JPH0658294B2 - Beam contour extraction device - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a light beam contour extraction device for adjusting irradiation light distribution in a vehicle headlight or the like and for determining an irradiation direction in inspection.

[Prior art]

The irradiation direction of the headlights for automobiles is
It is stipulated that the safety standards and inspection standards should be adjusted and inspected to ensure safety such as dazzling when passing by an oncoming vehicle. These standards differ from country to country, and export cars and other vehicles must follow the standards of the other country. Currently, there are three types of standards, namely, domestic standards, SAE (US) standards, and ECE (Europe) standards.
It is related to the standard. According to the domestic standard, the maximum luminous intensity axis is used as the lamp optical axis, and aiming so that the axis is parallel to the axis of the vehicle, the SAE standard is based on 20% (upper and lower edges) and 30% (left and right edges) of the maximum luminous intensity. Aiming is performed so that the luminous intensities at predetermined upper and lower edge positions and left and right edge positions are below the reference.

[Problems to be Solved by the Invention]

However, in recent years, due to the tendency toward high luminous intensity (halogen bulb) and irregular shape in design, there are cases in which the above standards cannot be used for adjustment. For example, on the highest luminous intensity axis referred to in domestic standards, when there are two luminous intensity distribution maximum points having the same luminous intensity value, there are some which cannot be determined as the reference, and the light distribution pattern is complicated, It is necessary to review the standards based on the basic principle of ensuring safety. In view of the above, it is an object of the present invention to provide a light beam contour extraction device capable of capturing a light beam having the most remarkable effect among the properties of light distribution that acts on the human eye and obtaining a reference that matches visual recognition. .

[Means for solving problems]

A means for inputting the illuminance value of each point on the screen illuminated by a vehicle headlight, a means for converting the input illuminance value using a predetermined function, and a means for converting the density of each point. A means for smoothing the value using the values of neighboring points, a means for spatially differentiating the value of each smoothed point, and a ridge line of the image obtained by the spatial differentiation (a line connecting points like mountain ridges) ), And a means for obtaining the center of gravity of a frame circumscribing the ridge line or a region surrounded by the outermost ridge line and calculating a reference point for determining the irradiation direction based on the frame or the center of gravity. Set up.

[Work]

By extracting the contour of a light beam that has a remarkable effect on the visual sense and determining the irradiation direction of the vehicle headlight or the like based on this, it is possible to make adjustments that match the visual sense.

Examples of the invention

FIG. 2 is an explanatory view of the concept of the light beam defined in the present invention.
FIG. 2 shows the situation when a headlight (not shown) is illuminated on the screen 21. In the figure, the region 22 is a part of the illuminated light that is visually recognized as being extremely bright. It is defined as a light beam. Further, 23 is the other region, and the boundary 24 between the regions 22 and 23 is the light beam contour. FIG. 3 shows the illuminance distribution along the observation line 25 in FIG. 2, where A and B are contour points. As shown in FIG. 3, the light areas are particularly bright. The light beam contour extraction device according to the present invention uses the axis passing through the center of the circumscribing frame of the light beam or the center of gravity of the light beam region as the optical axis, and the dazzling effect on the oncoming vehicle is considered to be remarkable when the light beam contour point enters the field of view. Therefore, the upper edge of the circumscribing frame of the light beam and the side edge on the oncoming vehicle side are used as references. The light beam contour extracting device according to the present invention is for extracting the contour 24 shown in FIG. 2, and the construction of one embodiment thereof is shown in FIG. In FIG. 1, 1 is a headlamp (headlight), 2 is a transmissive screen, 3 is an industrial television camera, and 4 is an A / D.
A conversion circuit, 5 is a density conversion circuit, 6 is a smoothing circuit, 7 is a spatial differentiation circuit, 8 is a ridge line detection circuit, and 9 is a reference point calculation circuit. In the embodiment shown in FIG. 1, there is a transmission screen as an example, but a reflection screen is also used as the input means of the light distribution pattern.
In addition, depending on the facing condition of the camera and the screen (for example, when observing the screen from an oblique direction without directly looking at the screen), the Affine transformation may be performed to form a normal viewing pattern. Further, a means for obtaining an equivalent reduced light distribution pattern using a Fresnel lens or the like (for example, the one described in Japanese Patent Laid-Open No. 60-194325 "Light distribution pattern detection device for automobile headlights") is used. May be. In such a configuration, the distribution of the light emitted from the headlamp 1 is input to the industrial television camera 3 via the screen 2. The video signal of the camera 3 is digitized at the television rate by the A / D conversion circuit 4, and is once stored as a multivalued image in a frame memory of 256 × 256 size, or directly input to the density conversion circuit 5. Then, density conversion (Log conversion) is performed by a lookup table method or the like. When the data is once stored in the frame memory, after the storage, different clock signals are read out in accordance with the subsequent processing time, and the processing is performed at the optimum rate for the subsequent processing. Assuming that the digital image output from the A / D conversion circuit 4 is IP and the converted image output from the density conversion circuit 5 is JP, the following relationship is established between the digital image IP and the converted image JP. To do. When IP ≧ 1: JP (i, j) = Log (IP (i, j)) When IP = 0: JP (i, j) = 0 Such a converted image JP is input to the smoothing circuit 6. However, as the smoothing circuit 6, a simple average 3 × 3 spatial filter as shown in FIG. 4 (a) may be used, or as shown in FIG. 4 (b).
It is possible to use a 3 × 3 spatial filter in which a large weight is given to the center as shown in FIG. Assuming that the smoothed image output from the smoothing circuit 6 is KP using a spatial filter as shown in FIG. 4 (a), the converted image JP and the smoothed image K are obtained.
The following relationship is established with P. Adding the smoothing process in this way has the meaning of suppressing fluctuations in the quantization noise in the differential process in the subsequent stage. Such a smoothed image KP is input to the space differentiating circuit 7, and as the space differentiating circuit 7, a Sobel derivative or the like that outputs a positive value of the gradient with respect to the smoothed image KP can be applied. As an algorithm in this case, an averaged image K of a 3 × 3 local area as shown in FIG.
When P is considered, the differential image LP with respect to its center point e = KP (i, j) is expressed by the following equation. LP (i, j) = | SX | + | SY |, where SX = (C + 2f + i)-(a + 2d + g) SY = (g + 2h + i)-(a + 2b + c) The ridge line detection circuit 8 can extract the maximum point on the image LP to extract the light beam contour. The algorithm of this ridge line detection circuit is
It is as shown in FIG. 6 in a flow chart in the direction along the coordinate i of (i, j). First, in FIG. 6, i = 1. First image LP with j = 1
Specify (1,1). Image LP (1,
1) is taken out, and it is determined whether or not this image LP (1,1) is maximum. If the image LP (1,1) is the maximum, the image LP (1,1) is the ridge point of the differential image LP, that is, the light beam contour point.
1) = 1 is performed. When this processing is completed or when the image LP (1,1) is not maximum, i = i + 1, that is, the coordinate i is counted up in step. This results in i = 2. In the next step, it is determined whether the coordinate i is larger than 256. Screen is 256
Since it has a size of x256, it is determined in step whether the coordinate i has reached the end. If the coordinate i has not reached 256, the process returns to the step to take out the image LP (2,1), and it is judged whether or not this image LP (2,1) is the maximum.
After the process of setting P (2,1) = 1, the process of i = 2 + 1 is performed in the step, and if it is not maximum, the process of i = 2 + 1 is directly performed in the step. This process is repeated until the coordinate i> 256, and if i> 256 is determined in the step, i = 256 in the step.
1, j = 1 + 1 is set, and if it is determined that j> 256 is not satisfied in step, the process returns to step. In step, the image LP (1,2) is taken out and it is determined whether or not the image LP (1,2) is maximum. Hereafter, perform the same processing as j> 25
Repeat until it reaches 6. When j> 256, the processing for one screen ends, and all “1” s are stored at the ridge points of the differential image LP. A process along the coordinate j is performed based on the same idea. In this way, the two images detected in the directions along the coordinates i and j are ORed to obtain the ridge line image MP. The reference point calculation circuit 9 calculates a reference point for determining the irradiation direction based on the ridge line image MP. An example of the calculation of this reference point is shown in FIG. FIG. 7 shows a ridge line image MP and projection data MPX and MPY of the image MP on the X axis and the Y axis. In the reference point calculation circuit 9, the coordinates MP at the end of the projection data MPX and MPY
The circumscribing frame of the ridge line image MP is extracted by X _1, MPX _2, MPY _{1, and} MPY _{2 ,} the center of the circumscribing frame is obtained, or the center of gravity of the area surrounded by the outermost ridge line of the ridge line image MP. (Calculate the weight of each picture element in the area as "1"). As the reference point, the center of the circumscribing frame or the center of gravity of the area for adjusting the optical axis is used for the domestic standard, and the upper side Y coordinate value MPY ₁ of the circumscribing frame for the SAE standard is used. The X coordinate value MPX ₂ of the side on the oncoming vehicle side is used.

【The invention's effect】

According to the present invention, the irradiation direction of the headlamp is extracted based on the contour of the light beam having a remarkable effect on the visual sense and the direction is determined based on the contour, so that the adjustment that matches the visual sense can be achieved and the traffic safety is also good. Is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a light beam contour extracting device according to the present invention, FIG. 2 is an explanatory view of the concept of a light beam, and FIG.
FIG. 4 is an illuminance distribution diagram along the observation line shown in FIG. 4, and FIG. 4 is a configuration diagram showing an embodiment of a filter used in a smoothing circuit.
FIG. 5 is an explanatory view of the action of the Sobel differential, FIG. 6 is a flowchart showing an algorithm for extracting the ridge line of the image, and FIG. 7 is an explanatory view of the ridge line image and its projection pattern. 1: headlamp, 2: transmissive screen, 3: camera, 4: A / D conversion circuit, 5: density conversion circuit,
6: smoothing circuit, 7: spatial differentiating circuit, 8: ridge line detecting circuit, 9: reference point calculating circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-60-93938 (JP, A) JP-A-55-65131 (JP, A) JP-A-52-80076 (JP, A)

Claims (1)

[Claims] 1. A means for inputting an illuminance value at each point on a screen illuminated by a vehicle headlight, a means for converting the inputted illuminance value using a Log function, and a density conversion. A means for smoothing the value of each point using the values of neighboring points, a means for spatially differentiating the value of each smoothed point, and a ridge line of an image obtained by spatial differentiation (a point like a mountain ridge) And the center of gravity of a region circumscribed by the ridge line or the area surrounded by the outermost ridge line, and a reference point for determining the irradiation direction is calculated based on the frame or the center of gravity. A device for extracting an outline of a light beam, comprising: