KR100822053B1 - Image Acquisition Device and Image Acquisition Method - Google Patents

Abstract

An apparatus and a method for obtaining images are provided to improve low illumination characteristics by adopting a dual band pass filter for transmitting all optical signals of different bands, and improve color reproducibility by correcting effects of infrared rays. A camera unit comprises a dual band pass filter(50) and an image sensor(60). The dual band pass filter transmits an optical signal of at least a visible ray area and an optical signal of an infrared ray area. The image sensor converts the optical signals of an image concentrated through the dual band pass filter into an electric signal, and outputs the converted signal. A light emitting unit(80) emits the infrared rays and light of a wavelength different from the infrared rays. An image signal processor(90) corrects an image signal outputted from the camera unit. By obtaining distortion components caused by infrared rays included in color pixels of the image sensor, the image signal processor performs original color correction.

Description

Image Acquisition System and Image Acquisition Method {APPARATUS AND METHOD FOR TAKING A PICTURE}

1 is an exemplary cross-sectional view of a general camera module employing an IR filter.

Figure 2 is a cross-sectional view of the camera module as an image acquisition device according to an embodiment of the present invention.

3 is an exemplary block diagram of an image acquisition device according to an embodiment of the present invention.

4 is an exemplary band characteristic diagram of the dual band pass filter illustrated in FIGS. 2 and 3.

5 is a video signal processing flowchart according to an embodiment of the present invention.

The present invention relates to an image acquisition apparatus, and more particularly, to an image acquisition apparatus and an image acquisition method capable of eliminating the influence of infrared rays.

Cameras mounted on digital cameras and mobile phones as image acquisition devices typically use CCD or CMOS to convert optical signals into electrical signals to implement images. The optical signal includes not only an optical signal in the visible region (400 to 700 nm) but also an optical signal in the infrared region (˜1150 nm). Light in the infrared region negatively affects the image sensor applied to the camera. For this reason, digital cameras are equipped with an IR cut off filter (also called an IR filter) for removing optical signals in the near infrared region.

또는

)을 교대로 증착시킴으로서 제조된다. 이러한 방식으로 제조된 IR필터는 가시광 영역의 광신호는 투과시키고 근적외선 영역의 광신호는 반사시킨다. IR필터를 카메라 모듈에 적용할 때에는 IR필터 원판을 필요한 크기로 절단하여 CCD나 CMOS 앞에 장착한다. 이러한 IR필터가 적용된 카메라 모듈의 구조를 예시한 도면이 도 1에 도시되어 있다.IR filters are manufactured by vacuum thin film deposition techniques. For example, two materials with different refractive indices on a glass substrate (

or

) Is alternately deposited. The IR filter manufactured in this manner transmits the optical signal in the visible region and reflects the optical signal in the near infrared region. When applying an IR filter to a camera module, cut the original IR filter plate into the required size and mount it in front of the CCD or CMOS. 1 is a diagram illustrating a structure of a camera module to which the IR filter is applied.

As shown in FIG. 1, in the general camera module, a window cover 26 is disposed at the outermost part of the upper part, a barrel 16 is disposed below the upper part, and an upper convex lens 12a is disposed inside the barrel 16. ) And the lower convex lens 12b are disposed to face each other. The spacer 14 is located between these convex lenses 12a and 12b. In addition, there is a space in which the IR filter is located below the lower convex lens 12b, and an IR filter 20 having a predetermined thickness is inserted into the space. Sensors CCD and CMOS are disposed below the IR filter 20. The IR filter 20 disposed directly in front of the sensor transmits an optical signal in the visible region while reflecting the optical signal in the infrared region, thereby minimizing signal interference by the optical signal in the infrared region.

When using a camera module having the above-described structure in a low light environment, it is possible to use lighting means together as a means for obtaining good image quality or as an auxiliary means for recognizing the movement of an object having a pointing intention in the pointing device with the above-described camera module. Can be.

As an example of the luminaire, an infrared light emitting diode that can be easily mounted on a camera module may be used. What should be considered when using an infrared light emitting diode is that an optical signal in the infrared region is reflected by the IR filter 20. That is, when the infrared light emitting unit is employed as a means for obtaining good image quality in a low light environment, the above-described IR filter 20 transmits only the optical signal in the visible light region, so that an image having a desired image quality cannot be obtained normally.

This problem can be solved by employing a filter capable of transmitting both the optical signal in the visible region and the optical signal in the infrared region. In this case, however, the color reproduction effect is degraded by the optical signal in the infrared region. It will cause problems.

Accordingly, an object of the present invention is to provide an image acquisition device that can improve the low light characteristics by adopting a dual band pass filter that transmits all optical signals of different bands, and to improve the color reproducibility by correcting the influence of infrared rays,

Furthermore, another object of the present invention is to provide an image acquisition device and an image acquisition device including a light emitting unit that emits light in different wavelength ranges to compensate for insufficient light when photographing, but also capable of color correction by infrared rays.

Image acquisition apparatus according to an embodiment of the present invention for achieving the above object,

A camera unit including a dual band pass filter for transmitting at least an optical signal in the visible region and an optical signal in the infrared region, and an image sensor for converting and outputting an optical signal of an image collected through the dual band pass filter into an electrical signal Wow;

A light emitting unit for emitting infrared light and light of different wavelengths from the infrared light;

And an image signal processing unit for correcting an image signal output from the camera unit and acquiring a distortion component by infrared rays included in color pixels of the image sensor to correct primary colors.

According to the characteristics of the present invention, by adopting a dual band pass filter and an infrared LED that transmits all the optical signals of different bands, it is possible to obtain a good image by the infrared LED in a low light environment, such as dark night In addition, since the amount of infrared rays included in the color pixels is acquired in advance, the photographed image may be corrected using the same, and as a result, a good quality image may be obtained in both day and night.

Furthermore, the light emitting unit of the image acquisition device according to an embodiment of the present invention includes an infrared LED and a white LED, characterized in that each LED is located in the same cap.

This is to provide different lighting means day and night, and to implement a compact camera module.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a cross-sectional view illustrating a camera module as an image acquisition device according to an embodiment of the present invention, FIG. 3 is a block diagram of an image acquisition device according to an embodiment of the present invention, and FIG. A band characteristic diagram of the dual band pass filter illustrated in FIG. 3 is illustrated.

First, as shown in FIG. 2, the camera module of the image acquisition apparatus according to the embodiment of the present invention has a lens unit 30, a housing 40, a dual band pass filter 50, an image sensor 60, and a printed circuit. And a substrate 70.

The lens unit 30 is for forming an image of a subject and is inserted into a lens joint provided in the center of the housing 40 and threadedly coupled to the housing 40. This is merely an example and may be combined with the housing in various ways. .

The dual band pass filter 50 is positioned inside the housing 40 to transmit the optical signal in the visible light region (400 to 700 nm) and the infrared signal (730 to 5000 nm) passing through the lens unit 30.

In order to obtain a good image quality in a low light environment, it is preferable that the near infrared transmission band wavelength of the dual band pass filter 50 is optically designed to match the infrared LED wavelength which is one component of the light emitting unit 80 to be described later. For example, when the infrared LED wavelength of the light emitting unit 80 is 820 nm, the transmission band wavelength of the dual band pass filter 50 may be designed to be 820 nm, and when the emission wavelength of the infrared LED is 840 nm, the dual band pass filter ( The transmission band wavelength of 50) is also preferably designed to be 840 nm.

For reference, in order to design the dual band pass filter to transmit both an optical signal in the visible region and an optical signal in the near infrared region, an essential macleod program, which is one of optical coating design algorithms, may be used. This program was developed by ThinfilmCenter in the United States. Using a personal PC, it is possible to design optical filters with desired band characteristics by setting basic specifications such as reflectance, transmittance, and thickness, and setting specifications of the product such as deposition equipment characteristics and color. Can be.

Referring back to FIG. 2, the image sensor 60 is positioned on the printed circuit board 70 and converts and outputs an optical signal of an image collected through the dual band pass filter 50 into an electrical signal. The image sensor 60 includes an optical sensing element array unit in which a plurality of color (R, G, B) pixels are arranged, and are generally classified into a CCD type and a CMOS type.

On the other hand, the image acquisition device according to an embodiment of the present invention further includes a light emitting unit 80 including an infrared LED as a means for measuring the amount of infrared rays further to obtain a good image quality of the subject in a low light environment. . The light emitting unit 80 further includes a white LED as another illumination flash in addition to the infrared LED. The infrared LED and the white LED may be disposed in the same cap, thereby simplifying the appearance of the set. The light emitting unit 80 serves as a means for emitting illumination to the subject, and the arrangement position thereof is located on the upper surface of the housing 40 centering the lens unit 30 so that the emitted light is directed toward the subject as shown in FIG. Can be placed. Of course, the camera module may be separated into a separate module and mounted on a mobile terminal. For reference, the light emitting unit 80 may be controlled to be turned on under the control of a controller of an electronic device on which a camera module is mounted. The light emitting unit 80 may be controlled by an image signal processor (ISP), which is an image signal processing unit as in the embodiment of the present invention. It may be.

Hereinafter, referring to FIG. 3, the configuration of an image acquisition device according to an embodiment of the present invention will be described in detail.

First, as described above, the lens unit 30 forms an image of a subject on the image sensor 60, and the dual band pass filter 50 uses an optical signal and an infrared region in the visible light region passing through the lens unit 30. All of the optical signal of the transmitted to the image sensor 60. The lens unit 30, the dual band pass filter 50, and the image sensor 60 may be referred to as a camera unit. In some cases, the camera unit may further be referred to as a camera module including an ISP 90 to be described later. have.

The light emitting unit 80 also includes an infrared LED 82 and a white LED 84 as described above, and emits light of infrared and white light having different wavelengths to the subject under the control of the ISP 80 to be described later.

ISP 90, which is an image signal processing unit, processes and corrects an image signal output from the camera unit, that is, the image sensor 60, and corrects a distortion component by infrared rays included in color pixels of the image sensor 60. Acquire and correct the primary color of the captured image and output it. The ISP 90 basically performs various top functions for improving the performance of the image sensor such as color interpolation, auto white balance, and gamma correction.

For reference, a value for correcting the primary color of the photographed image may be extracted from, for example, the values of the color pixels obtained by controlling on / off the infrared LED under indoor lighting.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. 5, which shows a video signal processing flowchart according to an embodiment of the present invention. In the following description, it is assumed that an image is taken under room lighting.

First, according to a user's operation, the image acquisition device according to the embodiment of the present invention operates in the preview shooting (step S1) mode. Through the signal processing of the preview image obtained in such an operation mode, the ISP 90 compares the luminance level (Y) of the captured image with a preset threshold value, so that the current illuminance is a low light environment or a general light (not low light). Illuminance) environment can be checked (step S2). The illuminance check step may use data obtained in the ISP 90 but may be determined according to a signal applied from an external device such as an illuminance sensor.

If the low-light environment, the infrared LED 82 in the light emitting unit 80 is controlled "on" (step S3) and the image is taken (step S4), so that the image of the subject by infrared rays is transferred to the lens unit 30 and the dual band pass. The image sensor 60 is detected through a filter (DBPF) 50.

Therefore, the image acquisition device of the present invention can obtain an image of good quality according to the detection of the subject image by infrared light in a low light environment.

On the other hand, if the general illumination, ISP 90 "on" control the infrared LED 82 so as to saturate the amount of light by infrared light (S5 step) and then take an image (S6 step). In this case, due to the characteristics of the dual band pass filter 50, the color component of the subject image obtained by the visible light includes the distortion component due to the infrared ray. In order to detect a wavelength region of a specific color in an environment where infrared rays are saturated, the ISP 90 acquires a wavelength region value of a red pixel among the color pixels of the image sensor 60, as shown in FIG. 6. Save as "A" value (step S7). After the infrared LED 82 is turned off (step S8), the subject image is acquired again (step S9), and the red pixel wavelength range value is stored as the value "B" (step S10). Even if the infrared LED is turned off, the influence of the infrared rays by the light source cannot be excluded, and therefore, the distortion component due to the infrared rays is slightly included in the wavelength region value B of the red pixel.

Meanwhile, the wavelength region values "A" and "B" of the red pixel obtained through the above steps are subtracted (step S11), and the result is stored as C (step S11). The reason is as shown in Fig. 6 that image tuning is performed on the wavelength area value A of the red pixel obtained by saturation in the amount of light due to infrared rays, and the wavelength area value E of the red pixel which should be preferably reproduced in primary colors. This is because, if secured in advance by the method, the difference C between A and B is obtained, and as a result, a correction value D for correcting the distortion component of the infrared ray can be obtained.

As described above, when the correction value D for correcting the distortion component of the infrared ray is obtained, the image data may be corrected using this value. That is, the primary color is corrected (step S13) by subtracting the correction value D for correcting the distortion component of the infrared ray from the red pixel value of the image data B obtained by photographing the image (step S12). When the primary colors are restored as described above, the ISP 90 performs post-processing operations such as auto white balance (AWB), gamma correction, and color interpolation as in the general video signal processing unit, and corrected images obtained by the post-processing operations. Output data (step S14) or store it.

That is, according to the present invention, even if the distortion component due to the infrared ray is included in the color component of the subject image due to the characteristics of the dual band pass filter 50, it is possible to obtain the effect of correcting it normally to the primary color.

Although not described in the above embodiments, in some cases, a correction value (D) for correcting a distortion component of a color component due to infrared rays is obtained through experiments, and then stored in a memory and shipped to a product, thereby distorting the product in a later sale. It may be possible to correct distortion components caused by infrared rays in general illumination without extracting the components.

On the other hand, the image acquisition method according to an embodiment of the present invention is a method executable in the above-described image acquisition apparatus,

The luminance level (Y) of the preview image obtained through the camera unit is compared with one or more threshold values, and if it is greater than or equal to the first threshold value, infrared LEDs are sequentially emitted to correct distortion components caused by infrared rays by judging it as day. And lights out. In this case, the ISP obtains a distortion component by infrared rays included in each preview image obtained in the infrared light emission and off state, and outputs the corrected image.

More specifically, the correction of the photographed image is obtained by obtaining a wavelength range value for each color pixel of the image sensor, respectively, in an infrared emission state and an unlit state, and then, the difference between the obtained values and the wavelength range value of the color pixel for primary color reproduction. Is calculated to finally obtain a correction value for correcting the distortion component caused by the infrared ray. Subsequently, the final obtained correction value is subtracted from the photographed image data, thereby obtaining the primary color correction effect of each pixel.

If the obtained luminance level has a value between the first threshold value and the second threshold value, it is regarded as a night situation and only the white light source is controlled to be lit. If the luminance level is less than or equal to the second threshold value, the light source is controlled according to the ambient light in such a manner that only the infrared LED is turned on in consideration of a dark night situation.

As described above, the ISP of the image acquisition apparatus corrects and outputs the image acquired through the camera unit while controlling the light source according to the ambient illumination, so that the user can conveniently obtain a good image quality without any manipulation. .

As described above, the image acquisition device of the present invention employs a dual band pass filter for transmitting optical signals in the visible light region (400 to 700 nm) as well as the near infrared region (730 to 5000 nm) to the image sensor. According to the LED driving, it is possible to obtain a good image of the subject, and even in an environment having general illumination, an effect of obtaining an image close to the primary color by correcting a distortion component of a color component due to infrared rays.

In addition to the use of infrared LEDs, a light source that acts as a flashlight is used to select a suitable light source according to the illuminance, and to capture images. A side effect can be obtained that can be simplified.

On the other hand, the present invention has been described with reference to the embodiments shown in the drawings, but this is only illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. . Therefore, the true technical protection scope of the present invention should be defined only by the appended claims.

Claims (9)

A camera unit including a dual band pass filter for transmitting at least an optical signal in the visible region and an optical signal in the infrared region, and an image sensor for converting and outputting an optical signal of an image collected through the dual band pass filter into an electrical signal Wow; A light emitting unit for emitting infrared light and light of different wavelengths from the infrared light; And an image signal processing unit for correcting an image signal output from the camera unit and acquiring a distortion component by infrared rays included in color pixels of the image sensor to correct primary colors. The image acquisition apparatus of claim 1, wherein the light emitting unit comprises an infrared LED and a white LED. The image acquisition apparatus according to claim 2, wherein the infrared LED and the white LED are located in the same cap. The method according to claim 1 or 2, wherein the video signal processing unit, By controlling the light emitting unit on / off, obtain a wavelength range value for each color pixel of the image sensor, calculate the wavelength range value (E) of the color pixel for the primary value and the obtained value by the infrared ray And a primary color correction by obtaining a correction value for correcting the distortion component. The method according to claim 1 or 2, wherein the video signal processing unit, The luminance level (Y) of the preview image obtained through the camera unit is compared with one or more preset thresholds, and according to the comparison result, any one light source emitting light of different wavelengths is turned on or off. Image acquisition device. The image acquisition apparatus according to claim 1 or 2, wherein the camera unit and the image signal processing unit are integrated into one camera module. Image acquisition device comprising: a camera unit having a dual band pass filter for transmitting at least an optical signal in the visible region and an optical signal in the infrared region; and a light emitting unit for emitting infrared light and light having a wavelength different from that of the infrared region In the method, Comparing the luminance level (Y) of the preview image obtained through the camera unit with at least one threshold value; Controlling the light emitting unit to emit and turn off infrared rays according to a comparison result; And acquiring a distortion component by infrared rays included in each preview image obtained in an infrared light emission and an extinction state, and outputting a corrected photographed image. The method of claim 7, wherein the photographed image correction output step, Acquiring wavelength range values for respective color pixels of the image sensor under infrared light emission and off; Obtaining a correction value for correcting a distortion component caused by infrared rays by calculating a difference between the obtained value and a wavelength region value of a color pixel for primary color reproduction; And correcting the photographed image data by using the finally obtained correction value. The method of claim 7, further comprising: controlling light emission of light having a wavelength different from that of infrared rays according to a result of comparing the luminance level (Y) of the preview image obtained through the camera unit with at least one threshold value. Acquisition method.

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