Patent Description:
A large number of techniques for presenting a vehicle-periphery image obtained from images captured by image-capturing apparatuses installed in a vehicle have been proposed in order to assist safe driving.

For example, an image generating apparatus disclosed in <CIT> maps captured images in a predetermined space model. <CIT> discloses a method in which, by using a bowlshaped model as the space model in the above case, images of objects that are present in the periphery of a vehicle are combined so as to be as similar to real objects as possible all around the vehicle and are displayed to a driver. This method is advantageous in enabling the driver to easily recognize the situation in the periphery of the subject vehicle because an image from a point of view as if looking down on the subject vehicle from above can be generated.

In addition, <CIT> proposes a method for calculating three-dimensional image data on the basis of image data obtained by a stereo camera that captures images of the periphery of a vehicle. As disclosed in the above document, the following method is well known. If two or more cameras are disposed so as to capture images in overlapping fields of view from different points of view, and information such as the positions and orientations of the cameras is obtained in advance, by so-called trigonometry from the correspondence relationship between points in the captured images, it is possible to calculate the three-dimensional position of an object that is present in the overlapping fields of view. <CIT> discloses a method in which, by restricting a region that is the target of three-dimensional measurement, information of the periphery of a vehicle is mapped on a three-dimensional map that is more similar to the actual environment and in which an image with a transformed point of view is generated while suppressing the calculation cost to some extent. <NPL>, that apparently has been recorded inside a moveable apparatus comprising a touchscreen. The touchscreen shows two different images containing simulated content. One image shows a car from above. This part of the touchscreen is used to control the content that is shown on the other image, which may have several different points of view: a view out of the front window of the car; a view out of the back window of the car; and two virtual perspectives of the car (from a point of view that is slightly above, behind, and left/right from the car). <NPL>, and apparently has been recorded inside a standing vehicle. There is a display with two images, each showing a simulated image of a car, which appears to be standing inside a building. The person who is presumably recording the video is making movements with his right hand, which appear to be related to the rotations of the view of the vehicle in one of the images. In summary, D2 merely discloses the generation of images and the installation of a display into a car. It is related to Auto Park Distance Control (PDC) in the new "X5" that is equipped with it. According to the audio, it detects when the vehicle is pulled into a parking space and automatically activates the PDC system, and signal tones and visual displays are used to alert the driver when it detects objects in front of or behind the vehicle. <NPL>, relates to sensing failures of light detection and ranging (LIDAR) given the presence of a mirror. Using only LIDAR information, mirrors are detected by utilizing the property of mirror symmetry. <NPL>, relates to detecting and reconstructing transparent objects. <NPL>, shows a robot hand lifting glasses. <CIT> relates to an image synthesis device. Two visible light cameras are attached inside a front glass of a vehicle, and a far-infrared light camera is attached near a front grille of the vehicle. Using input signals from the visible light cameras, three-dimensional data is generated and, in turn, used to perform viewpoint conversion. As a result, the viewpoint of the far-infrared light image and the visible light image coincide with each other, and, when superimposing both images, the misalignment of the objects having different object distances in a synthesized image is suppressed. <NPL>, relates to visual 3D reconstruction of transparent objects by specifically searching for geometry inconsistencies caused by refraction and reflection on the surfaces of the objects. In particular, inconsistent depth measurements are identified.

However, with the above techniques of the related art, it is difficult to display a light-transmissive object such as a glass surface or a reflective object in a vehicle-periphery image so as to be easily recognizable by a driver.

One non-limiting and exemplary embodiment provides an image generating apparatus that is suitable for generating an image including a light-transmissive object and a reflective object.

Embodiments and examples not falling under the scope of the independent claims are for illustrational purposes only.

It should be noted that general or specific embodiments may be implemented as an apparatus, a method, a system, an integrated circuit, a computer program, a computer-readable recording medium, or any selective combination thereof. Examples of the computer-readable recording medium include a non-volatile recording medium such as a compact disc-read only memory (CD-ROM).

According to the present disclosure, since the position of the light-transmissive object or the reflective object in the camera images is detected, an image that is easily recognized by a driver can be displayed at the position of the light-transmissive object or the reflective object in the generated image in a manner different from that of other objects.

As described above, in the techniques of the related art, it is not considered to display a light-transmissive object such as a glass surface or a reflective object in a vehicle-periphery image so as to be easily recognizable by a driver.

in <CIT>, since accurate positions of objects are not considered after all, an image of a light-transmissive object or a reflective object may be mapped in a generated image at a position different from the actual position thereof. Accordingly, in the generated image, an object may be displayed at a position different from the actual position thereof.

A periphery display apparatus according to <CIT> measures the three-dimensional position of an object by using image data obtained by a stereo camera. Accordingly, since a view looking down from above is displayed by measuring the actual position of an object, it is considered that the position of the object is considered to be displayed more accurately.

However, the inventors have focused on a new problem that arises if the position of an object is measured by using image data obtained by a stereo camera. The new problem is that it is difficult to measure the position of a reflective object or a light-transmissive object by using image data obtained by a stereo camera without considering the reflective object or the light-transmissive object.

Since the light-transmissive object or the reflective object has no texture, it is difficult to identify the position of the light-transmissive object or the reflective object by a typical method using image data obtained by a stereo camera. In addition, the position of an object located behind the light-transmissive object or an object reflected on the reflective object may be estimated as a wrong position of the light-transmissive object or the reflective object. As a result, an image is generated in which an object is located more distant from the light-transmissive object or the reflective object.

Thus, it is not desirable in assisting safe driving to generate an image in which an object is not displayed at an accurate position of the light-transmissive object or the reflective object and to provide such an image to a user.

Accordingly, an image generating apparatus according to an embodiment of the present disclosure is an image generating apparatus that generates an image to be displayed on a display, the image generating apparatus including at least one memory and a control circuit, in which the control circuit (a) acquires a plurality of camera images captured by a plurality of cameras installed in a vehicle, (b) calculates a distance between one of the cameras and a target included in the camera images in a three-dimensional space by using the plurality of camera images, (c) detects a position of a light-transmissive object or a reflective object in the camera images, and (d) generates an image from a point of view that is different from points of view of the plurality of camera images by using at least one of the plurality of camera images and the distance, the generated image including a predetermined image that is displayed at the position of the light-transmissive object or the reflective object.

With such a configuration, the position of the light-transmissive object or the reflective object in the camera images is detected, and accordingly, an image that is easily recognized by a driver can be displayed at the position of the light-transmissive object or the reflective object in the generated image in a manner different from that of other objects.

The control circuit may further (e) estimate a distance between the camera and the light-transmissive object or the reflective object and (f) correct the distance between the camera and the target at the position of the light-transmissive object or the reflective object in the camera images to the estimated distance, and in the (d), the image may be generated by using the plurality of camera images and the corrected distance.

With such a configuration, by estimating the distance to the light-transmissive object or the reflective object by a method different from the stereo distance measurement, it is possible to obtain, as the generated image, a camera image that has been rendered by using the estimated distance. Accordingly, it is possible to display the light-transmissive object or the reflective object at an estimated position of the light-transmissive object or the reflective object instead of the position based on the stereo distance measurement. Therefore, the generated image is useful in notifying the driver of the presence of the light-transmissive object or the reflective object.

In the (a), a polarized camera image captured by a polarization camera that captures an image through a polarization plate may be acquired, and in the (c), a position where brightness of the polarized camera image periodically changes may be detected as the position of the light-transmissive object or the reflective object.

With such a configuration, by using light polarization characteristics, it is possible to detect the position of the light-transmissive object or the reflective object.

The control circuit may further (g) acquire a plurality of infrared camera images captured by a plurality of far-infrared cameras and (h) calculate a distance between one of the far-infrared cameras and the target included in the infrared camera images in a three-dimensional space by using the plurality of infrared camera images, and in the (c), a position where a difference between the distance calculated by using the camera images and the distance calculated by using the infrared camera images is larger than a predetermined threshold may be detected as the position of the light-transmissive object or the reflective object.

With such a configuration, by using the difference between visible-light absorption characteristics and far-infrared-light absorption characteristics of glass, it is possible to detect the position of the light-transmissive object or the reflective object.

In the (c), a frame-shaped object included in the camera images may be recognized, and a region inside the recognized frame-shaped object may be detected as the position of the light-transmissive object or the reflective object.

With such a configuration, it is possible to detect the position of the light-transmissive object or the reflective object from the frame-shaped object typically provided in the periphery of the light-transmissive object or the reflective object such as a window frame provided for a glass window.

In the (d), a part of one of the plurality of camera images may be displayed at the position of the light-transmissive object or the reflective object in the generated image.

With such a configuration, the appearance of an object that is reflected on the light-transmissive object or the reflective object is displayed at the position of the light-transmissive object or the reflective object, and accordingly, the generated image with high visibility can be obtained.

In the (d), a camera image including a larger area of the light-transmissive object or the reflective object may be preferentially displayed among the plurality of camera images at the position of the light-transmissive object or the reflective object in the generated image.

With such a configuration, brightness mismatch between adjacent pixels in the generated image can be suppressed, and accordingly, it is possible to obtain the generated image that is easy to view.

In the (d), a camera image including a larger area of the light-transmissive object or the reflective object may be preferentially displayed among the plurality of camera images at positions of a plurality of light-transmissive objects or reflective objects in the generated image.

With such a configuration, brightness mismatch between adjacent pixels in the generated image can be suppressed for each light-transmissive object or each reflective object, and accordingly, it is possible to obtain the generated image that is easy to view.

The control circuit may further (i) separate a light-transmissive component and a reflective component from each other, the light-transmissive component and the reflective component being included at the position of the light-transmissive object in the camera images, and in the (d), the light-transmissive component and the reflective component may be displayed by being assigned weights at a predetermined ratio at the position of the light-transmissive object in the generated image.

With such a configuration, the image can be generated by, after separating the reflective component and the light-transmissive component from each other, assigning weights at the predetermined ratio, and accordingly, it Is possible to suppress the occurrence of a malfunction that both the reflective component and the light-transmissive component are present in the generated image, which is untidy and difficult to view.

In the (i), a polarized camera image captured by a polarization camera that captures an image through a polarization plate may be acquired, and the light-transmissive component and the reflective component may be separated from each other by using the polarized camera image.

With such a configuration, by using light polarization characteristics, it is possible to separate the reflective component and the light-transmissive component from each other.

In the (d), the predetermined ratio may be received from a user, and the light-transmissive component and the reflective component may be displayed by being assigned weights at the predetermined ratio received from the user at the position of the light-transmissive object in the generated image.

With such a configuration, it is possible to display the image by assigning weights to the reflective component and the light-transmissive component at a desired ratio at which the user considers the image is easy to view.

In the (d), the light-transmissive component and the reflective component may be displayed at the position of the light-transmissive object in the generated image by being assigned weights in such a manner that the weight of the reflective component is lower than the weight of the light-transmissive component when external light is brighter.

For example, during the daytime on a sunny day, since the falling sunlight is intense, specular reflection on a glass surface may cause glare to the driver. Since the reflective component is likely to be dominant, in this period of time or if the weather is like this, the ratio of the reflective component may be decreased compared with other periods of time or other weather. In addition, during evening to nighttime, the brightness inside a space separated by a glass surface may largely differ from the brightness outside the space. If the inside space is bright, the light-transmissive component is dominant, and accordingly, the ratio of the light-transmissive component may be decreased compared with other periods of time.

In the (d), if a predetermined condition that the camera images exhibit an appropriate exposure state is not satisfied, such a message may be displayed in the generated image that prompts a driver to see a periphery of the vehicle.

With such a configuration, if it is considered that it is not possible to detect the position of the reflective component or the light-transmissive component with sufficiently high accuracy from the camera images, specifically, if pixels more than or equal to a predetermined ratio are saturated in the camera images due to reflected light of the lamps of the subject vehicle and/or another vehicle, and/or if a histogram of the camera image includes a strong bias in a bright part and a dark part, the driver's attention can be attracted.

The plurality of cameras may include a first camera that captures an image of a forward area of the vehicle and a second camera that captures an image of a backward area of the vehicle, and the control circuit may further (j) acquire a heading direction of the vehicle, and in the (c), the position of the light-transmissive object or the reflective object may be detected by using a camera image obtained by a camera that captures an image in a direction that is same as the heading direction of the vehicle, the camera being selected from the first camera and the second camera.

With such a configuration, it is possible to obtain a generated image that is useful in assisting safe driving at a reduced calculation cost.

In the (c), if the estimated distance between the camera and the light-transmissive object or the reflective object is larger than a predetermined threshold, the distance between the camera and the target at the position of the light-transmissive object or the reflective object may not be corrected.

In the (c), if a detected lowest end of the light-transmissive object or the reflective object is higher than or equal to a predetermined threshold from a surface of a road, the distance between the camera and the light-transmissive object or the reflective object may not be estimated, and the distance between the camera and a point in a space to be projected at the position of the light-transmissive object or the reflective object may not be corrected.

In the (c), if a detected size of the light-transmissive object or the reflective object is smaller than a predetermined threshold, the distance between the camera and the light-transmissive object or the reflective object may not be estimated, and the distance between the camera and a point in a space to be projected at the position of the light-transmissive object or the reflective object may not be corrected.

Note that the image generating apparatus according to an embodiment of the present disclosure is not only implemented by a hardware configuration of corresponding functional units but also can be implemented as an image generating method including steps of the corresponding functional units. Alternatively, the image generating method can be implemented by a program on a computer. Further alternatively, the image generating method can be implemented by a computer-readable recording medium such as a digital versatile disk read only memory (DVD-ROM) recording the program thereon or an image processing apparatus that generates an image from a given point of view from captured images, for example.

Now, an image generating apparatus according to a first embodiment will be described below by taking an example of an image generating apparatus that is installed in a vehicle and that generates a vehicle-periphery image to be presented to an occupant (in particular, a driver).

<FIG> is a block diagram illustrating an example of a functional configuration of the image generating apparatus according to the first embodiment. As illustrated in <FIG>, an image generating apparatus <NUM> includes an image acquiring unit <NUM>, a distance calculating unit <NUM>, a light-transmissive object detecting unit <NUM>, and an image generating unit <NUM>.

The image acquiring unit <NUM> acquires a plurality of camera images <NUM> that are moving images captured by a plurality of cameras. Examples of the camera images <NUM> include images of the periphery of the vehicle.

The distance calculating unit <NUM> calculates the distance between a camera and an object included in the camera images <NUM> by using the plurality of camera images <NUM>.

The light-transmissive object detecting unit <NUM> detects the position of a light-transmissive object or a reflective object in the camera images <NUM>.

Here, the light-transmissive object is an object in an image of which, captured by a visible-light camera, transmitted light is dominant. Examples of the light-transmissive object include transparent glass, plastic, and the like.

In addition, the reflective object is an object in an image of which, captured by a visible-light camera, specular-reflected light is dominant. Examples of the reflective object include a mirror, shimmering metal, and the like.

The image generating unit <NUM> generates a vehicle-periphery image <NUM>, which is a generated image from a point of view different from the points of view of the camera images <NUM>, by using the plurality of camera images <NUM> and the distance calculated by the distance calculating unit <NUM>. A predetermined image is displayed at the position of the light-transmissive object or the reflective object in the vehicle-periphery image <NUM>.

Here, the image acquiring unit <NUM> may be, for example, a camera or a communication interface connected to a camera, or may be an interface that reads the camera images <NUM> stored in a storing apparatus that is separately provided.

The distance calculating unit <NUM>, the light-transmissive object detecting unit <NUM>, and the image generating unit <NUM> may be, for example, implemented by software such as programs executed on a computer or may be implemented by hardware such as an electronic circuit or an integrated circuit.

<FIG> illustrates a hardware configuration of the image generating apparatus implemented by a computer.

In <FIG>, a camera unit <NUM> captures images of objects in a space around the vehicle and outputs camera images, and then a computer <NUM> acquires the camera images and performs an image generating process, thereby displaying the resulting vehicle-periphery image on a display <NUM>.

Examples of the camera unit <NUM> include a stereo camera and is, in particular, a fish-eye stereo camera. Examples of the display <NUM> include a liquid crystal display and an organic electroluminescent (EL) display. The display <NUM> may be installed in a vehicle or may be a head-mounted display that a user wears.

The computer <NUM> includes an interface (I/F) <NUM>, a central processing unit (CPU) <NUM>, a read only memory (ROM) <NUM>, a random access memory (RAM) <NUM>, a hard disk drive (HDD) <NUM>, and a video card <NUM>. Programs for operating the computer <NUM> are stored in the ROM <NUM> or the HDD <NUM> in advance. Note that the HDD <NUM> may be implemented by an apparatus having the same functions as the HDD, such as a solid state drive (SSD).

The CPU <NUM>, which is a processor, reads and loads the programs from the ROM <NUM> or the HDD <NUM> to the RAM <NUM>.

The CPU <NUM> executes each command that is coded in the programs loaded to the RAM <NUM>.

In accordance with the execution of the programs, the I/F <NUM> loads the camera images from the camera unit <NUM> to the RAM <NUM>. The video card <NUM> outputs the vehicle-periphery image generated in accordance with the execution of the programs, and the display <NUM> displays the vehicle-periphery image.

Note that the programs may be stored in, not only the ROM <NUM>, which is a semiconductor device, and the HDD <NUM>, but also a digital versatile disk (DVD)-ROM or the like. In addition, the programs may be transmitted through a wired or wireless network, broadcast, or the like and may be loaded to the RAM <NUM> in the computer <NUM>.

Now, the operation of the image generating apparatus <NUM> will be described below with reference to <FIG>.

<FIG> is a flowchart illustrating the operation of the image generating apparatus <NUM> in this embodiment.

The image acquiring unit <NUM> acquires camera images from the camera unit <NUM>. Examples of the camera images include stereo images. More specifically, the image acquiring unit <NUM> acquires a plurality of camera images captured by a plurality of cameras.

On the basis of the acquired camera images and camera parameters (described later), the distance calculating unit <NUM> calculates the distance between a camera and a point in a space in the periphery of the vehicle to be projected in the camera images.

The point in the space in the periphery of the vehicle to be projected in the camera images corresponds to a target to be included in the camera images. That is, the distance calculating unit <NUM> calculates the distance between the camera and the target included in the camera images.

Examples of the target include all objects located in the periphery of the vehicle. Examples of the target include other vehicles, pedestrians, roads, and buildings. For example, the target may be a whole building, or the target may be identified in each pixel in the camera images.

In addition, the distance calculating unit <NUM> calculates the distance between one (also referred to as a reference camera) of the plurality of cameras and the target. For example, a memory may store the position of the reference camera, and the distance calculating unit <NUM> may acquire the position of the reference camera from the memory.

The light-transmissive object detecting unit <NUM> detects the position of the light-transmissive object or the reflective object in the camera images. That is, the light-transmissive object detecting unit <NUM> detects in which portion of the camera images the light-transmissive object or the reflective object is included.

The light-transmissive object detecting unit <NUM> may further estimate the distance between the camera and the light-transmissive object or the reflective object and may correct, to the estimated distance, the distance between the camera and the point in the space to be projected in the camera images at the detected position of the light-transmissive object or the reflective object.

By using at least one of the camera images and the calculated distance, the image generating unit <NUM> generates the vehicle-periphery image, which is a generated image from a point of view different from the points of view of the camera images. Examples of the point of view that is different from the points of view of the camera images includes a point of view looking down on the vehicle from above and a point of view looking at the vehicle from behind.

A predetermined image is displayed at the position of the light-transmissive object or the reflective object in the vehicle-periphery image.

Note that each of the steps illustrated in <FIG> may be performed by the computer <NUM> illustrated in <FIG>. Now, details of processing performed in each of the steps will be sequentially described below.

<FIG> illustrates an example of the image generating apparatus <NUM>, the camera unit <NUM>, and the display <NUM> installed in a vehicle. <FIG> is a view looking down on the vehicle from above.

Cameras <NUM> and <NUM> are provided at two positions in the rear portion of the vehicle so as to have different points of view and overlapping fields of view. The cameras <NUM> and <NUM> are included in the camera unit <NUM> that is a stereo camera. The image generating apparatus <NUM> is installed in a vehicle, and the display <NUM> is provided at a position where the driver in the cabin can view the display <NUM>.

Note that the individual cameras <NUM> and <NUM> included in the camera unit <NUM> may capture images in synchronization with each other at regular time intervals and may output the images. In this case, concurrently with an image capturing operation performed by the camera unit <NUM>, the image generating apparatus <NUM> performs S101 to S104 in accordance with a program specified in advance by the apparatus or the computer.

<FIG> illustrate examples of camera images captured during a parking scene. These examples are examples of a scene in which there is a parking lot in front of a building having windows that include a glass surface <NUM>, and a vehicle driven by a driver is performing a parking operation with the reverse gear in a direction toward the glass surface <NUM>. Accordingly, camera images captured by the rear cameras include a large area of the glass surface <NUM> behind the vehicle as illustrated in <FIG>.

<FIG> illustrate examples of camera images captured by the cameras <NUM> and <NUM>, respectively, during the above scene. The camera images include both reflective components and a light-transmissive component displayed at the position of the glass surface <NUM>. The camera images include a subject vehicle <NUM> and a tree <NUM> in the scene as the reflective components and an indoor lighting <NUM> behind the glass surface <NUM> as the light-transmissive component. Note that <FIG> illustrate examples of contrast-enhanced and contour-enhanced images for ease of understanding.

In addition, although images captured by fish-eye cameras are illustrated here as examples, the camera images are not limited to images captured by fish-eye cameras. By using a fish-eye camera or a wide-viewing-angle camera, an image of a wide viewing angle can be captured by a single camera. However, by increasing the number of cameras, even by using cameras with a narrower viewing angle, the same effects can be obtained.

Now, step S101 to step S104 performed by the image generating apparatus <NUM> will be described in detail below.

The image acquiring unit <NUM> acquires a plurality of images that form camera images captured by each of the cameras <NUM> and <NUM>.

In sets of images captured by different cameras, which are acquired by the image acquiring unit <NUM>, the distance calculating unit <NUM> calculates, by stereopsis, three-dimensional positions of points in a space in the periphery of the vehicle to be projected in an image.

Details of the calculation of the three-dimensional positions performed by the distance calculating unit <NUM> will be described below.

The distance calculating unit <NUM> first reads camera parameters including internal and external parameters of the cameras <NUM> and <NUM>, which are obtained in advance.

The relationship between internal parameters (f, k) of each camera, three-dimensional coordinates, and pixel coordinates is expressed by Expression <NUM>.

Expression <NUM> indicates the relationship between three-dimensional positions (x, y, z) of a camera in a coordinate system and pixel coordinates (u, v) where the internal parameter f represents a focal distance, and the internal parameter k represents a pixel size on an image sensor. The internal parameters (f, k) are obtained in advance by a widely known method typically called camera calibration. Note that although Expression <NUM> uses internal parameters when a projection model of a lens is equidistance projection, the projection model is not limited to a particular model, and another projection model such as stereographic projection or equisolid angle projection may be used.

The relationship between external parameters {Mq,r} of two cameras q and r that form a two-lens stereo camera and three-dimensional coordinates is expressed by Expression <NUM>.

The external parameters {Mq,r} are a matrix representing the positional relationship between coordinate systems of the two cameras q and r. The matrix Mq,r represents a <NUM> × <NUM> matrix that converts a three-dimensional position (xq, yq, zq) of the coordinate system of the camera q to a three-dimensional position (xr, yr, zr) of the coordinate system of the camera r. The external parameters {Mq,r} are also obtained in advance by a widely known method typically called camera calibration as in the internal parameters.

The distance calculating unit <NUM> forms a set of two camera images (image data) captured by different cameras, the camera images being received by the image acquiring unit <NUM>.

In the set of camera images, a plurality of three-dimensional positions in the camera images are calculated by stereopsis by using the camera parameters.

Then, the distance calculating unit <NUM> calculates a plurality of corresponding points between the two camera images.

That is, if two camera images captured by the cameras <NUM> and <NUM> are referred to as la and Ib, respectively, a plurality of corresponding points between the two images in a set of camera images (la, Ib) are detected.

The corresponding points between the two images means a set of points in the two images if a point of a subject in one image is also included in the other. For example, if the set of the camera images is (la, Ib), pixel coordinates (ubn, vbn) of a corresponding point in the camera image Ib, corresponding to pixel coordinates (uan, van) in the camera image la, are detected for all pixels.

If the pixel coordinates (uan, van) in the camera image la and the pixel coordinates (uan, vbn) in the camera image Ib are corresponding points, a pixel value ia (uan, van) and a pixel value ib (ubn, vbn) of the two points are equal to each other. This is referred to as brightness restriction. In addition, since a certain subject occupies a plurality of adjacent pixels in an image, there is a high possibility that a corresponding point of a pixel that is adjacent to the pixel coordinates (uan, van) in the camera image la is near the pixel coordinates (ubn, vbn) in the camera image Ib. This is referred to as smoothness restriction. The corresponding points between the camera images (la, Ib) can be obtained by estimating an aggregation of sets of (uan, van) and (ubn, vbn) that most satisfy the two conditions for the above-described brightness restriction and smoothness restriction.

Note that in order to acquire higher-density three-dimensional information on the periphery environment of the vehicle, it is desirable to calculate high-density corresponding points. The method for calculating the sets of pixel coordinates representing a high-density corresponding relationship between two images is specifically described in <NPL>, <NPL>, and the like. Therefore, further detailed description will be omitted here. High-density corresponding points can be calculated with real precision by the method according to the above documents, and accordingly, higher-density three-dimensional information on the periphery environment of the vehicle can be calculated with higher accuracy.

Then, by solving simultaneous equations in Expression <NUM> by using the coordinates (uan, van) and (ubn, vbn) of the corresponding points and external parameters Mb,a and internal parameters fa, ka, fb, kb of the cameras <NUM> and <NUM>, which have been obtained in advance, the distance calculating unit <NUM> calculates a three-dimensional position (xan, yan, zan) of each of the corresponding points.

Note that the three-dimensional position here is a coordinate value in a viewing coordinate system of the camera <NUM>.

The method for calculating the three-dimensional position by using a two-lens stereo method from the corresponding points between two camera images and the positions of the two cameras and the conversion of the coordinate value between two three-dimensional coordinate systems are specifically described in <NPL> and the like. Therefore, detailed description will be omitted here.

Lastly, the distance calculating unit <NUM> outputs as positional information the results of plural calculations of the corresponding points between two camera images and the three-dimensional positions thereof. Examples of information to be output are illustrated below.

Expression <NUM> represents an aggregation Pq,r of pieces of positional information pq,r,n of Nq corresponding points between two camera images Iq and Ir obtained by the two cameras q and r. in addition, {Pq,r} represents the positional information of all sets of images.

The positional information may be pixel-pair information (pixel coordinates and corresponding pixel coordinates) that identifies two pixels as in Expression <NUM> or may be information including the three-dimensional position corresponding to a pair of pixels identified by the pixel-pair information.

Note that the camera parameters may be parameters that are obtained in advance to be used as fixed values by the distance calculating unit <NUM> or may be read from a parameter storing unit that is additionally and externally provided. By externally providing the parameter storing unit, if the parameters vary, the parameter values can be corrected easily.

Through the above processing, the three-dimensional position of each corresponding point in the images can be obtained.

<FIG> illustrates an example of a distance image based on the distance calculated by the distance calculating unit <NUM> from the images in <FIG> captured by the stereo camera. The variation in brightness (shades) represents the distance from the camera. That is, a higher brightness indicates a smaller distance from the camera, and a lower brightness indicates a larger distance from the camera. Note that the region of the subject vehicle and a part corresponding to vignetting of the camera are masked in black (brightness = <NUM>) for visibility.

<FIG> illustrates a distance image (simulation image created on the basis of a known model) created from a correct three-dimensional position of the glass surface <NUM>.

Comparing the distances to the glass surface <NUM>, it is understood that the distance illustrated in <FIG> is calculated to be larger than the correct distance illustrated in <FIG>. Such an error in measuring the distance is explained as follows.

Typically, in a region with a larger brightness gradient, such as an edge or a texture region in an image, the corresponding points between two images can be calculated more accurately. On the other hand, a transparent glass surface has a small brightness gradient due to glass itself, and accordingly, it is not possible to calculate the corresponding points accurately.

<FIG> illustrates, for explanation, an image of only components reflected on the glass surface <NUM>, such as the subject vehicle <NUM> and the tree <NUM>, which are included in <FIG>.

In this example, as illustrated in <FIG>, as the distances to the subject vehicle <NUM> and the tree <NUM>, distances d1' and d2' to virtual images, not distances d1 and d2 to the glass surface <NUM>, are measured. This is because calculated corresponding points between the stereo camera images are corresponding points between reflected textures. Accordingly, as indicated by intersecting dotted lines in <FIG>, the distances to the virtual images of the subject vehicle <NUM> and the tree <NUM>, not the distances to the glass surface <NUM>, are measured.

<FIG> illustrates, for explanation, an image of only a component that is transmitted through the glass surface <NUM>, such as the indoor lighting <NUM>, which is included in <FIG>.

Also in this example, as illustrated in <FIG>, as the distance to the indoor lighting <NUM>, distances d3' and d4' to the main body of the indoor lighting <NUM>, not distances d3 and d4 to the glass surface <NUM>, are measured. This is because calculated corresponding points between the stereo camera images are corresponding points between transmitted textures. Accordingly, as indicated by intersecting dotted lines in <FIG>, the distance to the indoor lighting <NUM>, not the distance to the glass surface <NUM>, is measured.

Thus, the distance to a virtual image of an object represented as a reflective component or a light-transmissive component reflected on a glass surface and the distance to the object behind the glass surface are calculated in some cases. That is, the distance to the object represented at the position of the glass surface <NUM> in a camera image is estimated to be larger than the actual distance between the glass surface <NUM> and the camera. This results in a wrong determination that no object is present at the position of the glass surface <NUM>.

To address such an issue, the light-transmissive object detecting unit <NUM> detects the position (hereinafter also referred to as a glass region) of a light-transmissive object or a reflective object in the camera image and estimates the distance between a camera and the light-transmissive object or the reflective object. Further, the three-dimensional position of a point in the space, calculated by the distance calculating unit <NUM>, to be projected at the detected position of the light-transmissive object or the reflective object in the camera image is corrected by using the estimated distance. This prevents the distance to the light-transmissive object or the reflective object from being estimated to be larger than the actual distance. In other words, a wrong determination that no object is present at the position of the light-transmissive object or the reflective object is prevented.

The detection of the position of the light-transmissive object or the reflective object and the estimation of the distance thereto performed by the light-transmissive object detecting unit <NUM> will be specifically described. Note that the light-transmissive object or the reflective object is referred to as a glass surface in the following description.

It is difficult to estimate the position of the glass surface and the distance between a camera and the glass surface in a camera image by a typical stereo method. Accordingly, it is necessary to detect the position of the glass surface and to estimate the distance to the glass surface by the following method, for example, which is different from the stereo method.

As a method for estimating the region of a light-transmissive object such as a glass surface, it is effective to apply an image recognizing method using machine learning or the like. The method by which the above-described window region including the glass surface and a window frame can be detected in an image is disclosed in <NPL>. In this method, a plurality of candidate rectangular regions are calculated in the image, and a region that is "likely to be an entrance" on a probability basis is selected from among the calculated candidates on the basis of knowledge obtained in advance. In this document, mainly in order to detect an entrance, the distance between rectangular regions to be detected as the knowledge is restricted. However, if this method is applied to the detection of a window region, by decreasing the restriction value, it is possible to detect a window region in which windows are arranged side by side.

It is needless to say that the method for detecting the window region on the basis of learning is not limited to the method according to the above document, and for example, the detection may also be performed by a recognition method based on a very large database such as deep learning. It is typically known that the recognition can be performed with high accuracy if a large amount of learning data can be prepared in advance, and accordingly, the window region can be detected more accurately.

The above method based on recognition is advantageous because the window region can be detected by using camera images used for stereopsis without additionally providing a special sensor or the like.

On the other hand, it is known that the method based on recognition is likely to be affected by the variation in appearance. For example, if the appearance of an object such as a window frame is reflected on a glass surface, it might not be possible to successfully detect the entire glass surface as a glass region in some cases.

In contrast, it is widely known that the reflection of an object can be recognized by using light polarization characteristics. For example, in order to prevent reflection, a polarization filter is typically used. This uses a feature that light reflected on a glass surface is polarized in a certain direction but light transmitted through a glass surface is not polarized. That is, if a rotatory polarization plate is provided in front of a lens of the camera unit <NUM> and an image having different polarization directions is captured, reflection occurs, that is, a specular reflection component is present, at a part where sine-wave-form changes in brightness are seen. By obtaining a region with such changes in brightness, even if a reflective component having an appearance like a window frame is present in the glass region, a part that may be a glass region with high possibility can be obtained.

On the other hand, the method for estimating a glass region by using the above-described polarization characteristics assumes that the subject and the camera are both stationary when capturing a plurality of images while the polarization plate is rotated. Accordingly, if the camera and/or the subject moves, unfortunately, it is not possible to estimate the glass region accurately.

In contrast, it is known that light in a wavelength band of a visible light region passes through a glass surface, but light in a wavelength band of a far-infrared region is absorbed in a glass surface. That is, if an image of a glass surface is captured by a far-infrared camera, neither transmitted light nor reflected light is obtained, and the brightness is decreased in the glass region. That is, even if the same method, stereopsis, is employed, the obtained distance to the glass region may largely differ with high possibility between using a far-infrared stereo camera and using a normal stereo camera. Accordingly, if a far-infrared stereo camera is additionally installed, during a scene, a region in which the distance obtained by using the far-infrared stereo camera and the distance obtained by using the distance calculating unit <NUM> largely differ from each other, and the region having a fixed area may be detected as the glass region.

Note that if a special camera is additionally installed as described above, it is necessary to perform calibration in advance to calculate camera parameters indicating the positional relationship and the orientation relationship between the camera unit <NUM> and the additionally installed camera. By performing matrix conversion by using the camera parameters, the three-dimensional position of the glass surface calculated by the camera unit <NUM> by stereopsis and the three-dimensional position of the glass surface calculated by using the additionally installed far-infrared stereo camera can easily fit the same coordinate system. In the above case, images captured by the far-infrared camera may be received by the image acquiring unit <NUM> to be input to the light-transmissive object detecting unit <NUM>, for example.

The light-transmissive object detecting unit <NUM> estimates the three-dimensional position of a point in a space in the periphery of the vehicle to be projected in the glass region and replaces the three-dimensional position of the point calculated by the distance calculating unit <NUM> with the newly estimated three-dimensional position.

As illustrated in <FIG>, in many cases, the glass surface <NUM> is provided within a window frame <NUM> in a building <NUM>. Accordingly, a non-light-transmissive object region on the circumference of the glass surface <NUM> may be considered to be the window frame <NUM>, and on the basis of the three-dimensional position of the window frame <NUM> calculated by a stereo method from camera images, the position of the glass surface <NUM> can be estimated. Since the window frame <NUM> is a non-light-transmissive object, its three-dimensional position is calculated accurately by the distance calculating unit <NUM>. Accordingly, on the basis of the three-dimensional position of the window frame <NUM>, a plane in a three-dimensional space is calculated, and the plane is estimated to be the three-dimensional position of the glass surface <NUM>.

Typically, a plane in a three-dimensional space can be estimated on the basis of at least coordinates of three points. Accordingly, by selecting three points from points on the window frame <NUM> and applying robust estimation such as Random Sample Consensus (RANSAC), the plane formed by the points on the window frame <NUM> can be calculated, and the plane can be estimated as the three-dimensional position of the glass surface <NUM>. The light-transmissive object detecting unit <NUM> replaces the three-dimensional position of the glass region calculated by the distance calculating unit <NUM> with the three-dimensional position of the glass surface <NUM> estimated through the above procedure, thereby correcting three-dimensional information of a scene including the glass surface <NUM>.

Lastly, on the basis of the three-dimensional information of the scene, which is corrected by the light-transmissive object detecting unit <NUM>, the image generating unit <NUM> generates a vehicle-periphery image. Specifically, an image seen from a virtual camera that is provided above the vehicle and that has such a field of view that looks down on the periphery of the vehicle from above is generated by so-called computer graphics (CG) rendering on the basis of the three-dimensional information of the scene, images captured by the camera unit <NUM>, and predetermined camera parameters of the camera unit <NUM> and the virtual camera, and the generated image is output.

Now, the operation of the image generating unit <NUM> when generating a generated image Is by using the positional information {Pq,r} (see Expression <NUM>) generated from a set of rear stereo images will be described below.

First, the image generating unit <NUM> calculates pixel coordinates (us, vs) of all corresponding points pq,r,n according to the positional information {Pq,r} in the generated image Is. The pixel coordinates in the generated image Is can be calculated by the following method. The three-dimensional position (xs, ys, zs) of a virtual camera s in a coordinate system is calculated by using the three-dimensional position (xq, yq, zq) of the camera q in a coordinate system and external parameters Mq,s of the camera q and the virtual camera s corresponding to the generated image Is included in the corresponding points Pq,r,n. Then, by using the three-dimensional position (xs, ys, zs) and internal parameters (f, k) of the virtual camera s, the pixel coordinates (us, vs) of the virtual camera s are calculated (Expression <NUM>).

The image generating unit <NUM> calculates a pixel value from pixel values iq (uqn, vqn) and ir (um, vm) of the corresponding points in two images Iq and Ir and sets the pixel value as the pixel value of a pixel at the coordinates (us, vs) in the generated image Is. As a method for calculating one pixel value from the pixel values iq (uqn, vqn) and ic (um, vm) of the corresponding points in two images Iq and Ir, an average pixel value is used here.

This processing is repeatedly performed for all the positional information {Pq,r}, and the pixel values in the generated image Is are set. In the above manner, since the pixel value of each pixel in a virtual camera image can be calculated on the basis of images captured by the camera unit <NUM>, an image as if captured by the virtual camera can be generated.

In this case, an image is combined at the three-dimensional position of the glass region detected by the light-transmissive object detecting unit <NUM>, and an image captured by the camera unit <NUM> is combined at the position of the glass surface <NUM> in <FIG>, where nothing is combined according to the related art. That is, an image illustrated in <FIG> can be combined, and accordingly, the driver can be notified of the presence of the glass surface <NUM> and its position.

Note that the method for generating an image from a given point of view on the basis of three-dimensional information is specifically described in <NPL>, and therefore detailed description thereof will be omitted. Although the method using transformation of the point of view on a pixel basis has been described herein, in order to obtain a smoother and higher-density image with a transformed point of view, a polygon such as a square or triangle may be formed by using adjacent points in a three-dimensional point group in a two- or three-dimensional space, and the point of view may be transformed.

Note that the method for generating an image is not necessarily limited to the above-described method for generating an image on the basis of all three-dimensional positional information.

As described above, the position of an end (specifically, the window frame) of the glass surface in a three-dimensional space can be measured by stereo distance measurement, and on the basis of the position in the three-dimensional space, the position of an end (i.e., the glass region in the generated image) of the glass surface in the generated image can be obtained. Accordingly, the glass region in the camera image may be two-dimensionally transformed into a shape of the glass region in the generated image, and the shape may be pasted on the generated image. Thus, the combination result that is similar to that of <FIG> can be obtained at a lower calculation cost.

<FIG> illustrates a camera image captured by the camera unit <NUM> that is placed at the rear portion of the vehicle. Points a to d represent end points of the glass surface <NUM>. <FIG> illustrates a generated image obtained by transforming the point of view of the camera image in <FIG> to a point of view looking down on the glass surface <NUM> and the vehicle from a virtual camera above the subject vehicle by a method according to the related art. Nothing is combined to the glass surface <NUM>.

<FIG> illustrates a modified image from which strain is excluded from the camera image in <FIG> on the basis of camera parameters. The image in a region defined by the points a to d in the modified image in <FIG> is subjected to two-dimensional transformation, and the transformed image is attached to the region defined by the points a to d in the generated image in <FIG>, and thereby a generated image in <FIG> is obtained.

The processing in the above manner is effective in that heavy processing such as three-dimensional polygon processing can be omitted, thereby the processing can be performed at a high speed. Note that the generated image in <FIG> may also be obtained, without the modified image in <FIG>, by two-dimensionally transforming an image in the region defined by the points a to d in <FIG> and attaching (i.e., combining) the transformed image to the region defined by the points a to d in the generated image in <FIG>.

In summary of the above description, the image generating apparatus and an image generating method according to this embodiment of the present disclosure has a feature that a predetermined image is displayed in a form different from the forms of other objects at the position of a light-transmissive object or a reflective object (e.g., glass surface) in a generated image (e.g., vehicle-periphery image).

The predetermined image is, for example, a part of a camera image that is obtained, after correcting the distance to the light-transmissive object or the reflective object by a method different from stereo distance measurement, by rendering the camera image by using the corrected distance. As another example, the predetermined image is a part of a camera image that is two-dimensionally transformed and attached at the position of the light-transmissive object or the reflective object. Furthermore, as will be described later, the predetermined image may be an image representing a specific artificial design. In other words, the part of a camera image here has the same point of view as the camera image while the generated image has a point of view different from that of the camera image. That is, the part of a camera image means an image having a point of view that is not transformed.

That is, the predetermined image is displayed in a form different from that of an object other than the light-transmissive object or the reflective object in the generated image, and the driver can be notified of the presence of the light-transmissive object or the reflective object. Accordingly, a vehicle-periphery image is obtained, which is the generated image useful in assisting safe driving and in which the driver can easily recognize the light-transmissive object or the reflective object.

The first embodiment has described an example in which the camera unit <NUM> provided at the rear portion of the vehicle acquires an image of a backward area of the vehicle and the three-dimensional position in the ambient environment. This does not limit the place at which the camera is installed and the image capturing orientation and/or the image capturing area, and the camera may be installed at another position and/or in another image capturing orientation as long as images of the periphery of the vehicle can be captured.

<FIG> illustrate another example of the image generating apparatus <NUM>, the camera unit <NUM>, and the display <NUM> installed in a vehicle.

<FIG> are views looking down on the vehicle from above. Camera units 120a to 120d are each a stereo camera that can measure distances and are provided at four portions: the front, right, rear, and left of the vehicle. The individual cameras are distinguished from one another by referring to letters "a" to "d" at the last reference numeral, but each of the cameras is referred to as the camera unit <NUM> unless the individual cameras are distinguished from one another. By installing a fish-eye or wide-viewing-angle stereo camera at each portion, it is possible to measure distances all around the vehicle without a blind spot and to generate an image with a transformed point of view.

<FIG> illustrate examples of images captured during a parking scene in a parking lot in front of a store having glass windows. Note that <FIG> are subjected to the same processing as <FIG> for ease of understanding.

If the camera units 120a to 120d are each a fish-eye stereo camera, <FIG> illustrate examples of camera images captured by either camera in each of the stereo cameras. The image captured by the front camera unit 120a corresponds to <FIG>, the image captured by the right camera unit 120b corresponds to <FIG>, the image captured by the rear camera unit 120c corresponds to <FIG>, and the image captured by the left camera unit 120d corresponds to <FIG>. It is understood that images of the periphery of the vehicle are captured without a blind spot.

Note that the camera units 120a to 120d desirably capture images in synchronization with one another at regular time intervals and output the images.

<FIG> illustrates an example of a vehicle-periphery image generated by a method according to the related art on the basis of moving images captured in the above manner without a blind spot. In addition, <FIG> illustrates an example of a vehicle-periphery image further displaying a glass region by the method described in the first embodiment.

Thus, by performing an image generating process by using the vehicle-periphery image without a blind spot, an image from a point of view looking down on the entire periphery of the vehicle from above can be generated as illustrated in <FIG>, and accordingly, it is possible to present to the driver moving images from which the driver can more easily view how large a glass surface is and in which direction the glass surface is in the periphery of the vehicle.

Note that the image displayed in the glass region has been described above by taking an example of generating an image by using images captured by the camera unit <NUM>. Since the image generating apparatus according to this embodiment of the present disclosure aims to notify the driver of the presence of a glass surface, the image displayed in the glass region is not limited to the above-described camera image, but may be, for example, an image representing a specific artificial design.

For example, it is also possible to generate moving images from which the driver can easily view the presence of the glass surface by displaying straight lines extending from the surface of a road in the vertical direction (extending upward from the surface of a road in the vertical direction) are combined to the glass region. By drawing lines that are vertical to the surface of a road, it is possible to display an image from which the position and inclination of the surface is easily understood. For example, if the glass surface <NUM> and a glass surface <NUM> are present behind and in a side of the vehicle, an image in <FIG> may be displayed.

The image generating apparatus <NUM> described in the first embodiment combines images captured by a plurality of cameras to a glass region without any modification and obtains a generated image.

<FIG> illustrates an issue in this combining processing, in which a real image <NUM> is illustrated above the glass surface <NUM> and a virtual image <NUM> reflected on the glass surface <NUM> is illustrated below the glass surface <NUM>.

As illustrated in <FIG>, light beams that pass through a point-of-interest <NUM> on the glass surface <NUM> and that enter the camera units 120b and 120c having different points of view are from different objects (or virtual images) through the glass surface <NUM>. This results in brightness mismatch between adjacent pixels at the time of image generation. Accordingly, as illustrated in <FIG>, the generated image may be difficult to view.

Accordingly, in this embodiment, in order to address the above-described issue, the image generating unit <NUM> selects a camera with the highest ratio of the glass surface <NUM> in a part where the fields of view of cameras overlap with each other in the glass region and uses a camera image captured by the camera to be combined.

Accordingly, as illustrated in <FIG>, since the selected camera image is used at the time of combining an image to the glass region, it is effective in that a camera image with the largest area of the glass surface is combined to the glass region and that the image in the glass region is easily viewed.

Note that according to the above method, if there are a plurality of glass regions during a scene, a camera with the largest area of each glass surface is not selected in some cases. In contrast, if there are a plurality of glass regions during a scene, a camera with the highest ratio of a glass region in the field of view may be selected for each glass region. Thus, it is effective in that a camera with the largest area of each glass surface is selected and that the image of each glass region is viewed more easily.

The image generating apparatus <NUM> described in the first embodiment combines an image in a camera image to a glass region as illustrated in <FIG> without any modification and obtains a generated image. Accordingly, there are both a reflective component and a light-transmissive component in the generated image, which is untidy and difficult to view.

Accordingly, as illustrated in <FIG>, in an image generating apparatus 100a according to this embodiment, a reflective-component separating unit <NUM> and a reflective-component combining unit <NUM> are provided in an image generating unit 104a.

The reflective-component separating unit <NUM> has a function of separating transmitted light and reflected light from each other in an image (in particular, on the surface of a light-transmissive object such as a glass surface), and, on the basis of the result of separation by the reflective-component separating unit <NUM>, the reflective-component combining unit <NUM> combines an image after adjusting the ratio of the reflective component at the time of combination in a glass region on the basis of separately determined parameters when generating an image from a desired point of view. That is, the generated image is displayed by assigning weights to the light-transmissive component and the reflective component at a predetermined ratio at the position of the light-transmissive object in the generated image.

By combining an image in consideration of the reflective component in the generated image, it is effective in that the untidy appearance of the generated image can be improved.

Now, first, the operation of the reflective-component separating unit <NUM> will be described below.

A large number of methods for separating a reflective component or a specular reflection component from an image have been proposed. The methods mainly include a method using light polarization characteristics and movement.

The method using light polarization characteristics is specifically described in <NPL>. It is known that, among pixel values acquired through a rotatory polarization plate, a brightness component that changes in accordance with the rotation direction of polarization corresponds to a specular reflection component, and in this method, the specular reflection component is separated by using this knowledge.

In particular, if a rotatory polarization plate is used for the above-described light-transmissive object detecting unit <NUM>, this configuration can be directly used for the separation of a reflective component, and accordingly, the reflective component can be separated by using the same camera configuration.

On the other hand, the method using the movement is specifically described in <NPL>. In this method, when a moving camera captures an image including a reflective component, by using the fact that the movement of the reflective component largely differs from the movement of a light-transmissive component of an object that is transmitted through a glass surface in the image, the reflective component is separated.

Since the reflective component can be separated by using the camera configuration used for the distance calculating unit <NUM> without using a special camera, the reflective component can be separated with a simpler configuration.

The image generating unit 104a reconfigures an image in which the separated reflective component has been combined at a desired ratio, and on the basis of the reconfigured image, generates an image from a given point of view.

A driver often estimates the positional relationship between a glass surface and the subject vehicle from the reflective component in a glass region. In particular, if there is a glass surface in the heading direction, in accordance with the advancement of the subject vehicle, the mirror image of the subject vehicle seems approaching the subject vehicle quicker than a stationary object in the periphery. Accordingly, it is easy to recognize a reflective surface (glass surface) at the position where the mirror image is reflected. Therefore, if there is a large light-transmissive component with the reflective component in the glass region in the image captured by the camera unit <NUM>, the driver may be prevented from recognizing the position of the glass surface on the basis of the reflective component.

To address this issue, when each reflective component is combined at a desired ratio to reconfigure an image, if the combination ratio of the light-transmissive component is decreased, the light-transmissive component as a cause of lowering the visibility of the mirror image of the subject vehicle can be suppressed. Thus, the driver can easily view the reflective component on the glass surface.

On the other hand, the reflective component of the subject vehicle may seem moving on the glass surface in a direction different from the direction of the movement of the subject vehicle. That is, a driver sees a component that moves in a manner quite different from the movement of the subject vehicle overlapped on the glass surface. Accordingly, depending on the driver, it may be difficult to estimate the position of the glass surface on the basis of the reflective component in some cases.

In such a case, if the ratio of the reflective component is increased, on the contrary, estimation of the position of the glass surface may be interrupted. Accordingly, when each reflective component is combined at the desired ratio to reconfigure an image, by decreasing the ratio of the reflective component, the reflective component of the subject vehicle can be reduced.

Thus, the driver can easily view the light-transmissive component. Since the light-transmissive component is dominant in the display, it is effective in that some drivers can easily estimate the position of the glass surface.

As described above, at which ratio (weights) between the reflective component and the light-transmissive component are to be combined so that the driver can easily recognize the position of the glass surface differs depending on the driver. Accordingly, the ratio of the reflective component at the time of combination may be set in advance for each driver.

In addition, during the daytime on a sunny day, since the falling sunlight is intense, specular reflection on a glass surface may cause glare to the driver. Since the reflective component is likely to be dominant, in this period of time or if the weather is like this, the ratio of the reflective component may be decreased compared with other periods of time or other weather.

In addition, during evening to nighttime, the brightness inside a space separated by a glass surface may largely differ from the brightness outside the space. If the inside space is bright, the light-transmissive component is dominant, and accordingly, the ratio of the light-transmissive component may be decreased compared with other periods of time.

In addition, in the case of a cloudy weather or during the nighttime, the headlamp and tail lamp of the vehicle are often lit. In this case, in the glass region in a captured image, the reflection of lamps is noticeable, and the light-transmissive component is more difficult to view. In such a case, the ratio of the reflective component may be largely decreased.

In addition, if the reflection of lamps is noticeable as in the above case, the detection of the glass region itself may fail. Specifically, such a case corresponds to a case where pixels more than or equal to a predetermined ratio are saturated in a camera image due to reflected light of lamps of the subject vehicle and/or another vehicle and/or a case where a histogram of a camera image includes a strong bias in a bright part and a dark part.

Accordingly, in such a case, an image from a point of view looking down from above is not generated, and instead, a message that prompts the driver to see the periphery of the vehicle, such as "There may be a glass surface. Please check by yourself. ", may be displayed in a portion where the image from a point of view looking down from above has been displayed.

An image generating apparatus according to embodiments of the present disclosure aims to assist safe driving and to notify a driver of a glass surface that may pose a danger to the driver. Accordingly, it is not necessary to detect all glass surfaces in the periphery of the vehicle and to correct the distances to the glass surfaces. For example, for a glass surface that is unlikely to collide with the vehicle, one or more of a detection process, a distance estimation process, and a distance correction process may be skipped, and a generated image may be obtained by transforming the point of view by a method according to the related art. Thus, it is possible to obtain a generated image that is useful in assisting safe driving at a reduced calculation cost.

Specifically, as illustrated in <FIG>, it is considered that it is unlikely to collide with a glass surface <NUM> on the opposite side of a vehicle heading direction <NUM>. Accordingly, the light-transmissive object detecting unit <NUM> may detect the position of a light-transmissive object or a reflective object in a part excluding a part of the vehicle heading direction <NUM> in a camera image. Thus, it is possible to obtain a generated image that is useful in assisting safe driving at a reduced calculation cost.

<FIG> is a block diagram illustrating an example of a functional configuration of an image generating apparatus that performs a process for detecting a light-transmissive object by excluding, from the target of the process, a part of regions in a camera image. An image generating apparatus 100b illustrated in <FIG> includes an in-vehicle sensor information acquiring unit <NUM> and includes a light-transmissive object detecting unit 103b instead of the light-transmissive object detecting unit <NUM>.

The in-vehicle sensor information acquiring unit <NUM> receives in-vehicle sensor information <NUM> from in-vehicle sensors in the subject vehicle, acquires gear information of the subject vehicle from the received in-vehicle sensor information <NUM>, and transfers the gear information to the light-transmissive object detecting unit 103b. The in-vehicle sensor information <NUM> is read through a controller area network (CAN) bus (if CAN standard is employed) of an in-vehicle network. Note that the standard is not limited to CAN, and if another in-vehicle network standard such as FlexRay is employed, information may be read in accordance with the standard.

The gear information is a value assigned in accordance with the position of a shift lever of the vehicle. For example, if the gear is D (drive), N (neutral), R (reverse), and P (parking), different values of <NUM>, <NUM>, <NUM>, and <NUM>, respectively, are assigned as the gear information. It is needless to say that, since the relationship between the gear and the value differs depending on the vehicle and/or the sensors, the above case is merely an example, and the values are not limited to the above examples.

In accordance with the gear information, the light-transmissive object detecting unit 103b determines an area on which the process for detecting a light-transmissive object is to be performed, and then, as in the above-described light-transmissive object detecting unit <NUM>, estimates the region of the light-transmissive object in the periphery of the vehicle and performs the process for detecting a light-transmissive object by correcting the distance to the region of the light-transmissive object.

Specifically, a vehicle in which a first camera that captures an image of a forward area of the vehicle and a second camera that captures an image of a backward area of the vehicle (e.g., the front camera unit 120a and the rear camera unit 120c illustrated in <FIG>) are installed will be considered.

If the gear information of the vehicle is a value corresponding to R (reverse), since the vehicle is advancing backward, it is considered that it is unlikely to collide with a glass surface in front of the subject vehicle. Accordingly, as illustrated in <FIG>, a region <NUM> in front of the subject vehicle in a camera image captured by the first camera (front camera) is excluded from the target of the process for detecting a light-transmissive object, and the position of the light-transmissive object or the reflective object is detected by using a camera image captured by the second camera (rear camera). Thus, the calculation cost can be reduced.

Similarly, if the gear information is a value corresponding to D (drive), since the vehicle is advancing forward, it is considered that it is unlikely to collide with a glass surface behind the subject vehicle. Accordingly, as illustrated in <FIG>, a region <NUM> behind the subject vehicle in a camera image captured by the second camera (rear camera) is excluded from the target of the process for detecting a light-transmissive object, and the position of the light-transmissive object or the reflective object is detected by using a camera image captured by the first camera (front camera). Thus, the calculation cost can be reduced.

Note that the image generating apparatus that obtains a generated image that is useful in assisting safe driving at a reduced calculation cost is not limited to the above example.

For example, if the distance between a camera and the light-transmissive object or the reflective object estimated by the light-transmissive object detecting unit is larger than a predetermined threshold, it is possible not to correct the distance between the camera and a point in a space to be projected at the position of the light-transmissive object or the reflective object.

In addition, for example, if the lowest end of the light-transmissive object or the reflective object detected by the light-transmissive object detecting unit is higher than or equal to a predetermined threshold from the surface of a road, it is possible not to estimate the distance between the camera and the light-transmissive object or the reflective object and not to correct the distance between the camera and a point in a space to be projected at the position of the light-transmissive object or the reflective object.

Furthermore, for example, if the size of the light-transmissive object or the reflective object detected by the light-transmissive object detecting unit is smaller than a predetermined threshold, it is possible not to estimate the distance between the camera and the light-transmissive object or the reflective object and not to correct the distance between the camera and a point in a space to be projected at the position of the light-transmissive object or the reflective object.

In any of the above configurations, by skipping a process on a glass surface that is considered to be unlikely to collide with the subject vehicle, a generated image that is useful in assisting safe driving can be obtained at a reduced calculation cost.

A driver typically views the heading direction while driving. Thus, if a glass surface is present in a direction that is not the heading direction, the driver is more unlikely to notice the presence of the glass surface. Accordingly, in this case, a glass region in a generated image may be made noticeable by, for example, temporarily being made to blink.

In a case of autonomous driving, the above method can also be applied. It is known that the meaning of images to be presented to a driver is slightly different from assisting safe driving of the related art in the case of autonomous driving. That is, the images need to serve also as a user interface (UI) for notifying a driver that an autonomous driving vehicle correctly recognizes the ambient environment, thereby giving the driver a sense of security. In such a case, by combining an image captured by a camera to a glass region and by making the glass region noticeable by, for example, making a generated image to blink or superposing a color such as red or yellow, the driver can be notified that the autonomous driving vehicle recognizes the position of a glass surface.

Note that an image generating apparatus according to a modification may include a display unit for displaying the generated vehicle-periphery image.

<FIG> is a block diagram illustrating an example of a functional configuration of the image generating apparatus according to the modification. An image generating apparatus 100c illustrated in <FIG> has a configuration obtained by adding a display unit <NUM> to the image generating apparatus <NUM> illustrated in <FIG>. The display unit <NUM> includes a display circuit and may include, for example, the display <NUM> illustrated in <FIG>.

The above various embodiments described in this specification can be combined with one another unless there are inconsistencies between the embodiments.

All or some of the units or devices, or all or some of the functional blocks of the block diagrams of the image generating apparatus illustrated in <FIG>, the image generating apparatus illustrated in <FIG>, and the image generating apparatus in <FIG> in the present disclosure may be implemented by one or one or more electronic circuits including a semiconductor device, a semiconductor integrated circuit (IC), or a large scale integration (LSI). The LSI or IC may be implemented by one chip or may be implemented by a combination of a plurality of chips. For example, functional blocks other than the storage element may be integrated on one chip. Although the term "LSI" or "IC" is used herein, the name changes depending on the degree of integration and the term "system LSI", "very large scale integration (VLSI)", or "ultra large scale integration (ULSI)" may be used. A field programmable gate array (FPGA) that is programmable after production of the LSI or a reconfigurable logic device in which connections within the LSI is reconfigurable and setup of circuit cells within the LSI are possible may be used for the same purpose.

Further, all or some of functions or operations of the units, the apparatuses, and part of the apparatuses can be implemented by software-based processing. In this case, the software is stored on one or one or more non-transitory recoding media, such as a ROM, an optical disc, or a hard disk drive. When the software is executed by a processing device (processor), the software causes the processing device (processor) and its peripheral devices to carry out a specific function included in the software. A system or an apparatus may include one or one or more non-transitory recording media storing the software, the processing device (processor), and necessary hardware devices, for example, an interface.

The apparatus according to the present disclosure may be a computer system including a microprocessor and a memory, the memory may store the foregoing computer program, and the microprocessor may execute the computer program.

The foregoing program or digital signals may be transferred by recording it on the recording medium, or the foregoing program or digital signals may be transferred through the network or the like, so as to execute or process the program or digital signals in another independent computer system.

In addition, each of the components of the embodiments may be implemented by dedicated hardware or by executing a software program suitable for the component. Each of the components may be implemented as a result of a program executor, such as a CPU or processor, reading and executing a software program stored on a recording medium, such as a hard disk or semiconductor memory.

Claim 1:
An image generating apparatus for generating an image to be displayed on a display (<NUM>) installed in a vehicle, the image generating apparatus comprising:
at least one memory; and
a control circuit,
the control circuit is configured to:
(a) acquire (S101) a plurality of camera images (<NUM>) captured by a plurality of visible-light cameras (<NUM>, <NUM>) included in a stereo camera (<NUM>) that is installed in the vehicle; and
(b) calculate (S102), by using stereopsis and the plurality of camera images (<NUM>), a distance in a three-dimensional space between one of the cameras (<NUM>, <NUM>) and a target (<NUM>, <NUM>) included in the plurality of camera images (<NUM>);
wherein
the control circuit is configured to:
(c) detect (S103) a position of a light-transmissive object (<NUM>) or a reflective object (<NUM>) in the plurality of camera images (<NUM>), wherein the reflective object (<NUM>) is an object in the plurality of camera images (<NUM>) of which specular-reflected light is dominant;
(e) estimate, on the basis of a three-dimensional position of a non-light-transmissive and non-reflective object region (<NUM>) on a circumference of the light-transmissive object (<NUM>) or the reflective object (<NUM>), a distance between the one of the cameras (<NUM>, <NUM>) and the light-transmissive object (<NUM>) or the reflective object (<NUM>), wherein the three-dimensional position of the and non-reflective object region (<NUM>) is calculated by a stereo method from camera images;
(f) correct, to the estimated distance, the distance between the one of the cameras (<NUM>, <NUM>) and the target, wherein said target is at the detected position of the light-transmissive object (<NUM>) or the reflective object (<NUM>) in the plurality of camera images (<NUM>); and
(d) generate an image from a point of view that is different from points of view of the plurality of camera images (<NUM>) by using the plurality of camera images (<NUM>) and the corrected distance, the generated image including a predetermined image that is displayed at the position of the light-transmissive object (<NUM>) or the reflective object (<NUM>).