JP2002540650A - Printing security documents - Google Patents

Abstract

(57) Abstract Incorporation of identification features that are invisible to the eye but repeated over at least a portion of the surface of the document substrate for detection by a suitably programmed computing device to authorize the document or prevent its duplication. How to print security documents such as banknotes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION

The present invention relates to printing security documents, and more particularly to printing and encoding techniques that can be used by a data processor-based imaging system to identify the presence of signals related to security documents.

[0002]

BACKGROUND OF THE INVENTION

It is known to scan a document to be printed and convert the image into digital data for supply to a computer. This image digital data can be used to print a copy of the original document using a laser jet or inkjet printer, in which case an imaging device (usually a scanner)
, Computers and printers act as copiers. By editing or manipulating the stored data using graphics software, the final print can be a very accurate reproduction of the original. In addition, this data can be sent to a remote location, e.g., via the Internet or by modem and telephone lines, or stored on a disk or other memory device for future use; May be used to forge security documents such as ID cards and the like.

[0003]

[Prior art]

Methods are known for altering a document substrate so that a real substrate can be identified and distinguished from a counterfeit substrate. Typically, these methods involve marking a real substrate with a material that fluoresces under ultraviolet light or emits light only in certain regions of the visible spectrum, or includes a magnetic material or infrared absorbing dye. Or including a large watermark in the form of a picture or barcode on or in the substrate. All of these methods involve significant changes in the substrate (such as a watermarking method) or special materials that usually require a special detector to determine if the substrate of any document is genuine. Needs to be included. Such methods tend to be expensive, and the effects are usually easily visible to the naked eye, and it is not impossible to change paper and other substrates in a similar manner to disrupt the verification process.

[0004]

[Object of the invention]

It is an object of the present invention to provide a method for printing a security document having features that can be detected using a computer or other data processor based imaging system, but which does not impair aesthetics.

[0005]

Summary of the Invention

According to one aspect of the invention, a method of printing a security document includes incorporating a plurality of identifying features in the printing of the document, so as to represent said features when illuminated and imaged on a photosensitive device. An image data signal is generated at the output of the device, and the method is further characterized in that:

[0006] 1. By selecting a contrast between the identifying feature and either the remainder of the substrate surface or the print residue in the area containing the feature, the image data signal corresponding to that feature will result in an image data signal for the image of the substrate surface or surrounding and And / or substantially indistinguishable from the background noise signal, thereby making it invisible to the naked eye; By repeating this feature over at least a portion of the surface of the substrate, the time or position of the signal for each feature has at least one fixed relationship to the signal for the other of said features, thereby providing an image The computer device to which the data signal is supplied can be programmed to determine whether the at least one fixed characteristic identification characteristic signal is present in the data, and the identification characteristic signal is included in the image data signal. Is found, a document identification signal can be generated.

This identification feature may be regularly spaced over the area of the substrate. Each of the printed signatures may have similar characteristics to each of the other signatures.

[0008] The same type of document may be printed with similar identifying features having similar fixed relationships on the surface of the document. For example, one type of banknote may be printed with a particular type and a particular interval of identifying features that are unique to that type and currency.

The spacing may be chosen to be constant in one direction only, or to vary according to a special known pattern.

[0010] Similar or different intervals may be selected for identification features in another direction having a particular spatial relationship with respect to the first direction, for example, perpendicular to the first direction.

In a preferred example, the identifying features are arranged in a 2D matrix on the substrate surface.

The presence of such printed identification features constitutes a first sign of the substrate, whereby the substrate can be distinguished from a printed substrate that does not contain such features, or depending on the choice of features and / or spacing They can be distinguished from each other.

The second sign of the substrate may be achieved by introducing changes to the matrix, such as by removing features from specific locations in such a regular matrix. For example, all fourth features along each of the third lines may be omitted.

[0014] Preferably, the second document is encoded using both the first and second codes.

Additionally or alternatively, a second code may be provided when the matrix is formed from features having two properties, instead of omitting features at particular locations in the matrix. Are placed in one set of locations in the matrix, and the other type of features are placed in other locations in the matrix. In a simple example, a set of features may be generally circular, while interspersed features may have different shapes that are easily distinguishable, such as rectangles or triangles.

The code on the printed circuit board is selected by selecting the spacing between the identification features to be printed, or by selecting features having particular characteristics, such as identifiable shapes in the image data signal associated therewith, and Printed because features that have properties different from those of the other features in the matrix can be achieved by replacement at selected points in the matrix and / or omitting features at specific points in the matrix. There are almost countless possible combinations and permutations available to encode security documents.

The present invention thus not only allows a reliable method for the identification of security documents, for example, to easily detect counterfeits not printed on a suitable substrate, but also for example different types. Each of the individual types of security documents, such as banknotes, checks from different banks, passports issued by different establishments, and the like, if desired, in a particular first
And / or may be uniquely identified by a second code.

To identify regular patterns and / or dropouts in regular patterns, and / or the shape or color of detectable identifying features in images or the presence of other visually distinguishable features. Image analysis techniques are readily available and known, and can be used to check and verify image data by using high-speed processors such as DSPs and the like, or to perform virtually instantaneously when scanning printed documents. it can.

When a second code is present, any change in the first code that makes up the second code can be distinguished by the naked eye or by a photosensitive device such as used in a photocopier or document scanner. It is more preferable that it is hard to be picked up.

Preferably, the identification feature code to be printed is in the form of a repeating pattern. The signs or patterns or both may be repeated at regular intervals in one or more directions across the document.

Since this identifying feature does not affect or aesthetically impair the appearance of the security document (eg, banknote) to be printed, it is authenticated that does not include the encoded feature in the printing material. Older security documents (especially banknotes) can be distributed in parallel with those containing codes.

In any document, two or more different encoding techniques using printed identification features may be combined.

The substrate may be printed with a pattern using substantially transparent ink or ink of substantially the same color as the substrate, so that when it is imaged and converted to an image data signal. Except for their specific relationship to other similar data signals, the image data signal for that specially printed area becomes substantially indistinguishable from the image data signal for the remainder of the substrate surface.

Preferably, the pattern to be printed is a repetitive pattern extending over part or all of the surface of the substrate.

When the pattern to be printed includes a first code and a second code, it is preferable to generate multiple repetitions of the code on the substrate.

The printed identification pattern may extend only within one or more selected print areas of the document.

Redundancy caused by multiple iterations can be advantageously used because multiple similar iterations increase the detectability of code-forming features by increasing the effective signal-to-noise ratio. This facilitates the data processing device detecting the presence of a substantially invisible pattern of printed identification features.

In order for the document identification system to work, the code of the document may be specified by, for example, optically scanning the document to produce a computer-handleable image data signal, or specialized imaging and performing this function. It must be readable by using a signal analyzer.

A feature of this proposal is that any printed indicia that generates the code of the document can be read and detected using a suitably programmed data processing system,
It is almost indistinguishable to the naked eye, and the image data signal obtained by imaging and scanning a document uses that data signal when used, for example, to control a laser, ink jet or dye diffusion printer. It does not include a data signal associated with the coded indices of sufficient strength to reproduce the characteristics of the coded indices in any subsequent printing process.

[0030] The invention also resides in a security document having encoded printed identification features thereon that provide detectable features to enable identification of the document as described above.

The present invention also resides in a security document when printed as described above.

A primary application of the present invention is in printing code features on the surface of a substrate that, when detected in a scanning or copying process, cause a copy / print corruption or blocking process. The detection step is performed as an image data signal obtained by scanning a document, digitizing the resulting signals and applying them to an algorithm.

The present invention also provides one or more such devices that generate a document identification signal when detected in image data provided to a processor, such as by imaging and scanning a document, for recognition purposes. A document identification method is provided wherein the data processor is programmable to look for further specific codes. This may be used to verify the imaged document in the case of a banknote checker, or may prevent or prevent printing of a duplicate of the document in other cases.

The invention may also be used to identify the presence of a particular security document by checking that one or more patterns of one or more features are present in the document. A base document scanning device is provided.

Thus, for example, banknote validators associated with cash boxes in stores, banks and post offices can be provided at a relatively low cost, and it is possible to verify the publicly offered banknotes at the transaction point before receiving them. .

In the case of currency notes or the like, it may be of further interest to determine what type it is, and when more than one source organization is involved, It may be advantageous to determine which organization issued the bill. This type of computer-based document checking function can be used as a bill acceptor, can be used in a bill changer, and can be used by a blind person to find out which bank note he owns. it can.

[0037]

[Description of different print encoding technologies]

Any printing technique, such as lithography, dry offset, letterpress printing, ink jet printing, or electrophotographic transfer of ink or toner, may generally be used to create a faint repeating pattern on the substrate.

In one technique, a photo master of the code is created in the film so that the image is originally binary. In other words, it has light areas for "image" features and dark, opaque areas for "non-image" areas, or vice versa, where there are no "grey" areas. By this means the pattern is converted into a form suitable for assembling into a printing plate.

The second code is integrated into the print, typically by introducing changes into the image features and / or non-image areas of the photo master by changing the electronic signals used to produce the photo plates. You may.

Using such a lithographic printing plate, the document substrate is first printed using very light gray, yellow or brown ink that hardly differs from the original color of the substrate itself, so that the pattern on the document is Will be virtually invisible.

Alternatively, the ink may be colored. The substrate may be colored with dyes such as red, blue and green, which may be desirable in some documents.

The term printing is also intended to include any technique whereby a selected area of a paper substrate is impregnated with a fluid, such as a resin or lacquer, whereby the optical absorption or reflectance properties of the substrate or optical properties In order for the density to be sufficiently changed, the impregnated and non-impregnated areas can be distinguished during the scan for digitization under incident light, the selected area and the remaining area being the first code. And changes in the pattern (e.g., changes in edge, thickness and / or spacing) include a second sign.

In addition, the surface of the substrate may be formed with features that produce a different light reflection than the rest. Different surface treatments, such as the following, may be used.

[0044] (1) embossing in the first technique of carrying out the present invention, the substrate may be embossed during its manufacture. This is typically done in the production of paper or sheet plastic by a process known as a calender, which passes through a high pressure nip between two steel rollers in order to smooth the material sufficiently for printing. By forming a depression in one or both of these rollers, the paper or plastic substrate is pressed in between, forming an embossing pattern corresponding to the depression. By suitably encoding the embossed features, the substrate is encoded as required in the present invention and can be detected by suitable illumination and converted to a digital data signal by a scanner for analysis by a data processor. Become like

(2) Surface Treatment of Lacquer Paper When a resin or lacquer or other material is mixed with paper or plastic substrate material to provide a smooth surface for printing, the actual surface of the substrate has a security document there. The encoded structure is smooth enough to accept printing ink to make it printable, but also includes fine patterns in less smooth areas that would be less likely to accept printing ink. Can be formed on the surface.

(3) In order to impregnate with a fluid such as an impregnating resin or a lacquer, a selected area of the substrate exhibits a repetitive pattern, and the optical absorption or reflectance characteristic or the optical density of the substrate is sufficiently changed. The surface may be modified by a technique that makes it possible to distinguish between impregnated and non-impregnated areas under incident light during scanning for digitization.

(4) Printing is performed by etching the surface of the laser processing substrate with a laser beam (
Or await the printing) on the surface. This technique lends itself to the creation of very fine patterns on the surface of the substrate, and the laser beam can be adjusted very precisely so that, with or instead of the spacing edge or thickness, or instead, the depth of any such grooves or cavities. Can be used to introduce the adjustment of the height.

(5) Watermarking Watermarking changes the thickness and / or texture of a substrate, which can be made visible under incident light to form the first and / or second code of the present invention. Can be used. This can be formed in two ways.

In the method of producing a fourdrinier paper, when forming it, a wet paper is embossed using an embossing roller, whereby a mark corresponding to the embossing is stamped on the paper. By forming the embossments in a suitable repeating pattern extending over the area of the web, the paper can be encoded with a watermark pattern.

A second technique for forming a watermark uses a so-called cylinder molding method. In this method, a watermark is formed by a cylindrical wire mesh engraved with "molding" in the form of an image. Increase or decrease the amount of fiber on the mesh mound during paper manufacture, where the thicker paper gives a darker effect when seen in transmission, and thinner areas are seen in transmission Sometimes thinner. However, since both types of watermarks are only visible in the incident light, this can be used to provide the background code required by the present invention.

According to the present invention, a pattern may be applied to the surface of a substrate, especially a paper substrate, using any of the watermarking techniques, which pattern is substantially insensitive to the naked eye,
It is shown as a low contrast pattern when exposed to incident light as the document is positioned for scanning and digitization.

The techniques described so far provide a surface-encoded substrate that can then be printed to form a security document. However, some coding techniques, such as embossing, may be applied after some or all of the document has been printed.

For example, embossing may be applied after a title or other text, or in the case of an ID document, for example, personal data is printed on a flat substrate, and the surface code is formed as a post-print step. You.

The embossing encoding can be achieved while printing at least some areas of the document. Thus, surface encoding may be provided to the document by so-called "blind" intaglio printing or intaglio printing with colorless ink. In such a method, the image is printed using a plate containing the engraved areas, some of the engraved areas are filled with ink, and some are left empty in the case of blind intaglio printing. The ink is transferred to the substrate by pressing the appropriately inked engraving plate against the substrate under high pressure. The substrate may be embossed with the engraved image under applied pressure, and some of the substrate surface may be printed and other portions may simply be embossed.

Within the scope of the present invention, surface treatment of the substrate includes any technique that allows lighter and darker areas to be visualized on the treated surface of the substrate sheet when illuminated for scanning. Including. Either or both of the first and second signs may be in the form of a repetitive pattern that can be distinguished under appropriate illumination to provide detectable content in the digital signal obtained by scanning.

The encoding by embossing and printing may be achieved simultaneously. The code may be provided to the document by intaglio printing with substantially colorless ink. In such a method, an image is printed using a plate that includes an engraved area filled with ink. The engraving plate is properly inked and pressed against the substrate under high pressure to transfer the ink to the substrate. The substrate may be embossed with the engraved image under applied pressure, some of which may be printed and others may be left blank.

[0057]

[Explanation of the embodiment]

The process for printing the identifying features on the substrate of a manufacturing banknote (or other security document) will be apparent from FIG. 3 without further explanation. Similarly,
An alternative process for embossing identification features on a substrate will be apparent from FIG.

The resulting substrate is shown in FIG. 1, but in practice the printed or embossed identification feature, in this case a repeating bar code pattern, is invisible to the naked eye.

The banknotes are conventionally printed on a substrate and the results are shown in FIG. In practice, the discriminating feature is invisible to the naked eye, so it does not detract from aesthetics and does not affect the design freedom of the banknote image. It is noted, however, that the banknote design may be printed either before or after the identifying feature is formed, either by printing (FIG. 3) or by embossing (FIG. 4).

A detection computer-based device can detect the aforementioned signature in various ways, two of which are described below.

An encoded document is converted to digital form when scanned by a computer. This typically means that the image is analyzed into red, green and blue channels for each pixel or pixel. Pixel colors are assigned values on a scale of 0 to 255 (8 bits) in each of their channels, typically with maximum brightness assigned to the value 255 and “colorless” assigned to the value 0. That is, bright white is represented by all three channels having the value 255, and black is represented by zero intensity having the value 0.

When a real image, such as a printed banknote, is scanned into the system, most pixel values are located in the central region, eg, between 230 for the paper background and 40 for the darkest print. Pixels for low contrast codes are in bands that are very close to paper background values. For example, the sign is printed in a controlled manner so that it is always within a band of 20 pixel values on the paper background.

All values between a value slightly lower than the paper value (eg, 228 in this example) and the lowest value for the coding band (eg, 210 in this example) are 10 or 0 Reset to the value (almost black) and 21 in this example.
Resetting all other values between 0 and 0 to 230 (in other words, the same color as the paper background) is easy for computer programs.

This procedure is usually very small because it is not easily seen and all printed and unmarked features, except for signs and very weak features associated with the design that are not included in the design for aesthetic reasons. It has the effect of eliminating the design features. This procedure turns the code itself black (see FIG. 5), which can be read by programs specially designed to recognize this code. As a simple example, when the code is a series of alphanumeric characters, such as letters and numbers, the data can be read using an optical property recognition program to determine whether it is a known code. Alternately, more sophisticated image detection techniques may be used, especially when the codes are of a more complex type, such as those used for digital watermarking. In some cases, it may be preferable to show only the sign (
(Fig. 6).

Alternatively, the code can be extracted using a contrast enhancement routine such as that commonly known as “equalization”. This is shown in FIG. This type of routine sets the maximum value of pixels in each channel to 255, sets the minimum value to 0, and attempts to redistribute pixel values between the two evenly. This has the effect that the difference between the pixel value close to the paper background and the pixel value for the code increases, making it easier to recognize in an image recognition program or routine. This method has the disadvantage that the identification routine has to ignore any other design features that are not relevant to the code.

However, more sophisticated routines may be used that recognize complex code patterns, such as those used for high-level code in complex images and patterns.

[Brief description of the drawings]

FIG. 1 illustrates a banknote substrate imaged with bar code features that are in fact invisible to the naked eye.

FIG. 2 is a diagram showing a banknote image printed on a substrate.

FIG. 3 is a flowchart of a process for printing barcode features on a banknote substrate.

FIG. 4 is a flowchart of a process for embossing barcode features on a substrate.

FIG. 5 is a diagram showing an image of a banknote represented by a computer code extraction routine.

FIG. 6 is a diagram showing an image of a banknote represented by a computer code extraction routine.

FIG. 7 is a flowchart illustrating one of the possible deflection routines.

[Procedural Amendment] Submission of translation of Article 34 Amendment

[Submission date] January 19, 2001 (2001.1.19)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Contents of correction]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Contents of correction]

[0005]

According to one aspect of the present invention, a method of printing a security document to enable machine authentication includes incorporating a plurality of identifying features in the printing of the document, and is illuminated for that purpose. When imaged on a photosensitive device, an image data signal representative of the feature occurs at the output of the device, and the method is further characterized by the following.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Contents of correction]

[0006] 1. By selecting a contrast between the identifying feature and either the remainder of the substrate surface or the print residue in the area containing the feature, the image data signal corresponding to that feature will result in an image data signal for the image of the substrate surface or surrounding and And / or substantially indistinguishable from the background noise signal, thereby making it invisible to the naked eye; This feature is repeated in a pattern over at least a portion of the surface of the substrate such that during imaging, the position of the signal for each feature has at least one fixed relationship to the signal for the other of said features. The pattern is provided with an image data signal and a computer device programmed to perform image analysis by pattern recognition determines whether the at least one fixed characteristic identification signal is present in the data. The document identification signal is generated when the identification feature signal is found in the image data signal.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Contents of correction]

The present invention also resides in a security document having thereon a pattern of encoded identifying features generated by the method described above, the pattern representing said pattern when the completed document is illuminated. The image data signal can be recognized by a computer device supplied with the image data signal and programmed to perform image analysis by pattern recognition.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41M 5/00 G06T 1/00 500B 5B057 G03G 21/04 B41J 29/00 Z 5C076 G06T 1/00 500 G03G 21 / 00 554 (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA ( BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR , HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA , ZW (72) Inventor Stone, Robert George United States, 21042-4802 Maryland, Elliott-City, Burnside Drive, 10214 (72) Inventor Van Braeker, Paul Belgium, B-9800 Dainze, Pas Torries Rat, 88 F term (reference) 2C061 AP01 AQ05 AQ06 CL10 2C087 AA13 AB05 AC07 AC08 BA03 BD56 CB07 DA13 2H086 BA02 2H113 AA01 AA06 BA01 BA05 BB02 BB07 BC05 CA39 2H134 NA05 NA15 5B057 AA11 CA01 CB08 CA12 CB08 AA14 BA06

Claims (25)

[Claims] 1. A method of printing a security document, the method comprising incorporating a plurality of identifying features in a print of the document, the image representing the features when illuminated and imaged on a photosensitive device. A data signal occurs at the output of the device; and (i) an image data signal corresponding to the feature by selecting a contrast between the identifying feature and either the remainder of the document substrate surface or the print residue in the region containing the feature. Substantially indistinguishable from image data signals and / or background noise signals relating to the image of the substrate surface or surroundings, thereby making it invisible to the naked eye; and (ii) distributing the features over at least a portion of the surface of the substrate. By repeating, the signal for each feature Time or position having at least one fixed relation to the signal relating to the other of said features, whereby the computer device to which the image data signal is supplied is programmed to said at least one fixed relation Determining whether an identification feature signal having in the image data signal is present, and generating a document identification signal when the identification feature signal is found in the image data signal. 2. The method of claim 1, wherein the identification features are regularly spaced across an area of the substrate. 3. The method of claim 1, wherein each of the printed signatures has similar characteristics to each of the other signatures. 4. The spacing of the discriminating features is selected to be constant in one direction only, or to change according to a predetermined pattern, for example, perpendicular to said first direction. 4. A method according to any of the preceding claims, wherein similar or different intervals are selected for identifying features in another direction having a particular spatial relationship with respect to the first direction. 5. The method according to claim 1, wherein the identification features are arranged in a 2D matrix on the substrate surface. 6. The method of claim 5, wherein the second sign of the substrate is achieved by introducing a change to the matrix, such as by omitting features from specific locations in the regular matrix. 7. The matrix is formed from features having two properties, one type of feature being located at a set of locations in the matrix and the other type being located at another location within the matrix. The method of claim 5. 8. The method according to claim 1, wherein two or more different coding techniques using printed identification features are combined in the substrate. 9. A pattern is printed on the substrate using substantially transparent ink or ink of substantially the same color as the color of the substrate, so that when the image is converted into an image data signal, 2. The method according to claim 1, wherein the image data signal for the specially printed area is substantially indistinguishable from the image data signal for the rest of the substrate surface, except for their specific relation to other similar data signals. 9. The method according to any one of items 8. 10. The method of claim 9, wherein the printed pattern is a repeating pattern extending over some or all of the surface of the substrate. 11. The printed pattern includes a first code and a second code that preferably generate a plurality of repetitions of the code on the substrate.
The method described in. 12. The method according to claim 9, wherein the identification pattern to be printed extends only in one or more selected printing areas of the document. 13. The method of claim 1, wherein a faint repeating pattern of identifying features is generated on the substrate using a printing technique such as lithography, dry offset, letterpress printing, inkjet printing, or electrophotographic transfer of ink or toner. The method according to any of the above. 14. The second code is integrated into the print by introducing changes to the image features and / or non-image areas of the photo master, typically by altering the electronic signals used to produce the photo plates. 14. The method of claim 13, wherein the method is performed. 15. Using a lithographic printing plate, the document substrate is first printed on the document by using a very lightly colored grey, yellow or brown ink that hardly differs from the original color of the substrate itself. 15. The method of claim 13 or claim 14, wherein the pattern of the identifying features of is substantially invisible to the naked eye. 16. The method according to claim 1, wherein the surface of the substrate is physically formed with features that produce a reflection of light different from the rest of the surface. 17. The method of claim 16, wherein the substrate is embossed during its manufacture to form an identifying feature. 18. A paper or plastic substrate material mixed with a resin or lacquer or other material to provide a smooth surface for printing, and the actual surface of the substrate printed thereon to enable printing of security documents. 17. The surface of claim 16, wherein an encoded structure is formed on the surface that is sufficiently smooth to receive ink, but also includes a fine pattern of less smooth areas that are less receptive to printing ink. the method of. 19. In order for selected areas of the substrate to exhibit a repeated identification pattern by being impregnated with a fluid such as resin or lacquer, the optical absorption or reflectivity properties or optical density of the substrate can be modified sufficiently. The substrate surface is modified by such a technique that the area impregnated and the area not impregnated under incident light can be distinguished,
The method of claim 16. 20. The method of claim 16, wherein the surface of the substrate is etched with a laser beam to create an identifying feature in the form of a cavity or groove in the surface to be printed (or to await printing). 21. A watermark is used to change the thickness and / or texture of the substrate, which change can be visualized under incident light and used to form the first and / or second codes. The method of claim 16. 22. An encoded identification providing machine detectable features to enable identification of a document printed on a substrate on which the features have been generated by a method according to any of the preceding claims. A security document board having features thereon. 23. A security document printed with a design superimposed on the document substrate of claim 22. 24. The method of claim 23, wherein the document is detected in image data provided to a processor, such as by imaging and scanning the document, for recognition purposes. A method wherein the data processor is programmed to look for one or more specific codes that generate a document identification signal. 25. The method according to claim 24, wherein the device is used to verify an imaged document in the case of a banknote checking device, and is used to prevent or prevent printing of a duplicate of the document in other cases. the method of.