for the Conservation and Restoration of Documents SPF AR AN. 2011, issue (No.) 2.P.155-164.)

The closest in physical essence and the achieved technical result to the claimed method is the work (An investigation into the effect of wavelength in the laser cleaning of parchment / S. Sportun, M. Cooper, A. Stewart // Journal of Cultural Heritage. 2000, vol. . No. 1. P. 225-232.), In which the surface of the document is scanned by a laser beam to clean the parchment from surface contaminants. Unlike traditional chemical and mechanical cleaning, the use of laser radiation as a restoration tool, with the right choice of output parameters, avoids damage to the substrate of a paper document and is characterized by high efficiency of removing contaminants. However, the widespread adoption of this method in the field of practical restoration is hindered by the fact that when laser radiation affects a document, along with the removal of contaminants, the printing ink and ink that make up the text or graphics on the document can be destroyed.

The problem solved in the invention is the creation of a method for laser cleaning of paper-based documents without damaging the graphic information.

The problem is solved due to the fact that in the proposed method, as well as in the known, the document being cleaned is scanned with a laser. In contrast to the known method, in the proposed pre-create an image mask. By optical scanning of the document, a primary image of the area to be cleaned is obtained, the resulting image is downloaded to a computer and using a computer program designed to process graphics, the space around the alphanumeric information is cleaned. After that, the resulting image is converted to vector and inverted. The resulting image mask is loaded into the control system of the scanning system, then the cleaned document is positioned relative to the working field of the laser scan and the laser beam is scanned over the surface.

Achievable technical result is to increase the safety of the document being cleaned, by eliminating the effects of laser radiation on the areas that make up the text or graphics, through the use of scanning laser systems.

The first step in the implementation of the method is to create a mask image, which will be used to clean the selected section of the document. The primary image can be obtained by optical scanning of the area being cleaned. Further, after transferring the scanned image to a personal computer, this image must be edited in any computer program designed for processing graphics. The purpose of computer processing is to highlight the area of the document to be cleaned in white in the resulting graphic file, and, conversely, all the necessary alphanumeric information is painted black. After that, the resulting image is converted to vector and inverted.

Next, a previously edited vector and inverted image of the document (mask image) is loaded into the program for controlling the scanning system with a laser beam. After that, the positioning of the processed area of the paper sheet relative to the working field of the laser scanning is performed, for which an auxiliary laser is used that generates radiation in the visible region of the spectrum (for example, a red semiconductor laser), and the overall frame formed by the image applied to the paper sheet. Correct positioning can be carried out using reference marks previously applied to the cleaned area of the document or using a special mark. In the latter case, the positioning of the treated area relative to the working field of the laser system is carried out by combining the reference marks with the overall frame. After completing the preparatory work on the mutual orientation of the working field of the laser scan and the processed area of the document, the laser scanning program is launched with predefined radiation parameters corresponding to the operating modes of the laser system used.

Thus, the proposed method allows you to clean the page of the document by high-precision scanning of the laser beam on its surface, which carries out its selective effect on the contaminated areas, while the text and graphic information contained in the document remains intact.

The invention is illustrated by drawings:

where in FIG. 1 - the first stage of creating a mask image, an optical scan of the cleaned area of the document

FIG. 2 - the second stage of creating the image of the mask, cleaning the image of the area that will be subjected to laser scanning

FIG. 3 - the third stage of creating the image of the mask, uniform filling of the areas that make up the text or graphics

FIG. 4 - the fourth stage of creating a mask image, converting the image into vector and inverting it

Consider an example implementation of the method.

The first step of the proposed method is the optical scanning of a paper document, which will subsequently be subjected to selective laser cleaning. The resulting image is downloaded to a computer. Next, the image downloaded to the computer is edited using any computer program designed to process graphics to create a mask image.

In FIG. Figures 1-4 show the successive stages of the implementation of the image mask, using the example of a section of text that will be used to clean the surface of a document. Thus, the first stage of imaging the mask is shown in FIG. 1. Here, an optical scan of the area being cleaned and its precise cropping according to a previously applied frame or reference marks is performed.

The second stage of mask formation is shown in FIG. 2 and represents a complete cleaning of the area that will be subjected to laser scanning and preservation of intact areas containing text.

The third step shown in FIG. 3, provides for a uniform "fill" of the areas constituting the text and converting the resulting image into a vector one.

In FIG. Figure 4 shows the final version of the mask image, which is an inverted and vector version of the original image (Fig. 1). Such a variant of the image-mask will allow you to "fill" the area to be cleaned with uniform one-sided lines of a certain frequency, while excluding from the laser processing zone those sections of the surface of a historical document that have text or graphic images

After receiving the mask image, it is loaded into the control system of the scanning system.

The document to be cleaned is positioned relative to the working field of the laser scan along the overall frame formed by the pilot laser and showing the dimensions of the applied image. After completing all the preparatory steps, the control system of the scanning system is launched with the mask image loaded into it.

According to the results of the program, the cleaning of the area surrounding the text and graphics is achieved, while the surface areas of the document being cleaned that make up text and graphic information are not cleaned, which increases the degree of preservation of information on the document.

Claims (1)

Laser cleaning of paper-based documents by scanning the surface with a laser beam, characterized in that they preliminarily create an image mask, by optical scanning of the document, a primary image of the area being cleaned is obtained, after which the resulting image is downloaded to a computer and using a computer program designed to process graphics, the space around the alphanumeric information is cleaned, after which the image is converted into vector and inverted, the resulting image The mask mask is loaded into the control system of the scanning system, then the positioned document is positioned relative to the working field of the laser scanning and the laser beam is scanned over the surface.

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