WO2018130596A1

WO2018130596A1 - Method for operating a camera in dependency on a current state of an environmental region of the camera, camera, and motor vehicle

Info

Publication number: WO2018130596A1
Application number: PCT/EP2018/050615
Authority: WO
Inventors: Brian Michael Thomas DEEGAN; Patrick Eoghan Denny
Original assignee: Connaught Electronics Ltd.
Priority date: 2017-01-12
Filing date: 2018-01-11
Publication date: 2018-07-19
Also published as: EP3568972A1; DE102017100529A1

Abstract

The invention relates to a method for operating a camera (2) for a motor vehicle (1), in which an environmental region (7) of the motor vehicle (1) is captured by means of the camera (2) and the following steps are performed: a) determining a state indicator (12), which is characteristic of a current state of the environmental region (7) from the perspective of the camera (2); b) comparing the state indicator (12) with a multitude of reference state indicators (14), wherein each of the reference state indicators (14) is assigned to a reference state (16) of a multitude of reference states of the environmental region (7); c) assigning the current state of the environmental region (7) to one of the reference states (16) on the basis of a comparison from step b); d) selecting a camera setting (22) from a collection of camera settings (23) on the basis of the reference state (16) assigned in step c), wherein to each reference state (16) a camera setting (22) from the collection of camera settings (23) is assigned; and e) operating the camera (2) with the camera setting (22) selected in step d).

Description

Method for operating a camera in dependency on a current state of an environmental region of the camera, camera, and motor vehicle

The invention relates to a method for operating a camera for a motor vehicle, in which an environmental region of the motor vehicle is captured by the camera. The invention also relates to a corresponding camera as well as a motor vehicle with a corresponding camera.

Methods for operating a camera for a motor vehicle are known from the prior art. Cameras are commonly operated in dependency on camera settings. These camera settings are for instance exposure time, focal aperture width, and light sensitivity of the camera. The camera settings are commonly determined automatically. For instance a camera is operated in dependency on an automatic exposure system. The automatic exposure system facilitates for an automatic exposure control through coupling of focal aperture and closure. Prerequisite for the automatic exposure system is commonly an exposure meter built into the camera.

The known way of proceeding, however, often does not lead to a satisfying result, if it is required that the cameras in all kinds of light, driving, and weather conditions should work to produce the same level of quality. Moreover the cameras are commonly also susceptible to illumination jitter due to pulse width modulation techniques as it can occur in illumination diodes. Also in particular HDR (high dynamic range) cameras are particularly susceptible to unclear images, since most of the HDR cameras are based on a multiple capture scheme, in which a very short exposure time is required to capture the main motif.

It is the task of the invention to show a solution of how an image can be captured by a camera of a motor vehicle with less noise and more detail.

According to the invention this task is solved by a method as well as by a camera and a motor vehicle with the features according to the respective independent claims.

Advantageous embodiments of the invention are subject matter of the dependent claims, the description, and the figures. In a method according to the invention a camera for a motor vehicle is operated. An environmental region of the motor vehicle is captured by means of the camera and the following steps are performed:

a) determining at least one state indicator, which is characteristic of a current state of the environmental region from the perspective of the camera;

b) comparing the state indicator with a multitude of reference state indicators, wherein each of the reference state indicators is assigned to an, in particular different and/or in particular predetermined, reference state of a multitude of reference states of the environmental region;

c) assigning the current state of the environmental region to one of the reference states on the basis of a comparison from step b);

d) selecting a camera setting from a collection of, in particular predetermined, camera settings on the basis of the reference state assigned in step c), wherein to each reference state a camera setting is assigned from the collection of camera settings; and

e) operating the camera with the camera setting selected in step d).

By the method according to the invention it is rendered possible to capture images with less noise and more detail.

It has turned out that on the basis of manifold state indicators the current state of the environmental region can be determined, at least approximately. For this state then the most suitable camera setting can be selected from the collection of camera settings. Thereby manifold state indicators from the environmental region can be used to finally arrive at a captured image that is suitable for the situation and thus in particular low in noise and rich in detail.

In particular it is envisaged that, to start with, at least one of the state indicators is captured. Preferably, however, several state indicators are captured at the same time. The state indicator can for instance be present as speed of the camera or else as object in the environmental region or else as camera parameter. On the basis of at least one state indicator then a reference state is determined. The reference state is selected from several reference states. Each reference state in this connection is preferably assigned a camera setting. The camera setting for the current environmental region is then selected according to which reference state was determined. An advantage of this way of proceeding is that the camera setting can be configured for frequently occurring situations during the operation of the camera or the motor vehicle. Thereby an inaccurate setting of the camera, which does not correspond to the situation, can be prevented. An image capturing by means of the camera thereby is effected with less noise and more detail.

Preferably, it is envisaged that by the camera an image of the environmental region is captured and in the image an object, in particular at least one headlight of a further motor vehicle, is determined as the state indicator. The object, in particular the headlight, in this connection can for example be recognized by means of a method of machine vision in an image captured by means of the camera or a further camera. The headlight can then for instance be used as indicator of a current state of the environmental region. For instance headlights or light emitted by a headlight regularly occur at night or in low light conditions, for instance in twilight or bad weather. On the basis of the number of headlights of various further motor vehicles or also on the basis of the frequency of appearance of headlights it can be concluded whether the current environmental region is a rural or an urban environmental region. On the basis of the state of the environmental region determined in this way then the camera settings are selected so that the environmental region can be captured with the camera setting most suitable for the current situation and thereby in particular with less noise and more detail.

Preferably it is envisaged that a speed of the camera is determined relative to an earth- fixed coordinate system, and the speed of the camera is determined as the state indicator. The speed of the camera can for instance be determined through a sensor of the motor vehicle and can for instance be tapped at the CAN-Bus (CAN - Controller Area Network). The camera can move at the same speed as the motor vehicle or else at least temporarily at a speed that is different from the speed of the remaining motor vehicle. By the knowledge about the speed of the camera then again the current state of the

environmental region can be determined from the perspective of the camera. Thus the current environmental region from the perspective of the camera can for instance be subject to fast changes if the camera is moved fast. As the camera setting then for instance a short exposure time and/or a large focal aperture and/or a high light sensitivity of the image sensor of the camera can be selected. Thereby the environmental region can be captured with less noise and more detail. The motor vehicle can thereby in turn be operated more safely.

Preferably, it is envisaged that at least one, in particular an automatically determined, configuration parameter of the camera is determined, and the configuration parameter is determined as the state indicator. The configuration parameter in this connection is a parameter predetermined for the operation of the camera. This can for example be predetermined by a standard setting or else be determined by a known automatic camera configuration method, such as an automatic exposure system. For instance the configuration parameters identified by the camera itself can be used to determine the current state of the environmental region at least approximately and on the basis of the state of the environmental region then the camera setting most suitable for this state can be selected. The camera parameters can also be comprised by the camera setting.

However, the camera setting is determined on the basis of the assigned reference state, whereas the camera parameters are for instance immediately determined by sensors of the camera. Advantageous is the dependency on the assigned reference setting, since thereby for instance an undesired fast switching between different camera settings can be prevented. The capturing of the environmental region in turn can thereby be performed with less noise and more detail.

Preferably it is envisaged that as the configuration parameters an exposure time of the camera and/or a signal enhancement value of the camera and/or an exposure time ratio with regard to a long exposure time to a short exposure time in high contrast images captured by the camera is determined. The term exposure time or duration of exposure is the period of time, for which the image sensor is exposed to the light from the

environmental region for capturing an image. If for instance in a digital camera instead of ISO 100 a light sensitivity of ISO 400 is selected, the rise in sensitivity occurs through a signal enhancement, which is described by the signal enhancement value. In the case of high contrast images a scene is captured for instance several times with different exposure times. Then the short exposure time and the long exposure time is given. On the basis of at least these exposure times then for instance the exposure time ratio is determined. By the exposure time and/or the signal enhancement value and/or the exposure time ratio the reference state can be assigned more precisely and accordingly the camera setting can be selected more precisely.

Preferably it is envisaged that the exposure time and/or the signal enhancement value and/or the exposure time ratio are determined by an automatic exposure control. By the automatic exposure control a focal aperture of the camera and a closure of the camera are coupled. The automatic exposure control is based on an automatic exposure system of the camera. In particular the automatic exposure system comprises an exposure meter coupled with the camera, for instance installed in the camera. Comprised by the automatic exposure system are in particular shutter priority, aperture priority, and program mode. By the determining of the exposure time and/or the signal enhancement value and/or the exposure time ratio by means of the automatic exposure control the state indicator is precisely determined.

Preferably it is envisaged that as the configuration parameter an average brightness value and/or an average colour value of an image region of an image of the environmental region captured by means of the camera is determined. By the average colour value a statement about the brightness of the image in the image region is made. By the average colour value a statement about the colour in the image region is made. In each case an average of the values of pixels in the image region is formed. The average for instance can be formed as arithmetic mean or else as median. Both the average brightness value as well as the average colour value can be determined by pixels in only one intensity channel of the image or else by pixels in several intensity channels of the image. The image region can be present as part of the image or else as the entire image. An advantage of the average brightness value and/or the average colour value is an informative state indicator, by means of which the reference environmental region is assigned more reliably and more precise.

It may also be envisaged that as the configuration parameter an automatic white balance value of the camera is determined. A white balance on which the white balance value is based, serves for sensitizing the camera to the colour temperature of the light at the location where the image is captured. The digital recording of images allows for a colour temperature adjusted to the light conditions. Advantageous in turn is a state indicator rendered informative through the white balance value, by which the reference

environmental region is assigned more reliably and more precisely.

Preferably it is envisaged that at least one brightness value in the environmental region is determined by at least one brightness sensor of the motor vehicle, which does not form part of the camera, and the determined brightness value of the environmental region is determined as the state indicator. The brightness sensor, which is external to the camera, is arranged outside the housing of the camera. Preferably the brightness sensor, which does not form part of the camera, though, is coupled at least indirectly with the camera. The brightness sensor can for instance be comprised by an, in particular electronic, rear view mirror system of the motor vehicle. On the basis of the brightness sensor, which does not form part of the camera, for instance the brightness of a display of the motor vehicle can be adjusted or else an illumination of the motor vehicle can be switched on and off. Also several brightness sensors, which do not form part of the camera, can be used. For instance one of the brightness sensors can be arranged at a front of the motor vehicle, whilst another brightness sensor is for instance arranged on a rear part of the motor vehicle. The respective brightness sensor can for instance be used for detecting light of the headlights of a further motor vehicle in the environmental region. Then manifold scenarios are possible. For instance the brightness sensor at the front can detect a brightness in the environmental region below a brightness threshold value, whereas the brightness sensor at the rear end simultaneously detects a brightness in the

environmental region above the brightness threshold value. This can then for instance already be indicative of the fact that the light incident upon the rear brightness sensor is light of a headlight of a further motor vehicle in the environmental region of the motor vehicle.

Preferably it is envisaged that on the basis of the brightness value at least one headlight of a further motor vehicle in the environmental region is recognized, and the recognized headlight is determined as state indicator. An advantage of the headlight as state indicator is that the current state of the environmental region thereby can be assigned more precisely to the respective reference state. Thereby there can be reference states, which differ with respect to the presence of headlights of at least one further motor vehicle. This is particularly helpful at night, if one of the headlights enters the capture area of the camera only for a certain period of time. In the selection of the camera setting this can then be considered. For instance the camera setting can be selected in such a way that two headlights in an image captured by means of the camera are distinguishable from each other. Thereby it can then be recognized that a further motor vehicle is present in the environmental region and not only a different kind of light source, such as for instance a street lighting, which commonly is not represented as two light sources at a certain distance from each other and essentially at the same height above the street surface in the image.

Preferably, it is envisaged that as the camera setting a parameter set for an, in particular local, tone mapping method of the camera is predetermined. In the tone mapping method or a dynamic compression the dynamic range of high contrast images, i.e. of digital images with high brightness range, is compressed. In the tone mapping method the contrast range of a high contrast image is reduced to be able to present it on common output devices. By the selected parameter set the image is captured by means of the camera for the respective situation with less noise and more detail.

Preferably it is envisaged that as the camera setting a control signal for adjusting a screen brightness of a screen of the motor vehicle, which is coupled with the camera, is generated. By the control signal the screen is for instance dimmed. The dimming can also be done only locally, i.e. in a partial area of the screen. In particular the screen is dimmed, in case a light source, such as a headlight of a further motor vehicle is shown in an image to be output on the screen. Then for instance also only the partial area of the screen, in which the shown headlight is located, can be dimmed. By the dimming a shining representation and lens artefacts are suppressed, whereby the image is output more clearly on the screen. The safety of the motor vehicle can thereby be increased. It can also be envisaged that the image brightness is controlled in dependency on a recognized headlight. For instance the screen can be operated undimmed, in case no headlight is contained in the image to be output, whilst the screen is dimmed, in particular locally, in case a headlight of a further motor vehicle or a different light source, such as a street lighting, is contained in the image to be output.

Preferably it is envisaged that as the camera setting a further control signal for adjusting an efficiency of an anti-reflection coating of a rear view mirror of the motor vehicle is generated. By the anti-reflection coating a shining of the rear view mirror can be reduced. Preferably the efficiency of the anti-reflection coating is increased, in case in an image captured by means of the camera and taken of part of the environmental region, which can also be seen by means of the rear view mirror, a light source, in particular a headlight of a further motor vehicle can be recognized. In case no headlight is recognized, the efficiency of the anti-reflection coating is reduced or kept at a standard level. The motor vehicle can be operated more safely by the adjusting of the anti-reflection coating depending on the situation at hand.

Preferably it is envisaged that the reference state of the environmental region is predetermined as day light state and/or urban night state and/or extra-urban, dark night state and/or extra-urban night state with light from headlights of a further motor vehicle in the environmental region. The daylight state is in particular a state, in which the sun has risen and thereby a normal brightness prevails. However, it may also be cloudy. In the case of the urban night state the sun has already set, but a plurality of artificial light sources is given, which for instance are given through stationary street lighting, such as street lamps or traffic signs or illuminated advertising, or illumination of other traffic participants. The extra-urban, dark night state is characterized by the essentially complete absence of environmental light or at least the presence of less environmental light than in the urban night state. In the case of the extra-urban night state with light from headlights of a further motor vehicle in the environmental region the environmental region is illuminated as in the case of the extra-urban night state, wherein as spot light source the light of the headlights is added. The light of the headlights is in particular in the capture area of the camera. By the reference states the camera setting can be predetermined precisely adapted to the situation and accurately by the collection. From this in turn then the suitable camera setting for the situation can be selected. With the suitable camera setting for the situation the image is captured by the camera with less noise and more detail. The safety of the motor vehicle is thereby raised again.

The invention also relates to a camera for a motor vehicle. The camera is configured for performing a method according to the invention. The camera is preferably comprised by a driver assistance system of the motor vehicle. The driver assistance system can therein be configured for instance as CMS (camera monitoring system), by means of which the environmental region of the motor vehicle can be captured at least partly.

The camera in particular has a motor vehicle fastening element, by which the camera can be fastened to a motor vehicle.

Further, the invention relates to a motor vehicle with a camera according to the invention. The motor vehicle is preferably configured as passenger car.

The preferred embodiments presented with regard to the method according to the invention and their advantages apply in analogy to the camera according to the invention and the motor vehicle according to the invention.

Further features of the invention derive from the claims, the figures, and the description of the figures. The features and feature combinations previously mentioned in the description as well as the features and feature combinations named in the following in the description of the figures and/or shown in the figures alone are employable not only in the respective indicated combination, but also in other combinations, without leaving the scope of the invention. Thus, also embodiments of the invention are to be considered as being comprised and disclosed, which are not shown and explained explicitly in the figures, however derive through separated feature combinations from the explained embodiments and can be generated therefrom. Also embodiments and feature combinations are to be considered as being disclosed, which thus do not have all features of an originally formulated independent claim. Moreover, embodiments and feature combinations are to be considered as disclosed, in particular by the embodiments explained in the above, which go beyond the feature combinations set out in the back-references of the claims or deviate from them. The invention now is explained in more detail on the basis of a preferred embodiment as well as by reference to the added drawings.

These show in:

Fig. 1 a schematic representation of an embodiment of a motor vehicle according to the invention with a camera;

Fig. 2 a flow diagram of a method for assigning a current state of an environmental region to a reference state of the environmental region; and

Fig. 3 a histogram of an image captured by means of the camera, on the basis of which a headlight of a further motor vehicle in an environmental region of the motor vehicle in the image is recognized.

In the figures same elements or elements having the same functions are equipped with the same reference signs.

Fig. 1 shows an embodiment of a motor vehicle 1 with a camera 2. The camera 2 is arranged on a front 3 of the motor vehicle 1 . The arrangement of the camera 2, however, is possible in manifold ways, e.g. the camera 2 can for instance also be arranged on a rear part 4 of the motor vehicle 1 or a left side 5 of the motor vehicle 1 or a right side 6 of the motor vehicle 1 .

The camera 2 according to the embodiment is arranged in such a way on the motor vehicle 1 that an environmental region 7 of the motor vehicle 1 is captured at least partly. Also several cameras 2 can be arranged on the motor vehicle 1 . The cameras 2 can for instance be arranged in such a way on the motor vehicle 1 that the environmental region 7 is completely captured. Thus the cameras 2 can for instance be comprised by an environment monitoring system of the motor vehicle 1 .

The camera 2 has an image sensor 8. The image sensor 8 is preferably configured as CCD sensor (CCD - charge-coupled device) or as CMOS sensor (CMOS - complementary metal-oxide semiconductor). Further the camera 2 is preferably configured as video camera which captures an image sequence of individual images. According to the embodiment the camera 2 comprises an evaluation unit 9. The evaluation unit 9 is configured to be separate from the camera 2 or else integrated within the camera 2. By the evaluation unit 9 the image sequence is evaluated and/or corrections, for instance by application of filters, are made to the respective individual images.

According to the embodiment in the environmental region 7 a further motor vehicle 10 with at least one headlight 1 1 is arranged. The headlights 1 1 are captured by the camera 2 and emit light in the direction of the motor vehicle 1 .

The camera 2 now according to an embodiment is operated as follows. To start with, a state indicator 12 is determined. On the basis of the state indicator 12 it is to be recognized in which current state the environmental region 7 is from the perspective of the camera 2. The state indicator 12 is determined for instance as speed of the camera 2 relative to an earth-fixed coordinate system. The earth-fixed coordinate system can for instance relate to the WGS 84 (World Geodetic System 1984). If the camera 2 is fixedly attached to the motor vehicle 1 , the speed of the camera 2 also corresponds to the speed of the motor vehicle 1 .

For determining the state indicator 12, however, also an image of the environmental region 7 can be captured by means of the camera. The image then is checked for presence of a known object. Thus in the image for instance the headlight 1 1 of the further motor vehicle 10 can be present as the object. The headlight 1 1 then issues an indication that in the environmental region 7 at that moment there is oncoming traffic. Also the headlight 1 1 can indicate that at that point in time it is quasi not as bright as in daylight. Then for instance the number of headlights or their appearance frequency can be determined as the state indicator 12.

Further, however, also a configuration parameter 13 of the camera 2 can be determined as the state indicator 12. The configuration parameter 13 is for instance an exposure time, a signal enhancement value, or an exposure time ratio. The exposure time ratio is determined on the basis of a long exposure time and a short exposure time in the case of an HDR image (high dynamic range). The exposure time, the signal enhancement value, or the exposure time ratio in this connection can be determined for instance by means of an automatic exposure system of the camera 2. Additionally or alternatively the state indicator 12, however, can also be determined by an average brightness value and/or an average colour value of an image area of the image captured by means of the camera 2. As average for instance the arithmetic mean can be formed.

However, also a brightness value in the environmental region 7 can be determined as the state indicator 12, which for instance is captured by means of a brightness sensor of the motor vehicle 1 , which does not form part of the camera. According to the embodiment on an interior mirror 17 of the motor vehicle 1 a first brightness sensor 18 is arranged, which in particular only captures a front part 19 of the environmental region 7, and on the rear part 4 a second brightness sensor 20 is arranged, which in particular only captures the rear part 21 of the environmental region 7. The first brightness sensor 18 and/or the second brightness sensor 20 is arranged preferably in the interior of the motor vehicle 1 and captures the light incident through the respective vehicle window from the

environmental region 7. The brightness sensors 18, 20 can also be used by another system of the motor vehicle 1 or provided by same, for instance in order to adjust in dependency thereon an interior illumination degree or a dimming degree of a rear mirror of the motor vehicle 1 .

In particular several of the state indicators 12 can be captured and combined. The state indicators 12 can for instance also be weighted.

The state indicator 12 is compared to a multitude of reference state indicators 14. Thus a reference state indicator 15 of the multitude of reference state indicators 14 can be given for instance as speed of the camera 2. The reference state indicator 15, however, can also be given as light of a headlight in the image and as not present in the image.

To each of the reference state indicators 15 a reference state 16 (shown in Fig. 2) is assigned. By the reference state 16 a predetermined, for instance sample state or model state, of the environmental area 7 is described from the perspective of the camera 2.

Via the comparison now the reference state 16 is determined or selected. That reference state 16 is selected, in which the reference state indicators 14 are most similar to the state indicators 12. By the reference state 16 the current state of the environmental region 7 is described approximately in the best possible way. To each reference state 16 a camera setting 22 is assigned from a collection of camera settings 23. The collection of camera settings 23 can for instance be present as database. The respective assigned camera setting 22 is provided especially for the respective reference state 16. Thereby with this camera setting 22 then images can be captured by the camera 2, which are particularly low in noise and rich in detail.

The reference state 16 of the environmental region 7 is preferably predetermined as daylight state 42 and/or urban night state 43 and/or extra-urban, dark night state 44 and/or extra-urban night state 45 with light from the headlights 1 1 of the further motor vehicle 10 in the environmental region 7.

In particular by including several state indicators 12 from different sources, i.e. from speed sensors of the motor vehicle 1 , brightness sensors 18, 20 of the motor vehicle 1 or from the camera 2 itself, the camera setting 22 can be selected to better suit the respective situation than if a setting of the camera 2 as is common is effected only on the basis of the automatic exposure system.

As the camera setting 22 can also be generated a control signal 23. By the control signal 23 a screen brightness of a screen 24 of the motor vehicle 1 coupled with the camera 2 is adjusted. Thus the screen brightness can for instance be reduced, in case the headlight 1 1 is recognized in the image, and the image is output on the screen 24. It is also possible that only the partial area of the screen 24, in which the part of the image with the headlight 1 1 is located, is reduced with regard to its brightness.

Additionally or alternatively as the camera setting 22 also a further control signal 25 can be generated. By the further control signal 25 then an effectiveness of an anti-reflection layer 26 of a rear view mirror of the motor vehicle 1 , for instance an interior mirror 17 is adjusted. Thus, the anti-reflection layer 26 can for instance be adjusted more effectively, in case a, possibly glaring, illumination source, such as for instance the headlight 1 1 , is recognized in the capture area of the rear view mirror.

Fig. 2 shows a flow diagram of a method for assigning the current state of the

environmental region 7 to the reference state 16 of the environmental region 7. In a step S1 the daylight state 42 is assumed. The camera 2 is operated with the camera setting 22 for the daylight state 42. In a step S2 the brightness value of the first brightness sensor 18 is determined. If the brightness value is below a daylight threshold value 26, step S3 follows. In case the brightness value is not below the daylight threshold value 26, it is leaped back to the step S1 .

In the step S3 it is checked whether the exposure time ratio is larger than an exposure time ratio threshold value 27, and whether the average brightness value is larger than an average brightness threshold value 28. If this is the case, a step S4 follows. If this is not the case, a step S5 follows.

In the step S4 the extra-urban night state 45 with light from the headlights 1 1 is given. The camera setting 22 is selected to correspond to the extra-urban night state 45 with light from the headlights 1 1 . In a step S6 it is checked whether the exposure time ratio is smaller than the exposure time ratio threshold 27, and whether the average brightness value is smaller than the average brightness threshold value 28. If this is not the case, it is proceeded with the step S4. If this is the case, it is proceeded with the step S5.

In the step S5 it is checked whether the brightness value determined by means of the first brightness sensor 18 is smaller than an urban brightness threshold value 29. If this is the case, it is proceeded with a step S7. If this is not the case, it is proceeded with a step S8.

In the step S7 the extra-urban, dark night state 44 is given. The camera setting 22 consequently is selected accordingly and the camera 2 is operated in the extra-urban, dark night state mode. Starting from the step S7 a step S9 follows. In the step S9 it is checked whether the brightness value determined by means of the first brightness sensor 18 is smaller than the urban brightness threshold value 29. If this is the case, a step S10 follows. If this is not the case, a step S1 1 follows.

In the step S10 it is checked as in the step S3 whether the exposure time ratio is larger than the exposure time ratio threshold value 27, and whether the average brightness value is larger than the average brightness threshold value 28. If this is the case, the step S4 follows. If this is not the case, the step S7 follows.

In the step S8 it is checked whether the signal enhancement value is smaller than a signal enhancement threshold value 30 or, whether the brightness value of the first brightness sensor 18 is larger than a further daylight threshold value 31 . If one of the two options is the case, the step S1 follows. If none of the two options is the case, a step S12 follows. In the step S12 the urban night state 43 is given. The camera setting 22 is selected according to the urban night state 43 and the camera 2 is operated in the urban night state mode. After step S12, step S3 follows again.

In step S1 1 it is checked whether the brightness value of the first brightness sensor 18 is larger than the further daylight threshold value 31 . If this is the case, step S1 follows. If this is not the case, step S12 follows.

The camera setting 22 fixes in particular the following settings: image capture rate, flickering suppression, colour value, white balance, brightness, image sharpness, noise suppression, gamma value, and/or tone mapping. By the flickering suppression an incorrect representation of a light source in the image due to pulse width modulation of the light source, in particular in the case of light-emitting diodes, is counteracted. In the case of the flickering suppression for instance the dynamic region of the image can be selected more narrow than was originally the case. The flickering suppression is performed for instance in the case of the daylight state with high intensity, whilst the flickering suppression in the case of the extra-urban night state with light from the headlights 1 1 is merely effected at low intensity or not at all, in order to be able to represent the headlights 1 1 in the image in greater detail. In the case of deactivated or lower flickering suppression it is then accepted that some light-emitting diodes, for instance of luminous advertising by the roadside, are represented at times more incomplete or with less detail.

The image capture rate is kept in particular at a standard rate of 60 images per second. In particular with the exception of extra-urban, dark night state and/or in case the

temperature of the camera 2 exceeds a temperature threshold value, the image capture rate is reduced, for instance to 30 images per second. The image capture rate, however, can also be reduced in dependency on the speed of the camera 2 relative to the earth- fixed coordinate system. The higher the speed, the lower the image capture rate is set.

The tone mapping method can also only be applied locally to a partial area of the image.

By the camera setting 22, however, also exposure time, focal aperture width, and light sensitivity of the camera 2 can be predetermined.

The camera setting 22 can be adjusted from individual image to individual image during the capture of an image sequence by means of the camera 2. The headlights 1 1 of the further motor vehicle 10 can for instance be recognized either by means of a method of machine vision on the basis of an image of the environmental region 7 by means of the camera 2 or else on the basis of a heuristic method based on a histogram of the image.

Fig. 3 shows a histogram 32 of an image of the environmental region 7 captured by means of the camera 2. Based on the histogram 32 the heuristic method for recognizing the headlights 1 1 is performed. The histogram is drawn into a coordinate system 33 with an abscissa 34 and an ordinate 35. A value range 36 of the histogram is described by the abscissa 34 and extends for instance from 0 to 255 in an 8 bit image. At an end 37 of the value range 36, which has the higher values of the value range, a histogram range 38 is determined. In the histogram range 38 are the values of the value range 36, which are larger than the value threshold 39. The presence of the headlights 1 1 in the image is only assumed, if a frequency value 40 of the histogram 32, marked on the ordinate 35, is within the histogram range 38 is larger than a frequency threshold value 41 . The shown histogram 32 can for instance occur, if a smaller bright light source is contained in a mainly dark image.

Claims

1 . Method for operating a camera (2) for a motor vehicle (1 ), in which an

environmental region (7) of the motor vehicle (1 ) is captured by the camera (2) and the following steps are performed:

a) determining at least one state indicator (12), which is characteristic of a current state of the environmental region (7) from the perspective of the camera (2); b) comparing the state indicator (12) with a multitude of reference state indicators (14), wherein each of the reference state indicators (14) is assigned to a reference state (16) of a multitude of reference states of the environmental region (7);

c) assigning the current state of the environmental region (7) to one of the

reference states (16) on the basis of the comparison from step b);

d) selecting a camera setting (22) from a collection of camera settings (23) on the basis of the reference state (16) assigned in step c), wherein each reference state (16) is assigned a camera setting (22) from the collection of the camera settings (23); and

e) operating the camera (2) with the camera setting (22) selected in step d).

2. Method according to claim 1 ,

characterized in that

by the camera (2) an image of the environmental region (7) is captured and in the image an object, in particular at least one headlight (1 1 ) of a further motor vehicle (10), is determined as the state indicator (12).

3. Method according to claim 1 or 2,

characterized in that

a speed of the camera (2) is determined relative to an earth-fixed coordinate system, and the speed of the camera (2) is determined as the state indicator (12).

4. Method according to any one of the preceding claims,

characterized in that

at least one, in particular an automatically determined, configuration parameter of the camera (2) is determined, and the configuration parameter is determined as the state indicator (12).

5. Method according to claim 4,

characterized in that

as the configuration parameter an exposure time of the camera (2) and/or a signal enhancement of the camera (2) and/or an exposure time ratio with respect to a long exposure time to a short exposure time in the case of high-contrast images captured by the camera (2) is determined.

6. Method according to claim 5,

characterized in that

the exposure time and/or the signal enhancement value and/or the exposure time ratio are determined through an automatic exposure control of the camera (2).

7. Method according to any one of claims 4 to 6,

characterized in that

as the configuration parameter an average brightness value and/or an average colour value of an image region of an image of the environmental region (7) captured by the camera (2).

8. Method according to any one of the preceding claims,

characterized in that

at least a brightness value in the environmental region (7) with at least one brightness sensor (18, 20) of the motor vehicle (1 ) that does not form part of the camera is determined, and the determined brightness value of the environmental region (7) is determined as the state indicator (12).

9. Method according to claim 8,

characterized in that

on the basis of the brightness value at least one headlight (1 1 ) of a further motor vehicle (10 in the environmental region (7) ) is recognized, and the recognized headlight (1 1 ) is determined as the state indicator (12).

10. Method according to any one of the preceding claims,

characterized in that

as camera setting (22) a parameter set for an, in particular local, tone mapping method of the camera (2) is predetermined.

1 1 . Method according to any one of the preceding claims,

characterized in that

as the camera setting (22) a control signal (23) for adjusting a screen brightness of a screen (24) of the motor vehicle (1 ), which is coupled with the camera (2), is generated.

12. Method according to any one of the preceding claims,

characterized in that

as the camera setting (22) a further control signal (25) for adjusting an efficiency of an antireflection layer (26) of a rear view mirror (17) of the motor vehicle (1 ) is generated.

13. Method according to any one of the preceding claims,

characterized in that

the reference state (16) of the environmental region (7) is predetermined as day light state (42) and/or urban night state (43) and/or extra-urban, dark night state (44) and/or extra-urban night state (45) with light from headlights (1 1 ) of a further motor vehicle (10) in the environmental region (7).

14. Camera (2) for a motor vehicle (1 ), which is configured to perform a method

according to any one of the preceding claims.

15. Motor vehicle (1 ) comprising a camera (2) according to claim 14.