WO2004063993A1

WO2004063993A1 - Printed commercial instrument and method of generation thereof

Info

Publication number: WO2004063993A1
Application number: PCT/IB2004/000081
Authority: WO
Inventors: Daniel Gorostidi; Muriel Caraccia; Charles-Paul Friden
Original assignee: Elca Informatique S.A.
Priority date: 2003-01-13
Filing date: 2004-01-12
Publication date: 2004-07-29
Also published as: EP1584072A1

Abstract

A method of generating a printed commercial instrument including the steps of entering in a data processing system unique identification information provided on a separate stamp produced with professional printing systems automatically retrieving from a stamps database of the data processing system image information of said stamp; selecting or retrieving transaction information specific to an event or transaction to which said commercial instrument relates from a database of the data processing system; generating a unique ticket information set comprising at least part of said stamp information and at least part of said transaction information; graphically encoding and incorporating at least said unique ticket information set in a commercial instrument image printing file.

Description

Printed Commercial Instrument and Method of Generation Thereof

This invention relates to printed commercial instruments and to a method of generating such instruments.

The invention relates in particular to commercial instruments such as ^"tickets for transportation (air, rail, tram, boat, etc), tickets for attending entertainment events (cinema, opera, theatre, sports events, etc), vouchers, coupons and other sorts of tickets bearing a commercial value to be printed on plain paper or other non- special substrate or easily available substrate and non-professional printers.

A primary consideration in the generation of printed commercial instruments, such as bank notes, vouchers, transportation tickets, entertainment event tickets and other tickets or coupons bearing a commercial value, is to provide sufficient safeguards against forgery. The required degree of difficulty in producing a forgery will depend above all on the value, the duration of validity and the generality of the commercial instrument. For example, bank notes which are not related to any specific event and remain valid for many years, require security features that are extremely difficult to reproduce. On the other hand, tickets of relatively limited duration, for example transportation tickets, such as train tickets valid on a certain day for a certain destination, or theatre tickets for a specific show, require lower level security features, as long as they ensure that the instrument is difficult to reproduce in the remaining time to the event or requires excessive technical means or human effort in comparison to the value of the commercial instrument.

Verification of the authenticity of many commercial instruments is often based on a visual and tactile control. Although it is easy to provide commercial instruments with unique security features such as encrypted bar codes, their verification entails the use of electronic processing means that are unpractical or inefficient in many situations. In commercial instruments relying primarily on a visual control of authenticity, a common security feature is the provision of special substrates that are difficult or too costly to reproduce for a potential forger in relation to the underlying value of the commercial instrument. A disadvantage of the use of special substrates or special printing techniques is that they do not allow the generation of commercial instruments at sites that are not under the issuer's control, whether directly or indirectly.

In view of the wide-spread use of communications networks, such as the internet or local area networks, there is a demand for enabling the generation of visually verifiable printed commercial instruments, such as transportation tickets and entertainment event tickets, at the buyer's site, for, example at home with a PC and standard printer.

In international application WO 00/67192, a method of generating a commercial instrument with certain visually verifiable security features for printing on a standard printer is described. In the aforementioned application, data relevant to the commercial instrument are manipulated in accordance with predetermined rules to generate a pattern which is visually recognizable to an informed person. The security against forgery of an instrument generated according to the latter method relies on the potential forger's ignorance of the predetermined rules.

Reliance on predetermined rules has a number of disadvantages. Firstly, the rules must be communicated to persons responsible for controlling authenticity, which becomes impractical where many controllers are involved. Secondly, the rules must result in features that are visually recognizable, with the consequence that a potential forger could, on the basis of a number of commercial instruments, be able to deduce the rules with a sufficient degree of approximation to generate forgeries using different data. In this regard, it should be noted that the relatively sophisticated image creation and editing software widely available and for use on PC provide the forger with fairly powerful tools to reproduce images and text manipulated in order to emulate visually recognizable patterns provided on authentic commercial instruments on the basis of predetermined rules as described in international application WO 00/67192.

An object of this invention is to provide a method of generating a unique printed commercial instrument that is difficult to forge, yet enables visual verification of the authenticity thereof, and that can be substantially generated with non-professional printing systems, such as standard PC printers, on plain paper.

It would be advantageous to provide a commercial instrument with security features that are easy to verify visually by a controlling person with limited information on hidden or encoded security features or other information unavailable to uninformed persons.

It would be advantageous to provide a method for generating printed commercial instruments that is able to generate printed commercial instruments rapidly and that are event specific, for example relating to a specific person and destination for a transportation ticket, or a specific show and seating for a theatre ticket.

It would be further advantageous to provide a method that enables the printing of printed commercial instruments by a customer with access to data processing and database means through a communications network such as the internet.

Objects of this invention have been achieved by providing a method of generating a printed commercial instrument according to claim 1.

Objects of this invention have been achieved by providing printed commercial instruments according to claims 17, 25 or 26.

Disclosed herein is a method of generating a printed commercial instrument including the steps of: entering in a data processing system unique identification information provided on a separate stamp produced with professional printing systems automatically retrieving from a stamps database of the data processing system image information of said stamp; selecting or retrieving transaction information specific to an event or transaction to which said commercial instrument relates from a database of the data processing system; generating a unique ticket information set comprising at least part of said stamp image information and at least part of said transaction information; graphically encoding and incorporating at least said unique ticket information set in a commercial instrument image printing file.

In a first embodiment, the graphical encoding and incorporation of the unique ticket information set comprises the steps of

generating in the data processing system a dither matrix representing a microstructure comprising microstructure elements representing said unique ticket information set; - selecting or retrieving a contextual image from a database of the data processing system; and optionally merging it with stamp graphical elements resulting in a background image; and fusing in the data processing system said background image with said microstructure image, said fusing procedure including applying said dither matrix to said background image.

The dither matrix of the microstructure may be applied to the image by a halftoning process, whereby the pixels of the dither matrix are compared with the pixels of the background image and, for example, if the pixel of the background image has a grey level greater than the inverse grey level of the dither matrix, then the pixel is printed as white, otherwise it is printed as black. The fusing of the microstructure and image may further comprise a step of balancing the half-toned image.

Advantageously, in view of the fusion process, the event or transaction specific information and the unique stamp information is extremely difficult to separate out of the background or contextual image and is therefore difficult to replace with other information in view of producing forgeries. The microstructure dither matrix may advantageously comprise letters and/or numbers, such that the event or transaction specific information or unique stamp information may be provided in the form of words or numbers. This enables information, such as the date, the price, the destination, the seat number, personal identification, credit card number, ticket transaction number, stamp identifier, or any other information specific to the event or transaction and the stamp to form part of the microstructure image. The microstructure dither matrix may also comprise other characters, graphical elements, logos and other special designs, some of which may correspond to those printed on the stamp.

In another embodiment, the graphical encoding and incorporation of the unique ticket information set comprises the steps of

generating a plain image file incorporating said unique ticket information set; visually encrypting at least a portion of the plain image file comprising a graphical representation of said unique ticket information set.

The graphically encoded portion of the ticket image may be decrypted by means of a complementary transparent sheet that constitutes the decryption key which is also called herein the "revelator". The revelator is used by a controller who places it on the issued and printed ticket to reveal the unique ticket information set, thus allowing the verification of the validity of the ticket. Visual encryption is per se a known technique described in US 5,488,664, for example. In yet another embodiment of the invention, the graphical encoding and incorporation of the unique ticket information set in the instrument image printing file comprises the steps of generating a base image in which at least a portion thereof comprising the unique ticket information set is transformed into a basic screen of a moire pattern, whereby the unique ticket information set is readable by applying a master screen moire pattern transparency to the commercial instrument image. The techniques for generating and reading moire patterns are perse known and for example described in US 6,249,588.

The stamp is printed with professional printing systems preferably on a substrate provided with an adhesive surface so that the stamp can be bonded by the user on a designated (marked) area of the printed commercial instrument. The stamp is identified by a unique alpha-numerical identification code, comprised of letters and/or numbers, that is related to the unique ticket information set. This unique stamp information set is used in the microstructure or visually encrypted portion of the ticket image can thus be verified visually, by a human controller, with the corresponding information in the microstructure or encrypted portion of the printed instrument.

The combination of stamp information and information relating to the transaction, that is repeated as elements of the microstructure, or encoded with visual encryption techniques or moire patterns in the printed commercial instrument, make the instrument unique and very specific, since every stamp is unique and the transaction information is specific, which makes the protected image extremely difficult to forge. Moreover, an important advantage of the separate stamp and printed ticket is that they combine to form a single original instrument that cannot be duplicated (i.e. any other stamp/printed instrument combination will be different). The stamps however do not need to bear any commercial value in themselves, although they could. Advantageously the stamps do not need to relate to any specific event transaction or other purpose for which the commercial instrument serves, which enables them to be easily distributed and used. The stamps are difficult to forge, since they are printed with professional printing systems on special substrates and special ink. This makes duplication of the commercial instrument very difficult. Moreover, the unique stamp information is stored in a database of the data processing system, such information serving to generate the microstructure elements of the dither matrix or the elements of the plain image prior to enencoding, depending on the embodiment.

In practice, a user would receive by mail, or obtain by any other means a stamp or a number of stamps that could be used for generating printed commercial instruments that could relate to various transactions. The stamp identification code is entered by the user in the data processing system, which then selects those elements corresponding to the stamp identification code (if valid) for incorporation in the microstructure or enencoded portion of the image.

The stamp image information or graphical elements may comprise graphical representations or logos that may be used as in the unique image information set. For the first embodiment, the stamp may further comprise graphical orientation lines indicating the geometrical orientation and shape that the microstructure should have on the printed commercial instrument. Such lines would define the geometrical transformation matrix applied to the dither matrix, for at least a portion of the microstructure image.

One should not be able to guess the stamp image information from the stamp identification code, but the stamp graphical elements may advantageously be related to the identification code, for example if the graphical element is chosen to be a watch dial, the hour, minute, and second hands could correspond to numbers of the stamp identification code. The stamp may comprise guidelines to identify the position of special graphical elements.

The background image may advantageously comprise a photographic representation or portrait of the customer, and/or a background image that may be changed from time to time, as well as graphical representations shown on the stamp. The contextual image may further comprise written ticket transaction information.

Further objects and advantageous aspects of this invention will be apparent from the following detailed description of embodiments of this invention with reference to the accompanying figures, in which:

Fig. 1 is a schematic illustration of a distributed data processing system for implementing a method of generating a printed commercial instrument according to this invention;

Fig. 2 is a flow-chart describing in a simplified manner various steps of a method according to this invention;

Fig. 3 is a schematic illustration similar to Fig. 1 of a data processing system in the form of an enterprise server system for implementing a method of generating a printed commercial instrument according to this invention;

Fig. 4 is a schematic illustration similar to Figures 1 and 3 of a data processing system in the form of a local or stand-alone server system for implementing a method of generating a printing commercial instrument according to this invention;

Fig. 5 is a flow-chart illustrating a procedure for creating a commercial instrument image according to a first embodiment of this invention;

Fig. 6 is an illustration, concerning the first embodiment, of the transformation of a microstructure image to a microstructure dither matrix (graphically represented);

Fig. 7 is an illustration, concerning the first embodiment, of a process of fusing a contextual image and a dither matrix by a halftoning process; Fig. 8 is an illustration, concerning the first embodiment, of the balancing of a halftoned microstructure image with the contextual image to form an image for printing;

Figures 9a to 9g are various graphical representations, concerning the first embodiment, of alphanumerical character of a microstructure dither matrix according to this invention;

Fig. 10 is a flow-chart, concerning the first embodiment, illustrating a procedure for visual verification of a printed commercial instrument according to this invention;

Fig. 11 is an illustration, concerning the first embodiment, of an example of a printed commercial instrument generated with a method according to this invention;

Fig. 11 a is a detailed view of part of the image of Fig. 11 ;

Fig. 11 b is a detailed view of part of the image of Fig. 11a showing second level microstructure elements;

Fig. 11c is a detailed view of part of the image of Fig. 11 showing an additional non-linear warping of the microstructure;

Fig. 12 is an illustration, concerning the first embodiment, representing an example of the application of a microstructure dither matrix on an image;

Fig. 13 is a flow chart illustrating a procedure for producing stamps;

Fig. 14 is a flow chart illustrating a procedure for creating a commercial instrument image according to a second embodiment of this invention, where a portion of the ticket image is graphically enencoded; Fig. 15a is a representation of the printed ticket image and a revelator or transparency for deencoding the ticket image shown separately;

Fig. 15b is a representation of the revelator positioned on the printed ticket showing the deencoded ticket image;

Fig. 16 is a flow-chart illustrating a procedure for creating a commercial instrument image according to a third embodiment of this invention using moire patterns;

Fig. 17 is an illustration of a printed ticket and a master transparency placed thereon, showing the moire patterns;

Fig. 18 is a flow-chart illustrating a generic procedure for creating a commercial instrument image according the various embodiments of this invention.

Referring to Fig. 1 , a data processing system in the form of a web-based server system 2 for generating commercial instrument printable files, is accessible via a global communications network such as the internet 4 by a user or a customer at a client site 6, having a printer 8 and a personal computer 10 or other computing means connected to the communications network 4. The server system may be a distributed system comprising a plurality of servers and/or databases at a single site, or at different sites interconnected with a communications network such as the internet, an intranet, or a local area network. The web-based server system 2 comprises a web server 12 including, or connected to, a database or databases 14, 15 in which information on printed stamps 69 and/or on customers is stored, a payment server or system 16, for example for effecting credit card payments, bank transfers and the like, and a production server 18 for performing calculations and other operations to create ticket images and package data files for transmission and printing. The production server may be interconnected to a context database 20 for storing background images and other information concerning the commercial instrument. It will be understood by skilled persons in the art that the configuration of the above described server system may be modified without departing from the scope of this invention, the various servers and databases being depicted merely as examples in order to understand the function of a possible server system for generating printed commercial instruments 68 according to this invention.

The data processing system for creating the commercial instrument may also be an enterprise server system as illustrated in Fig. 3, whereby the user accesses the enterprise server system 2' through a local area network or direct connection from a terminal 10'. In this configuration, a user would typically be the issuer of the commercial instrument and the payment transaction would occur between the purchaser of the commercial instrument and the user.

Referring to Fig. 4, a local or stand-alone server system 2" is shown incorporating in a single data processing system the functions of the enterprise server system 2' of Fig. 3.

Referring to Fig. 2, a flow-chart generally illustrating the generation of a commercial instrument, such as a printed ticket, with a data processing system such as the server system described above, is shown. Initial operations include connection 22 of the customer or user to the server system 2, 2', 2", and subsequently selection and specification 24 of the product. For example, if the commercial instrument is a transportation ticket, the customer may specify the journey departure place and destination, the travel date and/or time, the class, the seat, etc. The initial steps may also comprise an identification procedure 26 of the printed stamp, or of both the printed stamp and of the customer, particularly if customer information from a customer database is to be retrieved for inclusion in the printed commercial instrument. The identification procedure may be after or before the step of product selection and specification. The stamp information identifying the stamp and the personal information identifying the customer may also be entered separately at different stages in the process. The stamp information, and as the case may be, the personal customer information, is verified with information stored in the database or databases 14 to check the validity thereof.

The term "product" shall be understood herein to generally mean the event, service, or item being purchased or transacted to which the commercial instrument relates.

Once the product has been selected and specified and the stamp validly identified, a payment order is created, for example using credit card, bank transfer or cash card information supplied by the customer to the server system which then logs the payment order and/or sends a provisional payment order to a payment system 16. The transaction amount will not be debited according to the payment order until confirmation that the ticket has been sent to the customer site.

After product selection and specification in step 24, a ticket image printing file is generated in the production server 18 using information received from the web server portion 12 and, as the case may be, the customer 14 and stamp 15 information database and the context database 20, such that product information, stamp information, personal information and contextual information may be included in the ticket image generation process.

It may be noted that ticket image generation may be performed in parallel, before or after generation of the provisional payment order (step 28). The ticket image file is then packaged and preferably compressed such that it can be efficiently transmitted over a communications network such as the internet, and printed on a standard PC printer. The ticket image may for example be received on the user's or customer's computer screen as a page displayed in a web browser, or by e- mail, for example in commonly used text and image formats such as PDF, GIF, PNG, and the like that enable printing on personal PC printers with the appropriate PC software. The sending of the commercial instrument image file to the user's or customer's computer or terminal also generates a confirmation to execute the payment order in waiting. In addition, the information on the used stamp is deleted or marked as "used" in the stamp information database 15, to prevent subsequent use thereof.

It will be apparent from the above that the security of the commercial instrument does not reside in the inability to print or copy numerous tickets, since the customer receives the printing file, or could simply copy a printed instrument. Security against the use of multiple copies (i.e. duplication) is provided by unique information provided on the stamp in conjunction with information relating to the event or transaction, and personal information, as the case may be. The stamp information in conjunction with the corresponding printed ticket will ensure that the transportation or event ticket is usable only once, since the stamp information is unique and is incorporated in the image of the printed ticket, and can be easily verified by visually checking and comparing information on the ticket image with information on the stamp bonded on to the ticket. Moreover, personal information such as a photographic portrait of the bearer of the instrument will make the commercial instrument unusable by other persons (i.e. non-transferable).

The combination of the unique stamp information, comprising a unique identifier in the form of a unique number or set of alpha-numerical characters as well as graphical elements, and the printed commercial instrument incorporating the unique stamp information in its printed image, thus makes the commercial instrument unique with a single original, so that it can be used only once. This is particularly useful for producing value bearing coupons, such as gift vouchers, or customer fidelity program vouchers, or other instruments that need to be unique, for example a transportation ticket for a specific trip but without restriction on date or time of use. The unique original also allows the value of the ticket to be refunded, if unused (e.g. unpunched).

In Fig. 18, a flow-chart illustrating various generic steps or operations in the generation of a ticket image according to this invention is shown. Figures 5, 14 and 16 show flow-charts illustrating various steps in the generation of ticket images according to first, second and third embodiments of this invention. After connection to the data processing system via a user terminal, the user specifies the product information 38 that is to be purchased and enters stamp information 39. The stamp information to be entered includes in particular the unique identifier code 70 (see Figures 11a, 15b or 17b), that enables identification of the stamp and retrieval of stamp information from the database 15. The database may also include personal information on customers, which may for example include a library of photographic portraits of customers.

In the example shown in Fig. 5, on the basis of the customer identity entered by the user, the corresponding portrait 42 of the customer or other personal information (date of birth, address etc) is retrieved from the customer database for inclusion in the ticket image. However, it is not mandatory to include customer information in the ticket image, in view of the uniqueness of the ticket combination with the non reproducible unique stamp, preventing the use of multiple print outs of the same ticket image by different persons.

The product information 38 is sent to the production server or production server portion of the server system and may be used to select a background image 44 from the context database 20 and certain display encoding parameters such as the pattern or orientation of elements that will be reproduced in the image.

For example, in the embodiment shown in Fig. 5, the display encoding parameters determine the microstructure pattern or shape 46 that will be applied to microstructure elements 48 in a mapping procedure 50, for example a planar mapping procedure.

The product information 38, or at least part of the product information, as well as the stamp information 39, or at least part of the stamp information, are selected to form a unique ticket information set 41 for incorporation and encoding in the ticket image printing file 62 sent to the customer. This unique ticket information set will be unique in the sense that no other ticket or commercial instrument generated will comprise the same combination of information. Moreover, since this unique ticket information set comprises information on the product (i.e. the transaction) as well as the unique stamp, a ticket controller can verify both the relationship of the ticket to the specific transaction and the validity of the printed ticket with relation to the separate stamp bonded thereon. The graphical incorporation and encoding of the unique ticket information set within the ticket image file makes the ticket image file very difficult to replicate by an unauthorized person attempting to produce a forgery. The combination with the separate unique stamp produced by professional printing systems, but which need not be dedicated to any particular transaction or event, ensures that only a single original may be generated since, although numerous prints or copies of the printed ticket on the basis of the ticket image file sent to the customer may be generated, only a single stamp will be available and correspond to the printed ticket.

It may be noted that the integration of the contextual background image and certain encoding parameters as well as the unique ticket information set in the encoded parts of the ticket image increases the difficulty of forgery by a malicious user attempting to generate a non-valid ticket image file.

In the embodiment shown in Fig. 5, the unique ticket information set is formed of microstructure elements 48 that are organized so as to provide both stamp and transaction (or product) information in particular in the form of readable text and numbers and, optionally, graphical elements that identified the transaction and that reproduce stamp image parameters.

For example in the case of a train ticket, the microstructure elements may indicate the journey starting and destination places, the date, and possibly additional information such as the class, the price and any other product specific information. The microstructure elements are also organized so as to provide unique stamp information, for example the unique identifier code 70 shown on the printed stamp. It is also possible to include in the microstructure elements customer information such as the customer's name, address, date of birth or other information specific to the customer. The microstructure elements may also comprise elements having various graphical shapes or logos, some of which may be printed on the stamp as part of the stamp information, enabling correspondence between the stamp and ticket to be easily visually verifiable.

The product information is also used by the production server or server portion to generate a product information layer that may include a simple presentation of the product specific information, in the present example of a transportation ticket, relating to the starting place and destination, the class, the price, the validity, date or period, possibly further including electronically verifiable security features such as an encrypted number code or a bar code 66. The encoded or electronically verifiable security feature provides additional verification means for a person controlling the authenticity of the ticket in case there is any doubt after a visual verification, or for any other reason, such as arbitrary spot checks.

The contextual image 44 may be a photographic image, a drawing, or any other image that is preferably non-uniform and difficult to synthesize by data processing means, and representing places, objects, events, or other things that may be easily recognized and interpreted visually. Advantageously, photographic images are difficult to synthesize yet often have some meaning or have characteristic features that facilitate the memorizing and recognition thereof by persons, which assist in the verification of authenticity of the instrument. The contextual image is preferably an image that is proprietary and not easily available to the general public. The contextual image may be changed on a regular basis or as a function of ticket attributes or options in order to increase the difficulty of reproducing the ticket image.

Where the commercial instrument comprises a portrait 42 of the customer, the contextual and portrait images 44, 42 may be merged by any standard merging technique or by superposition 45 of the photograph on the background image to form the contextual image layer 54, that also may comprise stamp graphical elements. A simple graphical product information layer 52 may be superposed 61 or otherwise merged with the encoded portion of the ticket image to result in the completed commercial instrument image file 62 for electronic transmission to the user's computer. The information layer may further comprise a bar code 66, which preferably includes the unique ticket information set encoded and encrypted to form a unique identification number that may be used as an additional verification means used in random checks, or in case of doubt of the authenticity of the ticket, or for other reasons.

Referring to Figures 5 to 12, particularities of the first embodiment will now be described.

The microstructure pattern or shape 46 is for example a mathematical image deformation algorithm as used in planar mapping or other known image deformation techniques. The microstructure shape or pattern may vary between different types of commercial instruments on criteria established by the issuer, for example, different shapes for different ticket values, events, days of the week, months, etc. The shape or pattern may also be regularly changed, for example, when the background image is changed, in order to make reproduction of forgeries more difficult by reducing the time during which a background image and a pattern on the image remain valid. The shape or pattern may also advantageously correspond, at least over a portion of the printed ticket, to a shape or pattern shown on the stamp 69, as best seen in Fig. 11. This enhances the ease of visual verification of correspondence between the stamp and printed ticket. Other geometrical mapping functions may be applied to the microstructure stage, such as non-linear warping functions as shown in Fig. 11c, illustrating a "fish-eye-lens" deformation of the microstructure shape.

The microstructure elements 48 include in a preferred embodiment alphanumerical characters that enable product specific information such as the date or period of validity, the event, seating number, information on the journey starting place and destination, and the stamp identification code 70, to be read. As can be seen in figures 5 and 11 , the microstructure elements 48 correspond to the alpha-numerical stamp identification code 70 and to certain graphical elements 74 shown on the stamp. The text that identifies the specific purpose of the commercial instrument may in itself be unique and usable once (such as a combination of the title, date, venue and seating number of a theatre event). In many instances however, the commercial instrument will only be unique and usable once in conjunction with unique stamp information.

As will be described further on, the microstructure elements are used to create a dither matrix representative of a microstructure image layer 56 that is fused with the contextual image layer 54. In other words, the microstructure elements are used as discrete printing screen elements that may be used to generate images, much like traditional screen dots, the size of which is varied to adjust the grey level intensity. The generation of microstructure elements, for example in the form of letterset characters and their use in a dither matrix is known perse, for example in artistic screening as described in the article "Artistic Screening, V. Ostromoukhov, R. D. Hersch, in ACM Computer Graphics, Annual Conference Series, 1995, pp. 209-228".

The microstructure elements used in the present invention, which include alphanumerical characters, are generated at a size that enable their reading at a personal document reading distance which may typically be in the order of 20 to 50 cm from the eye. The microstructure elements are thus significantly larger than the screen dot sizes provided in even the lowest resolution printed images typically available.

Referring to Figures 9a to 9g, various graphical representations of a microstructure element are shown. The microstructure element 48 may be represented as a three-dimensional element 61 against a background 63 as shown in Fig. 9a, whereby the depth of the element, in the direction coming out of the paper of Fig. 9a, may be separated into a plurality of planes parallel to the paper, each plane defining a grey level. The microstructure element may for example be defined in 256 planes that correspond to 256 grey levels, which equates with the number of grey levels commonly defined in standard printing techniques. The background 63 comprises "noise" that can be graphically represented as randomly distributed "peaks" that, when intersected by the high grey level planes, give the background a grainy aspect as shown in Figures 9b to 9d. When the grey level is very high, the character will be at its thickest with a dark background, as illustrated in Fig. 9b, the background getting lighter as the grey level decreases as represented successively by Figures 9c to 9e. For an intermediate grey level, the character is of medium thickness as shown in Fig. 9f, or if there is a very low grey level, the character is very thin as shown in Fig. 9g. In this example, grey levels are thus varied by adjusting the thickness of the characters, in addition to varying the density of the grainy background for the high grey levels, whereby it should be noted that the characters are preferably hormomorphic such that, as they reduce in thickness, their general shape remains. The latter property ensures the readability of the characters, whether depicting a low grey level or a high grey level.

Instead of adjusting the thickness, other techniques are available for defining the microstructure element grey level, for example the character may be defined by a dark border of a constant outer shape and dimensions while varying border thickness towards the center of the character depending on the grey level.

The representation of lettering as microstructure elements is for example depicted in Fig. 6, whereby the lettering on the left side of the figure are simple characters and on the right side of the figure shown as three-dimensional microstructure elements that graphically represent the microstructure dither matrix. In Fig. 6, the elements have already been subjected to a planar mapping procedure 50 with a microstructure shape (which in the specific example emulates the positioning of text lines around a cylinder). It should be noted that the 3D representations of Fig. 9a and on the right side of Fig. 6 are merely means of assisting the reader in obtaining a visual interpretation of microstructure elements which are in fact defined in a dither matrix and could be represented in other ways.

In generating the dither matrix, account is taken of both the text of microstructure elements and the microstructure shape. Moreover, the microstructure image is scaled to the same size as the contextual image. The contextual image and microstructure images 54, 56 are then fused.

Fusion 57 includes the operations of halftoning the contextual image using the dither matrix, whereby the contextual image is defined as a grey level input image. The halftoning process compares the grey level value, which is typically between 0 and 255, of each point of the grey level input image with the inverse grey level value of the corresponding point of the dither matrix. Depending on the result of the comparison, the corresponding point of the resulting halftoned image is set to white or to black. This may for example be described in terms of computer language pseudo-code for halftoning an image with a dither matrix as follows:

For all pixels of the Contextuallmage if ContextuallmageGreyLevel < Inverse(DitherMatrixGreyLevel) then Halftoned I mageValue = WHITE else

Halftoned ImageValue = BLACK end if end for

The results of such a comparison are illustrated for example in Fig. 7, whereby the contextual image and microstructure image are subjected to the above described halftoning procedure resulting in a halftoned image 58. As may be noticed in this halftoned image, in the light areas of the contextual image, the microstructure characters are very thin (because of the low grey level value) and in the dark areas very thick (because of the high grey level value). The grey level value of the dither matrix between microstructure elements is preferably set at a low grey level value varying randomly such that the shape of the microstructure element remains visible (even in dark areas) after the halftoning process.

It may be further noticed that the thickness of the microstructure characters vary along portions thereof, depending on the grey level of the contextual image in the vicinity of the portion of character in question.

Referring to Fig. 12, the effect of applying a microstructure dither matrix of a microstructure element 48' to an image 44' by a halftoning technique is illustrated. This halftoned image 58 shows the varying thickness of the character "T" 61 and the density of the background grain 63 as a function of the grey level of the image 44.

The visual quality of the computed halftoned image 58 is often not optimal due to the size of the microstructure elements composing the dither matrix. In order to improve the quality, the fusion procedure may further include a balancing procedure which compares the halftoned image with the contextual image, as illustrated in Fig. 8. A balancing technique that may be employed includes examining the neighbourhood of each point of the halftoned image, subsequently counting the number of black points and white points which are then used to compute an average grey level value, for example the number of white points divided by the total number of points in the considered neighbourhood. These average grey level values are compared with the grey level value of the corresponding point of the contextual image and if the difference is small, (for example below a defined or approximated value), then it is considered that the halftoned image is a good approximation of the contextual image at that point. If the difference between the compared grey level values is large, then it is considered that the halftoned image is locally a bad approximation of the contextual image and that the considered point of the halftoned image should be inverted, in other words, set to white if originally black, or set to black if originally white. A probalistic function may be used to determine whether the difference between the compared grey level values is to be considered small or large.

While the halftoning and balancing procedures have been described as separate procedures hereinabove, it would be possible to combine these two procedures in a single procedure, even if the terms "halftoning" and "balancing" are used separately.

A simple graphical product information layer 52 may be superposed 61 or otherwise merged with the fused image 60 to result in the completed commercial instrument image 62, such as the sporting event ticket image illustrated in Fig. 11.

As can be seen in the example of Fig. 11 , the ticket comprises a ticket information zone 71 and a stamp information zone 72. In the ticket information zone, the simple product information layer 64 indicates the validity date, the event name, and the price in an easy to read format, at least a part of this product information also being present in the microstructure of the fused image. The stamp identifier code 70 is included in the microstructure of the stamp information zone 71 , and is oriented in the same direction as the lines 73 and code 70 printed on the stamp

69. However, information concerning the product and concerning the stamp may be provided in both zones in various combinations. Both the product and stamp information included in the microstructure are easily readable at a normal document reading distance of say 20 to 50 cm from the eye.

The contextual image which in this example includes a photograph of mountains and part of an anonymous person's portrait in the stamp information zone, is well- defined at normal document reading distance, and even improves beyond the document reading distance, say at arms length from the eye where the microstructure characters become less apparent. Visual verification of a commercial instrument generated according to this invention may include the steps shown in Fig. 10, whereby a ticket controller would check the relevance of the ticket information by reading the product information layer 64, and the microstructure information, which should correspond to the product information. The controller may also verify the contextual image and the microstructure shape or pattern and in this regard should be informed of the background image and microstructure pattern that applies to the type of commercial instrument at its date of validity and/or other attributes of validity. The controller may further verify the correspondence between the stamp information and the microstructure.

A bar code 66 which preferably includes the encoded and encrypted unique ticket information set, may be used as an additional verification means in case of doubt of the authenticity of the ticket, or for other reasons, such as random checks.

The stamp information may further include graphical elements 74 that are reproduced in the ticket image, either as a microstructure element or in the contextual image to which the microstructure dither matrix is applied. In the example of Fig. 11 , the graphical element represents a watch dial that overlaps the ticket information and stamp information zones on the contextual image layer. The microstructure dither matrix is thus also applied to the watch dial in order to generate the printing image thereof.

Referring to Fig. 11a, a detailed view of a portion of the printed ticket of Fig. 11 is shown. The smallest screen dots used for printing the image are conventional screen dots using traditional shapes, such as an ellipse or circle. The screen dots may however be provided with a special shape that could be changed on a regular basis to increase the security against forgery. This security technique may be taken further by introducing additional layers of microstructure elements having sizes intermediate the smallest printed screen dot and the microstructure elements verifiable at normal reading distance, using a fusion procedure as set forth above. Verification of the intermediate microstructure elements may be performed by close visual inspection of the printed instrument, for example at a distance of 10 to 20 cm from the eye. As best seen in Fig. 11b, in this example a second layer of smaller microstructure elements comprising the characters "-03" is provided. In other words, a plurality of microstructure image layers formed by microstructure elements of a different size for each layer could be fused with the contextual image with the fusion procedure described above.

Referring to Fig. 13, the production of stamps will now be briefly described. Unique identification codes are generated and allocated to individual stamp information files in conjunction with information on graphical elements, such as the microstructure orientation lines or other information to be printed on the stamp. The unique stamp information for each stamp is stored in a database or in databases 15, that may also be linked or comprise personal information on customers. The unique stamp information files are also sent to a printing server for printing on special substrates with professional printing systems, preferably using special inks, such that the printed stamp cannot be forged by mere copying on plain paper substrate. The stamps may further be provided with an adhesive layer on the non-printed side, in order to enable them to be bonded to printed commercial instruments.

It may be noted that the stamps do not necessarily need to be related to any specific event or transaction, as long as the data processing system used by the ticket issuer for generation of the ticket image also has access to the stamp information database.

The stamps may be distributed or sold by the ticket issuer to actual or potential customers. A practical example of the use of such stamps would for example be for vouchers or coupons offered or sold by retailers and bearing a value for the purchase or exchange of goods. The stamps may also be used to generate tickets to events where it is not practical to provide unique information, such as personal information or information related to specific seating, date and venue, for example a ski pass or a bus or train ticket.

Once the stamp information has been used to generate a commercial instrument image, for which payment transaction has occurred, the stamp information is removed from the database, or marked as "used", such that another attempt at generating a printed commercial instrument with the same unique stamp information would be invalid and result in a refusal message sent to the customer's terminal.

Referring to Fig. 14, and Figures 15a and 15b, the particularities of the second embodiment will now be further described.

In the second embodiment, after selecting the elements forming the graphical representation and graphical parameters to form the unique ticket information set and the information layer, a plain image file is generated that combines both the information layer 52, with for example the code bar 66 and readable alphanumerical information on the transaction in a certain zone or zones of the ticket, and the unique ticket information set 41 comprising product information 38 and stamp information 39. Subsequently, the portion of the plain image file comprising the unique ticket information set 41 is encrypted with a known visual encryption technique, for example as described in US 5,488,664, and packaged with the information layer into a ticket image printing file for transmission via the communication network to a user's computer for printing under the user's control. The encryption of the encoded portion of the ticket image is performed with an encryption key supplied from a revelator database 78 that corresponds to a complementary decryption key used for generating the transparency (also called revelator) 80 used by the ticket controller.

To verify the validity of a ticket, the controller places the transparency on the user's printed ticket, thereby revealing the unique ticket information set in the encoded portion of the printed ticket. The controller verifies the conformity of the revealed unique information with the transaction to which the ticket relates, and the information on the separate printed stamp 69 stuck onto the printed ticket.

As in the first embodiment, once the ticket image printing file is sent to the user, the product and stamp databases are notified and the status thereof changed accordingly. Referring now to Figures 16 and 17, particularities of the third embodiment of this invention will now be described.

In this embodiment, the steps for generating the ticket image file are in general quite similar to the previously described embodiment, in that the selected graphical representation and parameters are incorporated into a ticket image file comprising an information layer 52 and a unique ticket information set. This embodiment differs principally in that a moire pattern transformation is applied to the zone of the ticket image comprising the unique ticket information set 38, 39, the parameters of this moire transformation being received from a revelator database 78. Part of the moire transformation parameters may be related to the unique ticket information set. The moire transformation algorithm for the ticket to be printed is associated with a corresponding revelator transparency that is positioned by the controller on the printed ticket in order to reveal certain attributes of the unique ticket information set that are not found in the ticket printed by the user. The use of moire patterns is known per se and described for example in US 6,249,588.

As in the other embodiments, the unique ticket information set revealed by the revelator comprises both transaction information and unique stamp information that is verified, respectively, with respect to the transaction to which the ticket relates, and to the stamp information 69 bonded by the user on the printed ticket.

Advantageously therefore, the printed commercial instrument generated by the method described herein can be printed at home or at other remote locations under the user's control, on ordinary paper, yet with a high level of security. Furthermore, a single original is guaranteed by the combination of the printed ticket with the separate stamp, in itself unique and difficult to forge since it is printed with professional printing systems and special inks, whereby unique stamp information and transaction is included in an encoded portion of the printed ticket.

Claims

1. A method of generating a printed commercial instrument including the steps of:

entering in a data processing system unique identification information provided on a separate stamp produced with professional printing systems automatically retrieving, from a stamps database of the data processing system, image information of said stamp; selecting or retrieving transaction information specific to an event or transaction to which said commercial instrument relates from a database of the data processing system; generating a unique ticket information set comprising at least part of said stamp information and at least part of said transaction information; graphically encoding and incorporating at least said unique ticket information set in a commercial instrument image printing file.

2. Method according to claim 1 , wherein the graphical encoding and incorporation step comprises:

generating in the data processing system a dither matrix representing a microstructure comprising microstructure elements representing said unique ticket information set; - selecting or retrieving a contextual image from a database of the data processing system and optionally merging it with stamp graphical elements resulting in a background image; and fusing in the data processing system said contextual image with said microstructure image, said fusing procedure including applying the said dither matrix to said background image.

3. Method according to claim 2, wherein the microstructure image is formed of readable microstructure elements including alphanumerical characters corresponding to an alpha-numerical identification code provided on said separate printed stamp.

4. Method according to claim 2 or 3, wherein the microstructure further includes readable microstructure elements providing information on said event or transaction.

5. Method according to anyone of claims 2 to 4, wherein at least some of said microstructure elements including alphanumerical characters generated by said microstructure dither matrix are of a sufficiently large size to enable reading at a normal document reading distance.

6. Method according to anyone of claims 2 to 5, wherein said microstructure image is provided with a non-linear shape by a geometrical mapping function.

7. Method according to anyone of claims 2 to 6, wherein the microstructure image and contextual image are scaled to the same size.

8. Method according to anyone of claims 2 to 7, wherein the fusing process includes a technique of halftoning the contextual image with the dither matrix and balancing of the halftoned image with the contextual image.

9. Method according to anyone of claims 2 to 8, further comprising the steps of generating a dither matrix representing a second microstructure comprising microstructure elements of a size intermediate said readable microstructure elements and a smallest printing screen dot, and further applying said second dither matrix in said fusing procedure.

10. Method according to claim 1 , wherein the graphical encoding and incorporation of the unique ticket information set comprises the steps of generating a plain image file incorporating said unique ticket information set; visually encrypting at least a portion of the plain image file comprising a graphical representation of said unique ticket information set, whereby said encryption is performed using an encryption key complementary to a master decryption key used for producing a revelator transparency.

11. Method according to claim 1 , wherein the graphical encoding and incorporation of the unique ticket information set comprises the steps of

generating an image file incorporating said unique ticket information set and applying a moire pattern transformation, the moire pattern transformation parameters provided by a revelator database and being complementary to a moire master pattern provided on a revelator transparency.

12. Method according to any one of the preceding claims, wherein the stamp information included in the unique ticket information set includes a unique alphanumerical identification code provided on the separate stamp, as well as stamp image information.

13. Method according to any one of the preceding claims, wherein the unique ticket information set further comprises information identifying or personal to the user.

14. Method according to any one of the preceding claims, wherein said contextual image comprises a portrait of a bearer selected from a customer database on the basis of information identifying said bearer.

15. Method according to any one of the preceding claims, wherein the image of the printed commercial instrument is generated in a server system, said server system preparing and packaging a printable file for printing said printed commercial instrument on a standard printer.

16. Method according to the preceding claim, wherein said printed commercial instrument is printed on said standard printer at a customer site remote from said server system and accessible to said server system via a communications network such as the internet.

17. A commercial instrument generated by a method according to claim 1 or 2, comprising a printed image on a plain substrate and a separate printed stamp, said image comprising a contextual image fused with a microstructure image by applying a dither matrix^' representing said microstructure image, said microstructure image comprising readable microstructure elements organized in such a manner as to provide information obtained from a database uniquely identifying said separate printed stamp, said information also printed on the stamp, and information on an event or transaction to which said commercial instrument relates.

18. Commercial instrument according to claim 13 or 14, wherein said microstructure elements include alphanumerical characters printed at a size that enables their reading at a personal document reading distance.

19. Commercial instrument according to claims 17 or 18, wherein the microstructure image comprises a non-linear shape resulting from a geometrical mapping function.

20. Commercial instrument according to any one of claims 17 to 19, wherein the contextual image comprises a photographic background image.

21. Commercial instrument according to any one of claims 17 to 20, wherein the microstructure image is scaled to the same size as the contextual image.

22. Commercial instrument according to any one of claims 17 to 21 , wherein the microstructure image comprises personal information in the form of text relating to a bearer of the instrument.

23. Commercial instrument according to any one of claims 17 to 22, wherein the microstructure elements in at least a portion of the microstructure image are oriented in a direction provided by visual direction indicators provided on the stamp.

24. Commercial instrument according to any one of claims 17 to 23, wherein the microstructure elements include alpha-numerical characters representing a unique alpha-numerical identifier code printed on the stamp.

25. Commercial instrument generated by a method according to claim 1 or 10, comprising a printed image on a plain substrate and a separate printed stamp, said image being obtained by encoding unique ticket information and comprising information readable with a complementary master revelator transparency that forms the decryption key, said revealed image comprising readable elements organized in such a manner as to provide information obtained from a database uniquely identifying said separate printed stamp, said information also printed on a stamp, and information on an event or transaction to which said commercial instrument relates.

26. Commercial instrument generated by a method according to claim 1 or 10, comprising a printed image on a plain substrate and a separate printed stamp, said image being encoded at least partially with a moire pattern transformation and comprising information revealable with a complementary master revelator transparency, said revealed image comprising readable elements organized in such a manner as to provide information obtained from a database uniquely identifying said separate printed stamp, said information also printed on a stamp, and information on an event or transaction to which said commercial instrument relates.