JPH0896118A - Circumferential state display device for vehicle - Google Patents

Abstract

PURPOSE: To relax a distortion of an image without causing any increase in the cost of the device and to cape with the variance of lenses and temperature characteristics, etc. CONSTITUTION: This device is equipped with a lens 101 consisting of a wide-angle lens or fisheye lens having barrel-shaped distortion, a CCD camera which converts light obtained by picking up an image through the lens 101 into an electric signal through photoelectric conversion and outputs it as an image signal, a coordinate converter 104 which inputs the image signal from the CCD camera and converts the coordinates of the image signal in pixel units by using a nonlinear odd function, and a display monitor 107 which displays an image. Here, 103 is an A/D converter, 105 is an image memory, and 106 is a D/A converter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, as an image display for front and left recognition at an intersection with poor visibility, a method for picking up and displaying a monitor for rear recognition when changing lanes, and in particular, BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle ambient condition display device that clearly captures a vehicle ambient condition over a wide range and displays a natural image that is easy to recognize.

[0002]

2. Description of the Related Art As a conventional vehicle surroundings display device,
For example, there is one shown in FIG. This device
The lens 1701 forms an image (light) on the image sensor 1702, and the image sensor 1702 converts the image (light) into an electric signal by photoelectric conversion, thereby reading the light image as an image signal (electric signal), After that, the read image signal is displayed on a display monitor 1703 such as a liquid crystal television so that the driver can recognize the surrounding condition of the vehicle.

The lens 1701 and the image sensor 1702 are arranged at the rear, side or front of the vehicle, and the display monitor 1703 is arranged at a position visible from the driver's seat. Further, the lens 1701 is arranged such that its optical axis is directed to a target point (a target position to be displayed on the display monitor 1703), and light (image) within a range of an angle of view θ centered on the optical axis is image sensor 1702. And is imaged. In other words, light (image) outside the range of the angle of view θ is not imaged on the image sensor 1702, so that the display monitor 1
It cannot be displayed on 703.

Therefore, for example, as shown by the dotted line in FIG. 17A, if a large image sensor 1704 is used, the angle of view θ'can be increased. However, in this case, the price of the image sensor 1704 becomes high,
There is an inconvenience that the cost of the device is increased.

Further, by reducing the imaging magnification,
Although the angle of view can be increased, for example, the lens 17
If the focal length of 01 is shortened and the imaging magnification is reduced, the lens 1701 can be brought closer to the image sensor 1702, so that the angle of view becomes wider, but if the imaging magnification of the lens 1701 is reduced, the resolution on the optical axis is reduced. It causes the inconvenience. Further, if the focal length is shortened, the depth of focus becomes shallower, and the inconvenience that the accuracy of the distance from the lens 1701 to the image sensor 1702 becomes stricter occurs.

Therefore, in order to solve these inconveniences, a device has been proposed in which a wide-angle lens or a fish-eye lens is used to increase the angle of view. FIG.17 (b) is
An example in which the wide-angle lens 1705 is used is shown. As shown, the light is bent by the wide-angle lens 1705, the light within the wide angle of view θ ′ is guided to the image sensor 1702, and is displayed on the display monitor 1703. Although not shown in the drawings, the fish-eye lens is a lens configured to obtain an angle of view of 180 ° or more by bending light more strongly than the wide-angle lens 1705. Therefore, an image with a wide angle of view can be displayed as with the wide-angle lens 1705.

[0007]

However, according to the above-mentioned conventional technique, when a wide-angle lens or a fish-eye lens is used, light near the optical axis with a small angle of view can hardly be bent. However, there is a problem that barrel distortion occurs in the image formed on the image sensor because the image is strongly bent.

Further, due to the occurrence of barrel-shaped distortion, nearby objects appear to be smaller than they actually are, which makes it difficult to obtain a sense of distance, and further, when the image is strongly distorted, it is difficult to determine the distance. To do.

FIG. 18 shows an example of an image received by the image sensor. FIG. 18A shows an image sensor using the above-mentioned lens 1701 and FIG. 18B using the above-mentioned wide-angle lens 1705, which are image sensors of the same size and have the same magnification. As is clear from FIG. 18B, by using the wide-angle lens 1705,
For example, it is possible to receive an image of a light or a child at a position X, a dog at a position Y, and the like, and display a wider range of vehicle surroundings. If the mold is distorted, it is displayed smaller than it actually is, or if the image is distorted more strongly, it becomes difficult to identify it.

Further, in the prior art, as a method of correcting the image distortion, a method of performing coordinate conversion by referring to a table (look-up table) created in advance is conceivable, but there are variations in lens and There were problems that it was difficult to cancel the effects of temperature characteristics, etc., and that a large table was required, which resulted in high costs and difficult implementation.

Specifically, when a 512 × 512 dot image sensor is used, in the method of referring to the look-up table, (9 bits + 9 bits) × 512 × 512 = 4.
A memory of 7 Mbit or more is required.

The present invention has been made in view of the above, and in displaying an image formed by a lens having a barrel-shaped distortion characteristic, by performing coordinate conversion using an odd function that is not linear, The objective is to alleviate image distortion and to deal with lens variations and temperature characteristics without increasing the cost of the device.

[0013]

In order to achieve the above object, a vehicle ambient condition display device according to a first aspect of the present invention comprises a lens means including a wide-angle lens or a fisheye lens having barrel-shaped distortion characteristics, and the lens. The light imaged through the means is converted into an electric signal by photoelectric conversion and output as an image signal, and the image signal is input from the photoelectric conversion means, and the image signal is converted by using a non-linear odd function. It is provided with a coordinate conversion means for performing coordinate conversion on a pixel-by-pixel basis and a display means for displaying an image by inputting the image signal after the coordinate conversion from the coordinate conversion means.

According to a second aspect of the present invention, there is provided a vehicle ambient condition display device, wherein a lens means including a wide-angle lens or a fish-eye lens having barrel-shaped distortion characteristics, and light formed through the lens means are converted into electricity by photoelectric conversion. Photoelectric conversion means for converting into a signal and outputting as an image signal; coordinate conversion means for inputting the image signal from the photoelectric conversion means and performing coordinate conversion of the image signal on a pixel-by-pixel basis using a non-linear odd function;
Interpolation processing means for inputting the coordinate-converted image signal from the coordinate conversion means to interpolate the image signal in the converted coordinate system; and inputting the interpolated image signal from the interpolation processing means, And a display unit for displaying an image.

Further, in the vehicle surrounding condition display device according to a third aspect, the coordinate conversion means sequentially outputs the image signal after the coordinate conversion in pixel units according to the address in the coordinate system after the conversion, and the interpolation processing. When the means inputs an image signal in pixel units from the coordinate conversion means, the previously input image signal is output to the display means until the next image signal is input, thereby performing interpolation processing of the image signal. Is.

Further, in the vehicle surrounding condition display device according to a fourth aspect, the coordinate conversion means has a distance between outer pixels in a diameter direction of a circle centered on a pixel corresponding to a center point of the lens means. Coordinate conversion is performed so as to enlarge.

In the vehicle surroundings display device according to a fifth aspect of the present invention, the coordinate conversion means performs coordinate conversion so that the distance between pixels in the vertical direction, the horizontal direction, or both the vertical and horizontal directions of the lens means is enlarged. Is to do.

According to a sixth aspect of the present invention, there is provided a vehicle surrounding condition display device in which the vertical distortion characteristic of the lens means is smaller than the horizontal distortion characteristic, and the coordinate conversion means coordinates the image signal only in the horizontal direction. It is to convert.

Further, in the vehicle surrounding condition display device according to the seventh aspect, at least one coefficient included in the non-linear odd function of the coordinate conversion means can be changed.

[0020]

According to the vehicle ambient condition display device of the present invention (claim 1), an image of light is formed on the photoelectric conversion means through the lens means which is a wide-angle lens or a fisheye lens having barrel-shaped distortion characteristics. The photoelectric conversion means converts the imaged light into an electric signal by photoelectric conversion and outputs it as an image signal. Next, the coordinate conversion unit performs the coordinate conversion of the image signal on a pixel-by-pixel basis by using an odd function that is not linear, thereby alleviating the distortion of the image without increasing the cost of the apparatus. After that, the display means inputs the image signal after the coordinate conversion to display the image.

Further, the vehicle ambient condition display device according to the present invention (claim 2) forms an image of light on the photoelectric conversion means through the lens means which is a wide-angle lens or a fish-eye lens having a barrel distortion characteristic. The imaged light is converted by the photoelectric conversion means into an electric signal by photoelectric conversion and output as an image signal. Next, the coordinate conversion means performs coordinate conversion of the image signal on a pixel-by-pixel basis by using an odd function that is not linear, thereby alleviating the distortion of the image without increasing the cost of the device, and the interpolation processing means performs the conversion. The density of the image signal data is increased by performing the interpolation processing of the image signal in the subsequent coordinate system. After that, the display means inputs the image signal after the interpolation processing and displays the image.

The vehicle surroundings display device according to the present invention (claim 3) is the vehicle surroundings display device according to claim 2, wherein the coordinate conversion means converts the coordinate-converted image signal. According to the address in the coordinate system, the pixel signals are sequentially output, and when the interpolation processing unit inputs the image signal from the coordinate conversion unit in the pixel unit, the previously input image signal is input until the next image signal is input. By outputting to the display means, the interpolation processing of the image signal is performed with a simple configuration.

Further, in the vehicle surroundings display device according to the present invention (claim 4), in the vehicle surroundings display device according to claim 1 or 2, the coordinate conversion means corresponds to a center point of the lens means. By performing coordinate conversion so that the distance between pixels on the outside in the diameter direction of a circle centered on the pixel to be expanded, the barrel distortion is effectively mitigated.

According to the present invention, there is provided a vehicle ambient condition display device (claim 5), wherein the coordinate transformation means includes a vertical direction and a horizontal direction of the lens means. By performing coordinate conversion so that the distance between pixels in the horizontal direction or in both the vertical and horizontal directions is expanded, barrel distortion can be effectively mitigated with a simple configuration.

Further, the vehicle ambient condition display device according to the present invention (claim 6) is characterized in that, in the vehicle ambient condition display device according to claim 1 or 2, the longitudinal distortion characteristic of the lens means is a lateral strain. The coordinate conversion means, which is smaller than the characteristic, performs the coordinate conversion of the image signal only in the lateral direction, thereby effectively mitigating the barrel distortion with a simple configuration.

Further, the vehicle ambient condition display device according to the present invention (claim 7) is included in the non-linear odd function of the coordinate conversion means in the vehicle ambient condition display device according to claim 1 or 2. Since at least one of the coefficients can be changed, it is possible to easily deal with variations in the lens and temperature characteristics.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle surrounding condition display device according to the present invention will be described below in the order of [Example 1], [Example 2], [Example 3], [Example 4], [Example 5]. Will be described in detail with reference to.

[Embodiment 1] FIG. 1 is a block diagram of Embodiment 1, showing a lens 101 composed of a wide-angle lens or a fisheye lens having barrel-shaped distortion characteristics, and a lens 101.
The image sensor 102 as a photoelectric conversion means for converting the light imaged via the light into an electric signal by photoelectric conversion and outputting it as an image signal, and an image signal (analog signal) from the image sensor 102 is input to convert it into a digital signal. An A / D converter 103 for conversion, and a coordinate converter 104 for inputting an image signal (digital signal) from the A / D converter 103 and performing coordinate conversion of the image signal on a pixel-by-pixel basis using a non-linear odd function, An image memory 105 for temporarily storing the image signal after the coordinate conversion from the coordinate converter 104 and a D / A converter 106 for converting the image signal (digital signal) output from the image memory 105 into an analog signal. , D / A
It is composed of a display monitor 107 as a display means for displaying an image by inputting an image signal from the converter 106.

The image memory 105 has a number of dots larger than that of the image sensor 102. The coordinate converter 104 is composed of a microcomputer.

Next, the principle of coordinate conversion processing by the coordinate converter 104 will be described. FIG. 2 is an explanatory diagram showing characteristics of the lens 101 (wide-angle lens or fish-eye lens). The light at the point 201 located at the height h from the optical axis passes through the lens 101 and forms an image on the image sensor 102. At this time, if the lens 101 has no distortion characteristics and the light is not bent, the position R of the image on the image sensor 102 is the position obtained by multiplying the height h by the magnification m of the magnification of the lens 101. On the other hand, if the lens 101 has a distortion characteristic, the light is bent, so that the position R ′ at which an image is actually formed has a relationship of R ′ <R.

In general, the material and shape of the lens 101 are designed so as to be center-symmetric with respect to the optical axis. That is, the image formation by the lens 101 is performed in the diametrical direction (the R direction in the figure) with the point P corresponding to the center of the lens 101 as the center
Has symmetry. Therefore, when the height h is −h, R ′ moves to −R ′. From such characteristics, the position R ′ at which an image is actually formed can be expressed by an odd function of R. That is, when the actually imaged position R ′ is expanded to a power of R, it can be displayed by the following equation. R ′ = R−k ₁ R ³ −k ₂ R ⁵ −k ₃ R ⁷ (1) It should be noted that all the powers of the formula (1) are odd numbers, and the coefficients k ₁ , k ₂ , k ₃ ... Has a positive, zero or negative value.

From equation (1), it can be seen that the distortion is small in the vicinity of R = 0, the R becomes large, and the distortion becomes larger as the screen becomes larger. Also, the coefficient k ₁ in equation (1),
k _2, k ₃ ... are determined by the shape, material, etc. of the lens, it is to vary with temperature and manufacturing variation.

Therefore, from the relation of the above equation (1),
Although it is theoretically possible to obtain R from the position R ′ on the image sensor 102, actually, in the equation (1),
Given R ', it is difficult to find R.
Therefore, in the present invention, the property that the solution of the formula (1) is always an odd function is used, and the coordinates (x ″, y ″) calculated by the following formulas (2) and (3) are expressed by the formula ( The approximate value of the solution of 1) is obtained as.

Specifically, the coordinate converter 104 has a coordinate system X'-Y 'in which the coordinates of the point P corresponding to the center point of the lens 101 on the image sensor 102 are (0, 0).
The coordinates (x ', y') at
Convert to coordinates (x ", y") using (3). x "= x '(1 + k 01 R' 2 + k 02 R '4 + ......) ‥‥ (2) y" = y' (1 + k 01 R '2 + k 02 R' 4 + ......) ‥‥ (3) ^{However, R '2 = x' 2} + y '2

At this time, the coefficients k ₀₁ , k _02, ... Are externally input and determined as adjustment coefficients. That is, the coefficient k contained in the non-linear odd function of the coordinate converter 104.
₀₁ , k ₀₂ ... Can be changed by external input.

The operation of the first embodiment having the above configuration will be described. The light image formed on the image sensor 102 via the lens 101 is output to the coordinate converter 104 via the A / D converter 103. The coordinate converter 104 uses the non-linear odd function represented by the above equations (2) and (3) to coordinate the image signal pixel by pixel (x ′, y ′) →
The coordinates are converted into (x ", y") and written in the image memory 105. After that, the image signal of the image memory 105 is output to the display monitor 107 via the D / A converter 106, and the image is displayed on the display monitor 107.

FIG. 3 shows an example of an image obtained by coordinate-converting the image shown in FIG. 18B according to the first embodiment. However, Figure 3
In (a), adjustment factors k ₀₁ = -0.7 and k ₀₂ = 4,
This is an example in which the coefficients of the terms R ^{7 and} above are set to 0. Moreover, FIG.
In the example of (b), the adjustment coefficient k ₀₁ = 1.3 and the coefficient of the term of R ⁵ or more is 0. As is apparent from the drawing, according to the first embodiment, it is possible to obtain an image sensor having the same size, the same magnification, and a wide angle of view and little distortion. Further, comparing FIG. 3A and FIG. 3B, the distortion is smaller in FIG. 3A in which the coefficients of the higher order terms in the equations (2) and (3) are set. . However, the number of adjustment coefficients set is small and the order is low, which allows faster calculation. The adjustment coefficients k ₀₁ , k _02, ... May be manually input to cancel the influence of the temperature characteristics of the lens 101. However, for example, the temperature is detected by a temperature sensor or the like, and the corresponding coefficients are obtained from the look-up table. May be automatically referred to and set as the adjustment coefficient.

Generally, signals are sequentially output from the image sensor 102 in the horizontal and vertical directions. For example, in Figure 1, ...
(-1, 1,), (0, 1), (1, 1), ..., (-1,
0), (0,0), (1,0), ..., (1, -1),
Image signals such as (0, -1), (1, -1), ... Are output, and the display monitor 107 is configured to sequentially convert horizontal and vertical data into images.

In order to perform coordinate conversion using the equations (2) and (3) and to output the converted data (x ", y") to the display monitor 107 in sequence, refer to FIG. As shown, the image memory 105 for one screen (at least a half screen) is required.

As described above, in the first embodiment, the property that the solution of the equation (1) always becomes an odd function is utilized, and the equation (2),
Since the coordinates (x ", y") calculated in (3) are used as the approximate value of the solution of the equation (1) to perform the coordinate conversion, the coordinate conversion is performed without creating a look-up table. It can be performed. Therefore, an expensive memory is not required and high-speed calculation is possible.

Further, the adjustment coefficient k _{01 of} the equations (2) and (3),
Since k ₀₂ ... Can be changed by an external input, it is possible to easily deal with variations in lens characteristics and lens temperature characteristics.

[Embodiment 2] Embodiment 2 shows an example of performing coordinate conversion by using a line memory 401 for one line instead of the image memory 105 of Embodiment 1 shown in FIG. is there.

FIG. 4 is a block diagram of the second embodiment. In the figure, a lens 101, an image sensor 102, A /
D converter 103, coordinate converter 104, D / A converter 10
6 and the display monitor 107 are the same as those in the first embodiment. Four
Reference numeral 01 is an image memory that stores the data converted by the coordinate converter 104, and is a line memory that stores an image signal for one line. That is, in the first embodiment, the memory for the half screen or the one screen of the expanded screen is required, but in the second embodiment, the capacity of the image memory is reduced. In this case, the coordinate converter 104 uses the equation (2),
Since the coordinate conversion in the diameter (R) direction by (3) cannot be performed, the calculation for the coordinate conversion is executed using the following formula instead. The adjustment factors k ₀₁ , k _02, ...
It is determined by an external input as in the first embodiment. x "= x '(1 + k 01 x' 2 + k 02 x '4 + ......) ‥‥ (4) y" = y' (1 + k 01 y '2 + k 02 y' 4 + ......) ‥‥ (5)

The operation of the second embodiment having the above configuration will be described. The image signal input to the image sensor 102 is output to the coordinate converter 104 via the A / D converter 103. By the coordinate converter 104, the coordinates (x ′,
The data of y ') is calculated by the equations (4) and (5),
It is written in the coordinates (x ", y") on the line memory 401. The data in the line memory 401 is the D / A
It is output to the display monitor 107 via the converter 106.

FIG. 5 is an example of an image obtained by coordinate-converting the image shown in FIG. 18A according to the second embodiment. According to the second embodiment, the strain relaxation effects of the equations (4) and (5) are smaller than those of the equations (2) and (3) used in the first embodiment, but the two-dimensional memory is not required. ， There is an advantage that the price of memory can be reduced. Also, equations (4) and (5)
Since the distortion in the horizontal and vertical directions is relaxed by the above, there is an effect that a sense of distance can be easily obtained, as is clear from comparison with the conventional image example shown in FIG.

[Third Embodiment] In the third embodiment, the coordinate converter 10 is used.
After the coordinate conversion is performed in step 4, the image signal after the coordinate conversion is input from the coordinate converter 104, and the interpolation processing means for interpolating the image signal in the coordinate system after the conversion is arranged. Since the other configurations are similar to those of the second embodiment, the description thereof will be omitted.

FIG. 6 is a block diagram of the third embodiment, in which the coordinate-converted image signal is input from the coordinate converter 104, and the image signal is interpolated in the converted coordinate system (hereinafter referred to as electronic zoom). The interpolation processing unit 601 for performing (described) is provided. The interpolation processing unit 601 is composed of a microcomputer, and in practice, a microcomputer common to the coordinate converter 104 can be used.

Although the distortion of the image can be reduced by the coordinate conversion by the method only by the coordinate conversion according to the above-described first and second embodiments, as is apparent from FIGS. 3 and 5, the image is converted by the coordinate conversion. Due to the expansion, the data density in the area away from the center of the image is low.

This problem can be solved by performing electronic zoom (interpolation processing of the third embodiment). Here, the electronic zoom is defined as a function of inputting an image signal in pixel units from the coordinate converter 104 and outputting the previously input image signal to the display monitor 107 until the next image signal is input.
In other words, it is a function of continuously outputting the latest data until the next data is read.

FIG. 7 is an explanatory diagram of a method for realizing electronic zoom. First, assume that the data of coordinates (x ', y') is moved to coordinates (x ", y"), and the next data (x '+ 1, y') becomes (x "+ Δ, y"). Let's move. As data between x ″ and x ″ + Δ, (x ′,
The data density can be increased by using the data of y ') as it is. FIG. 8 shows that the image of FIG. 18B is subjected to coordinate conversion based on the equations (4) and (5), and the interpolation processing unit 60
It is an example of an image that is electronically zoomed in 1. As compared with the image example of the second embodiment (see FIG. 5) in which the electronic zoom is not performed, it can be seen that the data density in the portion away from the central portion of the image is high and the image is easy to see.

Next, the electronic zoom by the interpolation processing unit (microcomputer) 601 will be described with reference to the flowchart shown in FIG. First, 1-dot data (pixel-based image signal) is read from the image sensor 102 (S901), and the address x'is advanced by 1 dot (S90).
2). Next, the address x ″ and the address x ″ + Δ corresponding to the address x ′ + 1 are calculated (S903). Here, the adjustment factors k ₀₁ , k _02, ... _Are input.

Next, while writing the data read in step S901 to the line memory 401 (S90
4), x "is advanced by one dot (S905), x" + Δ
(S906). When the writing is finished, read the next data and repeat the process. The interpolation processing unit 601 realizes the electronic zoom by such a simple procedure.

As the electronic zoom in the interpolation processing unit 601, in addition to the above method, for example, coordinates (x'-1,
A method such as predicting data between x ″ and x ″ + Δ may be used with line data complementing the data of y ′) and coordinates (x ′, y ′).

[Fourth Embodiment] In the fourth embodiment, the coordinate converter 104 to the D / A converter 106 are used without using an image memory.
In the configuration in which the image signal is output to the display monitor 107 via the, the expansion of the image signal is one-dimensional only in the horizontal direction.

FIG. 10 is a block diagram of the fourth embodiment. Since the basic configuration is the same as that of the first embodiment, only different parts will be described here. Coordinate converter 1
When the coordinate conversion is performed, 04 performs the calculation of the following equation instead of equations (2) and (3) or equations (4) and (5). The adjustment factors k ₀₁ , k _02, ... _Are determined by external input as in the first and second embodiments. x "= x '(1 + k 01 x' 2 + k 02 x '4 + ......) ‥‥ (6) y" = y' ‥‥ (7)

The operation of the fourth embodiment having the above configuration will be described. The image signal input to the image sensor 102 is output to the coordinate converter 104 via the A / D converter 103. By the coordinate converter 104, the coordinates (x ′,
The image signal of y ′) is coordinate-converted based on the equations (6) and (7), and is displayed on the display monitor 10 via the D / A converter 106.
7 is output.

According to the fourth embodiment, by using the equations (6) and (7), the processing can be executed in real time without using the image memory.

FIG. 11 shows an example of an image obtained by subjecting the image shown in FIG. 18 (b) to coordinate conversion according to the fourth embodiment and further electronically zooming in the lateral direction as in the third embodiment. As can be seen from the figure, since the expansion is one-dimensional, the strain relaxation effect is small, but the image is clear and easy to see.

[Fifth Embodiment] FIG. 12 is a block diagram of the fifth embodiment. In the figure, 1201 is an image sensor, 1202 is a buffer for amplifying signal charges from the image sensor 1201, 1203 is a high input impedance buffer used for executing electronic zoom, 12
Reference numeral 04 is a capacitor for holding analog data for one dot (one pixel) output from the image sensor 1201,
1205 is a timing control circuit for outputting the analog data held in the capacitor 1204 to the display monitor 1206. Switching elements 1207 and 1208 are opened and closed by the timing control circuit 1205. In the first to fourth embodiments, the A / D converter and the D / D converter are used.
Although the A converter is used to convert the image data into a digital signal and then back-convert it into an analog value, the analog value may be stored as it is. Therefore, in the fifth embodiment, instead of using the A / D converter and the D / A converter, a capacitor 1204 that holds an analog value for one dot is used.

In the fifth embodiment, the buffer 12
02, 1203, capacitor 1204, switching elements 1207, 1208 and timing control circuit 120
The coordinate conversion means and the interpolation processing means are constituted by 5.

The operation of the fifth embodiment having the above configuration will be described. The image signal output from the image sensor 1201 is amplified by the buffer 1202 and stored in the capacitor 1204. Next, the timing control circuit 12
05, the image signal is based on equations (6) and (7),
It is output from the capacitor 1204 to the display monitor 1206 via the buffer 1203. In this case, the buffer 12
By 02, the signal charge is amplified, the noise resistance is improved, and the signal can be easily handled. In the case of only coordinate transformation, the buffer 1203 is not necessary, but nondestructive readout is required to execute electronic zoom, and a buffer with high input impedance is required. Example 5
Is suitable for high-speed real-time processing as in the fourth embodiment.

As described above, in Examples 1 to 5,
Although the image processing by the coordinate converter and the electronic zoom using the coordinate converter or the timing control circuit has been described, in the application of the vehicle surroundings display device, the displayed angle of view may be a wide angle even in the horizontal direction. Since the direction may be narrow, the following asymmetric lenses can be used.

FIG. 13 is an explanatory view showing an asymmetric lens. 13A is a front view, FIG. 13B is a central transverse sectional view, and FIG. 13C is a central longitudinal sectional view. As shown in the figure, the asymmetric lens 1300 has a wide-angle shape only in the lateral direction, and is not point-symmetric with respect to the center P like a general lens. That is, a vertical groove 1301 is provided in the center of the lens 1300. However, as a method of widening the angle in only one direction, there is also a method of making the material non-point-symmetrical in addition to making the shape non-point-symmetrical so that light can be strongly bent only in the lateral direction.

FIG. 14 shows an image on the image sensor when the asymmetric lens 1300 is used.
It can be seen that the vertical distortion is small and the horizontal distortion is large. FIG. 15 shows an asymmetric lens 1300,
9 is an example of an image that is expanded by combining the image processing and the electronic zoom according to the fourth or fifth embodiment. In this case, it can be seen that the image can be displayed at the highest speed and distortion can be minimized. Note that the asymmetric lens 1300 may be used to perform image processing and electronic zoom according to the first or second embodiment.

Although the wide-angle lens has been described above, a concave mirror or a combination of a lens and a concave mirror may be used as long as it strongly bends light. Figure 1
Reference numeral 7 denotes a mirror having a concave shape in the X direction and a flat shape in the Y direction. By using such a mirror, the same effect as that of the asymmetric lens can be obtained.

[0066]

As described above, the vehicle surrounding display device according to the present invention (claim 1) is provided on the photoelectric conversion means via the lens means including the wide-angle lens or the fisheye lens having the barrel-shaped distortion characteristic. An image of light is formed, and the photoelectric conversion means converts the formed light into an electric signal by photoelectric conversion,
The image is output as an image signal, and then the coordinate conversion unit performs the coordinate conversion of the image signal on a pixel-by-pixel basis using a non-linear odd function, so that the distortion of the image is alleviated without increasing the cost of the device, and It is possible to deal with lens variations and temperature characteristics.

Further, the vehicle ambient condition display device (claim 2) of the present invention forms an image of light on the photoelectric conversion means through the lens means including the wide-angle lens or the fisheye lens having the barrel distortion characteristic. The photoelectric conversion means converts the imaged light into an electric signal by photoelectric conversion and outputs it as an image signal, and then the coordinate conversion means uses the non-linear odd function to coordinate the image signal pixel by pixel. Since the conversion is performed, the distortion of the image can be alleviated and the variation of the lens and the temperature characteristic can be dealt with without increasing the cost of the device. Further, since the interpolation processing means performs the interpolation processing of the image signal in the coordinate system after the conversion, the data density of the portion apart from the central portion of the image becomes high, so that the image can be easily viewed.

Further, in the vehicle surroundings display device (claim 3) of the present invention, the coordinate conversion means sequentially outputs the image signal after the coordinate conversion in pixel units according to the address in the coordinate system after the conversion, and performs interpolation. When the processing means inputs the image signal in pixel units from the coordinate conversion means, the previously input image signal is output to the display means until the next image signal is input. Therefore, the interpolation processing of the image signal is performed with a simple configuration. It can be carried out.

Further, in the vehicle surroundings display device (claim 4) of the present invention, the coordinate conversion means is arranged between pixels on the outside in the diameter direction of the circle centered on the pixel corresponding to the center point of the lens means. Since the coordinate conversion is performed so that the distance is increased, the barrel distortion can be effectively mitigated.

Further, in the vehicle surroundings display device (claim 5) of the present invention, the coordinate conversion means is arranged so that the distance between the pixels of the lens means in the vertical direction, the horizontal direction or both the vertical and horizontal directions is enlarged. Since the conversion is performed, barrel distortion is effectively mitigated with a simple configuration.

In the vehicle surroundings display device according to the present invention (claim 6), the distortion characteristic in the vertical direction of the lens means is smaller than the distortion characteristic in the horizontal direction, and the coordinate conversion means coordinates the image signal only in the horizontal direction. The conversion effectively reduces barrel distortion with a simple configuration.

Further, in the vehicle surroundings display device (Claim 7) of the present invention, at least one coefficient included in the non-linear odd function of the coordinate conversion means can be changed, so that the lens variation. And temperature characteristics can be easily accommodated.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment.

FIG. 2 is an explanatory diagram showing characteristics of a lens (a wide-angle lens or a fisheye lens).

FIG. 3 is an image example converted according to the first embodiment.

FIG. 4 is a block diagram of a second embodiment.

FIG. 5 is an image example converted according to the second embodiment.

FIG. 6 is a block diagram of a third embodiment.

FIG. 7 is an explanatory diagram of electronic zoom.

FIG. 8 is an example of a digitally zoomed image.

FIG. 9 is a flowchart for performing electronic zoom.

FIG. 10 is a block diagram of a fourth embodiment.

FIG. 11 is an image example converted according to the fourth embodiment.

FIG. 12 is a block diagram of a fifth embodiment.

FIG. 13 is an explanatory diagram of an asymmetric lens.

FIG. 14 is an image example on an image sensor when an asymmetric lens is used.

FIG. 15 is an image example in which an asymmetric lens is used to perform expansion by combining image processing and electronic zoom according to the fourth or fifth embodiment.

FIG. 16 is a perspective view of a mirror having a concave shape in one direction.

FIG. 17 is a block diagram showing an example of a conventional vehicle surroundings display device.

FIG. 18 is an explanatory diagram showing an example of an image received by a conventional image sensor.

[Explanation of symbols]

101 lens 102 image sensor 103 A / D converter 104 coordinate converter 105 image memory 106 D /
A converter 107 display monitor 1202, 1103 buffer 1204 capacitor 1205 timing control circuit

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H04N 7/18 J

Claims (7)

[Claims] 1. A lens means composed of a wide-angle lens or a fisheye lens having barrel-shaped distortion characteristics, and photoelectric conversion means for converting the light imaged through the lens means into an electric signal by photoelectric conversion and outputting it as an image signal. An image signal is input from the photoelectric conversion unit, coordinate conversion unit that performs coordinate conversion of the image signal on a pixel-by-pixel basis using a non-linear odd function, and an image signal after coordinate conversion is input from the coordinate conversion unit. A vehicle surrounding condition display device, comprising: display means for displaying an image. 2. Lens means comprising a wide-angle lens or fisheye lens having barrel-shaped distortion characteristics, and photoelectric conversion means for converting the light imaged through said lens means into an electric signal by photoelectric conversion and outputting it as an image signal. An image signal is input from the photoelectric conversion unit, coordinate conversion unit that performs coordinate conversion of the image signal on a pixel-by-pixel basis using a non-linear odd function, and an image signal after coordinate conversion is input from the coordinate conversion unit. , An interpolation processing means for performing an interpolation processing of the image signal in the coordinate system after the conversion, and a display means for displaying the image by inputting the image signal after the interpolation processing from the interpolation processing means. Vehicle surroundings display device. 3. The coordinate conversion means sequentially outputs the image signal after coordinate conversion in pixel units according to an address in the coordinate system after conversion, and the interpolation processing means outputs image data in pixel units from the coordinate conversion means. 3. The vehicle surroundings according to claim 2, wherein when a signal is input, the image signal interpolated is output by outputting the previously input image signal to the display means until the next image signal is input. Status display device. 4. The coordinate conversion means performs coordinate conversion so that a distance between outer pixels increases in a diameter direction of a circle centered on a pixel corresponding to a center point of the lens means. The ambient condition display device for a vehicle according to claim 1 or 2. 5. The coordinate conversion means performs the coordinate conversion so that the distance between pixels in the vertical direction, the horizontal direction, or both the vertical and horizontal directions of the lens means is enlarged.
Or the vehicle surroundings display device according to 2. 6. The lens unit has a vertical distortion characteristic smaller than a horizontal distortion characteristic, and the coordinate conversion unit converts the image signal only in the horizontal direction. 2. The vehicle surroundings display device according to 2. 7. The vehicle surrounding condition display device according to claim 1, wherein at least one coefficient included in the non-linear odd function of the coordinate conversion means is changeable.