DE102020203585A1 - Arrangement and filters for image processing, computer-implemented method for controlling such a filter, control device for an imaging sensor, camera for polarizing light and control system for a vehicle comprising such a camera - Google Patents

Abstract

An arrangement for image processing comprising at least a first liquid crystal (LC1) and a second liquid crystal (LC2) which are arranged one behind the other with respect to a first direction (z), the first liquid crystal (LC1) moving in a second direction in response to a first field (x) and the second liquid crystal (LC2) can be oriented in a third direction (y) in response to a second field. The invention also relates to a filter (F) for image processing, a computer-implemented method for controlling a filter (F), an imaging sensor (APS) comprising the filter (F), a control unit (20) for an imaging sensor (APS), a camera ( C) and a control system (30) for a vehicle (V) comprising the camera (C).

Description

The invention relates to an arrangement and filters for image processing, a computer-implemented method for controlling such a filter, a control device for an imaging sensor, a camera for polarizing light and a control system for a vehicle comprising such a camera

It is known from the prior art to use polarization filters in digital imaging methods in order to remove reflections from surfaces in recordings, for example highlights caused by reflections, to increase contrasts and to enlarge the dynamic range of an imaging sensor.

It is also known from the prior art to polarize light by means of liquid crystals. For example, in CH 532 261 a nematic rotary cell as a liquid crystal cell, also called twisted nematic liquid crystal, abbreviated TNLC, is disclosed. the DE 10 2016 012 341 A1 discloses a driver assistance system for a motor vehicle with an exposure-compensated camera comprising two polarization filters which can be rotated relative to one another with a liquid crystal layer arranged between them, preferably an electrochromic liquid crystal layer.

When using static polarization filters, half of the incident light is usually filtered out for further image processing. This makes image processing difficult for low-light conditions.

In addition, electrochromic filters lead to color falsification. For example, those in de 10 2017 118 506 A1 The electrochromic cells described are not suitable for use in cameras in the automotive sector. Tungsten trioxide becomes active when an electrical voltage is applied and turns blue. A tungsten trioxide coating in a vehicle camera system would change the color perception of an image sensor in a vehicle camera. Dye-doped polymer-dispersed liquid crystals are opaque when they are not subjected to an electric field and transparent when they are subjected to an electric field. If an electrical voltage in the vehicle were to break away, no light would be passed on to the image sensor with such a liquid crystal when used with a vehicle camera. For reasons of functional safety, this is not acceptable for a vehicle camera.

The object of the invention was how the disadvantages of the polarization filters known from the prior art can be overcome.

The invention solves this problem by connecting layers of liquid crystals one behind the other, which in a neutral position have no polar filter effect. This improves image processing in low-light conditions, for example in tunnels. By selectively driving the liquid crystals, the invention provides a selective polarization camera that detects surface properties, for example wetness or icing on a road.

According to one aspect, the invention provides an arrangement for image processing. The arrangement comprises at least a first liquid crystal and a second liquid crystal, which are arranged one behind the other with respect to a first direction. The first liquid crystal is orientable in a second direction in response to a first field. The second liquid crystal is orientable in a third direction in response to a second field.

In another aspect, the invention provides a filter for image processing. The filter comprises an arrangement according to the invention of first liquid crystals and second liquid crystals. With respect to a right-angled coordinate system, the second liquid crystals are arranged behind the first liquid crystals with respect to a first coordinate axis. The first liquid crystals can be oriented parallel to a second coordinate axis in response to a first field and the second liquid crystals can be oriented parallel to a third coordinate axis in response to a second field in order to achieve a filter effect depending on the orientations of the liquid crystals.

• • Erhalten von ersten Signalen des Bildgebungssensors,
• • Analysieren der ersten Signale
• • in Abhängigkeit der Analyse der ersten Signale Bestimmen von ersten und/oder zweiten Flüssigkristallen des Filters, die in Reaktion auf ein erstes und/oder zweites Feld orientierbar sind, um Pixeln des Bildgebungssensors polarisiertes Licht bereitzustellen,
• • Anlegen des ersten und/oder zweiten Feldes an die bestimmten ersten und/oder zweiten Flüssigkristalle.

According to a further aspect, the invention provides a computer-implemented method for controlling a filter according to the invention which, when used with respect to incident light, is arranged in front of an imaging sensor. The method comprises the steps

• • Receiving the first signals from the imaging sensor,
• • Analyze the first signals
• • as a function of the analysis of the first signals, determining first and / or second liquid crystals of the filter, which can be oriented in response to a first and / or second field in order to provide polarized light to pixels of the imaging sensor,
• Application of the first and / or second field to the specific first and / or second liquid crystals.

In another aspect, the invention provides an imaging sensor. The imaging sensor comprises one according to the invention Filter. The filter is implemented as a layer on the imaging sensor.

• • eine erste Schnittstelle, um erste Signale des Bildgebungssensors zu erhalten,
• • eine Recheneinheit, die ausgeführt ist, Befehle eines Computerprogramms auszuführen, die bewirken, dass die Recheneinheit ein erfindungsgemäßes Verfahren ausführt, wenn das Computerprogramm auf der Recheneinheit läuft, und
• • eine zweite Schnittstelle, um ein erstes und/oder zweites Feld an von der Recheneinheit bestimmte erste und/oder zweite Flüssigkristalle anzulegen.

According to a further aspect, the invention provides a control device for an imaging sensor. The control unit includes

• • a first interface to receive first signals from the imaging sensor,
• A processing unit which is designed to execute commands of a computer program which cause the processing unit to carry out a method according to the invention when the computer program is running on the processing unit, and
• A second interface in order to apply a first and / or second field to first and / or second liquid crystals determined by the computing unit.

In another aspect, the invention provides a camera for polarizing light. The camera comprises an imaging system, an imaging sensor, a filter according to the invention and a control device according to the invention. The filter is arranged in front of the imaging system with respect to incident light, or is arranged between the imaging system and the imaging sensor, or is implemented on the imaging sensor.

According to a further aspect, the invention provides a control system for a vehicle. The control system comprises a camera according to the invention for recognizing surface properties of a road. A control unit of the camera or a control unit for longitudinal and / or lateral guidance of the vehicle is designed to execute commands from a computer program that cause the control unit to determine a coefficient of friction for the road based on an analysis of surface images of the camera and actuators for the longitudinal and / or controls lateral guidance of the vehicle as a function of the coefficient of friction when the computer program is running on the control unit.

Further refinements of the invention emerge from the subclaims, the drawings and the description of preferred exemplary embodiments.

Image processing includes electronic image processing. The filter according to the invention is used in image generation and / or in methods for generating information from an image. An image is generated, for example, in that voltage values at pixels of an imaging sensor are read out and brightness and / or color information is obtained. Information that is generated from an image includes, for example, brightness and / or color histograms, that is to say frequencies of gray and / or color values.

According to one aspect of the invention, the first direction corresponds to a direction of incidence of light.

According to one aspect of the invention, the first and the second liquid crystal each comprise means for applying an electrical voltage in order to build up the first and second fields. Depending on the field strength, the liquid crystals are oriented, for example parallel to the vector of the respective field strength. For example, atoms or molecules of the liquid crystals orient themselves. According to one aspect of the invention, the first field is equal to the second field in terms of amount and / or direction.

According to one aspect of the invention, the first and / or second field are electrical, magnetic or electromagnetic fields.

According to one aspect of the invention, the liquid crystals comprise ferroelectric liquid crystals. Ferroelectric liquid crystals are, for example, in EP 0 294 852 B1 disclosed. Ferroelectric liquid crystals maintain their adopted orientation when the electric fields disappear. Ferroelectric liquid crystals switch the optical axis with switching times in the microsecond range at a contrast ratio of 100: 1. This enables high levels of contrast to be achieved. Ferroelectric liquid crystals are functional in a temperature range from -20 ° C to + 60 ° C, which is advantageous for automotive applications, for example for use as filters in vehicle cameras.

According to a further aspect of the invention, the first liquid crystal and / or the second liquid crystal are each arranged as a third layer between a first layer and a second layer, the first layer and the second layer each being designed as an electrode. The first liquid crystal and / or the second liquid crystal is thus sandwiched between electrodes. The electrodes correspond to the means for applying an electrical voltage. Such a layer arrangement is called a liquid crystal cell.

According to one aspect of the invention, the first liquid crystal and the second liquid crystal are each implemented as such a liquid crystal cell.

According to a further aspect of the invention, the first layer and / or the second layer of the liquid crystal cells comprise indium tin oxide. For example, the first and / or the second layer is made of indium tin oxide glass. Indium tin oxide is transparent in visible light. So be get transparent electrodes. The image generation is not disturbed by the transparency.

According to a further aspect of the invention, only the first or the second layer of the liquid crystal cells comprises indium tin oxide. The respective other layer comprises a different, for example translucent, transparent or colored material.

The liquid crystal cells have, for example, a thickness of approximately 2-10 micrometers, for example 5 micrometers. Such a thickness enables the liquid crystal cells to be implemented on the imaging sensor.

1. 1. Erstes Feld an, zweites Feld aus, zweite Flüssigkristalle unorientiert: Erste Flüssigkristalle lassen linear in x-Richtung polarisiertes Licht durchgehen. Zweite Flüssigkristalle filtern nicht. Ergebnis: In x-Richtung linear polarisiertes Licht verlässt den Filter.
2. 2. Erstes Feld an, zweites Feld an: Erste Flüssigkristalle lassen linear in x-Richtung polarisiertes Licht durchgehen. Zweite Flüssigkristalle lassen linear in y-Richtung polarisiertes Licht durchgehen. Ergebnis: In x-Richtung linear polarisiertes Licht wird von den zweiten Flüssigkristallen herausgefiltert. Damit verlässt kein Licht den Filter.
3. 3. Erstes Feld aus, erste Flüssigkristalle unorientiert, zweites Feld an: Erste Flüssigkristalle filtern nicht. Zweite Flüssigkristalle lassen linear in y-Richtung polarisiertes Licht durchgehen. Ergebnis: In y-Richtung linear polarisiertes Licht verlässt den Filter.
4. 4. Erstes Feld aus, erste Flüssigkristalle unorientiert, zweites Feld aus, zweite Flüssigkristalle unorientiert: Keine Filterwirkung. Ergebnis: Einfallendes Licht verlässt den Filter ungefiltert.

According to one aspect of the invention, light is incident on the first liquid crystal cells in the z direction of a Cartesian coordinate system. The second liquid crystal cells are arranged behind the first liquid crystal cells in the z direction. When the first field is applied, for example a first electric field, the first liquid crystals are oriented in the x direction. With such an orientation, the first liquid crystals only allow the portion of the incident light to pass that is linearly polarized in the x-direction. When the second field, for example a second electric field, is applied, the second liquid crystals are oriented in the y-direction. With such an orientation, the second liquid crystals only allow that portion of the light which has passed through the first liquid crystals to pass through which is linearly polarized in the y-direction. The following configurations then result:

1. 1. First field on, second field off, second liquid crystals unoriented: First liquid crystals allow light polarized linearly in the x-direction to pass through. Second liquid crystals do not filter. Result: light polarized linearly in the x-direction leaves the filter.
2. 2. First field on, second field on: First liquid crystals allow light polarized linearly in the x-direction to pass through. Second liquid crystals allow light polarized linearly in the y-direction to pass through. Result: Light polarized linearly in the x-direction is filtered out by the second liquid crystals. This means that no light leaves the filter.
3. 3. First field off, first liquid crystals unoriented, second field on: first liquid crystals do not filter. Second liquid crystals allow light polarized linearly in the y-direction to pass through. Result: light polarized linearly in the y-direction leaves the filter.
4. 4. First field off, first liquid crystals unoriented, second field off, second liquid crystals unoriented: No filter effect. Result: Incident light leaves the filter unfiltered.

Since the liquid crystal cells only absorb light when the fields are applied, light can reach the imaging sensor in the event of a voltage failure and is therefore compliant with functional safety. This corresponds to the configuration 4 described above. This is particularly relevant for a vehicle camera with an imaging sensor and a filter and control device according to the invention.

Configuration 2 described above realizes a blackout device.

A vehicle camera is, for example, a camera that records an outside area of a vehicle, for example road sections and traffic scenarios lying ahead. When used, the vehicle camera is arranged, for example, in an interior of the vehicle behind a windshield, for example a front window. The vehicle camera is, for example, a camera of a driver assistance system or an autonomous driving system.

Conversely, if the liquid crystal cells only let light pass when a voltage was applied, the vehicle camera would no longer be able to capture the surroundings in the event of a voltage failure.

These different filterings are achieved without static, linear polarizing filters. Liquid crystals connected in series and orientable by means of an electric field strength are required.

According to one aspect of the invention, the filter comprises a first array of a plurality of the first liquid crystals and a second array of a plurality of the second liquid crystals, wherein the second array is arranged behind the first array with respect to the first coordinate axis and wherein the first liquid crystals and / or the second liquid crystals can each be controlled individually.

For example, the first liquid crystal cells comprising the first liquid crystals are arranged in the first array and the second liquid crystal cells comprising the second liquid crystals are arranged in the second array.

Due to the individual control, selective and dynamic filtering is achieved at the same time. According to one aspect of the invention, the individual control takes place for each of the multiple first liquid crystals in the first array by means of a first control device and for each of the multiple second liquid crystals in the second array with a second control device. The first and second control device controls a time curve of an electrical voltage in order to turn on or off the first and second fields turn off. This provides a selective and dynamic filter.

Computer-implemented means that the method is carried out by a computer. The method selectively determines the first and / or second liquid crystals with which a filter effect is to be achieved. For example, the first and / or second liquid crystal cells are selectively driven. According to one aspect of the invention, pixels of the imaging sensor are assigned to first and / or second liquid crystals. For example, first and second liquid crystals are assigned to each pixel or a group of pixels. Since the liquid crystals, for example the liquid crystal cells, can be controlled individually, selective filters are thus provided for each pixel or groups of pixels of the imaging sensor. One of the four filter effects described above is thus achieved for each pixel or for groups of pixels.

Imaging sensors include a sensor surface including pixels. Imaging sensors include image sensors in the visible range and in the infrared range. The infrared range is relevant, for example, for a vehicle camera that takes night photos. For example, the imaging sensor is a charged-coupled device, that is a CCD sensor, or an active pixel sensor based on complementary metal-oxide-semiconductor, abbreviated CMOS, technology. The advantages of an active pixel sensor include that each pixel has its own amplifier and is processed separately. This enables, for example, high frame rates compared to CCD sensors of the same size. The diagonal of the imaging sensor is between 21 mm and 43 mm long, depending on the sensor format.

According to a further embodiment of the method, highlight pixels of the imaging sensor are determined as a function of the first signals and the first and / or second liquid crystals are determined which can be oriented in response to the first and / or second field in order to generate the highlight by means of polarization of the incident light - Darken pixels. In this way, highlights, which are caused, for example, by reflections from surfaces, are filtered by darkening them, for example by the second of the four configurations described above. Glare is avoided in the same way. This enables longer exposure times without overexposed highlights. This increases the dynamic range of the imaging sensor.

The imaging sensor according to the invention with an implemented filter according to the invention has the advantage that separate parts can be saved in an optical system. In addition to the imaging sensor, no further separate filter component is required in order to achieve a polarizing effect, since the filter is already integrated in the imaging sensor.

According to one aspect of the invention, in addition to the filter according to the invention, further layers are integrated in the imaging sensor, for example low-pass filters, infrared filters, microlenses or color filters, for example color filters comprising a Bayer matrix.

The first signals that the control device receives via the first interface are, for example, brightness values of individual pixels of the imaging sensor.

According to one aspect of the invention, the control device according to the invention controls the liquid crystals or the liquid crystal cells individually, selectively and dynamically. Thus, according to one aspect of the invention, the four configurations described above can be switched for each pixel or for a group of pixels of the imaging sensor. In particular, each pixel or group of pixels can be individually and selectively darkened according to the second configuration. If, for example, intense solar radiation hits areas of the imaging sensor, the liquid crystals are activated, which darken an image section corresponding to the current position of the sun. The dynamic control reacts accordingly to a change in the sun's position. For example, the control unit tracks the position of the sun by reading out the first signals. The control device is for example an electronic control device, also called electronic control device, abbreviated ECU.

According to one aspect of the invention, the control device controls and / or regulates the imaging sensor according to the invention.

According to a further aspect of the invention, the control device is a microcontroller of the imaging sensor, which controls the liquid crystals or the liquid crystal cells individually, selectively and dynamically.

The computing unit is, for example, a microcomputer and comprises a memory unit in which the computer program is stored. While the computer program is being executed, the microcomputer reads the memory unit. The commands of the computer program are program instructions. The commands are written, for example, in a procedural programming language such as C or an object-oriented programming language such as C ++ or are available in machine code. The control device outputs, for example, an electrical voltage via the second interface.

The imaging system of the camera comprises at least one lens or an objective comprising a plurality of lenses.

The camera is, for example, a vehicle camera of a driver assistance system or an autonomous driving system. As such, it improves image recordings in intense sunlight or low sun angles through polarization, or reduces or even eliminates annoying glaring light from oncoming vehicles or reflective surfaces and thus reduces glare. Reflective surfaces are, for example, wet or icy road surfaces. In the case of reflections, the reflected light is at least partially polarized. At the Brewster angle, only the portions of the electric field component polarized perpendicular to the plane of incidence are reflected; the reflected light is then linearly polarized. This polarized light is then filtered out by means of the filter according to the invention. It is within the scope of the invention to also use the camera in surveillance systems in order to better control difficult lighting conditions in this area as well.

According to one aspect of the invention, the liquid crystals or liquid crystal cells are assigned to individual pixels or groups of pixels of the imaging sensor. Depending on the extrinsic and / or intrinsic parameters of the camera, the control device determines the liquid crystals for which a darkening of the corresponding pixels is required.

Intrinsic parameters of the camera determine how optical measurements of the image sensor of the camera and image points, in particular pixel values, of the image sensor are related. For example, the focal length of an optical system or the pixel density of the image sensor are intrinsic parameters of the camera. Extrinsic parameters are external parameters of the camera, for example the geometric arrangement of the camera in space. For example, the position of a rearview mirror and the position of a fixation of the camera on the rearview mirror are extrinsic parameters of the camera. With knowledge of the extrinsic and intrinsic parameters of the camera and the position of the sun in the real world or on the image sensor, which the arithmetic unit receives via the first interface, the arithmetic unit creates a one-to-one assignment between liquid crystal cells and pixels of the image sensor. In this way, the control device can control the liquid crystal cells individually and selectively in a targeted manner by means of the second interface.

The invention thus provides a selective polarization camera with which different applications can be implemented at the same time on different areas of the camera. A static polarization camera or a combination of several static polarization cameras is not required.

The surface properties of the road that the control system detects are, for example, wetness or icing. A wet or icy road surface has a different coefficient of friction than a dry road surface. The actuators that are controlled by the control unit include actuators for braking, engine power and steering. Driving strategies adapted to wet or icy road surfaces are achieved through the activation of these actuators depending on the coefficient of friction. In the case of a coefficient of friction determined for icy road surfaces, actuators for the longitudinal guidance are controlled, for example, in such a way that the wheel speed is low when starting off. The coefficient of friction is determined, for example, using look-up tables that correlate certain features of the surface images with coefficients of friction. Alternatively, the coefficient of friction is determined using machine learning. Machine learning is a technology that teaches computers and other data processing devices to perform tasks by learning from data, recorded therefrom, instead of being programmed to perform the tasks.

• 1 ein Ausführungsbeispiel einer erfindungsgemäßen Anordnung,
• 2 ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Anordnung oder ein Ausführungsbeispiel eines erfindungsgemäßen Filters,
• 3 ein Ausführungsbeispiel eines erfindungsgemäßen Filters in einer ersten Konfiguration,
• 4 ein Ausführungsbeispiel des Filters aus 3 in einer zweiten Konfiguration,
• 5 ein Ausführungsbeispiel des Filters aus 3 in einer dritten Konfiguration,
• 6 ein Ausführungsbeispiel des Filters aus 3 in einer vierten Konfiguration,
• 7 ein Ausführungsbeispiel eines erfindungsgemäßen Filters,
• 8 ein Ausführungsbeispiel eines erfindungsgemäßen Steuergeräts,
• 9 eine schematische Darstellung des erfindungsgemäßen Verfahrens,
• 10 ein Ausführungsbeispiel einer erfindungsgemäßen Kamera,
• 11 ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Kamera und
• 12 ein Ausführungsbeispiel eines erfindungsgemäßen Steuerungssystems.

The invention is illustrated in the following exemplary embodiments. Show it:

• 1 an embodiment of an arrangement according to the invention,
• 2 another embodiment of an arrangement according to the invention or an embodiment of a filter according to the invention,
• 3 an embodiment of a filter according to the invention in a first configuration,
• 4th an embodiment of the filter 3 in a second configuration,
• 5 an embodiment of the filter 3 in a third configuration,
• 6th an embodiment of the filter 3 in a fourth configuration,
• 7th an embodiment of a filter according to the invention,
• 8th an embodiment of a control device according to the invention,
• 9 a schematic representation of the method according to the invention,
• 10 an embodiment of a camera according to the invention,
• 11 a further embodiment of a camera according to the invention and
• 12th an embodiment of a control system according to the invention.

In the figures, the same reference symbols denote the same or functionally similar reference parts. For the sake of clarity, only the relevant reference parts are highlighted in the individual figures.

The in 1 second liquid crystal shown LC2 is behind the first liquid crystal with respect to the z-direction LC1 arranged. The first liquid crystal LC1 and the second liquid crystal LC2 are ferroelectric liquid crystals. The first liquid crystal LC1 and the second liquid crystal LC2 each form a third layer that is between a first layer E1 and a second layer E2 is sandwiched. The first layer E1 forms an electrode. The second layer E2 forms an electrode. The electrodes are made of indium tin oxide glass, for example. The control device according to the invention 20th applies an electrical potential to the electrodes. When an electrical potential is applied, an electrical field is created between the electrodes. Atoms or molecules of the first liquid crystal LC1 orient themselves parallel to the field lines of the first electric field. Atoms or molecules of the second liquid crystal LC2 orient themselves parallel to the field lines of the second electric field. The layer structure E1 , LC1 , E2 forms a first liquid crystal cell LCC1 . The layer structure E1 , LC2 , E2 forms a second liquid crystal cell LCC2 . The arrangement of the 1 comprising the first liquid crystal LC1 or the first liquid crystal cell LCC1 and the second liquid crystal LC2 or the second liquid crystal cell LCC2 forms a filter according to the invention F. .

2 shows a first array A1 comprising a plurality of the first liquid crystals LC1 or more of the first liquid crystal cells LCC1 and a second array A2 comprising a plurality of the second liquid crystals LC1 or more of the second liquid crystal cells LCC2 . The first array A1 and the second array A2 form a filter according to the invention F. . The second array A2 is behind the first array in the z-direction A1 arranged. Each of the first liquid crystals LC1 or each of the first liquid crystal cells LCC1 can be controlled individually by means of a control unit ECU1 . Each of the second liquid crystals LC2 or each of the second liquid crystal cells LCC1 can be controlled individually by means of a control unit ECU2 .

3 until 6th show possible configurations of the filter according to the invention F. . In 3 is the first electric field in the state 1 , that means on. The second electric field is in the state 0, that is to say off. The second liquid crystals LC2 are disoriented. The first liquid crystals LC1 allow light polarized linearly in the x-direction to pass through. The second liquid crystals LC2 do not filter. As a result, light polarized linearly in the x-direction leaves the filter F. .

In 4th the first electric field and the second electric field are in the state, respectively 1 . The first liquid crystals LC1 allow light polarized linearly in the x-direction to pass through. The second liquid crystals LC2 allow light polarized linearly in the y-direction to pass through. As a result, it will be after the first liquid crystals LC1 light linearly polarized in the x-direction from the second liquid crystals LC2 filtered out. This means that no light leaves the filter F. .

In 5 is the first electric field in the state 0. The first liquid crystals LC1 are disoriented. The second electric field is in the state 1 . The first liquid crystals LC1 do not filter. The second liquid crystals LC2 allow light polarized linearly in the y-direction to pass through. As a result, light polarized linearly in the y-direction leaves the filter F. .

In 6th the first electric field and the second electric field are each in the state 0. The first liquid crystals LC1 and the second liquid crystals LC2 are each unoriented. No filter effect is achieved. As a result, incident light leaves the filter F. unfiltered.

In 7th are form the first array A1 and the second array A2 and with it the filter F. a layer of the imaging sensor APS and are thus on the imaging sensor APS integrated. The imaging sensor APS is for example an active pixel sensor.

8th shows the control device according to the invention 20th comprising a first interface 21 and a second interface 22nd . The arithmetic unit 23 leads the in 9 shown steps of the method according to the invention.

In the process step V1 are the first signals from the imaging sensor APS obtain. In the process step V2 the first signals are analyzed, for example with regard to brightness or gray value. Depending on the analysis of the first signals, the method step V3 the first and / or second liquid crystals LC1 , LC2 of the filter F. determined, which are orientable in response to a first and / or second field, to pixels P. of the imaging sensor APS provide polarized light. In the process step V4 the first and / or second field is attached to the specific first and / or second liquid crystals LC1 , LC2 created.

10 and 11 each show a camera according to the invention C. . The camera C. includes an imaging system LS , for example a lens system comprising two lenses. The camera also includes C. the filter according to the invention F. . In 10 is the filter F. between the imaging system LS and the imaging sensor APS arranged. In 11 is the filter F. before the imaging system LS arranged. It also includes the camera C. the control device according to the invention 20th , for example as in 8th shown. The camera C. takes a picture of an object I. , for example a traffic scene when the camera C. is used as a vehicle camera of a vehicle control system.

Via the first interface 21 receives the control unit 20th first signals from the imaging sensor APS , for example brightness values of pixels P. of the imaging sensor APS . The control unit analyzes these brightness values 20th . For example, the control device checks which brightness values exceed a predetermined threshold value for brightness. The pixels P. whose brightness values exceed the threshold value are, for example, highlight pixels. About the extrinsic and intrinsic parameters of the camera C. is the assignment of the individual first and second liquid crystals LC1 , LC2 to the respective pixels P. , for which a darkening or a polarization filtering is to be achieved, for example for the highlight pixels, are known. This assignment is implemented, for example, in the computer program that the computing unit 23 of the control unit 20th executes. The control unit determines this assignment 20th the first and second liquid crystals LC1 , LC2 that should be used as filters, for example to darken the highlight pixels. The electrodes are then connected via the second interface E1 and E2 of the determined first and second liquid crystals LC1 , LC2 electrical potentials are applied so that the first and second liquid crystals LC1 , LC2 orientated themselves in the electric fields in order to achieve the filter effect. That’s the camera C. a selective polarization camera.

The in 12th control system shown 30th determines a control unit ECU3 a coefficient of friction on the road S. depending on an analysis of a surface property R. . The surface property R. , for example a puddle of rainwater that reflects light and creates highlights, is shown with the camera C. certainly. The control unit ECU3 regulates and / or controls actuators for longitudinal and / or lateral guidance of the vehicle V depending on the specific coefficient of friction.

List of reference symbols

LC1

first liquid crystal

LCC1

first liquid crystal cell

A1

first array

ECU1

first control unit

LC2

second liquid crystal

LCC2

second liquid crystal cell

A2

second array

ECU2

second control unit

E1

first layer

E2

second layer

F.

filter

APS

Imaging sensor

P.

pixel

I.

object

20th

Control unit

21

first interface

22nd

second interface

23

Arithmetic unit

C.

camera

LS

Imaging system

V

vehicle

30th

Control system

ECU3

Control unit

S.

Street

R.

Surface property

V1-V4

Procedural steps

z

z direction

x

x direction

y

y direction

O

the end

1

a

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102016012341 A1 [0003]
• WO 102017118506 A1 [0005]
• EP 0294852 B1 [0020]

Claims (11)

An arrangement for image processing comprising at least a first liquid crystal (LC1) and a second liquid crystal (LC2) which are arranged one behind the other with respect to a first direction (z), the first liquid crystal (LC1) moving in a second direction in response to a first field (x) and the second liquid crystal (LC2) can be oriented in a third direction (y) in response to a second field. Arrangement according to Claim 1 wherein the liquid crystals (LC1, LC2) comprise ferroelectric liquid crystals. Arrangement according to Claim 1 or 2 , wherein the first liquid crystal (LC1) and / or the second liquid crystal (LC2) are each arranged as a third layer between a first layer (E1) and a second layer (E2), the first layer (E1) and the second layer in each case (E2) is designed as an electrode. A filter (F) for image processing comprising an arrangement according to one of the Claims 1 until 3 , wherein with respect to a right-angled coordinate system the second liquid crystal (LC2) are arranged behind the first liquid crystal (LC1) with respect to a first coordinate axis (z), the first liquid crystal (LC1) in response to a first field parallel to a second coordinate axis (x) and the second liquid crystal (LC2) can be oriented parallel to a third coordinate axis (y) in response to a second field in order to achieve a filter effect as a function of the orientations of the liquid crystals (LC1, LC2). Filter (F) Claim 4 comprising a first array (A1) of several of the first liquid crystals (LC1) and a second array (A2) of several of the second liquid crystals (LC2), the second array (A2) behind the first with respect to the first coordinate axis (z) Array (A1) is arranged and wherein the first liquid crystals (LC1) and / or the second liquid crystals (LC2) are each individually controllable. Computer-implemented method for controlling a filter (F) according to Claim 4 or 5 which, when used in relation to incident light, is arranged in front of an imaging sensor (APS), comprising the steps of • obtaining first signals from the imaging sensor (APS) (V1), • analyzing the first signals (V2) • as a function of the analysis of the first Signals Determination of first and / or second liquid crystals (LC1, LC2) of the filter (F), which can be oriented in response to a first and / or second field in order to provide pixels (P) of the imaging sensor (APS) with polarized light (V3) , • applying the first and / or second field to the specific first and / or second liquid crystals (LC1, LC2) (V4). Computer-implemented method according to Claim 6 , whereby, depending on the first signals, highlight pixels (P) of the imaging sensor (APS) are determined and the first and / or second liquid crystals (LC1, LC2) are determined, which can be oriented in response to the first and / or second field, to darken the highlight pixels (P) by polarizing the incident light. Imaging sensor (APS) comprising a filter (F) according to Claim 3 or 4th , wherein the filter (F) is implemented as a layer on the imaging sensor (APS). Control unit (20) for an imaging sensor (APS) comprising • a first interface (21) to receive first signals from the imaging sensor (APS), • a computing unit (23) which is designed to execute commands of a computer program that cause the arithmetic unit (23) a method according to Claim 6 or 7th executes when the computer program is running on the computing unit (23), and • a second interface (22) to apply a first and / or second field to first and / or second liquid crystals (LC1, LC2) determined by the computing unit (23) . Camera (C) for polarizing light comprising an imaging system (LS), an imaging sensor (APS), a filter (F) Claim 3 or 4th and a control device (20) according to Claim 9 wherein the filter (F) is arranged in front of the imaging system (LS) with respect to incident light or is arranged between the imaging system (LS) and the imaging sensor (APS) or is implemented on the imaging sensor (APS). Control system (30) for a vehicle (V) comprising a camera (C) according to Claim 10 to recognize surface properties (R) of a road (S), whereby a control unit (20) of the camera (C) or a control unit (ECU3) for longitudinal and / or lateral guidance of the vehicle (V) is designed to execute commands of a computer program, which cause the control unit (20, ECU3) to determine a coefficient of friction for the road (S) as a function of an analysis of surface images from the camera (C) and actuators for the longitudinal and / or lateral guidance of the vehicle (V) as a function of the coefficient of friction controls when the computer program is running on the control unit (20, ECU3).

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