CA2330115C - System for contactless recognition of hand and finger lines - Google Patents

Abstract

A process for reproducing hand and/or finger lines with a camera works without skin contact with the recording device.
By using linearly or circularly polarized light in the paths of the illuminating and the reproducing light rays it is possible to obtain separate representations of the pattern of the epidermis and the one of the hypodermis. An image of the relief of the skin that is rich in contrast is obtained in this way, on the one hand, and it is possible to acquire information from the deeper disposed layers of the skin already supplied with blood. An algorithm searches the skin patterns of the palm of the hand for line elements of different strengths and directions (vectors). The computed numerical identification contains overall frequencies of vectors as well as amplitudes and phases of frequency components of projections of the vector images of both patterns. The process permits controlling people from a distance, complete protection of the measuring system and enhanced security against fraud.

Description

SYSTEM FOR CONTACTLESS RECOGNITION
OF HAND AND FINGER LINES

The invention relates to a process and a device for optically reproducing hand and finger lines without skin contact for the identification of persons, and, furthermore, concerns a recognition algorithm.

The pattern of the papillary ridgesof the fingers, which has been employed in the field of criminology since a long time in the form of fingerprints on objects or on paper, or used by illiterate persons as their signature, has gained significance more recently as an authorization control code for access to safes, safe-deposit rooms of banks, computers and other secured objects.

However, filing of a permanent color or fat imprint would not be practicable in this connection be,cause a computer evaluation must rapidly take place immediately, and it is pre-supposed that the same applicator is in each case used frequently.

There~ore, methods were developed first which make the pictue of the imprint briefly visible on a glass surface I
throuoh optical reproduction , exploiting impeded total or pa~tial reflection on a refractive interface.

atterns of the lines in the palm are suitable for the ident~ fication of persons as well. The method of imprinting such oatterns on a glass surface is feasible in this connection as welll; however, this method failed to gain wide acceptance if onl because the equipment would have to be substantially ~
larger and more complicated. Therefore, the development of evalua ion algorithms for this method has not yet reached an adv nced stage.

an access control system operating based on a skin line iriprint method is used possibly by a large number of person~ unobserved and anonymously, such use is adversely affect~d by the following factors:, (1) Soiling is caused on the measuring or contact pressure surfacelthat is no longer tolerated by the evaluation algorithm.
Dirt, o~ course, could be removed by simply wiping it off, if necelpsary with care agents. However, the drawback is then that th~s requires cooperation and care on part of the participating people, which cannot be always expected, or the user operating the system has to carry out the care and maintenance work, which is both cost- and labor-intensive.
(2) The contact surface of the sensor is a part of the path of the measuring rays that has to be always freely accessible, so that important components of the system may be-damaged in the event of vandalism or sabotage.

(3) Contact is made via the contact pressure surface of the applicator with a great number of persons, which, under aspects of hygiene, should be avoided. This applies in particular to areas in hospitals as well as medical and biological safety areas.

(4) The contact pressure surface of the applicator may transmit chemical or radioactive contamination.

(5) Methods requiring skin contact are less accepted than other,methods for psychological reasons, for example because of their association with a data file on "criminals", fear of infection, or aversion to skin contact, which, for example, may be ethnically conditioned in the latter case.

(6) The outermost surface of the skin is reproduced by most known optical imprinting methods as an interference with the reflection on a surface of glass. This has a negative effect inasmuch as inhomogeneities of the skin disposed at deeper levels of the skin, as well as blood circulation patterns, which contain individual information as well, are not accessible in this way. This limits the clarity and definition of such methods.

(7) Many known methods of skin pattern detection are designed to determine the genuine surface structure of the skin (i.e., the relief of the skin). The drawback here is that a relief can be easily reproduced by plastic reproduction methods, which consequently creates possibilities for fraud.

(8) With all methods requiring skin contact, a hardly visible imprint, i.e., the classical imprint of a finger or hand line, remains on the surface of the apparatus. The drawback here is that such an imprint can be made visible and can be misus.ed with means employed for detecting and.securing traces, and that such imprints would have to be eliminated, for example by wiping them off in cases where high safety requirements need to be satisfied.

(9) The simple conventional method, of course, needs to be mentioned here as well, which is to reproduce skin lines with a camera without contact with the object. Since the skin is always slightly translucent under conventional illumination, and the light scatters diffused to a certain extent, and since the uppermost layer of the papillary ridges is reflected at the same time in a more or less shiny way, the camera, like the human eye, normally "sees" an undefined superpositioning of the images of the epidermis and hypodermis.

It is basically possible with illumination aimed at an angle, i.e., slanted, to increase the contrast of the papillary ridges and furrows of-the skin. The drawback here is that this method does not uniformly work throughout the entire field of-vision, but is dependent upon the direction of the line pattern relative to the illumination (shadow effects), as well as upon the waviness of the surface of the object (gloss effects). Inclined illumination from all sides, or diffused illumination does in fact compensate waviness optically, but deteriorates the contrast of the ridges because the component of diffused reflection increases.

A relatively strong gloss and contrast effect is obtained with inclined illumination and inclined recording direction (according to the law on reflection) particularly with large angles of incidence or recording.
The drawback here is that when the object is set at an angle, or inclined, correction of distortion is required, for example according to the SCHEIMPFLUG principle, which is costly in terms of equipment requirements; and that the waviness of the skin has a very disturbing effect (image distortions).
For the enhanced representation of details of a fingerprint it is known from US 4,936,680 to arrange below a single polarization filter a pair of lamps whose axis of connection is disposed parallel with the polarization vector, and to make provision for another pair of lamps whose axis of connection is disposed perpendicular to the polarization vector. The polarization filter is turned together with the lamps via a motor and a driving belt while a pair of lamps illuminates an individual finger that is arranged above the polarization filter. As the polarization filter is being turned, a picture is taken by a camera with each angle of rotation of 3 degrees and filed in a storage unit. After one rotation has been completed, the one pair of lamps is switched off and the other pair of lamps is switched on, whereby this is followed by another rotation by an angle of 90 degrees so that the starting position of the second pair of lamps identically corresponds with the pair of lamps used previously. After said starting position has been reached, a picture is again recorded by the camera with each rotation of the polarization filter at intervals of 3 degrees and filed in a second storage unit. After this further rotation the data from the first storage unit and the second storage unit can be used in order to particularly obtain through formation of the difference a reproduction of the fingerprint that is rich in details.
However, it has to be noted that the required rotation of the polarization filter by means of the motor makes this device susceptible to trouble and, furthermore, increases the manufacturing cost. The overall measuring time is very long because the fingerprint is recorded by the camera in the form of many individual pictures, whereby it is not assured that the conditions in the course of the second series of measurements will exactly correspond with those of the first series of measurements because the finger, as a rule, is not kept still throughout the entire amount of 2.25 rotations.

According to the invention, the drawbacks of known methods described above are reduced or eliminated by a method for identifying persons with the help of their hand and/or finger lines, by which said hand and/or finger lines are optically detected without contact by means of a first polarization filter arranged in the path of the illuminating light rays, a second polarization filter arranged in the path of the reproducing light rays, and a camera, with omission of mechanical movements of the arrangement.

The operating mode can be enhanced in this connection by employing polarized light. Such light, on the one hand, (a) substantially increases the contrast of the papillary ridges through preferred reproduction of the glossy or shiny structures, but the papillary ridges (b) can be made visible as well by filtering out the shiny structures, on the other, so that the pattern of the hypodermis becomes visible. In particular, by using polarized light in the path of the illuminating rays and in the path of the reproducing light rays it is possible to select in a defined way the pattern of the epidermis and the pattern of the hypodermis. Possible are an accentuated representation of the shiny epidermis alone, an accentuated representation of the diffusely reflecting hypodermis alone, or a representation of both skin patterns in combination, for example one briefly after the other. The pattern of the hypodermis is predominantly supplied by the structures disposed at deeper levels, in particular by the structures of the adjacent layers of the skin that are already supplied with blood. In the case of linearly polarized light, the pattern of the epidermis is reproduced if the polarizing devices are set in parallel in the paths of the illuminating and reproducing rays, and the pattern of the hypodermis is reproduced when said polarizing devices are adjusted vertically.

In the case of circularly polarized light, the pattern of the epidermis is reproduced when the rotation of polarization in the paths of the illuminating and reproducing rays is adjusted not in the same sense, and the pattern of the hypodermis is reproduced when it is adjusted in the same sense, whereby the direction of rotation (right or left rotation) is defined here as the direction of rotation of the E-vector, looking in the direction of propagation of the light.

-7a-The benefits offered by the invention can be described in detail as follows:

(1) The sensor system is protected against soiling or contamination by the user because it is not touched, which makes frequent care and control superfluous.

(2) The system can be completely accommodated behind a protecting wall, for example made of bulletproof glass, so that it is protected against vandalism or sabotage.

(3) The devices can be designed in such a way that indirect contact with other persons is excluded for securing hygiene.

(4) The devices can be designed in such a way that no chemical or radioactive contamination is transmitted.

(5) Psychological reasons such as association with a "file on criminals", fear of infection or fear of skin contact are eliminated because the device operates without requiring contact.

(6) As opposed to a number of optical contact methods, structures of the hypodermis with additional information content are made accessible in connection with the present invention.

(7) The safety against fraud is enhanced because structures of the hypodermis, as with a watermark, cannot be copied or counterfeited easily, and because it is particularly not easy to successfully combine the two different types of contrast for fraudulent purposes.

(8) No finger of skin line imprint is produced on the apparatus that could be fraudulently used, for example for producing a skin duplicate, for example made from rubber.

(9) As opposed to conventional reproduction with a camera, .the present invention permits separation of the images of the epidermis and hypodermis and their separate evaluation.

In the field of the surface, the process as defined by the invention permits a uniform effect and independence of the direction of the lines and waviness of the surface. No inclined positioning'of the object is required for exploiting the gloss angle condition, and the rectification connected therewith is therefore not needed.

Details of the invention are described in the following with the help of exemplified embodiments in connection with the associated drawings, in which:

FIG. 1 is a side view of a first device for recognizing finger lines without contact.

FIGS. 2 and 3 show the path of the illuminating beam of light rays of the device shown in FIG. 1, by a top and, respectively, front view.

FIGS. 4 to 6 show exemplified embodiments of a sensor system for recognizing skin lines of the epidermis and hypodermis;

FIG. 7 shows a position pattern model for a hand;
and FIG. 8 shows a flow diagram of an image processing process.

A device for reproducing finger lines is described by way of example in FIGS. 1 to 3, said device being designed as a table model. It is adjusted in a fixed way for reproducing the epidermis. Finger 1 is placed on the support 2, so that it is present in object plane 3 or its zone of sharp focus, and so that it can be photographed with camera 10 via an interference light filter 4, carrier plate 5 (e.g. acrylic glass), reversing prism 6 and polarization filter 7. Camera 10 contains the lens 8 and an image receiver (for example a CCD-chip) in image plane 9, and, furthermore, may contain components (not shown) for image processing.

Components 4, 5, 6 and 7 are optically cemented with each other for constructional reasons, whereby retaining plate 5 is joined with housing pot 11 in a fixed way. Cover plate 12, which has to absorb and dissipate certain forces engaging the support 2, is joined on the edge with housing pot 11 as well (and not with retaining plate 5). Housing pot 11 has a borehole 13 for light to exit from. Housing pot 11 and camera 10 are solidly connected with each other via base plate 14.

FIGS. 2 and 3 show the path of the illuminating beam of rays. The light sources 15, which are mounted in two groups each comprising three light sources are mounted laterally of prism 6 (not visible in FIG. 1 in the plane of the section), are designed, for example in the form of light-emittiiig diodes with focusing lenses, and aligned with their directional (or aiming) lobes with object 1, aiming at the latter. The scatter disks 16 with forward characteristic and the polarization filter 17 are interconnected in each case. For the exit of light from housing pot 11, provision.
is made for two slots 18 in cover plate 12, as well as for corresponding slots in carrier plate 5. Instead of using individual polarization filters 17 it is possible also to employ 2 through-extending polarization foils each covering 3 light sources.

For adjusting the sensor for the separate reproduction of the pattern of the epidermis, all pole filters 17 and pole filter 7 in the path of the reproducing rays have to be adjusted in the same direction if light with linear polarization is used. The best effect for the selection of the epidermis is achieved if the common direction of polarization (E-vector) is disposed parallel with the drawing plane of FIGS. 1 and 2, or perpendicular to the drawing plane of FIG. 3. The latter plane is the plane of reflection in which the skin, with slanted illumination and adherence to the reflection condition (for example the Brewster angle), shows a polarizing effect. With approximately vertical illumination, the common direction of polarization may be any direction. If light with circular polarization is employed, filters 17 and 7 do not have to be adjusted with respect to the position of rotation.

FIGS. 4 to 6 describe exemplified embodiments for a sensor system for recognizing skin lines of the epidermis and hypodermis. Said devices may be advantageously designed as wall installation units. The system is accommodated in a housing 25, which has a bulletproof glass window 20 on one side. According to the invention, the housing with the sensor system can be mounted also in front of an existing, larger bulletproof glass wall.

Polarization and interference light filters are arranged in FIG. 4 as camera filters 7 and 4 in front of lens B.
Camera 10 is aimed at object plane 3, which is located in the outer space approximately 4 cm in front of glass panel 20.
The lighting consists of 4 lamps 15, of which 2 lamps are shown in the drawing. which are designed in the form of directional lamps, e.g. small halogen spotlights aimed at object plane 3. A scatter disk 16, which, however, may not be needed depending on which type of lamp is used, and a polarization filter 17 are connected in front of each of said lamps.

When light with linear polarization is employed, the polarization filters are adjusted in such a way that the pair of lamps shown in the drawing plane is polarized perpendicular to the plane of the drawing. If camera filter 7 is adjusted perpendicular to the plane of the drawing as well, the image of the epidermis is obtained with this arrangement (as in the preceding example shown in FIG. 1).

For representing the image of the hypodermis, camera filter 7 can be turned by 90 degrees with an electric drive providing for 2 locking points. More robust, however, is an arrangement which dispenses with mechanical movements. For this purpose, an additional pair of lamps of the same type is required, in association with a stationary filter 7.
Said additional pair of lamps, including the adjusted filters, is turned by 90 degrees on the optical axis versus the pair of lamps shown in FIG. 4. The two pairs of lamps are switched on and off one briefly after the other for recording the pictures of the epidermis and hypodermis.

The same procedure is used when light with circular polarization is employed, however, no filter adjustment is needed in this case, and the polarization rotation of filters 7, 17 and the turned arrangement 17 have to be taken into account according to the preceding explanations.

The user is required to insert his or her hand into sharp focusing zone 3 with the palm in the forward direction without touching the pane. A model 27 shown in FIG. 7, which is located on the glass pane, serves as a positioning aid.
The contours of a hand with spread fingers are ahown on the model, for example in a simplified or stylized form.
The hand line pattern always should be recorded with the fingers spread because fewer picture distortions will then appear, such distortions being caused by the fall of the wrinkles of the skin. The user is to be incited by the picture of the model to also spread the fingers because it is known from experience that instructions to this extent in a user manual are not always followed.

The path of the light rays may be bent by a mirror or a prism in order to obtain a more compact unit (not shown).
FIG. 5 is a variation of the preceding exemplified embodiment, whereby theobject plane 3 is spaced with.some distance from the wall. The distance may come to a few meters as well. Such a design is of interest in a case where the access and the control do not take place in the same location, the sensor system is located in the protected area (behind the bulletproof glass pane), and a sight connection exists with said system. The illuminating elements 15, 16, 17 are located in this connection near camera 10, which makes the volume of housing 25 relatively small. In this case, the positioning aid is designed in the form of a frame 22 which, on the inside, has the simplified or stylized contours of a hand with spread fingers, such frame being mounted on a wall mounting device or, with a larger spacing, on a freestanding column or pillar, or in some other location.
The user is required to insert his or her hand in the frame and to align the hand with the model, fully covering the latter.
The dimensions of the interior of the frame are selected in such a way that touching can be avoided without difficulties.
FIG. 6 shows a further variation, where the positioning plate 23 is mounted on a wall in an inclined position. This permits a more comfortable holding of the hand as well as a more compact structure in that the path of the light rays is bent on mirror 24. The slanted passage of the light rays through bulletproof glass pane 20 causes a certain amount of image distortion which, however, is only minor and can be corrected later. According to a further variation riot shown here, provision is made that the housing with the camera and the illumination is mounted, for example on the ceiling at a reachable level of height, and with the sight window aimed downwardly; and that a frame of the type of frame 22 or 23 is used as positioning aid, such frame, however, being mounted horizontally. The hand is inserted in such a frame with the palm facing up. Such a frame may be wholly or partially made of plastic, whereby an antenna may be integrated in said frame as well, if need be.

A further positioning aid for the arrangement described last is an "aerial" picture projected from the top into or onto the object plane of the camera. According to the invention, such an aerial picture is a double image, which is produced by 2 projectors - which are arranged next to one another - in such a way that both part pictures or images exactly coincide only in the object plane of the camera and, with correct positioning of the hand, appear coinciding in said plane.

Also holographically produced aerial pictures, for example of marks, hand contour lines or hands can be considered as aids for positioning the hand. In this connection, the hologram plate is preferably mounted on the inside in front of the bulletproof glass pane. A small hole in the hologram may serve for the camera to "look through".

With the design arrangements described last, where aerial images are employed as positioning aids, even accidental touching of any components of the installation can be excluded.

In order to prevent ambient light, in particular daylight from interfering with the measurements, and if simple measures such as elimination of interference sources, covering with a screening etc. are not adequate, the device can be made more insensitive to interfering light as follows:

(1) Cover plate 12 and finger support 2 in the first exemplified embodiment should be designed dark, in the best way black, and the surface should be roughed up, sb that only little foreign light is reflected.

(2) Narrow-banded light should be employed, for example with the help of narrow-banded filters or by using colored light-emitting diodes or lasers on the illumination side, and corresponding filters with narrow-banded passages on the reproduction side.

(3) Pulsed illumination such a flashlight, pulsed light-emitting diodes (LCD's) or pulses laser diodes have to be combined with an adapted short shutter time of the recording camera.

Finally, it has to be noted that space is also available in cover plate 12, finger support 2, model 21 as well as frames 22 and 23 for the.antenna of a contactless (electro-magnetic) ID card reader (proximity reader), so that a combination with this method of ID-reading is feasible.

Software Algorithm for Handline Recognition The comparison of two handline patterns with the goal of making a decision on the identity is, in the deal case, formally a correlation of the complete patterns. With conformity, and assuming that the quality of the reproduction is good, the coefficient of correlation is then practically 100%.
If the image of the person to be identified has to be compared in this way with a great number of stored complete images, however, the image processing expenditure and in particular the computing time would be too high and long.
More favorable are the storage and the comparison of characteristic identification data, or characteristics, containing the features required for a decision. Therefore, image data compression and coding are required. Such compression and coding should be adaptable in a simple manner to the desired conditions, in particular to the "sharpness" of the decision, The strategy of image processing selected in the present case is shown in Fig. 8 and explained in the following. In the text, reference is made to the different blocks of Fig. 8 by underlining.

Apart from any suppression of very high and relatively low room or space frequencies that may be required by-filtering (not shown here), the first processing step is segmentation of the epidermis and hypodermis images. This is a division in subunits, for example small boxes, which takes place in such a way that the number of image segments 7=19-.is reduced as much as possible versus the number of pixels of the initial or starting image in the sense of data compression; however, with the detail resolution in the segment image still being adequate for the task here on hand.

In the following line analysis, the segment contents are examined according to line elements having different intensities "s" and directions "r", with approximately 2 to 3 values for "s" and up to about 8 values at the most for "r".
Several vectors of the same type (parallel line segments of the same intensity) in one segment are added up. Each segment thus can be described by a number of different types of vector. When only one type of vector is viewed at a.
time, i.e., a combination of "r" and "s", vector images are obtained as a result for the various types of vector. It may be advantageous within the framework of optimization of the algorithm to additively combine images of different types of vector , for example in order to avoid excessively low numerical values.

The further data compression takes place through projection of the vector images, i.e., addition of the pixel values in different directions. This corresponds with the recording of a sectional plane according to the process of computer tomography, whereby the object, in this case, is an already digitized image field with integral pixel values lower than about 5, and the value zero can be found relatively frequently.

It is known that it is possible with a sufficiently large number of projections to reconstruct by means of the CT-algorithm the layer of an object because the totality of the projections contains the complete object information.

The image reconstruction (back projection) is not carried out here. However, the information of the projection functions is used for characterizing the image of the hand lines. The number of projections depends on the desired accuracy of image characterization. It is one advantage of the process that the required and adequate accuracy can be ad}usted by a simple rule, namely the selection of the number of projections.
Only a few projections are required in this connection as compared to the known computer tomography.

First of all, the overall frequencies result in a simple way from the projection functions for each type of vector.

The overall frequencies or their conditions are already suitable for roughly characterizing the line pattern.

The next step is the determination of the main direction of projection. For this purpose, we look at the picture of the sum of all vector images with the highest line intensity "s" without taking into account the direction "r", and at the projections of said summation image. The pair of projections with directions at about plus or minus 45 degrees relative to the longitudinal axis of the hand is a preferred pair in this connection because the three most strongly pronounced main lines, which are the furrow or groove of the thumb, the five-finger furrow and the three-finger furrow, regardless whether of the right or left hand, appear as maxima with a large amplitude. The well-identifiable maximum, for example of the five-finger furrow can be used for defining an object-related zero point:of the scale. With the other projections, said maximum may serve for fixing the zero point of the scale as well if a very clear maximum is recognizable. Otherwise the zero point is fixed randomly for example on the left edge of the image.

The main direction of projection is searched for with the help of the "printout" of the maxima within the range of plus or minus 45 degrees of the program. It then serves also as the reference direction for the other directions. In this way, a certain rotation invariance of the measuring method is produced as well.

For further data compression, the projection functions are subjected to a frequency analysis', whereby the shortest form, the amplitude and, if need be, the phase are selected for representing the frequency components. Characterizing of all projections in the main direction can take place through amplitude and phase values. With the other projections, phase data are object-related only in some cases and generally not, directly suitable for the characterization.

A possibility is to be mentioned here also as to how the not object-related phase information can be used for pattern identification: the projection functions can be reconstructed from the amplitudes and phases filed in the answerback code storage and a comparison of the shapes of the curves can be carried out by means of correlation. This possibility is not shown in the diagram.

The numerical identification based on the image of the epidermis and hypodermis contains conditions of overall freq,uencies of types of vectors, sets of amplitudes of the frequency components of the projections, as well as phases relating to the amplitudes of the main projections. It has to be determined empirically how many projections or amplitude/phase sets are generated. This type of characterization of handline patterns is translation-invariant with respect to the hand.

The features can be set up in the numerical identification file in a type of ranking order, which starts with global statements and ends with highly resolved patterns, i.e., at amplitudes and phases of the frequency components for the high space (room) frequencies. The process of feature comparison begins with the overall frequencies and is dis-continued in case of nonconformity. The quality of the conformity of handline images is the higher the farther one advances in the ranking order without receiving a negative message.

The analysis of the image of the hypodermis, which is not as strongly structured as the image of the epidermis (but in a different way), takes place in the same manner, whereby the zero points of the scale for the main projections are taken over from the associated images of the epidermis. The number of line intensities "s".may be lower with the hypodermis.

Once an identification has been computed, it is received and included in the data base when a person is registered for the first time. When a comparison of handline patterns is to be carried out, the features of the identificatiop to be checked are compared withthe identification data stored in the data base, following the ranking order, so that a positive f or negative decision can be made as shown in the diagram at the bottom.

As opposed to the algorithms of finger imprint recognition which determine the number or arrangement of minutiae, which are peculiarities or special features in the pattern of the papillary ridges, (sinusoidal) distribution patterns of "normal" line elements are detected in the handline recognition process proposed herein. In the present case, the information content lies less in the three main lines specified above, which individually do not vary very strongly, but more in the network of the slightly thinner secondary lines.

Claims (38)

Claims

1. A method of identifying a person using at least one of a hand and finger lines of the person and a light source, a polarization filter and a camera, characterized in that the at least one of the hand and the finger lines, patterns of papillary ridges, and a pattern of a hypodermis are optically detected without contact for recording an image by means of a first polarization filter arranged in a path of illuminating light rays, a second polarization filter arranged in a path of reproducing light rays, and the camera, with a rigid arrangement and with omission of any mechanical movements of the arrangement.

2. The method for identifying persons according to claim 1, characterized in that a numerical identification is computed by means of digital image processing, such identification permitting comparison with filed data of a same type.

3. The method for identifying persons according to claim 1 or 2, characterized in that an additional light source with a third polarization filter is provided in the path of the illuminating light rays, said light source including the third polarization filter being turned in an optical axis by 90 degrees versus the first polarization filter.

4. The method for identifying persons according to claim 3, characterized in that the light sources are briefly successively switched on and off for recording images of an epidermis and the hypodermis.

5. The method for identifying persons according to claim 3, characterized in that the method is carried out both with linearly and circularly polarized light for selectively representing an epidermis and the hypodermis.

6. The method for identifying persons according to claim 5, characterized in that selection of a pattern of the epidermis takes place with rotation of polarization adjusted in opposite senses in the path of the illuminating light rays and in the path of the reproducing light rays, and selection of the pattern of hypodermis with a rotation of polarization adjusted in a same sense, whereby a direction of the rotation is a direction of rotation of an E-vector viewed in a direction of propagation of light.

7. The method for identifying persons according to claim 3, characterized in that a pattern of an epidermis is selected with a direction of polarization adjusted parallel in the path of the illuminating light rays and the path of the reproducing light rays, and the pattern of the hypodermis is selected with a direction of polarization adjusted vertically.

8. The method for identifying persons according to claim 7, characterized in that the pattern of the epidermis and the pattern of the hypodermis are recorded with a camera with same coordinates one shortly after the other.

9. The method for identifying persons according to claim 7, characterized in that the pattern of the epidermis and the pattern of the hypodermis are each recorded with one camera.

10. The method for identifying persons according to one of claims 3 to 9, characterized in that the information content suitable for both the pattern of the epidermis and the pattern of the hypodermis with identical coordinates is combined.

11. The method for identifying persons according to one of claims 1 to 10, characterized in that the at least one of the hand and the finger lines are detected from a larger distance.

12. The method for identifying persons according to one of claims 1 to 11, characterized in that a relative position of minutiae is determined and evaluated in a direction of an identification for recognition of the finger lines by means of a recognition algorithm.

13. The method for identifying persons according to claim 12, characterized in that a frequency of orthogonal features is determined and evaluated in the direction of an identification for identifying the finger lines of the pattern of the epidermis by means of the recognition algorithm.

14. The method for identifying persons according to one of claims 1 to 13, characterized in that a starting image is divided in segments, and line sections of different strength and direction are determined in the segments for recognizing hand lines.

15. The method for identifying persons according to claim 14, characterized in that the segment, and the line sections are added up to frequency distributions in a way of a computer-tomographical sectional-view recording as pixel values in different directions.

16. The method for identifying persons according to claim 13, characterized in that the different directions are characterized by amplitudes and, if necessary, also by phases of components of harmonic approximations of the different directions, and the amplitudes are used with or without phase indication for numerical characterization of the pattern.

17. A device for carrying out the method according to claim 1, characterized by the light source arranged in the path of the illuminating light rays and directed at the at least one of the hand and finger lines, the pattern of the papillary ridges, and the pattern of the hypodermis by the first polarization filter, and by the second polarization filter arranged in the path of the reproducing light rays in front of the camera with an image receiver whose lens is focused on a plane of the at least one of the hand and the finger lines.

18. The device according to claim 17, characterized in that a reversing prism is arranged in the path of the reproducing light rays.

19. The device according to claim 18, characterized in that the light source is formed by a pair of lamps arranged on both sides of the reversing prism.

20. The device according to claim 18 or 19, characterized in that a second pair of lamps with a third associated polarization filter is arranged on both sides of the reversing prism.

21. The device according to one of claims 17 to 20, characterized in that the device is designed without the possibility of mechanical movement.

22. The device according to claim 20, characterized in that the first and second polarization filters are crossed by 90 and arranged in the path of the illuminating light rays and the path of the reproducing light rays.

23. The device according to one of claims 17 to 22, characterized in that the light source is switched on and switched off depending on a direction of polarization of the polarization filters associated with the light source.

24. The device according to one of claims 17 to 23, characterized in that the image receiver is a CCD-chip.

25. The device according to claim 17, characterized in that the light source is a diode laser.

26. The device according to claim 17, characterized in that the light source is a lamp with glowing metal surfaces under an inclined angle of viewing.

27. The device according to one of claims 17 to 26, characterized in that provision is made for two polarization filters in the path of the reproducing light rays with directions extending vertically in relation to each other with equally polarized light sources, these polarization filters can be individually selectively moved into the path of the reproducing light rays.

28. The device according to one of claims 17 to 27, characterized in that the camera, the light source and the first polarization filter are accommodated in a mechanically sealed housing, and optically accessible only via a glass pane.

29. The device according to claim 28, characterized in that the device is a unit for wall installation.

30. The device according to one of claims 17 to 29, characterized in that the at least one of the hand and the finger lines can be positioned within a field of vision and within a focusing range of the camera by means of one of a template and a frame.

31. The device according to claim 30, characterized in that an inner contour of the one of the template and the frame has an indicated form of a contour of a hand with spread fingers in a way of a positioning template.

32. The device according to claim 30 or 31, characterized in that the frame is supplied as a holographically produced air picture.

33. The device according to claim 30, characterized in that the frame is at least partly made of metal and designed and adapted in terms of high frequency so that it has an antenna function of a contactlessly operating ID-card reader.

34. The device according to one of claims 30 to 33, characterized in that an optical range finder set to a fixed distance is associated with the frame, by means of which range finder recording of the image is controlled.

35. The device according to claim 34, characterized in that the range finder operates optically according to a principle of triangulation.

36. The device according to one of claims 17 to 35, characterized in that switching-in of the device into at least one of a ready condition and a triggering of a measuring process takes place by producing a capacitive connection with a floor on which the person is located, through a body of the person or through capacitive detuning of a positioning frame operating as an HF-antenna, or of an antenna located in the frame, once the hand is in a correct position in the positioning frame.

37. The device according to claim 33, characterized in that the antenna of the ID-card reader operating without contact is integrated in a finger support or in a cover plate.

38. The device according to at least one of claims 17 to 37, characterized in that provision is made in the path of the illuminating light rays and the path of the reproducing light rays for circularly polarizing filters, the circularly polarizing filters being suitable for representing images of the epidermis and the hypodermis.