JPH0438444A - Image measuring device - Google Patents

Abstract

PURPOSE:To quantitatively correct output variations of measuring image due to lighting variations in the composition with a TV camera formed of an imaging device and a transparent material arranged on the light axis, by forming a shadowing zone on a part of the transparent material. CONSTITUTION:In an image measuring device to measure a scope distance, a shadow zone 6 attached on a corner of imaging part front glass 2 and an image input mechanism 5 consisting of imaging device 1- optical lens system 4, is formed with a proper photo-insulation material having a particular area. The image signal in an image measuring mechanism 8 is varied in its brightness measurement not only by the brightness of an actual object image but also by the opening diameter determined by an automatic iris mechanism and variations of automatic gain control from a signal processing circuit 3. Therefore, by correcting these values with using the brightness value corresponding to the shadow zone 6 in the image signal, a highly accurate scope distance measurement value can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an image measuring device using a television camera.

[Prior Art] FIG. 5(a) is a sectional view showing a conventional image measuring device disclosed in, for example, Japanese Patent Laid-Open No. 61-250540.
FIG. 5(b) is an enlarged front view of the background plate. In FIG. 6, (4) is an optical lens system, (5) is an image input mechanism, (8) is an image measurement mechanism, and (lO) is A background board that makes the background uniform when capturing an image (Ill is a background board (10
) is a background area for brightness reference that has a sufficient brightness difference from the background board brightness provided in a part of the area. +12) is lighting equipment that illuminates the measurement area, and (+3) is a television camera.

The image input mechanism (5) consists of a television camera (+3) and an optical lens system (4). In addition, the image measurement mechanism (8
) receives the image signal from the television camera (13) and extracts measurement information.

Next, the operation will be explained. The background plate (10) and the measurement target placed in front of it receive the scattered light of the illumination film @ (121) and reflect it according to their respective reflection characteristics, and the optical lens system (4) and the television camera (+3) The light is photoelectrically converted with an appropriate illuminance ratio and becomes an output signal.

The output signal is converted into a television signal by the signal processing circuit of the image measurement mechanism (8), and then measurement information is extracted. For example, when extracting the shape of the object as measurement information, if the lighting equipment (12) does not turn on due to a burnout, etc., the background board (10) may be extracted from the information measured by the image measurement mechanism (8). An abnormality in the lighting equipment is detected from information on the presence or absence of a brightness difference in a brightness reference background area (11) arranged therein.

[Problems to be Solved by the Invention] Since the conventional image measuring device is configured as described above, the background plate (lO) including the background area (11) for brightness festival arranged at the - corner thereof is It could only be used in imaging environments where images could be captured at all angles of view. In other words, it cannot be used at all for target images having general natural backgrounds (for example, sky, mountains, sea, etc.).

In addition, conventional image measurement devices can only detect whether the lighting equipment is on or off when abnormalities occur, and cannot respond to aging of lighting lamps, changes in sunlight or weather when using natural lighting in outdoor environments. It was something I couldn't handle.

This invention was made in order to eliminate the drawbacks of the conventional methods as described above, and it is capable of quantitatively correcting the output fluctuations of measurement images due to changes in the conventional lighting environment, and also provides image measurement that can capture images in any background. The purpose is to obtain a device.

[Means for Solving the Problems] An image measuring device according to the present invention includes a television camera configured with an imaging device and a transparent material disposed on the optical path of the television camera. A light-shielding area is formed in the area.

[Function] The manual image mechanism in this invention has a light-shielding area near the imaging surface, that is, the focusing surface, and uses the luminance value of this area to determine the black level, which is the reference for DC reproduction, between the optical system and the signal system. It is possible to include and manage reference information within a signal. Furthermore, the same effect as the light shielding area can be obtained by fixing the electrical output of the image sensor itself in the corresponding area to the base potential. The television camera has an image input function that always incorporates a reference level signal, which serves as a reference for the luminance signal, in the image signal.

[Embodiment 1] Hereinafter, as an embodiment of the present invention, an image measuring device for measuring line-of-sight distance, that is, visibility, which changes depending on weather conditions such as snow and fog, will be described with reference to the drawings.

FIG. 1(a) is a configuration diagram showing an image measuring device according to an embodiment of the present invention, and FIG. 1(fbl) is a front view of the imaging portion surface glass. In the figure, (1) is an imaging device such as a solid-state imaging device or an image pickup tube, (2) is the imaging unit surface glass of the imaging device (1), and (3) is a signal that processes the output signal from the imaging device (tl). processing circuit, (4) optical lens system,
(5) is an image input mechanism composed of an imaging device (1) to an optical lens system (4), and (6) is an imaging unit surface glass (2).
) is a light-shielding area affixed to the corner of the frame, which has an appropriate area and is made of an appropriate light-shielding material. (8) is an image measurement mechanism that receives an image signal from the image input mechanism (5) and extracts measurement information.

FIG. 2 is a configuration diagram showing how visibility is measured using the image input mechanism (5) of this embodiment. A target plate (9) with a certain area painted in black and white is installed at a certain distance D (mJ) from the image measurement mechanism (6). (14) is connected to the target plate (9) and the image measurement mechanism Mechanism (6)
This is snow or fog that occurred during the period.

Here, the black area of the target board (9) is assumed to be close to an ideal dark box.

FIG. 3 (al) is an example of an image captured and output by the image input mechanism (5), and FIG. 3 (bl to (e)) shows time on the horizontal axis and current value on the vertical axis. 9) It shows the image signal of the upper scanning line part, where FIG. 3 fbl is the image signal of the AA' scanning line, and FIG. d) (e) is Figure 3 (b)
, fcl image signal fluctuates due to fluctuations in DC reproduction of the signal processing circuit (3), changes in aperture diameter by the diaphragm mechanism corresponding to changes in illumination of the optical lens system (4), and automatic gain control of the signal processing circuit (3). The following five ranges are shown.

The visibility distance is measured by the following formula (A+).

V=Dxlnε/[1n(Cd/CO)]...(A)
However, Cd = (Bd - Bh) /Bh Co = (Bo - Bh), 'Bh■ = Visibility distance (
11) D: Distance from camera to target (m) ε: Discrimination criticality of large II￥L (ε=002 to 0.05 for road weather) Cd: Contrast ratio of target board (9) placed at distance co=Contrast ratio Bd of the target plate (9) placed in the immediate vicinity of the camera: Dark brightness value Bh of the target plate (9) placed at a distance Bh: Bright brightness of the target plate (9) placed at a distance Value Bo: This is the dark area brightness value of the target plate (9) placed in the immediate vicinity of the camera.

In Fig. 2, the image signal obtained by the image input mechanism (5) arranged so as to capture the target plate (9) as a part of the screen is processed by the image measurement mechanism (8) and calculated by the formula (A
) outputs the visibility distance measurement value calculated by Here, Bo is the dark area luminance value of the target plate (9) placed in the vicinity of the camera, but assuming an ideal dark box, Bo=O1, that is, C
It is assumed that o=-1.

However, in the image measurement mechanism (8), the image signal is not only the actual brightness value of the target image, but also the aperture diameter determined by the automatic aperture mechanism and the signal processing circuit, as shown in Figure 3 (d) and Ie). In accordance with the change in the automatic gain control (3), the brightness measurement values Bd, Bh, and Bo vary, making it impossible to obtain an accurate visibility measurement value (2).

In this example, these values are calculated from the light-shielded area (6
) is used to calibrate Bt, Bo, and Bd using the following equation (B), it is possible to obtain a highly accurate visibility distance measurement value.

Bd = Bd - Bblack Bh' = Bh - Bblack ... (B) B
o' = Bblack Here, it is obvious from the transformation of the equation that the equation (B) is the same as treating the BO in the equation (A) with an actual measured value of Bblack instead of O. However, the present invention solves the problem that conventional means for obtaining this value are physically difficult.

In this way, since the entire front region from which the reference luminance value can be read is included as part of the human-powered image mechanism, accurate luminance signal values including the characteristics of the signal transmission system of the target object can be obtained. can be measured, thereby realizing a highly accurate image measuring device. According to this embodiment, the black signal level of the reference area that serves as the standard is managed, so that the black signal level of the reference area that is the standard is managed, so that the detection of out-of-light lamps of lighting equipment, which was detected using the brightness ratio in the conventional example, can be done using the brightness ratio. Not only can this be easily detected by comparing it with the average brightness of the area, but it also becomes possible to quantitatively grasp information on changes in illumination during the red season.

FIG. 4 is a side view showing an imaging device according to another embodiment of the present invention, in which (7) is a side view showing the same area on the imaging device (11) in place of the light-shielding area (6) in FIG. It is a light-shielding (insensitive) region formed to output an output signal fixed to a base 1!4 potential.

Even with this configuration, the luminance output signal value corresponding to the light-shielding area can be used as information for compensating for DC reproduction fluctuations caused by the front-stage lens diaphragm and the rear-stage electric signal processing circuit, and the same method as in the above embodiment can be used. It has action and effect.

In addition, although the above embodiment shows an image measuring device that measures visibility, it is also possible to use an image measuring device that has an image input means using a television camera or the like to perform measurements in which the luminance signal output value itself has meaning. On the other hand, it becomes possible to provide a total illumination value that manages DC regeneration fluctuations.

[Effects of the Invention] As described above, according to the present invention, in a television camera configured with an imaging device and a television camera having a transparent material disposed on the optical path, part of the transparent material 5. By forming a light-shielding area in the area, it is possible to quantitatively correct output fluctuations in the measurement image due to changes in the lighting environment, and
This has the effect of providing an image measuring device that can image any background.

[Brief explanation of the drawing]

FIG. 1(al) is a configuration diagram showing an image input mechanism of an image measuring device according to an embodiment of the present invention, FIG. 1(b) is a front view showing an imaging device according to this embodiment, and FIG. 3 is an explanatory diagram illustrating captured images and image signals, and FIG. 4 is an imaging device according to another embodiment of the present invention. 5(a) is a sectional view showing a conventional image measuring device, and FIG. 5(b) is a front view showing an enlarged background plate of the conventional image measuring device. (1) )...Imaging devices such as solid-state image sensors and image pickup tubes,
(2)...Front glass of imaging section, (3)...Signal processing circuit, (4)...Optical lens system, (5)...Image input mechanism, (6)...Light blocking area, ( 7)... Light shielding (insensitive) area, (8)... Image measurement mechanism, (9)... Target board, (10)... Background board, (ll)... Background area for moderation reference, ( 12)...Lighting equipment, (13)...
...TV camera. In the drawings, the same reference numerals refer to the same 5 or corresponding parts.

Claims (1)

[Claims] An image measuring device comprising a television camera configured with an imaging device and a transparent material disposed on an optical path of the television camera, characterized in that a light-shielding region is formed in a portion of the transparent material. .