Driver assistance system and related image processing method

Abstract

The invention relates to a driving assistance system comprising at least one optical sensor and at least one associated protection device (3) comprising a transparent and rotatably mounted optical element (5). The protection device (3) comprises at least one acquisition element (11) for acquiring at least one information describing at least one angular position of the optical element in the capture of an image. The system comprises a processing unit configured to detect the presence of at least one defect (100) in the optical element (5), to receive information describing the angular position of the optical element, to determine based thereon at least one angular position of said defect in the optical element and to remove said defect in the captured image by means of image processing, taking into account the determined angular position of said defect in the optical element.

Description

[Technical Field]

[0001] The present invention relates to the field of driver assistance, in particular to driver assistance systems installed in certain vehicles, potentially comprising at least one optical sensor, and to an associated image processing method. [Background technology]

[0002] Optical sensors such as cameras, LIDAR (an acronym for "light detection and ranging" or "laser imaging, detection and ranging") and sensors based on the emission and / or detection of light in the human visible or invisible spectrum, in particular the infrared spectrum, are increasingly being installed in automobiles in recent years, forming in particular part of driver assistance systems such as parking assistance systems and lane departure detection systems.

[0003] In particular, it is known to equip automobiles with parking assistance rearview cameras that can detect obstacles behind the vehicle. These cameras can be installed inside the passenger compartment, for example against the rear window and facing rearward through the rear window of the vehicle. The cameras are thus well protected from bad weather and organic or inorganic pollutants.

[0004] However, such cameras located inside the passenger compartment do not always have an optimal viewing angle, particularly for parking assistance, since they cannot always see obstacles located near the rear of the vehicle, for example.

[0005] For this reason, it is preferable to position one or more cameras of a driver assistance system on the exterior of the automobile in various locations depending on the desired application, such as on the front or rear bumper of the vehicle or near the front or rear license plate. However, in this case, such cameras are likely to attract mineral or organic dust and dirt, which can accumulate on the camera's optics and reduce its effectiveness or even render it inoperable. This can have a significant impact on the operability of a driver assistance system equipped with such cameras.

[0006] To prevent dust from accumulating on such cameras, it is known to place an optical element, such as a transparent protective lens, in front of the camera to protect it from external attack, however, the protective lens may become dirty or damaged due to constant external attack.

[0007] The protective lens is rotatably positioned so that it can be cleaned by centrifugal effect. However, such cleaning may be insufficient to remove hard-to-remove types of dirt, such as tar. The protective lens may also be subject to collisions with objects, for example, while driving, which can result in scratches, chips, or other damage. This can lead to defects that degrade or darken the images captured by the optical sensor. This is because the defects move as the protective lens rotates. This can adversely affect the field of view and image quality of the images captured by the optical sensor. Summary of the Invention

[0008] The present invention proposes to at least partially remedy the above-mentioned drawbacks by providing an alternative means by which degradation of the image captured by the optical sensor can be avoided in the event of defects in an upstream optical element.

[0009] To this end, one subject of the present invention is a driver assistance system comprising at least one optical sensor comprising an optical component and configured to capture at least one image along an optical axis, and at least one protection device associated with at least one said optical sensor, said protection device comprising a transparent optical element rotatably mounted upstream of the optical component of the associated optical sensor along said optical axis, and comprising a motor configured to drive said optical element in rotation.

[0010] According to the invention, the protection device comprises at least one element for obtaining at least one piece of information describing at least one angular position of the optical element while the associated optical sensor captures at least one image.

[0011] The system includes a processing unit, the processing unit comprising: - detecting the presence of at least one defect on said optical element; receiving at least one said piece of information describing said angular position of at least one of said optical elements, - determining at least one angular position of at least one of said defects on said optical element based on at least one of said received description information; - removing by image processing at least one said defect from at least one said image captured by at least one said optical sensor, taking into account said at least one determined angular position of said at least one said defect on said optical element; It is configured as follows.

[0012] More specifically, the optical element is mounted so as to be rotatable about an axis of rotation.

[0013] In particular, the motor is configured to rotate the optical element around a rotation axis, so that the optical element can be cleaned by centrifugal effect.

[0014] The driver assistance system may further comprise one or more of the features described below, either separately or in combination.

[0015] According to one embodiment, the motor includes a fixed stator and a rotor rotatable about a rotation axis relative to the fixed stator. The motor may have a rotational speed of 1,000 to 50,000 rpm, preferably 5,000 to 20,000 rpm, and more preferably 7,000 to 15,000 rpm.

[0016] Therefore, the motor is configured to continuously rotate the optical element in front of the optical sensor when it is in operation at a speed such that any dust particles are blown off the optical element by centrifugal effect. In particular, the work done by the centrifugal force is sufficiently greater than the adhesion force of the dust particles to the optical element. Therefore, the optical sensor maintains good operability and its contamination is limited regardless of weather conditions. In this way, the driver assistance system maintains good visibility.

[0017] According to one embodiment, the motor is positioned on the opposite side of the optical element, in which case the rotation axis of the motor may coincide with the optical axis.

[0018] According to one aspect, the protection device advantageously comprises a holder or casing mounted rotatably about an axis of rotation.

[0019] The holder may, for example, define a housing for receiving the optical sensor such that the optical axis of the optical sensor coincides with the axis of rotation of the holder.

[0020] The protection device therefore comprises a fixed part including the stator and a movable part including the rotor, the holder and the optical element.

[0021] According to one embodiment, the optical element is mounted to rotate integrally with the holder and is configured to be located at the front of the holder. The expression "front of the holder" is understood to mean the part of the holder that is intended to be placed facing the road scene that the optical sensor is involved in capturing images of when the protection device is mounted on a motor vehicle. In contrast, the expression "rear of the holder" is understood to mean the part of the holder opposite the front and therefore the part that is furthest from the road scene.

[0022] According to one aspect, the processing unit may be configured to identify the angular position of at least one of the optical elements based on at least one of the received depiction information, and to estimate the angular position of at least one of the defects on the optical element from the identified angular position of the at least one of the optical elements.

[0023] According to another aspect, the processing unit may be configured to receive or identify at least one piece of information describing the rotational speed of the optical element and synchronize capture of the image to the rotational speed of the optical element.

[0024] At least one of the capture elements may include a rotation indicator disposed on the optical element such that the rotation indicator is within the field of view of the associated optical sensor.

[0025] The rotation indicator, commonly referred to as an OPR indicator, may be a reflective element that may take the form of a bar constructed of, for example, but not limited to, aluminum. According to another variation, the rotation indicator may take the form of a known non-random defect, such as an inscription on the optical element.

[0026] Alternatively or additionally, at least one said acquisition element may comprise an angle sensor. Preferably, the angle sensor is an absolute angle sensor.

[0027] The angle sensor can be arranged on the moving part of the protection device, in particular on the optical element or its holder, or on the rotor, for example in the area where the rotor connects to the stator.

[0028] The angle sensor may be magnetic, optical, and may employ photodiodes or phototransistors to detect reflection or transmission of light, particularly generated by light emitting diodes or laser diodes, or may be holographic, but is not limited to these.

[0029] The processing unit comprises at least one processing means for determining the position of the optical element based on at least one angle measurement transmitted from an angle sensor arranged in the protection device.

[0030] According to yet another variant, or additionally, at least one said acquisition element may comprise a measurement unit configured to measure phase currents of said motor.

[0031] The measurement unit may comprise one or more measurement resistors, such as shunts, that are capable of measuring the amplitude of the current.

[0032] According to another aspect, the processing unit may be configured to define an image capture frequency depending on the rotational speed of the optical element such that for each image capture, at least the defect is at at least one of the identified angular positions in the captured image.

[0033] The processing unit may comprise at least one image processing means configured to extract at least one said defect located at at least one said identified angular position in the captured image.

[0034] According to yet another aspect, the at least one optical sensor can be configured to capture at least two successive images.

[0035] At least one of the image processing means may be configured to extract at least one region from at least two of the images that includes at least one of the defects, and to superimpose the at least two images to construct a new image that is free of the at least one defect.

[0036] The invention also relates to a device for protecting an optical sensor for a driver assistance system as described above, comprising a transparent optical element configured to be rotatably mounted upstream of the optical sensor along its optical axis, and a motor configured to drive said optical element in rotation, said device advantageously comprising at least one element for obtaining at least one piece of information describing at least one angular position of the optical element while the optical sensor captures an image.

[0037] The invention also relates to a related method for processing captured images for a driver assistance system as described above comprising at least one optical sensor and an associated protection device, said method comprising: - detecting, for example by a processing unit, the presence of at least one defect on the optical element of the protection device; receiving, for example by at least one acquisition element of a protection device, at least one piece of information describing at least one angular position of said optical element while said optical sensor captures at least one image; - determining, for example by a processing unit, in particular by image processing, at least one angular position of at least one of said defects on said optical element based on at least one of said received description information; - removing, by image processing, for example by a processing unit, at least one said defect from at least one image captured by at least one said optical sensor, taking into account said at least one determined angular position of said at least one said defect on said optical element; Equipped with.

[0038] The method comprises: - determining, for example by a processing unit, said angular position of at least one optical element based on said at least one acquired description information; - estimating, based on said determined angular position of at least one of the optical elements, at least one angular position of at least one of said defects on the optical element, for example by means of a processing unit, in particular by image processing; The device may further include:

[0039] The method may further comprise receiving or identifying at least one piece of information describing a rotational speed of the optical element, and synchronizing image capture with the rotational speed of the optical element.

[0040] The at least one defect is removed by image processing from the at least one image captured by the at least one optical sensor in a manner synchronized with a rotation speed of the optical element while taking into account the at least one identified angular position of the at least one defect on the optical element, whereby this example is a method for synchronizing image capture and processing of the captured image.

[0041] Further advantages and features of the invention will become more clearly apparent on reading the following description and the accompanying drawings, given as illustrative and non-limiting examples. [Brief explanation of the drawings]

[0042] [Figure 1] FIG. 1 shows an example of a protection device for an optical sensor for a driver assistance system. [Figure 2] FIG. 2 is a front view of the optical element of the protection device of FIG. [Figure 3a] 3a is a perspective view of the movable part of the protection device of FIG. [Figure 3b] FIG. 3b is a rear perspective view of the movable part of the protection device in FIG. 3a. [Figure 4] FIG. 4 is a schematic diagram showing the interaction of the protection device with the processing unit of the driver assistance system. [Figure 5] FIG. 5 shows a schematic representation of the image processing steps utilized to remove defects from images captured by an optical sensor. DETAILED DESCRIPTION OF THE INVENTION

[0043] In these drawings, identical elements are designated with the same reference numerals.

[0044] The following embodiments are examples. Although this specification refers to one or more embodiments, this does not necessarily mean that each reference refers to the same embodiment or that a feature applies only to a single embodiment. Individual features of various embodiments may be combined or interchanged to obtain other embodiments.

[0045] The present invention relates to a driver assistance system intended to be installed in a motor vehicle. The driver assistance system may in particular comprise one or more optical detection devices, such as optical sensors that contribute to parking assistance or in particular autonomous driving. Advantageously, optical sensors intended to be installed in a motor vehicle are in question.

[0046] Support System

[0047] With reference to FIG. 1, the driver assistance system comprises, inter alia, at least an optical sensor 1 and an associated protection device 3 .

[0048] The optical sensor 1 is configured to capture at least one image along an optical axis. It is, for example, an image capturing optical sensor 1 such as a camera. It may be a CCD sensor (CCD stands for "charge-coupled device") or a CMOS sensor with a matrix array of small photodiodes. According to another variant, it may also be a LIDAR sensor (LIDAR stands for "light detection and ranging" or "laser imaging, detection, and ranging").

[0049] Furthermore, the optical sensor 1 comprises an optical component such as a lens. The optical component may be convex (curved) with a convex portion oriented towards the outside of the optical sensor. For example, a so-called fisheye lens may be in question.

[0050] The optical sensor 1 may be housed inside a protection device 3, as shown in the example of Figure 1. The protection device 3 may be mounted on the front, rear or side of the vehicle. The protection device 3 may be installed on any element of the vehicle, such as a body element or an exterior element, for example, on the bumper, near the license plate, or near one of the rearview mirrors. The protection device 3 may be fixed in place using any known technique.

[0051] The protection device 3 comprises an optical element 5 intended to protect the optical components of the optical sensor 1. The protection device 3 is therefore an element or mask for protecting the optical sensor 1.

[0052] The optical element 5 is arranged upstream of the optical components of the optical sensor 1. Here, the term "upstream" is defined relative to the optical axis of the optical sensor 1. The optical element 5 is therefore intended to be arranged along the optical axis between the optical components of the optical sensor 1 and the road scene. This optical element 5 is therefore potentially subject to external attack, i.e., water, pollutants, dust, but also solid debris such as gravel that may damage the optical components of the optical sensor 1. The optical element 5 is advantageously dimensioned to cover the entire optical surface of the optical sensor 1.

[0053] The optical element 5 is transparent so as not to reduce the effectiveness of the optical sensor 1. The optical element 5 may be constructed from glass or clear plastic. The optical element 5 may, for example, be a lens that is separate from the optics of the optical sensor 1 and therefore may be external to the optical sensor 1.

[0054] The optical element 5 is mounted so as to be rotatable about a rotation axis A. In the illustrated example, the optical element 5 is disposed at the center with respect to the rotation axis A.

[0055] Furthermore, the protection device 3 advantageously comprises a holder 7 or casing mounted rotatably about an axis of rotation A.

[0056] The holder 7 may define a housing for receiving the optical sensor 1 such that the optical axis of the optical sensor 1 coincides with the rotation axis A of the holder 7. The holder 7 is, for example, defined by a generally cylindrical or substantially cylindrical wall.

[0057] The optical element 5 is mounted to rotate integrally with the holder 7 and is configured to be located at the front of the holder 7. The expression "front of the holder 7" is understood to mean the part of the holder 7 that is intended to be placed facing the road scene involved in image capture by the optical sensor 1 when the protection device 3 is mounted on a motor vehicle. In contrast, the expression "rear of the holder 7" is understood to mean the part of the holder 7 opposite the front and therefore the part that is furthest from the road scene.

[0058] Furthermore, the holder 7 is preferably sealed.

[0059] The protection device 3 also includes an actuator that can drive the optical element 5 to rotate.

[0060] The actuator can be connected to the holder 7 for the purpose of rotationally driving it. Therefore, the optical element 5 is configured to be rotationally driven together with the holder 7 by the actuator, so that the optical element 5 can be cleaned by the centrifugal effect.

[0061] The actuator is powered, for example, by a power source connected to the general electrical circuit of the vehicle. The actuator can be a motor 9, for example an electric motor, for driving the rotation of the holder 7. As a non-limiting example, the motor can more specifically be a brushless motor.

[0062] In particular, the motor 9 includes a fixed stator 91 and a rotor 93 that is rotatable about a rotation axis relative to the fixed stator 91. The motor 9 may have a rotational speed of approximately 10,000 revolutions per minute.

[0063] According to the embodiment shown, the motor 9 is arranged at the rear of the holder 7, opposite the optical element 5. In this example, the rotation axis of the motor 9 may coincide with the rotation axis A of the holder 7 and thus with the optical axis.

[0064] The protection device 3 therefore comprises a fixed part including the stator 91 and a movable part including the rotor 93, the holder 7 and the optical element 5.

[0065] Furthermore, the driver assistance system comprises at least one element for acquiring at least one piece of information describing the angular position of the optical element 5. Such an acquisition element may in particular form part of the protection device 3 and be attached to said element. With regard to acquiring at least one piece of information describing the angular position of the optical element 5, various embodiments are conceivable.

[0066] According to one embodiment, the at least one capture element may take the form of a rotation indicator 11, a highly schematic example of which is shown in FIG.

[0067] The rotation indicator 11 may be positioned on the optical element 5 so that it is within the field of view of the optical sensor. Thus, the rotation indicator 11 appears in images captured by the optical sensor. In other words, when taking an image, the optical sensor simultaneously "reads" this rotation indicator 11.

[0068] Such a rotation indicator 11 is commonly referred to as an OPR indicator. The rotation indicator 11 may be a reflective element, for example, a bar-shaped reflective element. Such a bar may be made of, for example, but not limited to, aluminum. According to another variant, the rotation indicator 11 may take the form of a known non-random defect, such as an inscription on the optical element 5.

[0069] In the example of Figure 2, a single rotation indicator 11 is shown. Of course, multiple rotation indicators or OPR indicators can be provided to improve angular position detection.

[0070] 3a and 3b, the at least one acquisition element may be an angle sensor 13 capable of determining the rotational position of the optical element 5. Preferably, the angle sensor 13 is an absolute angle sensor.

[0071] The angle sensor 13 may be arranged on a moving part of the protection device 3, in particular on the optical element 5 or its holder 7 or on the rotor 93, for example in the area Z where the rotor 93 connects to the stator 91.

[0072] The angle sensor 13 may be magnetic, optical, and may employ photodiodes or phototransistors to detect reflection or transmission of light, particularly but not limited to, light emitting diodes or laser diodes, or may be holographic.

[0073] According to yet another embodiment, the angular position of the optical element 5 can be determined based on the phase currents of the motor 9. For this purpose, the protection device 3 comprises a measurement unit 15 (FIG. 4) configured to measure the phase currents of the motor 9. The measurement unit 15 comprises, for example, one or more measurement resistors, such as shunts, which are able to measure the amplitude of the current.

[0074] Furthermore, the driver assistance system comprises at least one processing unit 17. The processing unit 17 comprises, for example, at least one microprocessor or microcontroller.

[0075] At issue may be a central processing unit 17, such as a central processing unit of a vehicle. In this example, the central processing unit 17 is common to the optical sensors 1 and the protection devices 3. In other words, the central processing unit 17 may exchange information with multiple devices, specifically the optical sensors 1 and the protection devices 3. Alternatively, the processing unit 17 may be associated with, for example, one optical sensor 1 and one protection device 3. At issue may be, for example, a microprocessor or microcontroller, which may be dimensioned to process one or more images captured by the associated optical sensor 1, for example to deliver the processed images to a control system of the vehicle.

[0076] Advantageously, the processing unit 17 may comprise one or more means for processing images acquired and transmitted by at least one optical sensor 1 in the case where the motor vehicle is equipped with multiple optical sensors 1, or images acquired and transmitted by an optical sensor 1 associated with the processing unit 17.

[0077] Such a processing unit 17 may also receive one or more pieces of information describing the angular position of the optical element.

[0078] 2, according to one embodiment, the processing unit 17 may determine the angular position of the optical element 5 depending on the position of the rotation indicator(s) 11 in the image captured by the optical sensor 1. The angular position is determined more precisely by at least one image processing means of the processing unit 17. This solution does not require a specific measuring system to be located on the protection device 3. The optical sensor 1, arranged behind the optical element 5, detects the rotation indicator(s) 11. This provides information about the position of this rotation indicator(s) 11, from which the angular position of the optical element 5 can be deduced by image processing.

[0079] It is also possible to use image processing using a small number of reference pixels, such as peripheral pixels of an image illuminated through a disk with windows of different widths. This is a different way of manufacturing an element for acquiring at least one piece of information describing the angular position of the optical element 5. This is, in particular, a variant of the above-mentioned rotation indicator 11, i.e., OPR indicator. In particular, instead of providing a specific device, i.e., indicator 11, with a target on the movable part of the protective device, illuminating this target, in particular with a light-emitting diode, and detecting its transmission with a photodetector, it is possible, for example, to use the peripheral area of ​​the CCD matrix array of the optical sensor 1 to detect the passage of an inscription or a series of light and dark lines arranged directly on the lens (not shown) of the optical sensor 1 or on the protective optics (not shown). The acquired image can be interpreted by one or more image processing means of the processing unit 17 to identify the angular position of defects present on the lens of the optical sensor 1, thereby preventing them from affecting the image quality.

[0080] Alternatively or additionally, the processing unit 17 may receive one or more pieces of information, in particular from at least one angle sensor 13 (FIGS. 3a to 4). Accordingly, analysis means may be provided for analyzing and determining the angular position of the optical element 5 .

[0081] According to yet another alternative, the processing unit 17 may determine the angular position of the optical element 5 based on one or more measurements of the phase currents of the motor 9. These measurements are transmitted by the measurement unit 15. For this purpose, the processing unit 17 comprises, for example, at least one microcontroller capable of measuring the rotational speed and the angular position of the motor 9, which is in particular a brushless motor. Alternatively or additionally, the processing unit 17 may comprise at least one integrated circuit comprising a voltage amplifier capable of measuring in particular the phase currents.

[0082] Furthermore, as shown in a highly simplified schematic diagram in Figure 2, defects 100 may be present on the optical element 5 that are resistant to cleaning cycles, for example those involving spraying with cleaning fluid. The defects 100 may be impacts or scratches that have damaged the optical element 5, or dust or deposits that are very difficult to remove, such as tar.

[0083] 2 and 4, the processing unit 17 is configured to detect the presence of a defect 100 within the field of view of the optical sensor 1. Image processing may be used to achieve this detection.

[0084] The processing unit 17, or more precisely the one or more image processing means, may determine the angular position of the defect 100 in the image captured by the optical sensor 1. The angular position of the defect 100 may be estimated based on the angular position of the optical element 5, which itself is determined based on one or more pieces of information received from at least one acquisition element (examples of which are described above).

[0085] In case of detecting the defect 100, the processing unit 17 may be configured to remove the defect 100 appearing in the image captured by the optical sensor by image processing, the removal being performed taking into account the determined angular position of the defect 100.

[0086] For this purpose, the capture of images by the optical sensor 1 can be synchronized to the rotation speed of the optical element 5. This synchronization makes it possible to eliminate noise caused by the presence of this defect 100 rotating in front of the optical sensor 1.

[0087] For this purpose, the processing unit 17 may also receive and analyze at least one piece of information describing the rotation speed of the optical element 5 or may determine this rotation speed.

[0088] According to one embodiment, the rotation speed may be determined based on the angular position of the optical element 5. The processing unit 17 may comprise at least one processing or calculation means for deriving the position with respect to time and estimating therefrom the rotation speed of the optical element 5. As non-limiting examples, information about time can be obtained by measuring the time between two passes of the rotation indicator 11 or by precisely measuring the phase currents, for example by an internal clock of the microcontroller of the processing unit 17.

[0089] This rotation speed allows calculation of the movement of the defect 100 in front of the optical components of the optical sensor 1, which may produce a relatively circular blurred or dark area in the image captured by the optical sensor 1.

[0090] Based on the rotation speed, the processing unit 17 can define the frequency with which the optical sensor 1 captures images. This frequency is selected so that the defect 100 is in the same angular position for each image capture. In other words, the optical sensor 1 captures images when the optical element 5 is positioned so that the defect 100 is always in the same position. The optical sensor 1 can, for example, capture one image per rotation, which is sufficient for the human eye.

[0091] It is also possible to define multiple angular positions of the defect 100 for synchronization purposes. In this example, the frequency is selected so that the defect 100 is at one of the predetermined angular positions for each image capture. In other words, the optical sensor 1 captures images when the optical element 5 is positioned so that the defect 100 is always at one of the precise predetermined positions in the image. For example, and also referring to FIG. 5, the optical sensor 1 may capture one image every half rotation.

[0092] If the image capture is synchronized to the rotation speed of the optical element, the defect 100 that is always found at at least one precise position in the captured images can be removed, i.e. extracted, by image processing. For this purpose, the processing unit 17, in particular the at least one image processing means, can filter the captured images to extract the image of the defect 100.

[0093] According to one particular example embodiment, this filtering removes areas containing defects from multiple images that can then be superimposed to reconstruct a defect-free image.

[0094] In a particularly simplified example, shown diagrammatically in FIG. 5, the optical sensor is configured to capture at least two consecutive images i1 and i2. For example, the optical sensor may capture one image i1 and i2 per half rotation of the optical element 5. At a rotational speed of approximately 10,000 revolutions per minute, these two images i1 and i2 are captured very closely. In these two consecutive images i1 and i2, captured very quickly, the surrounding landscape and road scene change significantly between the images i1 and i2, i.e., they do not have time to move. Meanwhile, the defect 100 moves very quickly. In this example, the defect 100, or rather its image, is located in the upper region i11 of the first image i1 and in the lower region i22 of the second image i2, relative to the orientation of FIG. 5.

[0095] Through image processing, a region containing the defect 100 can be extracted, and a new image i3 can be constructed by superimposing defect-free regions. Thus, in this example, a new image i3 can be constructed by superimposing two images i1 and i2. The top region i11 of the first image i1 can be extracted, and the defect-free bottom region i12 of the first image i1 can be saved, as indicated by arrow F1. Similarly, the bottom region i22 of the second image i2 can be extracted, and the defect-free top region i21 of the second image i2 can be saved, as indicated by arrow F2. A new image i3 is obtained based on the top region i21 of the second image i2 and the bottom region i22 of the second image i2, as indicated by arrow F3. In this newly constructed image i3, the defect is no longer visible.

[0096] Image Processing Method

[0097] Generally, the method comprises at least one step of detecting the presence of at least one defect 100 on the optical element 5 of the protection device 3. This step is performed by the above-mentioned processing unit 17, for example by image processing.

[0098] If a defect 100 is detected, the method comprises at least one step of acquiring at least one piece of information describing at least one angular position of the optical element 5 while the optical sensor 1 captures the at least one image. This acquiring step may be performed at least in part by one or more acquisition elements 11, 13, 15 as described above. A processing unit 17 may receive the information describing the angular position of the optical element 5.

[0099] Then, at least one step follows of identifying, based on this depiction information, at least one angular position of the defect 100 on the optical element 5. This step may be performed by the processing unit 17, in particular by one or more image analysis and / or processing means of the processing unit 17.

[0100] In particular, when a defect 100 is detected on the optical element 5 within the field of view of the optical sensor 1, the method comprises at least one step of determining the angular position of the optical element 5 based on at least one depiction information received from at least one acquisition element 11, 13, 15 as described above, and estimating from that angular position the angular position of the defect 100 on one or more images captured by the optical sensor 1, in particular by image processing.

[0101] In a next step, taking into account the angular position of the defect 100 on the optical element 5 identified in the previous step, the defect 100 can be removed from at least one image captured by the optical sensor 1 by image processing. This removal step can be performed by the processing unit 7, in particular by one or more image processing means of the processing unit 7.

[0102] Advantageously, according to this method, the capture of images can be synchronized to the rotation speed of the optical element 5 .

[0103] The rotation speed of the optical element 5 can for example be determined by the processing unit 17 or can be obtained via a determination system embedded in the protection device 3 .

[0104] Based on the rotation speed, the capture of images by the optical sensor 1 can be synchronized to the rotation speed of the optical element 5. This synchronization can be performed by the processing unit 17. The processing unit 17 defines the frequency of image capture such that for each image capture, the defect 100 is at a predetermined angular position. This angular position can always be the same, or multiple angular positions can be defined.

[0105] The method then comprises one or more image processing steps to remove the defect 100 appearing in the captured image, for example by filtering the image area containing the defect 100 in a manner synchronized with the rotational speed of the optical element 5 and overlaying these images to reconstruct an internal image of the defect.

[0106] Therefore, the protection device 3 according to any of the above-mentioned variants can at least acquire rotation information and transmit it to the processing unit 17. The processing unit 17 can then remove defects that appear in the images captured by the optical sensor 1. In particular, the processing unit 17 can synchronize the image capture with the rotation speed and filter the captured images to extract the defects 100.

[0107] This processing unit 17 may be integrated into the protection device 13 or may form part of the central processing unit of the vehicle.

[0108] This allows the system 1 to filter out noise caused by the high speed rotation of the defect in front of the optical sensor 1 even if the defect 100 is within the field of view of the optical sensor 1, thereby extending the service interval of the protection device 3 and allowing the vehicle to continue driving while using it.

Claims

1. A driver assistance system, at least one optical sensor (1) comprising an optical component and configured to capture at least one image along an optical axis; at least one protection device (3) associated with at least one said optical sensor (1), the protection device (3) comprises a transparent optical element (5) rotatably mounted along the optical axis upstream of the optical component of the associated optical sensor (1), and a motor (9) configured to drive the optical element (5) in rotation; said protection device (3) comprises at least one element (11, 13, 15) for obtaining at least one piece of information describing at least one angular position of said optical element (5) while said associated optical sensor (1) captures at least one image; At least one of the acquisition elements comprises a rotation indicator (11) arranged on the optical element (5) so as to be within the field of view of the associated optical sensor (1); - said system comprises a processing unit (17), said processing unit (17) - detecting the presence of at least one defect (100) on said optical element (5); receiving at least one said information describing at least one said angular position of said optical element (5); - determining at least one angular position of at least one of the defects (100) on the optical element (5) based on at least one of the received description information; removing, by image processing, at least one said defect (100) from at least one said image captured by at least one said optical sensor (1), taking into account said at least one determined angular position of said at least one said defect (100) on said optical element (5); It is configured as follows: the processing unit (17) determines a rotation speed of the optical element (5) based on the information about the angular position of the optical element (5) and time; said information regarding time is obtained by measuring the time between two passes of said rotation indicator (11); The processing unit (17) synchronizes the capture of the image with the rotation speed of the optical element (5). A driver assistance system characterized by:

2. A driver assistance system, at least one optical sensor (1) comprising an optical component and configured to capture at least one image along an optical axis; at least one protection device (3) associated with at least one said optical sensor (1), the protection device (3) comprises a transparent optical element (5) rotatably mounted along the optical axis upstream of the optical component of the associated optical sensor (1), and a motor (9) configured to drive the optical element (5) in rotation; said protection device (3) comprises at least one element (11, 13, 15) for obtaining at least one piece of information describing at least one angular position of said optical element (5) while said associated optical sensor (1) captures at least one image; At least one of the acquisition elements comprises a measurement unit (15) configured to measure the phase currents of the motor (9); - said system comprises a processing unit (17), said processing unit (17) - detecting the presence of at least one defect (100) on said optical element (5); receiving at least one said information describing at least one said angular position of said optical element (5); - determining at least one angular position of at least one of the defects (100) on the optical element (5) based on at least one of the received description information; removing, by image processing, at least one said defect (100) from at least one said image captured by at least one said optical sensor (1), taking into account said at least one determined angular position of said at least one said defect (100) on said optical element (5); It is configured as follows: the processing unit (17) determines a rotation speed of the optical element (5) based on the information about the angular position of the optical element (5) and time; said information relating to time being obtained by measuring the phase currents of said motor (9); The processing unit (17) synchronizes the capture of the image with the rotation speed of the optical element (5). A driver assistance system characterized by:

3. The motor (9) is configured to rotate the optical element (5) around a rotation axis (A) so that the optical element (5) can be cleaned by centrifugal effect. The system of claim 1 .

4. The motor (9) is configured to rotate the optical element (5) around a rotation axis (A) so that the optical element (5) can be cleaned by centrifugal effect. The system of claim 2 .

5. The processing unit (17) - determining said at least one angular position of said optical element (5) based on said at least one received description information, - estimating said at least one angular position of at least one said defect (100) on said optical element (5) from said determined angular position of at least one of said optical elements; It is configured as follows: A system according to any one of claims 1 to 4.

6. At least one of the acquisition elements comprises an angle sensor (13). A system according to any one of claims 1 to 4.

7. the processing unit (17) is configured to define an image capture frequency depending on the rotation speed of the optical element (5) such that for each image capture, at least the defect (100) is at at least one of the identified angular positions in the captured image. A system according to any one of claims 1 to 4.

8. the processing unit (17) comprises at least one image processing means configured to extract at least one of the defects (100) located at at least one of the identified angular positions in the captured image; The system of claim 7.

9. A method for processing captured images for a driver assistance system according to any one of claims 1 to 4, comprising at least one optical sensor (1) and an associated protection device (3), comprising: - detecting the presence of at least one defect (100) on said optical element (5) of said protection device (3); receiving at least one piece of information describing said angular position of at least one of said optical elements (5) while said optical sensor (1) captures at least one image; - determining at least one angular position of at least one said defect (100) on said optical element (5) based on at least one of said received description information; - removing, by image processing, at least one said defect (100) from at least one said image captured by at least one said optical sensor (1), taking into account said at least one determined angular position of said at least one said defect (100) on said optical element (5); A method comprising:

Images