DE10005835A1 - Authenticating of documents containing security features having different spectral responses - Google Patents

Abstract

Entire document is scanned with multi-spectral beam so that security features (2-6) on the document react with different spectral responses which are detected by sensors. Complete document is scanned with multi-spectral light to detect position of security features relative to coordinate system of the document. Position of markings is detected due to brightness, contrast, color and pattern differences relative to the rest of the document background. Then the security feature is checked only in the image areas corresponding to the position detected. Security features are machine readable text (2) with a line which does not reflect in selected scan of near infrared light, a two-dimensional bar code (3), diffractive element (4) which reflects diffraction pattern in coherent light of specific wavelength and picture (5) containing steganographically hidden information.

Description

Numerous non-electronic personal documents such as identity card, passport, Visa documents or similar value documents such as shares, banknotes, bills of exchange, etc. Ä. are used to protect against counterfeiting during manufacture Provide security features. These characteristics can be divided into four major ones Categories are divided into:

Category A: for the human eye under normal observation invisible optical features, which under certain non- coherent lighting and shooting conditions visually or are recognizable by machine.

This includes printed structures, inserted threads etc. which under ultraviolet light can be seen in the visible by fluorescence. Personal documents and banknotes often come with such characteristics Mistake. The control is carried out manually by visual observation under a  Black light lamp, d. H. a lighting source, which is only in the emits invisible ultraviolet.

This category also includes introduced or printed dyes a special reflection behavior, often in the wavelength range of the near Infrared (abbreviated NIR). The spectral distribution of the remitted infrared light contains a typical signature, which is obtained by spectrometric methods can be checked. This is known as machine recognition.

The information hidden in pictures also belongs to this category, the so-called steganography, which uses certain modulation processes Grid can be introduced during rasterized image printing and with the help of Image processing methods can be extracted by machine.

Category B: visible to the human eye under normal observation optical characteristics, which can be found under a certain, non- change coherent lighting.

These include e.g. B. lines applied to many personal documents, which are visible in the visible, but when illuminated with a certain wavelength, mostly located in the NIR, disappear.

Category C: visible to the human eye under normal observation optical characteristics, which under certain, coherent Lighting arrangements determined due to light diffraction Generate diffraction patterns.

These include clear or metallized foils Diffraction gratings, which are special for a certain laser lighting Generate diffraction patterns, which with the help of photodetectors or Cameras can be checked.  

Category D: visible to the human eye under normal observation optical features that indicate an information-carrying represent machine readable code.

These include machine-readable imprints, 1-dimensional and 2-dimensional dimensional barcodes, 2-dimensional matrix codes u. Ä. which with the help be decoded by scanners or camera systems.

According to the prior art, only the features of the Category D is automatically evaluated using readers. These devices contain one or more cameras and one or more spectral different lights and are able to be machine readable Printouts such as the so-called ICAO line for personal documents, applied 1D or decode 2D barcodes automatically. The positions of these codes relative to a coordinate system based on the document are in the Rule set by international standards. The documents must be in one certain position to be placed on the viewing window of these devices to work correctly.

These automatic devices therefore only perform the "decode" functions by; they cannot be used for documents in which the position of the Code is not defined or the position of the document is free. To still to be able to work correctly, an automatic function "positioning" needed, d. H. automatic detection of the code or codes on the document and automatic positioning of an evaluation window at these points.

Those secured according to categories A (except UV characteristics), B and C. Documents can only be processed automatically. H. with the help of technical, usually optical procedures are checked. There are individual proposed solutions such as B. the use of microspectrometers for spectral analysis, Image processing method for recognizing those in the printed images contained information, which each fulfill a specific task.  

Newer documents are often secured at the same time with numerous of the features falling under categories A, B, C and D. The geometric position of these features on the document is very often not precisely defined:

• a) due to production tolerances z. B. the position of a imprinted diffraction feature fluctuate
• b) due to the lack of standards, there is no uniform one agreement
• c) due to the insecure position of the document in the image field of the positions are relative to the automatic tester Coordinate system of the scanner not known

These documents can either not be automatic at all or highest be checked semi-manually. The user must have the document in a hang up and position certain orientation. This process is uncertain and takes time.

As the variety of features applied at the same time increases significantly, there is also a great need for systems that automatically recognize which features are present in the document, these automatically find and check. Such systems are not yet available today.

The verification of the document itself is called "authentication". The Question whether the document shown, e.g. B. an identity card also to the Bearers are called "verification".

By the loss of intra-European customs controls, by the increase The number of passengers in the airports in  in the shortest possible time to authenticated and verified highly secure Personal documents strongly. Today's visual control, possibly under Using simple UV lighting systems or ICAO font readers cannot meet this requirement. Similar relationships also apply to the verification of documents of value such as banknotes, of secured Shipping documents u. documents. There is therefore a great need secure, fast and robust automatically testable and readable documents.

The object of the invention is a method and an arrangement for fast and automatic authentication with numerous optical features secured documents, where the position of the features relative to the Coordinate system of the document is not known or is known only approximately.

This object is achieved by the technical teaching of claim 1. The document is in its entirety or in parts in a first Work step illuminated with illuminants, their spectral and geometric distribution, polarization, coherence and temporal course of the optical properties of the lighting means are selected so that a through imaging sensors detectable image, in which the positions of the Security features due to brightness, contrast, color, Pattern differences relative to the rest of the document background automatically with methods of image processing can be seen that in a second Work step checking the corresponding characteristics only in the Image areas is made that the in the first step correspond to the positions found and the corresponding ones Image areas are illuminated in such a way that the corresponding features Generate images and / or spectral signatures, from which the Image processing and / or spectrometry for testing the features required information can be derived.  

It does not matter whether it is a single-path or a multipath scan takes place; in both process modes can according to the invention be worked.

The division of the security features into the described categories A to D is only one for a simpler description of the Invention ideas are useful classification. Other features that are not fit into one of these explicit categories are also part of the Invention ideas.

The inventive method allows the position of the Security features, both relative to the coordinate system of the scanned document, and of course to the coordinate system of the Scanners themselves. By recognizing the sheet margin against the dark Background of the cover flap the scanner "knows" how to document is aligned with its own coordinate system.

This allows the position of the features to be relative to the document Find coordinate system, which is important, if there is none standardized regulations or if, as a result of Production tolerances the exact position is unknown.

This position information is anyway the first time you scan found relative to the coordinate system of the scanner, regardless of the exact alignment of the document on the scanning window of the scanner. With This information can be used for the corresponding lighting and / or Line sensors of the scanner at these points in the document with high precision procedure and the actual examination of the authenticity features with high precision be performed.

Would you also like to check whether the position of the security features with that hidden by a standard or by other features  Target positions relative to the document coordinate system match, is a transformation between the scanner coordinate system and the Coordinate system of the document itself prepared by e.g. B. the left one upper corner of the sheet as the X0, Y0 coordinate origin of the document Are defined. By detecting at least two corners in the scan window the translation rotation matrix between the scanner coordinate system and Document coordinate system made.

This double effect is described in the special description section and in the Claims further characterized.

The invention consists, among other things, of using suitable ones Illumination process the position of the authenticity features relative to the Find document and / or relative to the scanner, this one Types of lighting may be different from those used when testing the Authenticity features are used.

Part of the inventive concept is also the storage and Archiving of all captured, pictorial information of the secured Document in a database simultaneously with the review of the Document.

For clarification, the inventive idea is based on a typical Document, namely one through a combination of numerous features secured personal document, explained.

The following illustrations are used for this:

Fig. 1 shows the schematic structure of a personal document with the security features ICAO line with NIR underscore, barcode, portrait printing with hidden in the image information and an applied on a metallized film diffractive feature FIG. 2 shows an example of the individual positions of the features to be tested, which are determined regardless of the position of the document on the device and the exact position with respect to the document itself

Fig. 3 shows schematically a typical proposed solution, in which the entire document is scanned with a high resolution line camera scanner at different spectral, geometrically and temporally different illuminations

The idea of the invention is exemplary, but not restrictive based on a personal document secured by several features at the same time explained.

According to FIG. 1, this document 1 is to be secured by the following features to be mechanically positioned and checked:

• a) by means of a machine-readable text 2 with a line which no longer reflects in the near infrared when spectrally selected lighting is used
• b) by a 2-dimensional barcode 3 , which contains cryptographically secured information
• c) by a diffractive element 4 , which is applied in the center of a star-shaped metallized film and which, under coherent illumination, reflects certain diffraction patterns at a specific wavelength
• d) by steganographically hidden information in portrait image 5 .

The text field 6 contains no security features and no machine-readable information. Nevertheless, it must be recognized mechanically as a field that is not to be evaluated.

The layout of the document can be determined by the position of this individual Features relating to an x, y- aligned at the edge of the document Coordinate system are described. These positions should be at Sampling through the arrangement according to the invention is not possible or only uncertainly be known, so that according to the invention in a first step Positions of these features with respect to the coordinate system are determined Need to become.

Fig. 2 shows an example of an arrangement for performing the step "positioning".

Document 1 is placed on device 12 with the side to be evaluated. The side is scanned line by line through the viewing window 13 with the motor-driven sensor head 15 , which is moved linearly along the bearing 14 .

Some methods for finding the individual are exemplary Characteristic positions and their identification through specific lighting described according to the inventive concept for the first method step.

To find the positions of the text field 2 , the 2-dimensional barcode 3 and the portrait 5 , the document 1 is alternately illuminated with a wavelength in the near infrared and with a wavelength in the visible light during the scanning by the diffuse illumination 16 . This can be done by switching over time of correspondingly spectrally selected light-emitting diodes (LEDs). If the switchover takes place synchronously with the line frequency, two images A and B are interleaved in the image memory of the computing unit 21 , A being intended to represent the one illuminated in the NIR range and B the one shown in the visible illuminated image.

• a) due to the illumination in the near infrared, the continuous line 11 in the text field 2 disappears while the line 11 remains clearly visible in visible light. The texts, both in field 2 and in field 6 , are clearly recognizable both in the NIR range and in visible light, since black printing absorbs a wide range of lighting wavelengths. By evaluating the pictorial information, which clearly differ in the two images A and B, the text field 2 can be distinguished from the text field 6 .
  Fig. 3 A and B shows the images with the corresponding image content. The position of the line 11 that disappears between A and B enables the position of the text field to be evaluated mechanically with respect to the xy coordinate system to be determined. At the same time, the disappearance of line 11 in Figure A means that the second procedural step, namely the checking of the security feature, is also processed.
• b) Field 3 with the 2-dimensional barcode is visible in both images A and B. It can be recognized from the rest of the image content using methods of pattern recognition known to the person skilled in the art on the basis of the high-frequency spatial frequencies which characterize the code pattern.
• c) the automatic positioning of the colored portrait picture 5 can, for. B. can be recognized by the fact that the color pigments of the portrait 5 change their reflection behavior between NIR illumination and illumination in the visible range, while the reflection behavior of the background paper remains similar.
  This property is illustrated in FIG. 3 by a weaker contrast between portrait and background in image A compared to the contrast in image B. This local difference allows the person skilled in the art of image processing to determine the position of the portrait with respect to the document coordinate system.
• d) by illuminating the document with the directed illumination 17 , the position of the metallized film which carries the diffractive element in the center can be recognized. While the contrast between the metallized film and the background paper appears relatively weak under the diffuse illumination 16 and this also relatively independently of the illuminating wavelength, the contrast difference between the specularly reflecting metal film and the paper of the background becomes very large due to the oblique illumination. The obliquely incident directional illumination reflects past the entrance pupil of the imaging lens 18 . This makes the slide appear darker than the background. This is shown in Fig. 3 in picture C.
  It is known to the person skilled in the art of optics that this contrast difference can also be achieved by a so-called bright field illumination, in which the illumination is arranged in such a way that it reflects directly into the pupil of the imaging lens through the reflecting film and thus brighter than the diffusely reflecting one Background appears.
  If the obliquely incident directional illumination is selected at least partially coherently at the same time, it is achieved at the same time that the actual security feature in the center of the metallized star, namely the diffractive element with one of the diffraction orders, reflects back into the pupil of the imaging optics and thus appears bright.
  It is easy for the person skilled in image processing to recognize both the position of the metallized star and that of the diffractive element in its center due to these high contrast differences.

Since the positioning step does not require high image resolution, which is the actual machine evaluation of the text field, the 2D code, which requires information hidden in the portrait as well as the diffraction patterns, According to the invention, the inclusion of the individual, the respective Illumination-associated images with reduced resolution be included. Technically, this can be done in that the imaging line sensor with a coarser step size during this Positioning step works.

Another idea of the invention is to synchronize the individual lights to switch to the line cycle of the imaging line sensor and thus a Series of interlaced lower resolution images in one scan obtained from which, as a result of the systematic contrast and Pattern differences the positions of each characteristic using methods of Pattern recognition and image processing can be determined.

It is important that both in the single-path and in the multipath method the entire document is illuminated with multispectral radiation is so that the authenticity features distributed accordingly on the document react with different spectral responses and with spectral differently recording sensors can also be recorded.

In the simplest case, light emitting diodes are used as radiation sources used because only a relatively low resolution is required.

There is a line sensor that contains a line of image-recording sensors includes which line sensor is now moved along the document. Such a silicon sensor would z. B. a spectral sensitivity from visible light to the NIR spectrum. When proceeding this  Line sensors are now alternately the LEDs per line controlled which emit visible light and alternately the LEDs that emit light in the NIR spectral range. This creates a partially interlocked overall image in the image memory that receives the signal, which z. B. consists of 1000 lines. 500 of these are lines with signals which correspond to the spectral response in visible light, while 500 lines are loaded with signals, which of the spectral Response of the authenticity features in the NIR area accordingly.

Using conventional software methods, these two image areas are Array processed separately and separately.

This process is mainly carried out in the single-path process because of this is particularly fast and produces a relatively low resolution.

In the image memory would be z. B. the locations and types of authenticity features according to FIGS . 3a to 3c virtually stored. In the infrared range, for. B. then in the image to be examined, the portrait according to number 5 no longer visible, while the other authenticity features, for. B. the defractive element 4 , is well readable in the NIR range.

In the visible (white light), for example, portrait 5 is very easy to read.

From this template, e.g. B. a 1000-line image array, which 500 lines of one picture and 500 lines of the other picture is now through Difference determination between the two read out images determines where the authenticity features are.

In relation to portrait image 5 , the portrait image would be easily readable in the visible area, while in the NIR area the portrait is difficult to read out or disappears completely, so that the determination of this difference image clearly states that there is a visible light at this location readable portrait picture is located.

The location of this portrait picture is clearly determined on the document.

Of course, not only the location of the Take portraits, but still z. B. color information or others Information that can be derived from the white light spectrum.

In an analogous manner, this also applies to the location of the other elements, where z. B. with respect to the machine-readable text 2, the line 11 disappears in the NIR area while it is present in the visible area, so that the location of this machine-readable text 2 can also be determined without further ado.

The invention is of course not only for the determination of one Limited difference image from two different spectral wavelengths, but - as previously stated in the invention - it is also that Direction of the incident light and the resulting Spectral response is a measure of the location and type of used Authenticity features.

The current claim 3 also states that the geometric distribution the lighting is used to find the authenticity features. Under the term "geometric distribution" is used for. B. understood the direction of incident light, but also the geometric distribution, e.g. B. in the form a lattice structure or a particularly distributed, geometric structure, such as e.g. B. concentric rings or other geometric arrangements of the Lighting sources.

All features mentioned in the current claim 3 can be individually or contribute to the solution of the invention task in different combinations.  

The degree of polarization of the illumination source can also be used, in order to obtain a specific readout of authenticity features.

The invention is also not based on the use of coherent light limited, but it can also be non-coherent or medium-coherent Light can be used.

The term "temporal activity" means that the Authenticity feature is illuminated with a certain pulse and the Impulse response and its decay in a certain time window examined is, so that the temporal activity of the impulse response for reading of the authenticity feature can be used.

All of the measures mentioned above are therefore initially used to determine the location the authenticity features distributed on the document.

There are now several ways to do this Method according to the invention:

According to a first embodiment, it is provided that - accordingly the above description - first with a lower resolution scans the entire document and determines the location of the authenticity features. This was explained in detail above.

If now the location of the authenticity features by appropriate Signal examinations were found to be run in a second scan scanned with higher resolution, and the signal image obtained is only on the positions examined more closely and special investigation methods subject to those specifically found at that location Authenticity features apply (multi-path scanning).  

The second scan can of course target specific areas of the Document to save time. Here it is important that the second scan is done at a relatively high speed can be, because yes only in certain places where authenticity features are recognized have to be scanned at high resolution.

That is, So, you can scan the speed, over the length of the Looking away from the document, change it so that you can only see where Authenticity features are present, with higher resolution scans while using the "empty" area of the document is driven at higher speed. This significantly increases the processing speed.

In another embodiment (secondary claim 2) the whole Document with the highest, for the detection of the authenticity features required resolution scanned once, then from the scanned image and the signal response obtained from it immediately the location of the authenticity features to determine.

If the location of the authenticity features from the signal response is fixed, then can the location of the signal received accordingly in software now Authenticity features are examined.

So it becomes a digital image in a multi-line array of the whole Document and the authenticity features contained thereon. By doing Another step is the authenticity check of each individual feature only exactly at the place where the authenticity feature was previously determined has been. Above all, this saves computing time and results in a much higher one Production output for the device according to the invention. The rest of it is now in a second scan possible, certain illuminants just drive up for this recognized location and this recognized location to beam and carry out the corresponding authenticity check.  

This means that all detection methods and features for the Detection and verification of this authenticity feature individually or in Combination can be used as in the general part (and have also been described in particular in claim 3). This is especially true for the type and form of illumination, for the spectral distribution of the Illumination source and the like. And always focused on that recognized location of the authenticity feature and only to this location. So that exists the main advantage that now due to the location of the Authenticity feature of the laser, which z. B. for the detection of a Authenticity feature is required, now highly accurate regarding this Authenticity feature can be positioned to expose this and the Measure radiation response accordingly. So there is an essential better signal-to-noise ratio, which is no longer due to inaccuracies depends on the positioning of the document.

This type of evaluation of Authenticity features for authenticity features that are based on Diffraction structures are built up. It comes down to a very precise one Positioning the radiation source in relation to the authenticity feature, and here are the advantages of the invention.

Other authenticity features can also be examined, e.g. B. the The fact whether there is a certain point in a document fluorescent thread is present. This thread is then with a corresponding radiation source illuminated. Here too is the positioning the radiation source with respect to the thread is extremely important to a to obtain a favorable signal-to-noise ratio. This results in the further advantage that due to the location and location of Authenticity features other areas in the document are approached in order to be able to hide there singularly (also arbitrarily attached) Find authenticity features. This is the case, for example, with bank robberies with extortion of cash that certain documents (banknotes)  be specifically marked, and such markings may differ are in other places than the pattern or are present on the document by default. Even hidden ones and singularly existing authenticity features can with the teaching of technical invention can be recognized and evaluated quickly and easily.

Another embodiment of the invention is that all spectral different lights are switched on simultaneously and in Beam path of the imaging optics through one or more wavelengths dependent beam splitter the corresponding images simultaneously on different Image sensors are mapped.

The arrangement described is only an example of the method and the design of the arrangement according to the invention. The use of Matrix sensors, point-by-point optical sensors or on one Chip integrated, spectral, coherence and / or direction dependent Sensor elements are part of the invention and the person skilled in the art of optics known, so that they need not be explained in more detail here.

According to the invention, the diffractive features are checked in that a coherent light source such. B. a laser diode is directed to the position, which were determined in the first step. This can be done, for example, by mechanically moving a laser diode in such a way that its light beam is directed onto the diffractive element directly or via optical intermediate elements such as mirrors, prisms, beam splitters, etc. The resulting diffraction pattern is z. B. converted into a real image of punctiform structures via a focusing screen and detected by an image sensor. The feature can be checked by checking the position and arrangement as well as the radiometric properties such as brightness conditions of these structures in the image captured by the image sensor 20 with the aid of a computing unit 21 .

According to the invention, the position of a diffractive feature can also be changed can be determined in which a coherent search grid Illumination source in the presumed positions of the feature Document illuminated locally and an image of it using an image sensor local region is won. If the diffractive element is hit, kick significant, a priori from the definition of the diffractive element in known Structures so that the positioning is done when this expected structures occur.

The definitions of the diffractive element in relation to its position, the art the diffraction structures generated, the information contained therein or Decoding instructions are according to the invention in other machine-readable Features of the same document deposited, e.g. B. cryptographically encoded in the 2-dimensional barcode or in the steganographic hidden information in the portrait image. This procedure has the big one Advantage that for such norms no fixed norms for the special document must have been hit. It allows individual for each document generate diffractive elements and the necessary for testing Information in the same document, but in one or more others Hide security features.

This procedure of the individual security feature, its test specification encoded in one or more other features of the same document not only applies to the diffractive security features, but fundamental to everyone else. So z. B. the shape or the type hidden by UV-visible features in the portrait image. With the Decoding this information also stands for the test specification for the machine review of the UV feature or features ready without any Database, a standard or another, outside of the actual one Document itself stored information source must be requested.  

Drawing legend

1

document

2

machine readable text

3rd

Barcode

4

diffractive element

5

Portrait picture

6

Text field

7

8th

9

10th

11

line

12th

device

13

Viewing window

14

storage

15

Sensor head

16

diffuse lighting

17th

directional lighting

18th

imaging lens

19th

20th

Image sensor

21

Arithmetic unit

Claims (18)

1. A method for the fast and automatic authentication of documents secured with optical features, in which the positions of the features relative to the coordinate system of the document and / or the automatic tester are not known or are known only approximately, characterized in that

• 1. in the first step, the document is examined for the presence of security features with low resolution of the recognition unit that
• 2. in the second step of the method, the location of the individual security features on the document is also determined with a low resolution of the recognition unit and that
• 3. In the third method step, this feature is examined for authenticity with high resolution at the location of the security feature found.

2. A method for the fast and automatic authentication of documents secured with optical features, in which the positions of the features relative to the coordinate system of the document and / or the automatic test machine are not known or are known only approximately, characterized in that

• 1. In the first process step, the document is scanned with the highest resolution required for the detection of the authenticity features, and that the location of the authenticity features is determined immediately from the scanned image and the signal response obtained therefrom
• 2. In the second method step at the location of the determined security features, the signal response obtained there is examined with high accuracy only at this location by software analysis of the signal response.

3. The method according to claim 1 or 2, characterized in that in the first step, the document ( 1 ) is illuminated in its entirety or in part with lighting means ( 16 , 17 ), their spectral and / or geometric distribution, and / or degree of polarization and / or alignment, and / or coherence and / or temporal activity are selected in such a way that one or more images of the illuminated document areas, which contain the position of the security features ( 2-6 ), can be detected by one or more imaging sensors ( 20 ). form a difference relative to the rest of the document background and that these positions are automatically determined using image recognition methods relative to the coordinate system of the document. 4. The method according to any one of claims 1 to 3, characterized in that in the second step the testing of the corresponding Features are made only in the image areas that the in the first Correspond to the positions found and the corresponding image areas are illuminated such that the corresponding characteristics of the images spectral signatures and / or others Generate optical patterns, from which using image processing methods and the spectrometry the information needed to check the characteristics can be derived. 5. The method according to any one of claims 1 to 4, characterized in that the different illumination sources ( 16 , 17 ) are switched in synchronism with the line change of the receiving image sensor ( 20 ) and thus an interleaved arrangement of images (A, B) of lower resolution arise, which line by line each correspond to one of the illuminations required for the detection of the position of the security features. 6. The method according to any one of claims 1 to 5, characterized in that all or more of the required illumination sources ( 16 , 17 ) are active at the same time and that the image of the document surface corresponding to each illumination source is imaged on its own image sensor via beam splitters. 7. The method according to any one of claims 1 to 6, characterized in that the type of the present security feature is determined from the Properties of the position determined in the first method step Security features. 8. The method according to any one of claims 1 to 7, characterized in that the position of a diffractive feature ( 4 ) is determined in that in a search grid a coherent illumination source in the suspected positions of the feature illuminates the document locally and with the aid of an image sensor an image of this local region is obtained and that these positions are varied until the expected image structures known a priori from the definition of the diffractive element ( 4 ) occur. 9. The method according to any one of claims 1 to 8, characterized in that that are required for positioning and checking a security feature Information and definitions in one or more others machine-readable features of the same document are stored. 10. The method according to claim 9, characterized in that the definitions of a certain security feature for each document ( 1 ) are defined individually and that the part of the definitions which is required for positioning and checking, in one or more other machine-readable features of the same document ( 1 ) are encoded. 11. The method according to any one of claims 1 to 10, characterized in that that those arising from the automatic evaluation of the document pictorial and other information in a document database are saved, from which further, about the correctness of the Security features and machine readable information  additional properties of the document at any time can be determined. 12. The method according to any one of claims 1-11, characterized in that the geometric and radiometric resolution to find the Security features may be less than the resolution for the actual one mechanical inspection of the characteristics. 13. The method according to any one of claims 1-12, characterized in that the difference between the security features ( 2-6 ) and the background of the document by optical and / or radiometric and / or spectral and / or temporally changing and / or imaging Pattern properties is formed. 14. Arrangement for performing the method according to one of claims 1 to 13, characterized in that the document to be checked with a optical arrangement of different lighting sources and one or several, the document sensing image sensors is scanned that the assigned to the individual lighting sources, by or Image sensors generated images converted into electrical digital signals and are stored and evaluated in a computing unit. 15. Arrangement according to one of claims 1-14, characterized in that that all spectrally different illuminations at the same time are switched on and in the beam path of the imaging optics by a or several wavelength-dependent beam splitters the corresponding images can be imaged on different image sensors at the same time. 16. Arrangement according to one of claims 1-15, characterized in that the diffractive elements ( 4 ) are checked in that a coherent light source such. B. a laser diode is directed to the position determined in the first step, and that a laser diode is mechanically moved so that its light beam is directed directly or via optical intermediate elements such as mirrors, prisms, beam splitters, etc. onto the diffractive element ( 4 ) and that The resulting diffraction image is converted into a real image of punctiform structures via a focusing screen and captured by an image sensor. 17. Arrangement according to one of claims 14 to 16, characterized in that the checking of the respective authenticity feature ( 2-11 ) is carried out by checking the position and arrangement, and by checking the radiometric properties, such as brightness ratios of these structures in that detected by the image sensor 20 Image using a computing unit 21 . 18. Arrangement according to one of claims 14-17, characterized in that the position of a diffractive element ( 4 ) is determined in that in the first method step in a search pattern defined on the document a coherent illumination source in the assumed positions of the feature ( 4 ) the document ( 1 ) is illuminated locally and an image of this local region is obtained with the aid of an image sensor ( 20 ).