WO2010136344A1 - Image acquisition method for recording several images by an automotive camera system, and corresponding image acquisition device of the camera system - Google Patents

Abstract

The invention relates to an image acquisition method, comprising: acquisition of several images by an automotive camera system and filtering the images, wherein said several images constitute a mutual object. When acquired, the images of the mutual object are filtered by at least one polarizing filter having varying polarization angles for said several images, or filtering only some but not all cameras. After filtering, said several images are combined to a joint display. The invention further relates to a corresponding image acquisition device of an automotive camera system having at least one camera and a polarizing filter device providing various polarization angles, or which filters only some but not all cameras. The at least one camera is configured to acquire several images constituting a mutual object, wherein the polarizing filter device is arranged between the mutual object and the at least one camera. For each camera, the polarizing filter device provides a polarizing filter, or for at least one camera but not for all, which is arranged between object and camera. The image acquisition device further comprises a combination device configured to put various images constituting a mutual object on top of each other to match the several images constituting a mutual object in order to combine the several images to/in a joint display.

Description

 description

title

Image acquisition method for acquiring multiple images by means of an automotive camera system and associated image capture device of the camera system

State of the art

The invention is based on camera systems for vehicles.

Camera systems for vehicles capture image data that is used for a variety of applications, including distance warning, traffic sign recognition and visual support of the driver, for example by means of a head-up display.

It is known to use such systems to take pictures of the environment in the perspective of the driver. At night, oncoming headlights and reflections are particularly disturbing. EP 0 490 029 A2 describes scanning the environment with a laser and using the reflected laser light for imaging. A polarization filter is used to separate the light emitted by the laser from the light from oncoming vehicles. The active one

Scanning therefore relies on emitting laser light, which has the inherent property of polarization, and "encoding" it through polarization, The polarizing filter is used to "encode" this emitted light upon receiving light signals from non-laser light distinguish and separate.

On the one hand, an active laser scanning means a significant outlay for the optics and the light emitter used, and on the other hand an elaborate downstream signal processing, since the laser only produces individual points of light over time and these have to be combined to form an image. Furthermore, with active laser scanning, the problem arises due to the high intensity To cause eye damage or the problem of short range when using low intensity lasers.

It is therefore an object of the invention to provide an image sensing method and apparatus for automotive camera systems which make it possible to easily suppress noise and do not require complex or expensive components.

Disclosure of the invention

The invention enables the suppression of interference without the use of an active lighting system. The invention may be provided by means of simple optical structures and with inexpensive components. In addition, known camera systems can be converted by simple modifications to implement the invention. In addition to the much simpler implementation, it is possible with the invention to obtain from the captured image data additional image information that goes beyond the usual brightness information of known video systems. The invention makes it possible in a simple manner to represent the degree of polarization of the imaged environment. This representation provides additional information about the nature of the environment and can in particular be combined with the image data acquired directly by the cameras, thereby obtaining a representation of the environment with a higher information content. In particular during night driving can be concluded by the representation of the distribution of the degree of polarization or by the polarization-related detection of the images on properties of the imaged objects, in particular reflections or reflections of headlights can be detected by, for example, wet road surface on the basis of this polarization. On the one hand, this makes it possible to deduce the properties of the object itself or to recognize the object, and on the other hand, the corresponding image area can be manipulated, for example by fading out or darkening recognized and unwanted reflections.

The concept underlying the invention is to extract the polarization information when capturing images that represent a common object, by taking both images under different polarization-related recording conditions and from the difference in brightness information that is present When comparing the images of different recording conditions results in the polarization direction and / or on the degree of polarization of the object or sections or pixels of the object to close. The recording of images with different polarization-related recording conditions is provided by taking pictures through polarizing filters of different polarization angles, or by taking at least one image through at least one polarizing filter and capturing an image without filtering through a polarizing filter. If several images are taken through polarizing filters, they have a different polarization direction. The polarization-related recording conditions are thus likewise considered to be the taking of images through polarization filters of different polarization directions, as well as the taking of an image through one (or more) polarization filters and at least one image without polarization filtering. Different recording conditions therefore result from different polarization angles as well as from taking a picture through a polarizing filter and without a polarizing filter.

The recording conditions therefore differ in the respective polarization angle which is used in the respective recording of the individual images, or by a recording through a polarizing filter with respect to a recording without a polarizing filter. The images are not necessarily identical, but all images to be compared relate to at least one common object or at least one common object section.

Instead of actively illuminating the environment and absorbing the reflected light, as proposed in the prior art, the invention uses passively two or more mappings of a common object to measure them one at a time and with different angles of polarization (generally also include a picture with and a picture without a filter). Polarization-related information is obtained by comparison of images taken with different polarization-related acquisition conditions, ie with different polarization angles or images of the same object with and without polarization filter. Since the method according to the invention and the device according to the invention itself are not directly based on emitting light, simple and inexpensive passive systems can be used. In particular, can be dispensed with an active lighting. In this context, as the passive illumination, as used in the invention, in particular the illumination is called by external light sources, the neither have to emit polarized light nor generate incident light from a particular direction, but merely serve to illuminate the environment. Therefore, the usual headlight of a motor vehicle is sufficient, so that no additional light sources need only be provided for the camera system.

According to the invention, an image acquisition method is provided in which at least two images are acquired under different polarization-related recording conditions with a camera system. The images represent a common object. The images are oriented essentially in the same direction and the respective captured images comprise at least one image section (in which the object is located), which represents the same object. The representation of the same object may be different for both images, for example both images may capture the same object (i.e., the same image portion) from different perspectives, the images may be shifted from each other, or a combination thereof. In addition to the displacement, other distortions of the images may be provided which are used for the

Images are different, so that there is only the requirement that the images each have a section that corresponds to the same object or the same object section, the images and in particular the section on which the object or the object section is shown, be distorted differently can, for example, by different perspectives, by displacement or by other distortions. According to the invention, therefore, at least two images are captured, filtered with different polarization angles, or one group of images is filtered and another group is not filtered, and combined in both variants, after filtering to form a common representation. This combination allows polarization information to be taken from the images.

For example, for a pixel of a polarizing filtered image, the intensity, i. H. the brightness, are taken and compared with the brightness value of the corresponding point of another image, wherein the other image was filtered at a different polarization angle or was not filtered.

If images of different polarization directions are compared, there is no difference for non-polarized pixels, whereas polarized pixels are given a different intensity due to the different polarization angles on one image than on the other image. If filtered images are compared with unfiltered images, un-polarized pixels of unfiltered images have an intensity or

Brightness expected to be twice as large as the corresponding pixels the associated filtered images. Since the environment is usually illuminated with unpolarized light, a high degree of polarization, that is to say a large difference in the intensity of the pixels of different images with images filtered at different angles and with a large deviation from the expected double intensity in the case of filtered and not filtered recording of the same

Environment section to conclude that the ambient light has been polarized. Such reflections occur in particular with reflections with a flat angle. This makes it possible to detect a pixel or an image region that corresponds to a reflection, and this can be filtered out, blanked out or darkened, in particular, since image regions with reflections have a disturbing effect, especially during night driving. The combination therefore consists in particular of a difference formation of brightness values of picture elements or image areas which belong to different images, were filtered with different polarization directions, but belong to the same object or the same object point. The combination also consists, in particular, in determining deviations from the assumed half intensity from a difference of brightness values of pixels or image areas belonging to different images acquired with and without polarization filter but belonging to the same object or the same object point ,

In principle, other types of combinations are also possible, but the combination comprises comparing pixels of different images that relate to the same object point or the same object section or the same object section.

As an object, the environment detected by the cameras is generally referred to, which, due to its application in the field of motor vehicles, may in particular comprise objects such as road characteristics, vehicles, stationary objects and traffic signs. In particular, the road surface, reflecting objects of the road surface (puddles and the like), reflections of oncoming headlights and

Similar things are also called objects. In particular, objects that are detected from different perspective angles but with at least partially overlapping field of view are referred to as a common object. This is particularly important in stereo imaging, where the environment is viewed with spaced-apart cameras pointing to a common area are aligned and thus able to capture depth information to reproduce later, for example, with a color display in the displayed image.

The multiple images are therefore captured by means of an automotive camera system and (at least one of them) filtered, the multiple images being a common

Object (i.e., an at least partially overlapping imaging area), and the images of the common object are filtered upon detection with at least one polarizing filter. According to a preferred embodiment, the polarizing filter between a camera and the object is stationary (with respect to the camera) arranged, and at least one other camera of the system has none

Polarization filter on. Alternatively, a camera is equipped with a movable, for example, rotatable polarizing filter with recesses, wherein the motion either the recesses or polarization filtering sections of the filter are placed in front of the camera, and thus depending on the (variable) position of the polarization filter either filtered or unfiltered images be recorded. For movement of the polarizing filter having recesses, the same mechanisms as used for the continuous polarizing filter described below can be used.

According to a further embodiment, the at least one polarization filter has different polarization angles for the plurality of images, so that they can be compared later, for example. The multiple images are combined into a common representation after filtering. In particular, the combination comprises not only the difference formation, but in general the comparison of the images or their brightness values, as a result of which polarization information develops. According to a preferred embodiment, the at least one polarizing filter comprises a rotating polarizing filter so that the images are filtered upon detection by the rotating polarizing filter. The polarizing filter rotates about an axis of rotation that is perpendicular to the plane in which the polarizing filter extends. The pictures are taken one after the other, for example from one and the same camera. Since the camera belongs to an automotive camera system, the movement of the motor vehicle produces a difference between successive recorded images. Since the polarization filter has rotated by an angle in the period between time points at which the images are taken, successive images with different polarization angles (or, in another embodiment, with and without polarization filter) are detected. The multiple images therefore differ in the times of their respective recording and, for example, in a forward movement shifted to each other (and additionally distorted differently according to the recording optics).

According to an alternative embodiment (which may optionally be combined with the embodiment described above), the images are captured from at least two different perspectives. The detection is therefore carried out with two laterally offset cameras, which are aligned in the same direction, so that they image a portion that is detected by both cameras. A common object which lies in the overlapping image section is thus detected by both cameras with different perspectives and with polarization filters of different polarization direction, or by both cameras with different perspectives, wherein only one of the cameras has a polarization filter. In general, therefore, the images according to this embodiment differ particularly in perspective, i. H. in the detection direction used in mapping a common object.

Such a stereoscopic camera system comprises two cameras, which are used according to the invention for capturing images with different perspectives. The images are captured by the two cameras by aligning the cameras arranged in different positions (for example laterally offset from one another), the cameras having an overlapping image section. The overlapping image section serves to image the common object. The common object thus lies at least partially in the overlapping image section in order to be able to acquire different images in different perspectives at different polarization angles of the same object or the same object section. Each camera captures an image filtered by a polarizing filter. The filtering is performed by polarizing filters, preferably one filter per camera (if it is to be equipped with a filter), wherein polarization filters of different cameras have different polarization angles (or at least one

Camera has no polarizing filter, while at least one further identifies a polarizing filter). The respective polarization angle, ie the respective polarization filter relative to the cameras, is fixed in this case. The imaging plane within the camera is thus fixed to the polarizing filter through which the camera captures the image (if the camera is equipped with a polarizing filter). According to a further embodiment of the invention, the image acquisition method comprises determining the respective polarization direction and / or the degree of polarization in each case for a multiplicity of image points or image regions of the images. The polarization direction and / or the degree of polarization is thus carried out for individual pixels, groups of pixels, in particular groups of mutually adjacent pixels or for image areas. For example, pixels of similar intensity can be grouped if they are adjacent to each other and have a minimum intensity difference to the surrounding pixels. For example, image areas can be defined that correspond to a reflected spotlight and that reproduce a bright spot.

The polarization direction can be determined by the ratio of the intensities of pixels (or groups of pixels or image areas or their mean values) of different polarization direction and of the same object segment. The polarization direction, d. H. The main direction of the polarization ellipse can be easily calculated by the quotient of the detected intensities, the difference angle between the two polarization directions and the corresponding trigonometric relationships. For example, at a differential angle of 90 °, the polarization direction α is given by the equation:

where / ₁ and h are the respective intensities of the pixels of different images (ie, and also different polarization angles). The degree of polarization P results in the same way by combining the respective intensities, ie by the

Amount of the quotient of the difference of the intensities to the sum of the intensities, denoting as intensities the different intensities of the images which relate to the same object point or the same object section but are filtered with polarization angles different by 90 °. Likewise, the intensity of the originally incident light can also be determined by the sum of the intensities of the filtered pixels. In the combination, when comparing an image captured by a polarizing filter with an unfiltered image, the double intensity of the filtered image is compared with the simple intensity of the unfiltered image to detect deviations indicative of polarization effects. The combination comprises either: reducing the intensity of the unfiltered image electronically when comparing the intensity, electronically with the image capture, electronically with an image preprocessing (before the comparison), or by darkening by means of a 3 dB non-polarizing filter (ie by means of an obscuration filter, which reduces the intensity by half regardless of the polarity), to compare the thus darkened image with the polarization filtered image, or doubling the intensity of the polarization filtered image to make the comparison of the intensities. Instead of a dimming device (such as the dimming filter), the camera (s) without polarization filter can (or may) be provided with a sensitivity that is equal to half the sensitivity of the camera with polarization filter. In the context of the invention, filtering is understood to mean only filtering by means of a polarizing filter, which is why filtering by means of the unpolarizing obscuring filter is termed "darkening". Therefore, the term "do not filter" means a shot without a polarizing filter, but this does not preclude darkening to half the intensity.

As already mentioned, strong degrees of polarization are produced, in particular, by reflections on flat surfaces on which unpolarized light impinges at an acute angle. Typical applications are thus the detection and removal of reflections of the road surface. Furthermore, the polarization direction provides information about the position in which the specular object is located. For example, in horizontal

Mirror planes, such as those provided by water puddles, result in light reflections that are substantially polarized vertically and whose horizontal component is comparatively small. Therefore, the polarization angles can also be related to the tilt of the camera to the horizon, thus typically masking out or recognizing vertically polarizing objects from the common image.

To the coupled to the environment absolute polarization direction, d. H. vertically or horizontally, the polarization angle of at least one polarization filter is related to the absolute position of the polarization filter or the

Camera to the environment, for example by detecting the angle between horizon and polarization angle or direction of gravity (vertical) to the polarization angle. Since the difference between the polarization angle, which has been related to the environment, and the polarization angle of another polarization filter is known, it is possible to deduce the absolute position of the further polarization angle by adding the difference angle to the absolute orientation. Furthermore, can Also, the polarization angle of various polarization filters are each related to the environment, ie the horizon of the environment, or to the position of the motor vehicle or to the direction of gravity.

As already noted, individual pixels corresponding to the same object portion may be related in intensity to determine polarization direction and / or degree of polarization. Furthermore, a group or a range of pixels can be compared in their intensity, wherein the intensity of the image group results, for example, by averaging or by other statistical combinations. The grouping of a plurality of pixels, the intensity of which is combined for later evaluation, can be achieved by comparing intensities of pixels, for example by differentiating adjacent pixels of similar intensity from pixels with significantly different intensities by means of a threshold value.

In the same way, a grouping of pixels can be performed by detecting a predetermined shape. Here, certain shapes to be recognized are predetermined, for example typical shapes of reflection stripes or the contour of typical reflection patterns in order to be able to detect a potentially reflective object. By the subsequent detection of the degree of polarization (or the direction of polarization) can then be deduced from the pixels of the recognized shape on the optical properties, in particular disturbing reflections nen first be recognized in their form and can be identified due to a high degree of polarization as interference , Since the shape alone is not necessarily unique to the type of object, i. H. Thus, by examining the degree of polarization of the detected shape according to the invention, it is possible to ascertain that it is a disturbance and not a non-interferer which merely has the approximate shape of a disturber and thus erroneously turns from shape recognition to one Group of interferers has been assigned.

According to a further embodiment, therefore, pixels, image areas or a single pixel are suppressed, having (or having) a degree of polarization (or) is (or are) by a minimum difference above a predetermined threshold or above an average value of The degree of polarization lies (or inclines), which results from a (common) image section. The threshold value can thus be fixed or can be adapted to the captured images. The - li ¬

Pressing these pixels, which are thus assigned to interferers, can be performed by darkening the pixels, replacing the pixels, cutting out the pixels or marking the pixels or their contour to provide the driver either a suppressed image or the driver an image in which the disturbers detected by their degree of polarization are identified.

For carrying out the invention and the image acquisition method according to the invention, an image acquisition device of an automotive camera system according to the invention is provided with at least one camera and one polarization filter device. The polarizing filter device provides a polarization angle or different polarization angles, i. H. either different polarization angles in chronological order, filtered and unfiltered images in chronological order, or at the same time in alignment different polarization filters by a plurality of polarizing filters or simultaneously filtered and unfiltered images with multiple cameras, which are not all equipped with a polarizing filter. For each polarization angle, a camera is preferably provided which is aligned with a polarization filter which provides the polarization angle. The camera is in its image capture and thus in its sensitive area aligned to the environment to capture multiple images that represent a common object.

In a plurality of cameras, this is achieved by the cameras provide an at least partially common image section. Preferably, the cameras are aligned to a common point. If the multiple images are created one after the other, a camera may be provided that faces forward, allowing the same camera to take various pictures of themselves

Reason the movement of the camera system relative to the environment differ. Thus, exactly one polarization filter is provided in front of each camera, be it one or more cameras, or in front of each, but in front of at least one camera. When multiple polarization filters are used, these are grouped into the polarization filter device. The polarization filter device is thus arranged between the common object and the at least one camera. For each camera (or for at least one camera, but not for all cameras) a polarizing filter is provided, which is arranged between the camera and the object. The image capture device further comprises a combination device connected to the camera or to the plurality of cameras. The

Combination device is set up, different pictures (ie different in time or in their perspective, different images), which represent a common object and thus have an at least overlapping image area to align with each other and to superimpose. The different images are superimposed to match the displayed common object or the common image section. If pictures are shifted against each other, then this becomes

Displacement is compensated by the combination device, for example by the combination device is arranged to capture certain features of the images and to assign the features of different images to the same object or the same object location.

When using a stereo camera system, the images taken at different projection angles are combined by the combination device arranged therefor. As a result, the combination device provides an image data or video data output at which a common representation of the compensated images is output.

When using a rotating polarizing filter, the polarizing filter device comprises a rotating device connected to the polarizing filter of each camera (or camera) equipped with a polarizing filter. The rotary device is connected to the polarization filter, for example via a shaft, whereby the rotary device transmits rotational movements via a corresponding mechanical connection to the polarization filter. The connection between the rotary device and the polarizing filter is such that the rotary device drives the polarizing filter (s) for rotation about an axis of rotation perpendicular to the plane in which the polarizing filter extends or the polarizing filters extend. Due to the mechanical connection and the drive of the rotation device, the image acquisition device (consisting of one or more cameras) acquires several images with a time-varying polarization angle or one after the other and alternately or periodically alternately images with and images without polarization filtering. The temporal change is predetermined by the rotation device.

According to a further embodiment, the image capture device comprises at least two cameras. In particular, the image capture device hereby includes a stereo camera system. The at least two cameras are arranged at a distance from one another. Furthermore, the two cameras are designed for a common point. directed or aligned in the same direction, so that the cameras have a common, overlapping image area. For each of the at least two cameras, the image capture device comprises a polarization filter, which is arranged between the assigned camera and the common point or object to be imaged by the camera. The polarizing filters of different cameras have different polarization angles. Further, only one of the cameras may be equipped with a polarizing filter, or at least one but not all cameras may be equipped with a polarizing filter.

According to another embodiment, the image capture device comprises a

Attachment that is set up to fix the camera. The fixture further provides an alignment for the camera (when located in the fixture) that the at least one camera captures at least one image through a windshield of a motor vehicle. The attachment is thus set up, on the one hand to be attached to the camera and, on the other hand, within one

Motor vehicle, for example, on the windshield to be attached and to orient the camera out to the windshield out. The attachment provides this orientation to the camera when the attachment is located directly or indirectly on the windshield. An immediate arrangement can be provided, for example, by a suction cup or a snap connection, wherein an indirect fastening is provided by a direct attachment to a roof or to a dashboard of a motor vehicle, wherein the windshield is fixed to the roof or dashboard in a known manner.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Show it

Figure 1 a is a plan view of an image capture device according to the invention for

Execution of the procedure;

Figure 1 b position of the polarizing filter of the device shown in Figure 1 a along the section A-A '; and Figure 2 is a polarizing filter orientation for a rotating polarizing filter. Embodiments of the invention

FIG. 1 shows a device according to the invention with two cameras. The cameras 10 a, 10 b are aligned in the same direction and both capture the

Object 20. Thus, the cameras 10 a, 10 b have an overlapping image section 30 in which the object 20 is located. The object 20 can be detected jointly and simultaneously by the cameras 10 a and 10 b. The overlapping area 30 is at a certain distance from the cameras and starts after a certain distance to a windshield 40. The cameras 10 a, 10 b are arranged on an inner side of the windshield 40, wherein the object 20 and also the overlapping area 30 are arranged outside the windshield. The cameras 10 a, 10 b form a stereo camera system. The image capture device comprises the cameras 10 a, 10 b and associated polarizing filters 50 a, 50 b, wherein exactly one polarizing filter is assigned to each camera. The polarizing filter 50 a is associated with the camera 10 a and the polarizing filter 50 b is associated with the camera 10 b, so that the image captured by the camera 10 a is associated with a beam path that passes completely through the polarizing filter 50 a and in the same way the of camera 10 b detected light passes completely through the polarizing filter 50 b. In one embodiment, not shown, a camera is provided with and without a polarizing filter, wherein the camera without polarization filter may also include a darkening filter to reduce the brightness to 50%. Such an embodiment is identical to the illustrated embodiment, except for the omission of one of the polarizing filters, wherein an obscuring filter replaces one of the polarizing filters in place and alignment.

The cameras 10 a, b each have an image output, which is connected to a combination device 60. The combination device 60 brings the images captured by the cameras 10 a, b into harmony with one another despite their different perspectives. The combiner thus performs stereo mapping and further calculates an intensity signal for each pixel (or frame) of each camera 10 a, b. Further, the combining device 60 outputs an image signal corresponding to the combination of the images captured by the cameras 10 a, 10 b. Connected to the combiner 60 is a polarization calculator 70 which detects the degree of polarization, the angle of polarization, or both. For this purpose, the polarization calculation device 70 is connected via a (double) connection with the combination device 60 in order to determine and compare the pixels, ie intensity values, of the images captured by the cameras 10 a and 10 b. As already mentioned, the comparison comprises, for example, the quotient formation of the intensities for polarization degree detection and the difference formation or the

Summation of the intensities in order to calculate the polarization angle of the associated pixel from the quotient between difference and sum. Since the polarization calculator 70 calculates the intensity data, i. H. If the image data of both cameras 10 a, b are required, the connection between polarization calculation device 70 and combination device 60 is shown in FIG. 1 a as a double connection. In this case, the combination device 60 is set up to shift or distort at least one of the two images in order to compensate for the different perspectives (or displacements) of the images of the cameras 10 a, b. After the combining device 60 reconciles the images by this combination, the images are compared by the polarization calculator 70 for detecting the degree of polarization and / or the polarization angle. Combiner 60 and polarization calculator 70 are preferably provided as software modules running on a programmable data processing system. Thus, the devices 60 and 70 may be provided as software or as software pieces stored in a memory, which in turn is connected to a CPU or a video chip which, by running the software or software sections, performs the associated method steps such as combining, Comparing, shifting, compensating the perspectives, calculating the polarization angle and / or the degree of polarization for each pixel or for an image portion and implementing the output of the polarization data in the form of an image signal.

The device shown in FIG. 1 a can furthermore be combined with a shape recognition which combines image pixels of an image section which lie within a predetermined and recognized form. This shape detection device may also be provided as software which searches an image according to predetermined shapes and marks them.

The polarization directions 152a, b and the polarization filter 150a, b are shown symbolically in FIG. 1b, the polarization filters 150a, b corresponding to the polarization filters 50a, b of FIG. 1, and FIG. 1b to the section AA in finance gur 1 a corresponds. It can be seen that the polarization filters 150 a, b in Figure 1 b have the same design, but have a mutually inclined polarization angle 152 a, b. Due to the difference in the polarization angles 152 a, 152 b, the polarization information (ie the polarization angle or the degree of polarization) can be detected. FIG. 1b further shows the cameras 110a, 110b in a schematic representation, which, viewed from above on the drawing plane, lie behind the polarization filters 150a, b. The direction pointing upwards from the plane of the drawing corresponds to the direction leading to the object 20, ie through the windshield 40.

FIG. 2 serves to explain a further embodiment of the invention. FIG. 2 shows a polarization filter 250 which has the polarization direction 252a in a first position. According to this embodiment, the polarization filter 250 is rotated along the direction of rotation 260 (for example by a rotation device, not shown, for example an electric motor) so that a polarization direction 252 b results from the polarization direction 252 a at a later time differs by which the polarizing filter 250 was rotated in the direction of rotation 260 in the meantime. If a first image is recorded in the position indicated by 252 a and a second image is recorded with the position designated as 252 b, then two images are obtained that were acquired with different polarization angles.

In addition to the rotation of the polarizing filter 250, the entire system undergoes a translation 270 by the movement of the vehicle in which the automotive camera system according to the invention is located. That is, not only the polarization angle 252 a rotates to the polarization angle 252 b, but also the image area 280 a, which is associated with the polarization direction 252 a, associated with the polarization angle 252 b. The offset between the image areas 280 a, b is compensated according to the invention in order to superimpose the respective images according to a jointly detected object and to align them with each other. Thus, the allowed

Invention, the detection of a first image, with a first polarization direction 252 a, which corresponds to the image area 280 a, and the detection of a second image (or other images), which is characterized with the image area 280 b, and that of a filtering according to the polarization direction 252nd b is subjected. The common overlapping image area corresponds to the field between the upper edge of the area 280b and the lower edge of the image area or image capture area 280a. The displacement between both image areas is due to the movement of the vehicle 270. The displacement shown in FIG. 2 is merely symbolic; in actual recordings, further trapezoidal distortions arise along the alignment lines of the camera alignment.

Claims

claims 1 . An image acquisition method, comprising the steps of: acquiring a plurality of images by means of an automotive camera system (10a, b) under different polarization-related shooting conditions, wherein the plurality of images represent a common object, the images of the common object are taken under different polarization-related shooting conditions; different polarization-related recording conditions is provided by filtering with at least one polarizing filter (40a, b) having different polarization angles (152a, b; 252a, b) for the plurality of images, or by taking at least one image through the at least one polarizing filter, and through Taking at least one image without filtering through a polarizing filter, and combining the plurality of images after filtering into a common representation. 2. An image acquisition method according to claim 1, wherein at least one of said plurality Images are filtered with a polarizing filter (40a, b) rotating about an axis of rotation, and the axis of rotation is perpendicular to a plane in which the polarizing filter (40a, b) extends. 3. Image acquisition method according to claim 1 or 2, wherein the images are detected from at least two different perspectives and the images are taken for different perspectives with different polarization-related recording conditions by filtering in the detection at different perspectives with different polarization angles (152a, b) or by Acquisition with different perspectives with and without Polarizing filter. 4. The image acquisition method of claim 3, wherein the images are captured with a stereoscopic camera system (10a, b), wherein the camera system used for detection comprises two cameras (10a, b) with different perspectives, and the images with the two cameras ( 10a, b) by aligning the cameras arranged at different positions with an overlapping image section, each camera capturing an image filtered by a polarization filter (40a, b) and the polarization filters (40a, b) used for detection capturing images with different polarization angles (152a , b) or the polarization filters (40a, b) used for the detection filter at least one image, but not all the images. 5. The image acquisition method according to claim 1, further comprising the step of: determining the respective polarization direction and / or the degree of polarization respectively for a plurality of pixels or image regions of the images, from the ratio of intensities of pixels or image regions of different images corresponding to each other , The image acquisition method according to claim 4 or 5, further comprising the step of: suppressing pixels or image areas having a degree of polarization that is less than a predetermined threshold or an average of the degree of polarization of at least a portion of a common image portion of images polarization-related recording conditions were recorded. 7. An image acquisition device of an automotive camera system comprising at least one camera (10a, b) and a polarization filter device (40a, b), which provides polarization-related recording conditions, wherein the at least one camera is aligned to capture a plurality of images that a common object (20 ), wherein the polarization filter device is arranged between the common object (20) and the at least one camera, the polarization filter device provides for each or at least one but not for all cameras a polarization filter which is arranged between object (20) and camera (10a, b ), and the image capture device further comprises a combination device (60) arranged to superpose different images representing a common object (20) to match the common object (20) represented by the different images, to the multiple images to a common representation wherein the polarization filter device (40a, b) determines the polarization-related recording conditions either by different polarization angles of the polarization onsfilter or the polarization filter device does not provide the filtering by means of (the) polarization filter (s) for all images or cameras. 8. An image sensing device according to claim 7, wherein the polarization filter device (40a, b) comprises a rotation device connected to the polarization filter (40a, b) of each camera, the rotating device being connected to the polarizing filter such that the rotating device of the polarizing filter (40a, b) drives for rotation about an axis of rotation perpendicular to the plane in which the polarizing filter extends or in which the polarization filters extend, whereby the image capture device acquires multiple images with time-varying polarization angle, and wherein the polarization filter is either continuous to continuously filter the camera irrespective of the rotation angle of the polarization filter, or the polarization filter comprises recesses, around the camera depending on the rotation angle of this polarizing filter to filter or not to filter. 9. An image sensing device according to claim 7 or 8, comprising at least two cameras (10a, b) spaced apart from one another and aligned with a common point, wherein for each or at least one of the at least two cameras, the image capture device comprises a polarizing filter (40a, b), which is arranged between the associated camera and the common point, and the polarization filters (40a, b) of different cameras (10a, b) have different polarization angles (152a, b) or at least one of the cameras has a polarization filter during at least one different camera of the cameras has no polarization filter. 10. The image capture device according to claim 7, wherein the image capture device comprises an attachment and the at least one camera is aligned such that the at least one camera has at least one image through a windshield of one Motor vehicle detected when the attachment is arranged directly or indirectly on the windshield.