Method and device for checking a value document

A method for testing a valuable document including illuminating the valuable document line by line such that a first group of lines is illuminated with light of a first wavelength and a second group of lines is illuminated with light of a second wavelength, reflection light that is reflected from the lines and/or transmission light that passes through the lines. First data are representative of the reflection light and/or transmission light assigned to the lines of the first group and second data are representative of the reflection light and/or transmission light assigned to the lines of the second group. Further, processing the first data such that a first image generated from the first data has a first resolution, and the second data such that a further image generated from the second data has a second resolution, comparing the first and second images with first and further reference images.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and claims the benefit of European Patent Application Serial No. 17 210 084.4, which was filed Dec. 22, 2017.

TECHNICAL FIELD

The invention relates to a method and a device for testing a valuable document.

BACKGROUND

It is known to test a valuable document, for example a banknote, a cheque, an identity card, a passport, a ticket or a share document, for various reasons. By way of example, it may be necessary to test that the valuable document is genuine. A device for testing the valuable document can for example be integrated in an automated teller machine or be a standalone device that can be used for example in a bank or in a business. Besides testing the authenticity of the valuable document, it may be necessary to test the state of the valuable document. This is also called a “fitness test”. The fitness test involves for example checking the extent to which the valuable document is contaminated and/or damaged.

Both for testing the authenticity and for testing the fitness of the valuable document it is known to illuminate the valuable document alternately with light of different colours and to detect the light reflected from the valuable document and/or the light transmitted through the valuable document. The image recorded from the valuable document in this way can then be compared with one or more corresponding reference images. This comparison involves comparing in particular special authenticity features and/or fitness features of the valuable document with the corresponding authenticity features and/or fitness features of the reference image. What is problematic here is that for the comparison of specific authenticity features and/or fitness features, the image of the valuable document should have a high resolution and a correspondingly large amount of storage space has to be kept available for the image. An additional factor is that in general a plurality of authenticity features and/or fitness features have to be tested per valuable document and that the demand for storage space is multiplied as a result. Moreover, a high computing power is required for processing the high-resolution image(s) and for the comparison with the reference image(s). Therefore, conventional methods and devices for testing a valuable document are very complex.

SUMMARY

One object of the invention is to provide a method for testing a valuable document which is implementable in a simple manner and/or by means of a simple device.

One object of the invention is to provide a device for testing a valuable document which is configured in a simple manner.

One object of the invention is achieved by means of a method for testing a valuable document, wherein: the valuable document is illuminated line by line in such a way that a first group of lines of the valuable document is illuminated with light of a first wavelength and that at least one second group of lines of the valuable document is illuminated with light of a second wavelength, wherein at least partly lines of the first group and lines of the second group alternate, reflection light that is reflected from the lines and/or transmission light that passes through the lines are/is detected in a manner assigned to the lines of the first group and the lines of the second group, wherein first data are representative of the reflection light and/or transmission light assigned to the lines of the first group and second data are representative of the reflection light and/or transmission light assigned to the lines of the second group, the first data are processed in such a way that a first image generated from the first data has a first resolution, and the second data are processed in such a way that a further image generated from the second data has a second resolution, which is different from the first resolution, and the first image is compared with a first reference image and the further image is compared with a further reference image.

Testing the valuable document is thus carried out with the aid of different images of the valuable document, wherein the corresponding images are recorded under illumination by means of light of correspondingly different wavelengths, that is to say of correspondingly different colours. Special features of the valuable document are suitable for the comparison the corresponding reference images, wherein a respective image that was recorded under illumination by means of light of a specific colour is particularly suitable for the comparison of said features. By way of example, an image that was recorded under illumination with light of a first colour is particularly well suited to the comparison of a first feature, and an image that was recorded under illumination with light of a second colour is particularly well suited to the comparison of a second feature. One aspect, therefore, is that one specific colour is particularly well suited to testing one specific feature, that another colour is particularly well suited to testing another feature, and that the colour that is particularly well suited to the corresponding feature is used for each feature to be tested. By way of example, a feature that reveals what the valuable document actually is, for example what denomination the corresponding banknote has, can be identified particularly well under illumination with red and/or green light. In contrast thereto, contamination that is an indication of the fitness of the valuable document22can be identified particularly well under illumination with blue light.

In addition, different minimum resolutions of the images are required for the comparison of the features. By way of example, the first image having at least the first resolution is required for the comparison of the first feature and the second image having at least the second resolution is required for the comparison of the second feature. Therefore, processing the data in such a way that the images have different resolutions makes it possible not to process every image with the maximum possible resolution. In particular, it is possible, for comparing a first feature, to use an image having a lower resolution than an image used for comparing a second feature. By way of example, the minimum resolution necessary in each case can be used for comparing all the features. One aspect, therefore, is that one specific minimum resolution is necessary for testing one specific feature, that another specific minimum resolution is necessary for testing another feature, and that the resolution actually used for each image is low, preferably the corresponding minimum resolution.

This contributes to the fact that the features can be tested particularly simply and precisely and to the fact that a low computing power is required for processing the images and for the comparison with the corresponding reference images, whereby the method for testing the valuable document is implementable in a simple manner and/or by means of a simple device.

The lines of the first group are all illuminated with light of the first wavelength, that is to say with light of a first colour. The lines of the first group can also be referred to as first lines or as lines of the first colour. If the first colour is red, for example, then the first lines can be referred to as red lines. The lines of the second group are all illuminated with light of the second wavelength, that is to say with light of a second colour. The lines of the second group can also be referred to as second lines or as lines of the second colour. If the second colour is green, for example, then the second lines can be referred to as green lines. In addition, the valuable document can be illuminated with light of further wavelengths, such that further groups of lines are generated.

Specific features of the valuable document are primarily used for the comparison of the images with the reference images. Said features can be for example authenticity features for testing the authenticity of a valuable document or fitness features for testing the fitness of a valuable document. Authenticity features can be for example watermarks, reflective regions and/or regions that are luminous under corresponding illumination. A fitness feature can be for example contamination of the valuable document. In accordance with one development, the first image shows a first number of lines of the first group, wherein the first data are additionally processed such that at least one second image generated from the first data shows a smaller number of lines of the first group and has a resolution that is correspondingly lower than the first resolution, and wherein the second image is compared with a corresponding second reference image. This makes it possible, firstly, on the basis of the lines of the first group, to generate two different images which can be used for the comparison of correspondingly two different features, and, secondly, to use in each case only images having a small number of lines, for example the minimum required number of lines, for these two comparisons. This furthermore makes a contribution to the fact that an even lower computing power is required for processing the images and for the comparison with the corresponding reference images, whereby the method for testing the valuable document is implementable in an even simpler manner and/or by means of an even simpler device.

In accordance with one development, the first data are additionally processed such that at least partly first data of successive lines of the first group are averaged and that at least one second image generated from these averaged data has a resolution lower than the first resolution, wherein the second image is compared with a corresponding second reference image. This makes it possible, firstly, on the basis of the lines of the first group, to generate two different images which can be used for the comparison of correspondingly two different features, and, secondly, to use in each case only images having a small resolution, for example the minimum required resolution, for these two comparisons. This furthermore makes a contribution to the fact that an even lower computing power is required for processing the images and for the comparison with the corresponding reference images, whereby the method for testing the valuable document is implementable in an even simpler manner and/or by means of an even simpler device. The two developments explained above can also be combined with one another. In particular, the first data can additionally be processed such that the second image generated from the first data shows a smaller number of lines of the first group than the first image and that at least partly first data of successive lines of the first group are averaged for the second image, such that the corresponding second image has a resolution that is lower than the first resolution.

In accordance with one development, the valuable document is moved in a movement direction relative to an illumination unit, by means of which the valuable document is illuminated, and the valuable document is illuminated in such a way that the lines are aligned perpendicular to the movement direction. This makes it possible in a simple manner gradually to illuminate the entire valuable document with progressive movement.

In accordance with one development, the first resolution or the second resolution corresponds to a native resolution of a detector for detecting the reflection light and/or transmission light. The native resolution corresponds exactly to the physical digital resolution, that is to say the number of pixels, of the detector. The detector is for example a line detector and accordingly comprises only one line of pixels. A sensor unit in which the detector is arranged can also be referred to as a camera.

In accordance with one development, the valuable document is a banknote, a cheque, an identity card, a passport, a ticket or a share document.

One object of the invention is achieved by means of a device for testing the authenticity of the valuable document, comprising: an illumination unit for illuminating the valuable document line by line in such a way that the first group of lines of the valuable document is illuminated with light of the first wavelength and that at least the second group of lines of the valuable document is illuminated with light of the second wavelength, wherein at least partly lines of the first group and lines of the second group alternate, the detector for detecting reflection light that is reflected from the lines, and/or transmission light that passes through the lines, in a manner assigned to the lines of the first group and the lines of the second group, wherein the first data are representative of the reflection light and/or transmission light assigned to the lines of the first group and the second data are representative of the reflection light and/or transmission light assigned to the lines of the second group, a data processing unit for processing the first data in such a way that the first image generated from the first data has the first resolution, and for processing the second data in such a way that the second image generated from the second data has the second resolution, which is different from the first resolution, and an evaluation unit, which compares the first image with the first reference image and the second image with the second reference image.

The effects, advantages and developments explained above in association with the method for testing the valuable document can readily be applied to the device for testing the valuable document. Therefore, at this juncture, a renewed presentation of said effects, advantages and developments is dispensed with and reference is merely made to the explanations above.

In accordance with one development, the first image shows the first number of lines of the first group and the data processing unit additionally processes the first data such that at least the second image generated from the first data shows the smaller number of lines of the first group and has the resolution that is correspondingly lower than the first resolution, and the evaluation unit compares the second image with the corresponding second reference image.

In accordance with one development, the data processing unit additionally processes the first data such that at least partly first data of successive lines of the first group are averaged and that at least one second image generated from these averaged data has a resolution lower than the first resolution, and the evaluation unit compares the second image with a corresponding second reference image.

The two developments explained above can also be combined with one another. In particular, the first data can additionally be processed such that the second image generated from the first data shows a smaller number of lines of the first group than the first image and that at least partly first data of successive lines of the first group are averaged for the second image, such that the corresponding second image has a resolution that is lower than the first resolution.

In accordance with one development, the device comprises a transport unit, by means of which the valuable document is moved in a movement direction relative to the illumination unit, wherein the valuable document is moved and illuminated in such a way that the lines are aligned perpendicular to the direction of movement.

In accordance with one development, the first resolution or the second resolution corresponds to a native resolution of the camera for detecting the reflection light and/or transmission light.

DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form part of this description and show for illustration purposes specific exemplary embodiments in which the invention can be implemented. Since components of exemplary embodiments can be positioned in a number of different orientations, the direction terminology serves for illustration and is not restrictive in any way whatsoever. It goes without saying that other exemplary embodiments can be used and structural or logical changes can be made, without departing from the scope of protection of the present invention. It goes without saying that the features of the various exemplary embodiments described herein can be combined with one another, unless specifically indicated otherwise. Therefore, the following detailed description should not be interpreted in a restrictive sense, and the scope of protection of the present invention is defined by the appended claims. In the figures, identical or similar elements are provided with identical reference signs, in so far as this is expedient.

Valuable documents such as security papers or e.g. banknotes, cheques, shares, papers having a security imprint, certificates, identity cards, passports, entrance tickets, travel tickets, vouchers, identification or access cards or the like can be provided with security features on their front side, their rear side and/or in a manner embedded in the material, in order to hamper or to prevent forgery thereof, and to be able to check the authenticity thereof. In the case of a banknote, for example, one type of security features may be a region printed with luminescent (e.g. phosphorescent and/or fluorescent) ink. Since the luminescence, the reflection and/or transmission behaviour of such a region of the banknote can be imitated only with high expenditure, this constitutes an effective security feature which, at the same time, is machine-testable.

FIG. 1shows a perspective illustration of one exemplary embodiment of a device20for testing a valuable document22. The device20is suitable in particular for testing an authenticity and/or a state, the so-called fitness, of the valuable document22.

The device20comprises a first illumination unit24. The first illumination unit24serves for illuminating the valuable document22at a first angle. Optionally, the first device20comprises a second illumination unit26. The second illumination unit26serves for illuminating the valuable document22at a second angle. By means of the illumination units24,26, the valuable document22can be illuminated in reflected light.

The valuable document22shown inFIG. 1has two longitudinal sides, which extend from left to right inFIG. 1, and two transverse sides, which are arranged perpendicular to the longitudinal sides, are shorter than the longitudinal sides and extend into the plane of the drawing inFIG. 1. In the exemplary embodiment illustrated inFIG. 1, the illumination units24,26and the sensor unit are also configured in elongate fashion, wherein their longitudinal sides extend perpendicular to the longitudinal sides of the valuable document22. Expressed illustratively, the device20is aligned perpendicular to the valuable document22. This brief discourse on the outer shapes and alignments of the valuable document22and of the device20serves merely to be able to precisely describe individual features and the spatial arrangement thereof hereinafter. In other embodiments, the valuable document22and/or the device can be configured differently and/or arranged differently with respect to one another.

The device20furthermore comprises a sensor unit28. The sensor unit28serves for detecting light, for example reflection light, which is reflected from the valuable document22owing to the illumination of the valuable document22.

Furthermore, the device20comprises a transport unit, which is not illustrated inFIG. 1, by means of which the valuable document22can be moved relative to the device20. By way of example, the transport unit moves the valuable document22while the device20remains stationary. As an alternative thereto, the valuable document22can remain stationary while the device20moves by means of the transport unit. In both cases the valuable document22is moved relative to the device20in such a way that the entire valuable document is illuminated in the course of the movement.

FIG. 2shows a lateral schematic illustration of the device20for testing the valuable document22in accordance withFIG. 1. It is evident fromFIG. 2that the illumination units24,26each comprise at least one, preferably a plurality of light sources33. By way of example, the illumination units24,26each comprise at least one, for example two lines comprising respectively a plurality of light sources33. If appropriate, the two lines of light sources33of one of the illumination units24,26can be parallel to one another. Alternatively or additionally, one or both lines of light sources33can be parallel to the longitudinal side of the corresponding illumination unit24,26. Alternatively or additionally, one or both lines of light sources33of one of the illumination units24,26can be arranged perpendicular to the longitudinal direction of the valuable document22. In the exemplary embodiment shown inFIG. 2, the lines of light sources33extend into the plane of the drawing, such that the light sources33shown inFIG. 2are in each case representative of one of said lines of light sources33. The light sources33can for example each comprise one, two or more light-emitting diodes.

The sensor unit28comprises a detector36and an optical element38. The detector36is a line detector comprising a plurality of pixels, not shown inFIG. 2. The pixels are arranged along a line, wherein the corresponding line extends into the plane of the drawing in the exemplary embodiment shown inFIG. 2. The optical element38can comprise a focusing lens, for example, which focuses the light coming from the valuable document22, for example the reflection light, and directs it onto the detector36. The optical element38can for example be extruded and extend parallel to the detector36into the plane of the drawing. As an alternative thereto, the optical element38can comprise a plurality of focusing lenses arranged parallel to the pixels of the detector36along a line. By way of example, each pixel can be assigned exactly one optical element38that directs the light coming from the valuable document22onto the corresponding pixel. The line of pixels of the detector36, the line of focusing lenses and/or, if appropriate, the extruded optical element38can be arranged for example parallel to the longitudinal direction of the sensor unit28and/or perpendicular to the longitudinal direction of the valuable document22.

FIG. 3shows a perspective illustration of one exemplary embodiment of a device20for testing a valuable document. The device20for testing the valuable document22may for example largely correspond to the device20for testing the valuable document22explained above. In the exemplary embodiment shown inFIG. 3, just one illumination unit24is arranged on a side of the valuable document22facing away from the sensor unit28. The illumination unit24illuminates the valuable document22by means of the illumination light. At least part of the illumination light30passes through the valuable document22and the corresponding transmission light35impinges on the detector36of the sensor unit28. By means of the illumination unit24, the valuable document22can be illuminated in transmitted light.

FIG. 4shows a lateral schematic illustration of the device20for testing the valuable document22in accordance withFIG. 3. It is evident fromFIG. 4that the first illumination unit24in this exemplary embodiment comprises at least four light sources33. In another exemplary embodiment, however, the first illumination unit24can also comprise more or fewer light sources33. The four light sources33may each be representative of a line of light sources33, wherein the corresponding lines extend into the line plane. By way of example, the lines of light sources33are arranged parallel to a longitudinal direction of the first illumination unit24and/or perpendicular to a longitudinal direction of the valuable document22.

In addition to the components explained above, the devices20for testing the valuable document22as explained with reference toFIGS. 1 to 4each comprise a control unit, a data processing unit and an evaluation unit. The control unit is coupled to the illumination units24,26, the sensor unit28, the data processing unit and the evaluation unit in such a way that it can control them and in particular can send signals to them and/or can receive signals from them. The data processing unit and the evaluation unit can also be parts of the control unit.

The data processing unit is coupled to the sensor unit28in such a way that it can receive data from the sensor unit28. The data are representative of the light detected by means of the sensor unit28. The data processing unit comprises at least one, preferably two or more resolution reducers, by means of which the data can be processed in such a way that an image of the valuable document22that is generated from the data has a lower resolution than an image of the valuable document22that is generated from the data and was not processed by means of the resolution reducer(s).

FIG. 5shows a schematic illustration of one exemplary embodiment of a line of pixels of a detector, for example of the above-explained detector36of the sensor unit28. The pixels are arranged alongside one another in linear form. The line of pixels is also referred to hereinafter as detector line40.

FIG. 6shows a schematic illustration of the line of pixels of the detector36in accordance withFIG. 5under various illuminations, wherein the illumination of the detector36is not effected directly but rather indirectly via the valuable document22. In particular, the detector36is illuminated by means of the light reflected from the valuable document22or by means of the light transmitted through the valuable document22.FIG. 6does not show a plurality of detector lines40at the same point in time, but rather the same detector line40at different points in time. In particular,FIG. 6shows one below another the detector line40on one occasion under illumination with light of a first wavelength, for example with red light, on one occasion under illumination with light of a second wavelength, for example with green light, on one occasion under illumination with light of a third wavelength, for example yellow light, and on one occasion under illumination with light of a fourth wavelength, for example blue light or infrared light.

FIG. 7shows a schematic illustration of one example of a valuable document under various illuminations, for example of the above-explained valuable document22under a periodically changing illumination in accordance with the three upper detector lines42shown inFIG. 6. In particular, while the valuable document22is moved relative to the device20for testing the valuable document22, said valuable document is illuminated alternately with red light, green light and yellow light, wherein this process is repeated until the entire valuable document22has been illuminated. Observation of the valuable document22during this process reveals that lines of different colours form successively on the valuable document22, as is illustrated schematically inFIG. 7. In particular,FIG. 7shows one below another the lines42,44,46of the valuable document22, in particular first lines42under illumination with light of a first wavelength, for example with red light, therebelow second lines44under illumination with light of a second wavelength, for example with green light, and third lines46under illumination with light of a third wavelength, for example yellow light. This order of the lines42,44,46is repeated until the valuable document22has been completely illuminated.

The first lines42form a first group of the lines42,44,46, the second lines44form a second group of the lines42,44,46and the third lines46form a third group of the lines42,44,46. The first lines42can also be referred to as red lines. The second lines44can also be referred to as green lines. The third lines46can also be referred to as yellow lines. It should be understood here that the lines42,44,46of the valuable document22in reality are not illuminated simultaneously, but rather successively. The schematic illustration inFIG. 7thus does not show a real image of the valuable document22under various illuminations, but rather presents an illustration of the temporal sequence of the illumination of the valuable document22.

Moreover,FIG. 7shows that the valuable document22has identification features52, which are illustrated schematically by means of a large triangle for better elucidation inFIG. 7.

FIG. 8shows an illustration of the line of pixels of the detector36when detecting the light from the valuable document in accordance withFIG. 7. In particular,FIG. 8shows one below another repeatedly the detector line40under the illumination in accordance withFIGS. 6 and 7. It is evident here that in the case of the upper two detector lines inFIG. 8, the identification feature52is not yet identifiable, but is detected by an increasing number of pixels in the underlying detector lines40in accordance with the triangular structure of the identification feature52. In a manner similar toFIG. 6,FIG. 8does not show a plurality of detector lines40at the same point in time, but rather the same detector line40at different points in time.

FIG. 9shows an illustration of processed data on the basis of the lines42,44,46of the valuable document22in accordance withFIG. 7. In particular,FIG. 9shows alternately one below another the first lines42, reduced first lines42′, the second lines44and a reduced third line46′. The reduced first lines42′ are generated by reducing the resolution of the first lines42. The reduced third line46′ is generated by means of reducing the resolution of the recording of the corresponding third line46, for example of the first third line46from the top as shown inFIG. 8. To put it generally, on the basis of the data representing the lines42,44,46it is possible to obtain data representing corresponding reduced lines, in particular by means of one or more resolution reducers.

FIG. 10shows images60,62,64,68that can be generated for example by means of the processed data in accordance withFIG. 9.

In particular, a first image60having a first resolution can be generated by means of the data representing the first lines42. The first resolution corresponds for example to a native resolution of the detector36.

A second image62having a second resolution can be generated by means of the data representing the reduced first lines42′. The second resolution is lower than the first resolution.

A third image64having a third resolution can be generated by means of the data representing the second lines44, wherein the third resolution is equal to the first resolution in this exemplary embodiment.

A fourth image68having a fourth resolution can be generated by means of the data representing the third lines46, wherein the fourth resolution is less than the first, second and third resolutions in this exemplary embodiment.

Consequently, a plurality of images60,62,64,68of the valuable document22can be generated by means of the illumination units24,26and the one detector line40, wherein the images60,62,64,68are generated in each case by means of light of a single colour, but overall are generated at least partly by means of light of different colours and have at least partly different resolutions.

All the images60,62,64,68show the identification feature52in the corresponding resolution for simple illustration. In reality, however, valuable documents22often have different identification features52. The illumination scheme and the resolutions of the images60,62,64,68can be chosen depending on the valuable document22to be tested in such a way that they are particularly expedient, for example optimal, for identifying the corresponding identification feature52. By way of example, the resolution necessary for identifying a first identification feature is lower than that necessary for identifying a second feature. If the low resolution is then actually used for identifying the identification feature, then in this way the data processing can be carried out particularly rapidly and particularly simply and thus with particularly low computing power. Alternatively or additionally, for identifying a second identification feature it may be sufficient to use only a portion of the lines of a specific colour, for example a portion of the first lines42. If the small number of lines is then actually used for identifying the identification feature, then in this way the data processing can be carried out particularly rapidly and particularly simply and thus with particularly low computing power.

FIG. 11shows an illustration of generation of different images60,62,64,70,71on the basis of differently processed data. In this case, the lines42,42′,44′ and lines49,49′ in the upper part ofFIG. 11are illustrated merely schematically as individual blocks. The images60,62,64,70,71illustrated underneath arise as a result of further transport of the valuable document22, a plurality of repetitions of the illumination scheme represented by the lines42,42′,44′ and lines49,49′, by detection of the corresponding for example reflected light and processing of the corresponding data, in a manner similar to that as illustrated with the aid ofFIGS. 6 to 10. In other words, the scheme shown inFIG. 11represents, in a greatly simplified manner, the fundamental scheme illustrated with reference toFIGS. 6 to 10, wherein at least partly other lines, colours and/or resolutions are used.

In particular,FIG. 11shows that the first image60having the first resolution is generated by means of the first lines42and that first reduced lines42′ are generated by means of the first lines42on the far left inFIG. 11. The second image62having the second resolution is generated by means of the first reduced lines42′. Second reduced lines44′ are generated by means of the second lines44. By means of the second reduced lines44′, the third image64is generated, although with a reduced resolution. A fifth image70having a fifth resolution and fourth reduced lines49′ are generated by means of fourth lines49. A sixth image71having a sixth resolution is generated by means of the fourth reduced lines49′. In this exemplary embodiment, the fifth resolution is less than the first resolution, but greater than the sixth resolution. Moreover, in this exemplary embodiment, the sixth resolution is equal to the second resolution and equal to the reduced resolution of the third image64. One line, specifically the third from the right inFIG. 11, is not used.

In this exemplary embodiment, the first resolution can be for example 100 dpi×100 dpi, the fifth resolution can be for example 50 dpi×50 dpi and the second and sixth resolutions and also the reduced resolution of the third image64can be for example in each case 25 dpi×25 dpi. The native resolution can be for example 100 dpi×100 dpi.

The first lines42and the first reduced lines42′ can be generated for example by means of red illumination light. The second reduced lines44′ can be generated for example by means of green illumination light. The fourth lines49and the fourth reduced lines49′ can be generated for example by means of blue illumination light.

The illumination and processing scheme illustrated inFIG. 11can be realized for example by means of a reflected-light illumination, as explained for example with reference toFIGS. 1 and 2.

FIG. 12shows an illustration of generation of different images1262,1264,1272,1274,1276,1278on the basis of differently processed data. In this case, the lines1254,1254′,1242′,1244,1244′,1256′ in the upper part ofFIG. 12are illustrated merely schematically as individual blocks. The images1262,1264,1272,1274,1276,1278illustrated underneath arise as a result of further transport of the valuable document22, a plurality of repetitions of the illumination scheme represented by the lines, by detection of the corresponding for example transmitted light and processing of the corresponding data, in a manner similar to that as illustrated with the aid ofFIGS. 6 to 10. In other words, the scheme shown inFIG. 12represents, in a greatly simplified manner, the fundamental scheme illustrated with reference toFIGS. 6 to 10, wherein at least partly other lines, colours and/or resolutions are used.

In particular,FIG. 12shows that the first image1274having a first resolution is generated by means of the first lines1254and the second image1276having a second resolution is generated by means of first reduced lines1254′ formed from the first lines1254. Furthermore, the third image1262having a third resolution is generated by means of second reduced lines1242′ formed from the second lines1242. The fourth image1264having a fourth resolution is generated by means of the fourth lines1244and a fifth image1272having a fifth resolution is generated by means of fourth reduced lines1244′ formed from the fourth lines1244. The first image1274having the first resolution is generated by means of the fifth lines1254. A sixth image1278having a sixth resolution is generated by means of seventh reduced lines1256′ formed from the seventh lines1256. The fourth image1264having the fourth resolution is generated by means of the eighth lines1244. In this exemplary embodiment, the second resolution, the third resolution, the fifth resolution and the sixth resolution are equal in magnitude. Moreover, the first resolution and the fourth resolution are equal in magnitude and greater than the other resolutions. Two lines, specifically the third from the left and the third from the right inFIG. 12, are not used.

In this exemplary embodiment, the first resolution and the fourth resolution can be for example 50 dpi×50 dpi and the second resolution, the third resolution, the fifth resolution and the sixth resolution can be for example in each case 25 dpi×25 dpi. The native resolution can be for example 50 dpi×50 dpi.

The second reduced lines1242′ can be generated for example by means of red illumination light. The fourth lines1244and the fourth reduced lines1244′, and also the eighth lines1244can be generated for example by means of green illumination light. The first lines1254and the first reduced lines1254′ and also the fifth lines1254can be generated for example by means of yellow illumination light. The seventh reduced lines1256′ can be generated for example by means of infrared light in a first wavelength range.

The illumination and processing scheme illustrated inFIG. 12can be realized for example by means of a transmitted-light illumination, as explained for example with reference toFIGS. 3 and 4.

FIG. 13shows an illustration of generation of different images1362,1364,1370,1372,1374,1376,1378,1380,1382on the basis of differently processed data. In this case, the lines1342′,1344,1344′,1349,1349′,1354,1354′ and1356′ in the upper part ofFIG. 13are illustrated merely schematically as individual blocks. The images1362,1364,1370,1372,1374,1376,1378,1380,1382illustrated underneath arise as a result of further transport of the valuable document22, a plurality of repetitions of the illumination scheme represented by the lines1342′,1344,1344′,1349,1349′,1354,1354′ and1356′, by detection of the corresponding for example transmitted light and processing of the corresponding data, in a manner similar to that as illustrated with the aid ofFIGS. 6 to 10. In other words, the scheme shown inFIG. 13represents, in a greatly simplified manner, the fundamental scheme illustrated with reference toFIGS. 6 to 10, wherein at least partly other lines, colours and resolutions are used.

In particular,FIG. 13shows that a first image1374having a first resolution is generated by means of the first lines1354. Furthermore, a second image1376having a second resolution is generated by means of the first reduced lines1354′ formed from the first lines1354. A third image1364having a third resolution and second reduced lines1344′ are generated by means of the second lines1344. A fourth image1372having a fourth resolution is generated by means of the second reduced lines1344′. A fifth image1362having a fifth resolution is formed by means of third reduced lines1342′ formed from third lines1342. A sixth image1370having a sixth resolution is generated by means of fourth lines1349. Furthermore, a seventh image1382having a seventh resolution is formed by means of fourth reduced lines1349′ formed from the fourth lines1349. The third image1364having the third resolution is generated by means of the fifth lines1344. An eighth image1378having an eighth resolution is generated by means of the sixth reduced lines1356′ formed from sixth lines1356. The first image1374having the first resolution is generated by means of the seventh lines1354. The third image1364having the third resolution is generated by means of the eighth lines1344. A ninth image1380having a ninth resolution is generated by means of the ninth reduced lines1354′ formed from the ninth lines1354. The sixth image1370having the sixth resolution is generated by means of the tenth lines1349. The third image1364having the third resolution is generated by means of the eleventh lines1344.

In this exemplary embodiment, the second resolution, the eighth resolution, the fifth resolution, the fourth resolution, the seventh resolution and the ninth resolution are equal in magnitude. Moreover, the sixth resolution and the first resolution are equal in magnitude and greater than the other resolutions mentioned above. The third resolution is the highest of all the resolutions.

In this exemplary embodiment, the third resolution can be for example 100 dpi×100 dpi, the sixth resolution and the first resolution can be for example 50 dpi×50 dpi, and the second resolution, the eighth resolution, the fifth resolution, the fourth resolution, the seventh resolution and the ninth resolution can be for example in each case 25 dpi×25 dpi. The native resolution can be for example 100 dpi×100 dpi.

The illumination and processing scheme illustrated inFIG. 13can be realized for example by means of a combination of a reflected-light illumination, as explained for example with reference toFIGS. 1 and 2, and a transmitted-light illumination, as explained for example with reference toFIGS. 3 and 4.

FIG. 14shows a flow diagram of one exemplary embodiment of a method for testing a valuable document, for example the valuable document22explained above. The method for testing the valuable document22can be carried out for example with the aid of one of the above-explained devices20for testing the valuable document22. For illustration, the method for testing the valuable document22is explained with the aid ofFIGS. 7 to 13besides the flow diagram shown inFIG. 14.

In a step S2, the valuable document22is illuminated line by line in such a way that a first group of lines of the valuable document22is illuminated with light of a first wavelength and that at least one second group of lines of the valuable document22is illuminated with light of a second wavelength, for example as explained in greater detail with reference toFIG. 7. At least partly lines of the first group and lines of the second group alternate. The first group of lines can be for example the first lines42. The second group of lines can be for example the second or third lines44,46. For this purpose, the valuable document22is moved in a movement direction relative to the first and/or second illumination unit24,26, by means of which the valuable document is illuminated. In this case, the valuable document22is illuminated in such a way that the lines are aligned perpendicular to the movement direction. As a result, gradually the entire valuable document22is illuminated with progressive movement.

In a step S4, reflection light that is reflected from the lines and/or transmission light that passes through the lines are/is detected in a manner assigned to the lines of the first group and the lines of the second group and are/is converted into one, two or more electrical signals carrying corresponding data, for example as explained in greater detail with reference toFIG. 8. In this case, first data are representative of the reflection light and/or transmission light assigned to the lines of the first group, and second data are representative of the reflection light and/or transmission light assigned to the lines of the second group. Steps S2and S4can be processed successively or simultaneously.

In a step S6, the first data are processed in such a way that a first image generated from the first data, for example the first image60or the third image64, has a first resolution, and the second data are processed in such a way that a further image generated from the second data, for example the fourth image68or second image62, has a second resolution, which is different from the first resolution, for example as explained in greater detail with reference toFIGS. 9 and 10.

In an optional step S8, the first data can additionally be processed such that at least one second image generated from the first data, for example the second image62, shows a smaller number of lines of the first group and has a resolution that is correspondingly lower than the first resolution, for example as explained in greater detail with reference toFIGS. 10 and 11.

In an optional step S10, the first data can additionally be processed such that at least partly first data of successive lines of the first group are averaged and that at least one second image generated from these averaged data, for example the second image62has a resolution that is lower than the first resolution. The step S10can be processed as an alternative or in addition to step S8.

In a step S12, the first image60is compared with a first reference image and each further image is compared with a corresponding further reference image. By way of example, the second image62is compared with a corresponding second reference image.

In a step S14, depending on the comparison, a decision is taken as to whether the valuable document22is genuine and/or has a sufficient fitness to be able to continue in circulation. This can be carried out for example on the basis of deviations between the images and the corresponding reference images and a comparison of these deviations with predefined threshold values.

Expressed illustratively, in the method explained above, the data, which can also be referred to as camera data, are generated in a plurality of exposure colours with defined and configurable time-division multiplexing. Since different algorithms for testing the identification features require different minimum image resolutions and the sensor unit28, which can also be referred to as a camera, and/or a processor, for example a CPU, of the device20in the case of conventional methods are/is often unable to yield or to process the maximum resolution for every exposure colour required, the data per colour and resolution are written directly via FPGA and DMA to a memory of the CPU into a dedicated 2D image memory area per valuable document22.

In the FPGA, the following logic blocks can be used for this purpose: the sensor unit28detects the light and the corresponding data of the individual lines exposed with a specific colour, for example in the native resolution (100 dpi or 200 dpi), in a defined time frame (cycle length e.g. 12). Optionally, a correction of the corresponding gain and/or offset is carried out; at least one resolution reducer reduces the resolution of individual lines by a factor, for example by a factor of 2, 3, 4 or more or by a non-integral factor; and the outputs feed different DMA channels, which then construct the images of different resolutions and colours in the memory of the CPU.

A plurality of parallel resolution reducers can be arranged. The resolution reducers can be configured individually per line. In this regard, it is possible to use a line of a specific colour for example in an image having a resolution of 100 dpi and in an image having a resolution of 25 dpi. This process can also be referred to as colour reuse.

Here for example in the first case it is possible to use four 100 dpi lines per cycle and in the second case, for example, only one of these four lines can be used and/or be reduced to 25 dpi.

The invention is not restricted to the exemplary embodiments indicated. By way of example, in the case of the device20, the illumination units24,26can be arranged such that both a reflected-light illumination and a transmitted-light illumination are possible. Furthermore, the illumination units can comprise more or fewer light sources than those shown and/or more or fewer lines of light sources.

Furthermore, additional or fewer colours than those explained above can be used for the illumination. Furthermore, more or fewer images than those explained above can be generated and compared with corresponding reference images. Furthermore, the images can have different resolutions than those explained above. Furthermore, different illumination schemes than those explained above are possible.