JPH03162078A - Monitoring camera apparatus - Google Patents

Abstract

PURPOSE:To improve the recognition rate of an object at low illuminance by varying an amplification factor with respect to an illuminance signal from an image pickup element and each color component signal based on a control signal corresponding to the inverse characteristic of a visual sensitivity characteristic when the detected illuminance is lower than a prescribed illuminance. CONSTITUTION:A level comparator 51 compares a level of a signal being the sum of R, B signals from a color separating circuit 6 with a level of a YL (or G) signal from an LPF 7 and outputs a gain control signal representing a prescribed sensitivity characteristic to a YH signal gain control amplifier (AGC) 52a, an R signal gain control amplifier (AGC) 52b and a B signal gain control amplifier (AGC) 52c in response to the compared level difference. However, the output operation of the gain control signal is set to apply gain control signal output when the level of the YH signal is a slow illuminance. Thus, the camera easily finds out an object with a color tone not eminent in a low illuminance as at night.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a surveillance camera device for commercial use, vehicle-mounted use, special photography, etc.

(Prior Art) Conventionally, in color imaging devices, sensitivity has been increased by simply increasing the degree of amplification as a countermeasure against a drop in video signal level during low illuminance.

By the way, the visibility of the human eye is determined by the photopic curve a in Figure 5.
As shown in the scotopic vision curve b, the illuminance is not flat over the visible wavelength range, so the illumination limit at which red and blue objects become invisible is higher than that of white and green objects. Therefore, when the degree of fishiness is low, objects with wavelengths with low visibility such as red and blue may be overlooked, and in particular, with surveillance camera equipment such as car-mounted cameras that prioritize safety, it is difficult to ensure safety in low-light conditions. There is a problem that it is difficult.

(Problems to be Solved by the Invention) As mentioned above, the visibility of the human eye is not flat over the visible wavelength range. There is a problem in that the illumination limit at which objects become invisible is high, and for example, the video output of a surveillance camera device at low illuminance has low visibility for objects in a wavelength range with low visibility.

The present invention is intended to solve the above-mentioned conventional problems,
Visibility hQ of a subject in a wavelength range with low visibility at low exposure
The purpose of the present invention is to provide a surveillance camera device that can improve performance.

[{^1 structure of the invention] (Means for solving the problem) The present invention provides a means for multiplying the illuminance signal and each color component signal from the image sensor, and a method for adjusting the visibility characteristic. a control signal generating means for generating a control signal corresponding to the inverse characteristic; a detecting means for detecting the illuminance of the imaging environment in the image sensor; and control means for varying the degree of amplification of each of the signals of the ground width means based on the control signal from the control signal generation means.

(Function) In the present invention, when the detected illuminance becomes lower than a predetermined illuminance, the illuminance signal from the image sensor and each color component signal are amplified based on the control signal corresponding to the inverse characteristic of the visibility characteristic. Variable degree.

Therefore, at low jd degrees, objects with low visibility, such as red and blue, are displayed brighter to compensate for the drop in visibility, so it is possible to correct the frequency dependence of visibility, and it is possible to correct the frequency dependence of visibility. The recognition rate can be increased.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram for explaining a surveillance camera device according to an embodiment of the present invention.

In the figure, 1 indicates the CCD imaging (g! section).

The CCD imaging section 1 is driven by a CCD drive circuit 2 that drives based on timing generated by a timing generation circuit 2. The imaging signal from the CCD imaging unit 1 is a pre-amplifier AGC (auto gain control) 4
is amplified by The amplified signal is inputted to the visibility correction seven-width control circuit 5, the color separation circuit 6, and the LPF 7.

The signal input to the color separation circuit 6 is separated and the R signal and B signal are output to the visibility correction amplification control circuit 5. The Y11 signal from the visibility correction amplification control circuit 5 is output to the NTSC encoder 9 via the luminance signal processing circuit 8.

Further, the R signal and B signal from the visibility correction amplification control circuit 5 are outputted to the NTSC encoder 9 via the color signal processing circuit 10 along with the YL signal from the LPF 7.

Next, details of the above-mentioned visibility correction width control circuit 5 will be explained in the second section.
This will be explained using figures.

As shown in the figure, the level comparator 51 includes a color separation circuit 6
The signal obtained by adding the R signal and B signal from
The level is compared with the YL (or G) signal from , and according to the compared level difference, the Yll signal gain control amplifier (AGC) 52a, the R signal gain control amplifier (AGC) 52b, and the B signal gain control are performed. A gain control signal having sensitivity characteristics shown in FIG. 3 is output to the amplifier (AGC) 52c. However, the output operation of the gain control signal is ON/OFF depending on the level of the Yl+ signal input to the level comparator 51.
It is something that is turned off. That is, it is turned on so that the gain control signal is output when the level of the Yl+ signal is low (for example, the illuminance is about 100 ILIX or less).

Next, the structure of the level comparator 51 mentioned above will be explained using FIG. 4.

As shown in the figure, the level comparator 51 includes a differential amplifier 5
A gate 512 is provided on the output side of the gate 11, and a converter 513 that monitors the YH signal level connects the gate 5.
Turn 12 ON/OFF.

When the gate 512 is OFF, the output of the gain control signal is at the GND level.

In the surveillance camera device configured in this way, when the illuminance is low, for example, 100 lux or less,
The level comparator 51 is turned on and a gain control signal is output to each gain control amplifier 52a to 52c, so that the color level of wavelengths at which visibility decreases, such as red and blue, is improved, and visibility is improved.

However, in this big example, it is low! ! Sensitivity is increased for objects with a tone that does not contain many G components, which have a good human IQ, at α degree ■I, so it is possible to recognize objects with only R and B components, which have low visibility. It is easy to use, and it is difficult for surveillance cameras such as those used in cars to get attached to 11 in low light conditions such as between the skin.
This is effective in terms of safety as it makes it easier to detect objects.

[Efficacy of Yumei] As explained above, in the surveillance camera device of the present invention, when the detected j(ξ(degree) becomes less than a predetermined degree Since the corresponding control signal L (accordingly to the illuminance signal from the image sensor and each color component) is varied, the degree of visibility for a(fM.{ degree, red, Objects such as stomach-colored objects are displayed brighter to compensate for the drop in visual sensitivity, so it is possible to correct the frequency dependence of visual sensitivity, and the object recognition rate at 11! can be increased.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining a surveillance camera device according to a Kazuo embodiment of the present invention, FIG. 2 is a block diagram for explaining details of the visibility correction width control circuit of FIG. 1, and FIG. is a diagram showing the sensitivity increase characteristic due to the current sensitivity correction amplification control path in Figure 2, Figure 4 is a diagram to explain the configuration of the level IL comparator in the second country, and Figure 5 is a diagram showing the BJ sensitivity line. FIG. 5...u cooperation iF. 51... Level comparison Kj, 52a-52c... Gain control amplifier (GCA), 5 1 1... Differential amplifier, 5
12...Gate, 513...Converter.

Claims (1)

[Scope of Claims] Amplifying means for amplifying the illuminance signal and each color component signal from an image sensor; control signal generating means for generating a control signal corresponding to an inverse characteristic of visibility characteristics; and an imaging environment in the image sensor. a detection means for detecting the illuminance of the detection means; and an amplification degree of the amplification means for each of the signals based on the control signal from the control signal generation means when the illuminance detected by the detection means becomes lower than a predetermined illuminance. 1. A surveillance camera device comprising: a control means for varying the .