HRP20080466A2 - Infrared print with processing colours - Google Patents

Abstract

Process color infrared printing is a part of security printing. The invention relates to the use of infrared effect in printing with application to protect the graphic product / print / forge, whether the print is made on paper, glass, ceramics or plastics, and using digital printing CMYK. This solution defines the creation of a color that behaves very differently in the areas of infrared (IR) light. IR response detection is only possible with instruments that "see" in wavelengths above 700 nm and convert IR graphics into an area visible to the human eye. Using specific properties that result from programming capabilities for digital and conventional printing, an algorithm was developed that involves applying two or more colors with the same tone (in daylight) but completely different behavior in IR light. The same image is separated by a double algorithm considering the determination of target visibility or invisibility in IR light. It is programmed to change the color of individual graphic surfaces with one and then another combination.

Description

The field of technology

According to the International Classification of Patents, the subject of the invention can be classified with the following designations:

B41 - PRINTING

B41M 3/14 – Printing of securities

B44F 1/00 - Drawings or pictures characterized by special or unusual lighting effects

B44F 1/12 - Valuable paper or paper money if image pattern or protection against counterfeiting is important

A technical problem and a solution to a technical problem for which protection is required

The technical problem solved by this invention relates to the use of the infrared effect in printing with application to the protection of graphic products, regardless of whether the print is made on paper, glass, ceramics or plastic. Detecting the IR response is possible only with instruments that "see" in wavelengths above 700 nm and convert the IR-graphics into the area visible to the human eye.

The task of security printing is to achieve the color that the designer has determined by looking at the graphics in daylight, and this solution defines the creation of a color that behaves extremely differently in areas under the influence of infrared (IR) light.

The color that responds to IR light is amenable to complex design. The goal is to use the property of such a color to change information under IR light. Programming involves the application of two or more colors with the same tone (in daylight) but completely different behavior in IR light. Scanning prints in IR light opens up many new areas of application in protective printing. Proposals for standardization of application have been made. Each color is seen as possible in the application of graphic product protection or, as the beginning of creating a new, individual solution in the general area of document and securities security.

State of the art

Colors in the human eye would not exist without light because light is reflected from a certain object creating the experience of color of a certain wavelength.

Each color has its own wavelength. The infrared spectrum, microwaves, radio and TV waves have a lower frequency than colors. Ultraviolet waves, X-rays and gamma-rays have a higher frequency. We detect these frequencies with instruments.

As far as is known, there are no generally known protection procedures with IR dyes. IR graphics can be found on banknotes, stocks, cards, bank papers, etc. It is important to emphasize that the instructions on recognizing the IR effect remain in the domain of the printer itself.

Graphic technology is included in the field of protection by creating products that are enhanced with special colors, papers and printing techniques. Security paints and security paper are widely used in business, administration, art and science. New chapters are opening in the fight against counterfeiting, as sophisticated printing techniques are available without previous controls and restrictions. For this reason, multiple protection methods are applied to make counterfeiting more difficult. At the same time, there is a hologram, UV and IR color, linear spot graphics in the same place of the document, and it is performed with several different printing techniques such as: offset, letterpress printing, intaglio printing, copper printing, screen printing, folio printing. For almost all types of printing, there are printing inks with a variable tone depending on the viewing angle, light intensity, light wavelength, amount of color application, special effects depending on the penetration of the color into the paper, and depending on the combination with the shape of the raster element.

Variable color printing in digital printing is a new unexplored area. Such printing with targeted application in the field of protective graphics appeared only in 2004, when it was shown for the first time with all protective measures. Color-changing toner for digital printing cannot be purchased commercially, so research with such materials in graphics is highly guarded without much public exposure.

Experiments and measurements show that RGB, Lab, HSB color systems provide color information only for light visible to the human eye. Each color can be created in multiple ways in relation to UV and IR readability. The mentioned systems do not deal with this issue and do not give an answer about the differences in their internal structure. Each color, depending on the material, gives different information when analyzed under infrared and ultraviolet light. This diversity in the UV and IR area is the starting point for creating, designing and designing top-quality graphic product protection.

Current color systems (HSB, Lab, Cie, RGB, CMYK) do not deal with the question of how the tone of the color was created or how the tone changes if the color is affected by sources from IR wavelengths of light.

Color tone, as seen in daylight, can be achieved in many ways. Information about the structure and origin of the color is deeply hidden. Different prints, with different created colors, can give our eyes the same experience of color tones, the same graphics. Therefore, we are not sure whether the print was made with the original colors, on the same paper and with the same printing techniques. Each component of the color from which it was created gives a separate response in IR light, which is the starting point for proving its authenticity. The simultaneous action of different light sources on the print reveals the presence; different mixed colors, combinations of different printing techniques, program generated graphics, simulation of tones created from different sources.

On today's documents, the IR effect appears mostly in one color. Either it is dark gray, dark brown, or green as most often. Graphics are usually split into two elements or not split at all. These colors are printed as spot colors /spot color is a pre-mixed color, for example greenish, brown, blue, which is also used for printing the given tone in one pass through the printing machine/.

Presentation of the essence of the invention:

The essence of the invention is in the superior protection of the printing print /protection against forgery/ using process colors (CMYK) for visibility and invisibility in the IR region, i.e. to improve the design of protective graphics using the property of cyan (C), magenta (M) and yellow (Y ) can give the impression of BLACK after printing one color over another but invisible in IR light. In the same place, the replacement of CMY with the black dye visible in IR light is programmed.

Using specific properties resulting from programming possibilities for digital printing and conventional graphic preparation, an algorithm was arrived at that involves the application of two or more color compositions with the same tone (in daylight) but completely different behavior in IR light. It is programmed to change the coloring of individual graphic surfaces with one, and then with another combination.

The subject invention also deals with color tone changes depending on light sources from 700 to 1000 nm, which can be used to prove the authenticity of print, paper and paint.

The goal of the invention is to improve the design of protective graphics with process (CMYK) printing colors for visibility in the IR region, because the color that responds in IR light is subject to complex design. The color property that responds to IR light is used to exchange information under IR light.

Proving the originality of graphics is proven on professional scanners that have IR light filters with the ability to change the wavelength.

This invention shows that by programming the structure of graphics elements, better protection can be achieved with the use of conventional colors if more is known about their structures. The use of conventional colors in the proposed IR protection does not make the printing process more expensive. It is preceded by an analysis of each color and its behavior in the invisible part of the spectrum. Programmed graphics that include a combination of the IR effect with conventional colors extend security printing with greater protective properties of the graphic product.

Designers tend to stick to the graphics they see in daylight. At the same time, they do not plan a security system and viewing in IR light. Only in some cases do they apply invisible UV paint. Knowledge of IR printing ink systems is a new area in printing. Programmed design, targeted design, and coded protection of the graphic product are opened. The study of many colors in IR light initiated the programming of protective graphics using these properties. Collaborators on this task developed visible RGB system separation algorithms for graphic preparation of process colors using information about light response in the IR range.

Process dyes behave differently in the IR range. Inks for offset, inks for inkjet, toners for digital printing have their own visibility properties at the transition of the visible and soft IR range (visible to IR 560 nm to 700 nm) and the range of wavelengths above 700 nm. Experimentally determined visibility properties of individual process colors are used for programmed mixing of colors with the aim that some parts of the image are visible and some parts of the image are not visible under IR radiation. CMYK separation depends on preference; what we want to see in the IR field and what we don't want to see in the IR field. A different RGB to CMYK transformation algorithm is applied to each pixel or line element of a vector graphic. The same image is separated with a double algorithm regarding the determination of target visibility or invisibility in IR light.

The color tone of the print must be independent of the addition or subtraction of a single CMYK component. In the attachment of this description, examples of separation for extreme image appearance at 1000 nm are shown. The visible range from 400 to 700 nm must remain the same as if no special separation had been programmed.

For a certain print (exemplified examples at Xeikon) it was determined that the dependence curve on the IR effect can be determined well enough for each color. The term "IR effect" can be "dosed" from the minimum to the maximum value, which depends on the previously mentioned minimum component system and the properties of toner visibility in the marginal areas of "soft IR". RGB to CMYK transformation implies achieving the same values of all RGB, HSB and Lab system parameters. This ensures the sameness of the image in the visible area of light, i.e. independence from the achieved RGB / CMYK separation.

Scanning prints in IR light opens up many new areas of application in protective printing. Proposals for standardization of application have been made. Each color is seen as possible in the application of graphic product protection, or as the beginning of creating a new, individual solution in the general area of document and securities security.

Industrial application of the invention

With the subject invention, printing becomes more interesting because printed materials contain hidden information that opens up new areas of study.

The invention can be applied in the production of all graphic products in commercial graphic design without increasing the cost of the printing process, with the aim of protecting the product or the manufacturer /trade mark/ but also a unique design that incorporates secret information obtained by experts with special knowledge of structures print, paint and paper.

Here are a number of application examples:

- tickets, membership cards, credit cards, packaging (medicines, cosmetic products, food, technical goods...), certificates (diplomas, certificates, memoranda, legal documents...), bank papers (payment slips, checks, payment certificates , reports, ...), labels (for glass and plastic packaging), barcodes, postage stamps, tax stamps, prize coupons, posters, magazines, brochures and books.

In addition to the above, it is possible to create a database of originals and counterfeits with precise information on IR protection on the graphic product.

Multiple application of different color tones on the same print will greatly prevent forgery. A print with proposed IR protection cannot be reproduced without retaining the same IR properties. Any scanning, recording or graphic processing destroys the internal structure of the information that is targeted as an IR effect.

Anyone who would engage in such work must have excellent instruments for IR graphics and complete knowledge of the internal color structure of the original. The field becomes the privilege of only researchers committed to studying the depth and particularity of graphics technology.

This invention can be illustrated in more detail by the following examples:

Pictures are attached:

Figure 1.1. Vector graphics of a portrait and a joke in color with the letters IVANA - 2 variants

Figure 1.2. Vector graphics 1.1 in 1000 nm IR light

Figure 2.1. Vector graphics of rosettes with green and purple colors and projected IR response at 1000 nm

Figure 3.1. Color typography and result in the IR range of 1000 nm

Figure 3.2. Protective graphics on postage stamps with masked IR response at 1000 nm

Figure 3.3. Merge of two pixel images. Šibenik with the mask of Rovinj and IR response at 1000 nm

Figure 4.1. Infrared effects on colorful images

Figure 5.1. Uniform background in barcode

Figure 5.2. Minimal contrast of lines and barcode background

Figure 5.3. Multicolor backgrounds of vector graphics in barcode

Figure 5.4. Multicolored backgrounds of pixel graphics in the barcode

Figure 6.1. Multicolor IR presentation with a dozen colors

Figure 6.2. Two-color checkerboard with two IR colors and two colors without IR response

Figure 7.1. Rosette with red IR color and blue color without IR response

Figure 7.2. Rosette with two green colors; visible and invisible in IR light

Figure 8.1. Continuous tone of two colors with IR response and two colors that do not respond in the IR range

Example 1. /for the sake of understanding, you should follow the pictures from the 1st Attachment, which contains the Portrait printed in its original form and its appearance under IR light/

The portrait in the picture was created by the vector method of creating graphics with the use of a dozen different nuanced tones. Some CMYK colors have low and some high representation. CMY colors react differently in IR light, and also depending on the representation, i.e. coverage.

In Figure 1.1. a print of the portrait with several different colors is given. Both images look the same under daylight, on a computer screen and in all printing techniques, while they differ drastically when viewed under IR light, which is the essence of this solution.

In the upper image, the colorful vector pattern has a black component, and the lower one does not. It is the opposite with the letters "IVANA" where there is no black component in the upper letters and there is in the lower letters. The letters are interspersed with tones enough to be glimpsed in the original in both the upper and lower graphics. The face is also covered with a black vector drawing. Figure 1.1. was scanned in IR 1000 nm /shown in Figure 1.2/. The gray scale of the IR scan shows the design of individual parts of the graphic. The letters in the above portrait have disappeared because they blocked the path to the colors below them, and they themselves have no black component. The bottom image of the portrait has removed the text "IVANA" because those colors have a black component. On a face that has been printed three times, the vector graphic of the contours of the face remains, because it is printed in black in all positions.

Experiments were also carried out for other values of IR light. From daylight to soft IR and hard IR areas, the color is analyzed in the loss of the IR effect. Each of the 16 observed colors /table HSB, Lab values of the impression on the portrait/ has its own path of «disappearance» under IR light.

Example 2 / for the sake of understanding, you should follow the pictures from the 2nd Attachment, which contains rosettes and test stamps /

Two rosettes and test stamps of green and purple colors were printed Figure 2.1. Stamps that do not have a black component cannot be seen in IR light. Both rosettes are printed in the same tone, with continuous changes from green to purple and a continuous flow of line thickness from purple to green. The upper rosette has a black component according to the recipe with the values indicated on the stamps (lower right edge). The upper rosette is visible under IR light, and the lower one disappears since the colors in the lower rosette are composed of CMY colors only.

The same principle can be used to design an IR application with other spot colors. The inclusion of two or more different colors with response in the IR region provides the designer with infinite combinations of protection.

Example 3. /for the sake of understanding, you should follow the pictures from the 3rd Attachment/

Typography in pixel graphics

A mask is placed on the colorful color image, which separates the image into visible and invisible areas in the IR wavelengths of light. The mask consists of a black and white drawing, graphic, sign. The black part of the graphic controls the visibility of the base image in the IR region. The white part of the graphic ensures the invisibility of the image in the IR range. Figure 3.1. shows the letters "sliced" in two or completely separated to achieve IR coloring through the mask. The examples show the effect of different masks for the IR test, and their application on postage stamps (Figure 3.2) and some future securities. A mask was added to the postage stamps that intersects the denomination and the head of the portrait.

Šibenik with the mask of Rovinj

The information about which pixel will be seen and which pixel will not be seen in the IR region can be determined in several ways. A software tool was developed that uses two images. The first is the one that is visible in the wavelength range for the human eye, and the second image is the one that determines the visibility of the first image in the IR region. The second image is just a mask that defines the area of delimitation visible only in daylight according to visibility in IR and daylight. The second image can be a continuous tone image. Aerial photographs of Šibenik and Rovinj are incorporated into a unique structure for IR concealment (Figure 3.3). Rovinj is a "mask" with a continuous tone that cannot be seen among the houses of Šibenik. The color image of Šibenik, viewed in IR 1000 nm, shows Rovinj with the color intensity values from the image of Šibenik.

Both the first and second images can be vector or pixel graphics. If the second image is a vector image and the first image is a pixel graphic, then the second image is previously translated into pixel graphics. The individualization of the IR area is solved by a mask generated at the time of printing, and depending on the task of the ratio visible area / IR area.

Example 4. /for the sake of understanding, you should follow the pictures from the 4th Attachment/

/Infrared effects on colorful images/

Incorporating the infrared effect is achieved with two images. The first image is visible to our eyes, called the original. The second image has the role of a mask. It is used to determine the area and intensity of the appearance of the first image in infrared light. Both images have the same number of pixels. The first example is a combination of a picture from the sea (A) with another picture (B), which only has a drawing of the letters: IŽ-KP-JŽV, the word "INFRARED" and a small text in the head of the picture. The combination of images A and B gives image C, which carries the information of both images (Figure 4.1). We cannot see that some information, hidden data, is embedded in picture A.

The print of image C, when taken under infrared light, will give an image that shows only those parts of image A that were affected by the mask. Since images A and C give the same experience to our eyes, only images C, which carry hidden information, are mainly illustrated here. In the area visible to the human eye, there is no information whatsoever about the presence of the letters from the mask in image B. The information carried by image C can only be detected in infrared light. It can be translated, through instruments that can detect this phenomenon, in such a way that we see it as black, gray or colored by the pseudocolor system.

The mask can be planned with the intensity of action. The same letters are embedded in the mask with different coverages; with complete concealment (1), with reduced coverage (2) and with very little coverage (3). Image C was subjected to different IR wavelengths. The response of the infrared effect is lower in lower wavelengths and the strongest in recording with 1000 nm.

Infrared image recording can be recorded as permanent information about the separation of some parts of the image that are designed to hide the image data.

By IR scanning image C, image A is created. The same is the case with photocopying or recording with a digital camera. After such copying and scanning procedures, the information from image C, which was created through the mask, or from image B, disappeared. The presented prints of image C were printed with a built-in infrared effect, so they can be subjected to subsequent analysis with an infrared scanner. Since images A and C look the same to our eyes in daylight, most of the illustrations are reproduced through images C only.

Example 5. /for the sake of understanding, you should follow the pictures from the 5th Attachment/

/Barcode in protective graphics /colored barcodes//

The near-infrared area is a function of the design of colored barcodes. The conventional approach to barcode printing is based on black and white graphics. Designers do not engage in experiments using colorful colors because of the uncertainty of the outcome of barcode readability.

Knowing the rules of response in IR light, it is possible to create an infinite number of different colors. Photocopying these prints, although in color with high-end devices, will not be legible. Mixtures of colors with a completely determined structure are needed. Figure 5.1.

Some examples show that it is possible to realize with a small contrast between the code and the background. Examples are given for pastel solutions as well as for dark color combinations. The background of the barcode is solved with two colors: magenta and yellow. Barcode lines are solved with carbon black and cyan. Figure 5.2.

The third group of examples is a design with a combination of several background colors in vector graphics. Such a design will be subject to applications on those products that are often counterfeited. The packaging becomes protected to a certain degree. By scanning or photocopying, it is not possible to achieve the same coloring structure that would later be readable with barcode readers. Figure 5.3.

The fourth group of examples is the design with a colorful background Figure 5.4. An image from nature is the basis of the barcode background. In these examples, it is also offered to change the colors of the code lines themselves on the same barcode. This expands the design space as well as the space of security graphics.

Example 6. / for the sake of understanding, you should follow the pictures from Attachment no. 6/

/IR in multicolor application/

The colorful pattern demonstrates a matrix /square/ of 36 randomly chosen tones. Figure 6.1. Some have an IR component added. This rich coloration is observed in visible daylight and colors visible in IR light (R). Half of the squares respond in IR wavelengths while the other squares are invisible in IR light. Some squares are equal in daylight.

Patterns (1, 2 and 3) /red-blue layout like a checkerboard/ look almost the same in daylight. Figure 6.2. Checkerboard from sample no. 1. has IR effect in vertical columns: first, third and fifth (R1). Columns 2, 4, and 6 are not visible in IR light.

Chessboard no. 2 responds to the IR component in all red squares. The blue color has no IR component. The color red begins its alternating arrangement with the lower right corner.

Chessboard no. 3 shows the visibility in IR wavelengths for the blue squares starting from the second position of the chessboard. For better orientation, a frame that responds to IR light is attached.

Example 7. / for the sake of understanding, you should follow the pictures from Attachment no. 7 /

/Infrared Rosettes/

The first graphic has blue lines and fills in dark red. In IR light, the fillings are visible, and the rosette lines are not visible, Figure 7.1. The following example is the same graphic printed in green and the lines and fill. In IR light, only rosette lines are visible, but no fills are visible; picture 7.2. The green color, with which the rosette was filled, responds to IR light.

Example 8. / for the sake of understanding, you should follow the pictures from Attachment no. 8/

/Infrared continuous tone/

The wealth of IR control is demonstrated with a continuous transition from red to green. Several samples were taken, defined as 1, 2, 4, 5, and 6. On sample 1 and 2, the prints are identical in daylight. The IR component is different; picture 8.1. In sample no. 1, the IR effect increases from green to red. Samples 4 and 5 are composed of green and red colors that appear differently in IR light with continuous transitions. It is shown that the independence of the appearance of the IR effect from the projected colors that we see with our eyes is possible. Example 6 shows that the same color tone can be achieved in an infinite number of ways. Continuous tonal transitions are possible for colors not visible in IR light and colors visible in IR light. Each of these ways can be used as a carrier of separate, targeted information, which is detected in IR light.

The power of protection is in the knowledge that there is no solid recipe for the formation of colors with the intention of using IR protective properties. The document protection designer is given a lot of freedom to mass-incorporate IR protection without disturbing the design of the graphics when viewed in daylight. The security visual designer remains on color planning for daylight viewing. He deals with the visualization of that graphic product and does not have to be burdened with the technology of IR security elements, which will be refined by an expert for printing IR visibility / invisibility in segments of the graphic product.

REMARK:

The prints in the attachment were made on a Xeikon so that the examples from the Attachment can be checked later, but with an IR scanner or a camera that has an IR filter.

Claims (5)

1. Infrared printing with process colors (CMYK) for the protection of graphic products in digital and conventional printing, indicated by the fact that during printing, three (CMYK) process colors (CMYK) or more with the same tone in daylight, but completely different, are applied , targeted, programmed behavior in IR light. 2. Infrared printing with process colors according to the 1st requirement, characterized by the fact that, during preparation for printing, the change of coloring of individual surfaces of the graphic is programmed with one, and then with another combination, whereby the second responds in IR light, but at the same time the visible area from 400 to 700 nm remains the same as if the separation (RGB/CMYK) did not take place with two different algorithms. 3. Infrared printing with process colors according to claim 1, indicated by the fact that the separation of CMYK colors depends on the desire to see what is desired in the IR area, whereby a different RGB to CMYK transformation algorithm is applied to each pixel or line element of the vector graphics, while where the transformation implies achieving the same values of all parameters of the RGB, HSB and Lab system, thus ensuring the sameness of the graphics in the visible area, i.e. independence from the achieved RGB/CMYK separation. 4. Infrared printing with process colors according to claim 1, indicated by the fact that the IR effect can be precisely dosed from the minimum to the maximum value. 5. Infrared printing with process inks according to the 1st, 2nd, 3rd and 4th requirements, indicated by the fact that knowing the IR system of printing inks opens up programmed and targeted design and coded protection of the graphic product.