CN1190952C - A digital image monitoring system that can automatically adjust the lens aperture and detect object movement - Google Patents

Abstract

A digital image monitoring system capable of automatically adjusting a lens aperture and detecting the movement of an object is provided, aiming at the requirements of traffic facilities, families or companies on video recording monitoring, an image capturing card matched with a lens and a CCD camera continuously captures digital images of a photographed object, the captured images are decomposed and converted into frequency spectrums of two parts of brightness, reflectance and the like by an image brightness-reflectance decomposition unit, an image brightness change detection unit is provided to analyze the brightness frequency spectrum change quantity of two continuous images and control the amplification or reduction of the lens aperture according to the change quantity, and an object movement detection unit is also provided to analyze the reflectance frequency spectrum change quantity of the two continuous images so as to judge whether the object in an image moves or not and not to judge the movement condition of the object by mistake.

Description

A digital image monitoring system that can automatically adjust the lens aperture and detect object movement

technical field

The invention relates to a digital image monitoring system, in particular to a digital image monitoring system which can automatically adjust the lens aperture and detect object movement.

Background technique

In general image monitoring systems, the images of vehicles captured by traffic law enforcement units are often used as the basis for proving that drivers have violated regulations; in the security measures of financial institutions, images captured by surveillance cameras are also used to track down crimes such as robbery; In department stores, surveillance cameras are also used to prevent plundering. The scope of its application is very wide, so many manufacturers have studied it.

At present, the simple video surveillance systems on the market generally only have a simple video recording function, and the video surveillance systems with strong functions can judge whether there is a change in the video screen. If the gray level change in the video screen is greater than a threshold The value (Threshold) will start video storage or issue an alarm, but these systems cannot rule out the grayscale value changes in the video frame caused by changes in light brightness. Therefore, when the brightness of the light changes or the aperture is zoomed in or out, the system will misjudge that the object in the image frame is moving.

It can be seen that the video surveillance systems developed by manufacturers today still have technically insurmountable deficiencies, and technical breakthroughs and improvements are needed.

Contents of the invention

The technical problem to be solved by the present invention is to provide a digital image monitoring system, which can detect the change of the light brightness and the movement of the object separately, so as not to misjudge the movement of the object. In addition, it can automatically adjust the lens aperture and automatically detect the movement of the object. function.

In order to achieve the above-mentioned purpose of the invention, the digital image monitoring system of the present invention mainly includes: a lens, a CCD camera, an image capture card (Frame grabber), an image brightness-reflectance decomposition unit (Illumination-reflectance decomposition), and an image brightness change detection unit and object movement detection unit. Use the image capture card to capture the region of interest in the image frame, and then decompose the image frame into brightness spectrum and reflectance spectrum data through the image brightness-reflectance decomposition unit, and provide the image brightness change detection unit as the detection light The change of brightness is used to control the size of the lens aperture, and the object movement detection unit is used as a technology to detect the movement change of the object to judge whether the object has moved.

That is to say, the present invention provides a digital image monitoring system capable of automatically adjusting lens aperture and detecting object movement, comprising: at least one video camera; at least one lens; an image capture card and at least one storage device, and the image capture card lasts Capturing a digital image for a photographed object; it is characterized in that it also includes: an image brightness-reflectance decomposition unit, which receives the digital image, and decomposes and converts the digital image into brightness spectrum data and reflectance spectrum data; an image The brightness change detection unit is connected with the image brightness-reflectance decomposition unit, and receives the brightness spectrum data decomposed and transformed by it, and then connects with the previous digital image stored in a storage device in the image brightness change detection unit Comparing the brightness spectrum data of the two digital images before and after, calculating the brightness spectrum difference value of the two digital images before and after, and comparing with a first critical value, so as to automatically adjust the lens aperture; It is connected with the decomposing unit, and receives the decomposed and converted reflectance spectrum data, and then compares it with the reflectance spectrum data of the previous digital image stored in another storage device in the object movement detection unit, and calculates the reflectance spectrum data of the two digital images before and after The difference value of the reflectance spectrum is compared with a second critical value to determine whether the object is moving.

It can be known from the above that the present invention can detect the change of the light brightness and the movement of the object separately, without misjudging the movement of the object, and it can really make up for the technology that the current manufacturers cannot break through.

The following are detailed descriptions and accompanying drawings of the embodiments of the present invention, so as to further illustrate the technical contents and objectives and effects of the present invention.

Description of drawings

Fig. 1 is a block diagram of a digital image monitoring system of the present invention;

Fig. 2 is an action flowchart of the image brightness change detection unit; and

FIG. 3 is a flowchart of the operation of the object movement detection unit.

Detailed ways

As shown in Figure 1, the system is mainly composed of a CCD camera 1, a lens 2, an image capture card 3, an image brightness-reflectance decomposition unit 4, an image brightness change detection unit 5, and an object movement detection unit 6. The image capture card 3 with the lens 2 and the CCD camera 1 continues to capture digital images of the photographed object; then the captured image is decomposed and converted into two components such as brightness and reflectance by the image brightness-reflectance decomposition unit 4. part of the frequency spectrum; next, the image brightness change detection unit 5 is used to analyze the brightness spectrum variation of two consecutive images, and the variation is used to control the enlargement or reduction of the lens aperture; and the object movement detection unit 6 is used for analysis The amount of change in the reflectance spectrum of two consecutive images is used to determine whether the object in the image screen is moving7. Wherein the principle of image brightness-reflectance decomposition unit 4 is described as follows:

Suppose the resolution of the image screen is M*N pixels (Pixel), and the grayscale value of the pixel at the coordinate position (x, y) is g(x, y), 0<x<M+1, 0< y<N+1; the value of g(x, y) can be read directly from the output value of the CCD camera 1 . If the brightness of the pixel at the coordinate position (x, y) is i(x, y), and the reflectance is r(x, y), then g(x, y)=i(x, y)*r(x , y), the value of i(x, y) and the value of r(x, y) cannot be read from the output value of the CCD camera 1. The image brightness-reflectance decomposition unit 4 first performs a natural logarithmic operation on all pixels of the entire image, namely

g'(x,y)=ln g(x,y)

＝ln i(x, y)+ln r(x, y)

＝i'(x, y)+r'(x, y)

  0<x<M+1, 0<y<N+1;

Then perform a fast Fourier transform on the entire image, that is,

G'(u,v)=F[g'(x,y)]

＝F[i'(x,y)]+F[r'(x,y)]

＝I'(u, v)+R'(u, v)

  0<u<M+1, 0<v<N+1;

I'(u,v)=F[i'(x,y)], R'(u,v)=F[r'(x,y)].

From the above formula, we can know that G'(u, v)=I'(u, v)+R'(u, v), that is, the gray scale value of the image takes the natural logarithm and then performs fast Fourier transform, which is equal to After taking the natural logarithm of the brightness of the image, do a fast Fourier transform and add the image reflectance to take the natural logarithm and then do a fast Fourier transform, that is, the spectrum G'(u, v) is equal to the spectrum I'(u, v) plus the spectrum R '(u,v). Most of the values of I'(u, v) are located at low frequencies, and most of the values of R'(u, v) are located at high frequencies. Therefore, we then weight I'(u,v) with the low frequency part of the spectrum G'(u,v), and in this way obtain an approximation I"(u,v) of I'(u,v); and use The high-frequency part of the spectrum G'(u,v) is weighted to R'(u,v) in this way to obtain an approximation R"(u,v) of R'(u,v). The following formulas are used to determine the values of I”(u, v) and R”(u, v)

If 0<u<M/2 AND 0<v<N/2, I”(u,v)=G’(u,v);

Otherwise, I" (u, v) = 0

If u＞M/2 AND v＞N/2, R”(u, v)=G’(u, v);

Otherwise, R" (u, v) = 0

In this way, we can use the image brightness-reflectance decomposition unit 4 to obtain the brightness spectrum I"(u,v) and the reflectance spectrum R"(u,v) after decomposition.

As shown in FIG. 2 , it is an action flow chart of the image brightness change detection unit 5. The brightness spectrum new_I"(u, v) of the current image is received from the image brightness-reflectance decomposition unit 4, and is communicated with the storage device 52. The brightness spectrum old_I”(u, v) of the previous image is used to calculate the difference 51 of the brightness spectrum of the two images before and after, so as to obtain the difference ΔI”:

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span><span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; N</span>}}\underset{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; new</span>}<span\; class="notranslate">\; \_</span>{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span><span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; old</span>}<span\; class="notranslate">\; \_</span>{\mathrm{<span\; class="notranslate">\; I</span>}}^{<span\; class="notranslate">\; \&prime;</span><span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>$

Introduce the value of ΔI" to judge whether the difference is greater than the first critical value? In the process of 53, if the value of ΔI" is smaller than the preset first critical value, the difference value 54 signal is not output to the lens 2; that is, the lens aperture does not need Change. If the value of ΔI" is larger than the preset first critical value, the difference value 54 signal is output to the lens 2, and the lens 2 enlarges or reduces the aperture according to this value.

Fig. 3 shows the action flow chart of the object movement detection unit 6, which receives the reflectance spectrum new_R"(u, v) of the current image from the image brightness-reflectance decomposition unit 4, and compares it with the previous image in the storage device 62 The reflectance spectrum old_R”(u, v) calculates the reflectance spectrum difference 61 of the two images before and after, so as to obtain the difference ΔR”:

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span><span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; N</span>}}\underset{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; new</span>}<span\; class="notranslate">\; \_</span>{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span><span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; old</span>}<span\; class="notranslate">\; \_</span>{\mathrm{<span\; class="notranslate">\; R</span>}}^{<span\; class="notranslate">\; \&prime;</span><span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span>{<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

Introduce the value of ΔR” to determine whether the difference is greater than the second critical value? In the process of 63, if the value of ΔR” is smaller than the preset second critical value, it means that the object in the video screen does not move 64; if the value of ΔR” is smaller than the second critical value If the preset second critical value is large, it means that the object in the image frame moves 65 .

Compared with the known technology, the digital image monitoring system that can automatically adjust the lens aperture and detect object movement provided by the present invention has the following advantages:

1. The image can be decomposed and converted into two parts of the spectrum, such as brightness and reflectance, and can be used to detect the change of light brightness and the movement of the object, so as not to misjudge the movement of the object.

2. For captured image frames, image frames can be captured from 2 or more than 2 groups of CCD cameras and lenses at the same time.

3. The image capture card can be set to only decompose and convert the region of interest in the image frame into a brightness spectrum and a reflectance spectrum, and use this to detect changes in light brightness and object movement in the region of interest, respectively. To control the lens aperture and detect whether the object is moving.

The above detailed description is a specific description of a feasible embodiment of the present invention, and is not intended to limit the protection scope of the present invention. All equivalent implementations or changes that do not depart from the present invention should be included in the protection scope of the patent requirements of the present invention middle.

Claims (5)

1. A digital image monitoring system capable of automatically adjusting lens aperture and detecting object movement, comprising: at least one video camera; at least one lens; an image capture card and at least one storage device, and the image capture card continuously captures digital images of photographed objects Imagery; characterized in that it also includes: An image brightness-reflectance decomposition unit, which receives the digital image, decomposes and converts the digital image into brightness spectrum data and reflectance spectrum data; An image brightness change detection unit is connected with the image brightness-reflectance decomposition unit, and receives the brightness spectrum data decomposed and transformed by it, and then connects with the previous one stored in a storage device in the image brightness change detection unit. Comparing the brightness spectrum data of the digital image, calculating the difference value of the brightness spectrum of the two digital images before and after, and comparing it with a first critical value, so as to automatically adjust the lens aperture; and An object movement detection unit is connected with the image brightness-reflectance decomposition unit, and receives the decomposed and converted reflectance spectrum data, and then compares with the previous digital image stored in another storage device in the object movement detection unit The reflectance spectrum data are compared, the reflectance spectrum difference value of the two digital images before and after is calculated, and compared with a second critical value to determine whether the object has moved. 2. The digital image monitoring system capable of automatically adjusting lens aperture and detecting object movement as claimed in claim 1, characterized in that said image capture card only decomposes and converts the area of interest in the image frame into brightness spectrum and The reflectance spectrum is used to detect the change of light brightness and the movement of the object in the region of interest respectively, so as to control the lens aperture and detect whether the object has moved. 3. The digital image monitoring system capable of automatically adjusting lens aperture and detecting object movement as claimed in claim 2, characterized in that said image frame is captured from a CCD camera and lens by means of an image capture card. 4. The digital image monitoring system capable of automatically adjusting lens aperture and detecting object movement as claimed in claim 2, characterized in that the image frame can capture image frames from two or more groups of CCD cameras and lenses at the same time . 5. The digital image monitoring system capable of automatically adjusting lens aperture and detecting object movement as claimed in claim 1, wherein said storage device uses detecting whether the object moves as a basis for whether to store the image.

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