KR101494638B1 - Vein visualization method using estimated reflectance spectrums, guide apparatus for vascular access using the method thereof and user authentication apparatus using the method thereof - Google Patents

Abstract

A method for imaging a blood vessel in a living body using reflection spectrum estimation, a vascular puncture guiding apparatus and a user authentication apparatus using the method. A method for imaging a blood vessel is to acquire an RGB image of a target living body using an RGB camera, to previously calculate an estimation factor for spectral estimation from image data including a plurality of sample colors, And generates an image in which blood vessels in the living body are visually displayed in accordance with the degree of reflection of light corresponding to the blood vessel from the estimated reflected spectrum image.

Description

TECHNICAL FIELD The present invention relates to a method of imaging a blood vessel in a living body using reflection spectrum estimation, a vascular puncture guide apparatus using the method, and a user authentication apparatus using the method method thereof}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for imaging blood vessels in a living body, and more particularly, to an imaging method capable of visually displaying blood vessels located in a skin by estimating a reflection spectrum from RGB images acquired using a general camera, A guiding device for visualizing and displaying the position of a blood vessel to a vascular puncture operator, and a user authentication apparatus using such an imaging method.

Multispectral imaging refers to images with spectral information for each pixel of an image. Unlike general red-green-blue (RGB) images, which have information of three bands of red, green and blue, multispectral images have information of several tens of bands. Multispectral images have been extensively studied and applied to various fields such as agriculture, mineralogy, and physics that can utilize such spectral information. Multispectral data can be acquired from a variety of devices, among which the most commonly used is a spectrometer. However, all of the various devices used to acquire multispectral images have a long time to acquire images and have limitations such as poor portability of the equipment. The prior art cited below introduces features of techniques that utilize information across multiple bands using multiple spectrums.

In order to overcome this problem, a study has been made to estimate the reflectance spectrum of a subject using RGB image information acquired through a general camera. However, spectral values estimated from the RGB information are limited in terms of the wavelength range that can be estimated, compared with spectral values measured by spectroscopy, and the accuracy is low. Therefore, in the limited fields such as color analysis of artwork, color reproduction, and quality improvement of endoscopic images Has been used.

Among various applications of multispectral imaging, there is a technique for visualizing blood vessels under the skin using a specific absorption spectrum of hemoglobin. And acquires blood vessel information by using a sensor that irradiates light of a wavelength appropriate for the wavelength and detects a signal of the wavelength band. However, since special equipment is needed to obtain this case, the use of such things as cost, use place, and application field is limited.

 P. Stigell, K. Miyata, and M. Hauta-Kasari, " Wiener Estimation Method in Estimating of Spectral Reflectance from RGB Images, " Pattern Recogn. Image Anal., Vol. 17, No. 2, pp. 233-242, 2007.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to overcome the limitations of the conventional method of acquiring a multispectral image, And to solve the inconvenience that special equipment must be mobilized to acquire blood vessel images.

According to an aspect of the present invention, there is provided a method of imaging blood vessels in a living body, the method comprising: obtaining an RGB image of a target living body using an RGB camera; Predicting an estimation factor for spectrum estimation from image data including a plurality of sample colors; Estimating a reflection spectrum image from the RGB image using the estimation factor; And generating an image in which a blood vessel in the living body is visually displayed according to a degree of reflection of light corresponding to the blood vessel from the estimated reflection spectrum image.

In a method of imaging blood vessels in vivo according to an embodiment, pre-calculating the estimating factor comprises: pre-acquiring real reflection spectral data from the sample color using a spectroscopic camera; Obtaining RGB data from the sample color in advance using an RGB camera; And calculating an estimation factor for minimizing an error between an actual reflection spectrum and a reflection spectrum to be estimated using the actual reflection spectrum data and the RGB data. Further, the estimation factor may be calculated based on a correlation matrix of a camera output and a reflection spectrum and an auto-correlation matrix of a camera output. Further, the camera output may be set in consideration of characteristics of a filter for passing signals of red, green, and blue bands, a spectrum of a light source, a sensitivity of a camera, and a reflection spectrum of a subject to be photographed.

In the method of imaging blood vessels in a living body according to an exemplary embodiment, the step of generating an image in which the blood vessels in the living body are visually displayed may include the steps of extracting, from the estimated reflection spectrum image, histogram stretching The contrast and brightness can be adjusted. The method may further include setting a region of interest that includes only a signal reflected from the skin and a signal reflected from the blood vessel in the estimated reflected spectrum image, and the histogram extension may be performed on the set region of interest . The histogram expansion may be performed by detecting a maximum value and a minimum value of the signal intensity for each frame of the estimated reflection spectrum image, linearly mapping the detected maximum value and minimum value, Can be increased. Further, the step of generating an image visually displaying the blood vessels in the living body may further include removing noise from the histogram extended image using a two-dimensional average filter and a median filter can do.

On the other hand, a computer-readable recording medium on which a program for causing a computer to execute a method for imaging blood vessels in vivo described above is recorded.

According to another aspect of the present invention, there is provided an apparatus for guiding a vascular puncture using vascular imaging in vivo, the apparatus comprising: an RGB camera for acquiring an RGB image of a subject to be punctured; Estimating an estimation factor for spectrum estimation from image data including a plurality of sample colors in advance, estimating a reflection spectrum image from the RGB image using the estimation factor, calculating a reflection spectrum image from the estimated reflection spectrum image, An image processing unit for generating an image in which a blood vessel in a living body is visually displayed according to a degree of reflection of the blood vessel; And a display unit for displaying the generated blood vessel image.

In the vascular puncturer guidance apparatus according to an embodiment, the image processing unit may generate a puncture guide line for a blood vessel near a skin to be contacted by a needle for a blood vessel puncture, and may highlight and display the guide line in real time through the display unit.

In the vascular punctor guide apparatus according to an embodiment, the image processing unit acquires real reflection spectral data from the sample color in advance using a spectroscopic camera, acquires RGB data from the sample color in advance using an RGB camera , An estimation factor that can minimize the error between the actual reflection spectrum and the reflection spectrum to be estimated can be calculated by using the actual reflection spectrum data and the RGB data.

In the vascular punctum guide apparatus according to an embodiment, the image processing unit generates an image that visually displays blood vessels in the living body by adjusting the contrast and brightness of the blood vessel image using the histogram expansion from the estimated reflection spectrum image In the histogram expansion, the maximum and minimum values of the signal intensity are detected for each frame of the estimated reflection spectrum image, and the detected maximum and minimum values are linearly mapped to increase the contrast of the skin have.

According to another aspect of the present invention, there is provided an apparatus for authenticating a user using blood vessel imaging in vivo, the apparatus comprising: an RGB camera for acquiring an RGB image of a living body of a user to be authenticated; Estimating an estimation factor for spectrum estimation from image data including a plurality of sample colors in advance, estimating a reflection spectrum image from the RGB image using the estimation factor, calculating a reflection spectrum image from the estimated reflection spectrum image, An image processing unit for generating an image in which a blood vessel in a living body is visually displayed according to a degree of reflection of the blood vessel; And an authentication processor for previously storing the blood vessel image of the authenticated user and comparing the blood vessel image generated by the image processor with the blood vessel image of the authentication user stored in advance and outputting the authentication result according to the matching.

In the user authentication apparatus, the image processing unit may acquire real reflection spectrum data from the sample color in advance using a spectroscopic camera, acquire RGB data from the sample color in advance using an RGB camera, The actual reflection spectrum data and the RGB data may be used to calculate an estimation factor that minimizes the error between the actual reflection spectrum and the reflection spectrum to be estimated.

In the user authentication apparatus according to an embodiment, the image processing unit generates an image in which the blood vessels in the living body are visually displayed by adjusting the contrast and brightness of the blood vessel image using the histogram expansion from the estimated reflected spectrum image , The histogram extension may detect the maximum and minimum values of the signal intensity for each frame of the estimated reflected spectrum image and may linearly map the detected maximum and minimum values to increase the contrast of the skin .

Embodiments of the present invention can generate reliable blood vessel images from images obtained using a general RGB camera, thereby making it possible to visualize the distribution of blood vessels from skin images regardless of time and place without requiring special optical / It can be used not only as a guide device for a venous puncture in real time, but also as a user authentication device using a blood vessel image.

1 is a view illustrating a blood vessel imaging process using an RGB camera proposed by embodiments of the present invention.
2 is a flowchart illustrating a method of imaging a blood vessel in a living body according to an embodiment of the present invention.
FIG. 3 is a comparative diagram for explaining a result of increasing the degree of contrast of blood vessels in the blood vessel imaging method according to an embodiment of the present invention.
FIGS. 4A and 4B are views for explaining a process of setting a region of interest in the blood vessel image of FIG. 3 and expanding the histogram using the region of interest.
FIG. 5 is a block diagram illustrating a vascular puncture guiding apparatus using vascular imaging in vivo according to an embodiment of the present invention. Referring to FIG.
6 is a block diagram illustrating an apparatus for authenticating a user using blood vessel imaging in vivo according to an embodiment of the present invention.

Before describing the embodiments of the present invention, the characteristics of the conventional multispectral image and the problems therefrom are briefly introduced. Then, in order to solve the problems, the technical means employed by the embodiments of the present invention are sequentially presented do.

A multispectral imaging system is a system that can provide spectral information for each pixel point of an acquired two-dimensional image. The multispectral image has total three-dimensional data by adding spectral information divided into a plurality of narrow wavelength bands to two-dimensional spatial data of an object to be photographed.

A common camera in everyday life is red-green-blue (RGB) image, which usually has information of three bands of red, green and blue. In a display device using light, RGB data is combined to reproduce colors. Multispectral images, on the other hand, are images that contain information in a narrow band of several hundreds of narrow wavelengths instead of three. As such, multispectral images have much more information than RGB images that have information of three bands because they have many wavelength bands of information. Also, while RGB images are limited to the visible light region that can be viewed by humans, multispectral images can be applied to a wider range of wavelengths, such as infrared, ultraviolet, and the like.

The simplest way to acquire multispectral images is to use a filter that passes a specific spectral band to a monochrome camera. It is a method of acquiring three-dimensional data by repeatedly photographing several filters manually or electronically changing several filters passing different bands through a monochrome camera. However, this method requires many filters as many as the number of bands to be photographed in order to increase the resolution with respect to wavelength, and it is inefficient because it takes a long time to acquire data due to repeated shooting.

The most commonly used equipment for obtaining multiple spectra is a spectrometer. There are various kinds of spectroscopes, such as prism spectroscopy, diffraction spectroscopy, and interference spectroscopy, and they distribute light through different methods. The most commonly used spectroscope is a prism spectroscope that disperses light from a slit through a prism and detects scattered light by a sensor to acquire spectral information.

Although the multispectral image can be acquired using various devices, it has a disadvantage in that data acquisition time is longer than that in the general RGB image acquisition. In the case of acquiring information of one wavelength by two-dimensional spatial data, it is necessary to repeatedly photograph as many times as the number of wavelengths to be watched. In the case of acquiring various wavelength information for one pixel point or one scanning line in one shot, It is necessary to repeatedly capture the pixel points or scanning lines of the spatial image. If the data acquisition time is long, the imaging equipment and the object to be photographed must be fixed for a long time, and the mobility of the equipment is deteriorated.

Although the human eye can only see visible light with a wavelength of 400-700 nm, there is a lot of information that can not be observed with the human eye even in a wide band other than visible light. In addition, when the wavelength of the light in the visible light region is divided to observe only the wavelength of the specific band, information other than the information obtained by the human eye appearing as a mixed state of visible light can be obtained. Veins located at shallow depth beneath the skin are difficult to observe with human naked eyes. However, if information other than human eyes can be used, visualization can be made into images. Let's look at the principle of visible vein using visible light with near-infrared or large wavelength.

When light is irradiated on the skin, some are reflected from the surface of the skin and others penetrate into the skin. Some of the penetrating light is absorbed into the body and the rest is transmitted through the body or reflected back out of the skin. At this time, the amount of light absorbed into the body is determined by the inherent light absorption characteristic of the cell, and hemoglobin also has a specific absorption coefficient. It is possible to obtain blood vessel information under the skin by using the specific absorption coefficient of hemoglobin.

At this time, in order to acquire blood vessel information under the skin, it is necessary to penetrate the skin under the light without being reflected from the surface of the skin. In general, the larger the wavelength of light, the deeper the depth of penetration into the body. Among visible rays, blue light with short wavelength is mostly reflected from the surface of skin and red light with long wavelength penetrates to the bottom of skin. This is also the reason why the light coming out from the white light is red when you put your finger on it. In other words, when blue light is irradiated on the skin, most of the light is reflected from the surface of the skin, so that only information on the surface of the skin can be obtained. Therefore, in order to acquire information about blood vessels located under the skin, light must penetrate deeply into the body, and long wavelengths should be used.

In order to penetrate deeply into the skin, a sufficiently long wavelength of light should be used, and the appropriate wavelength should be selected for the light absorption coefficient. Hemoglobin has a very large absorption coefficient at a wavelength of about 300-600 nm and a large absorption coefficient up to about 700 nm for deoxyhemoglobin. Therefore, when the light of this band is irradiated, hemoglobin absorbs a larger amount of light than the surrounding tissue. Therefore, it is possible to acquire blood vessel information by irradiating light in a band where hemoglobin absorbs a lot and observing how absorbed light is absorbed. As a method for observing the absorbed amount, there is a method of observing that the light that has been reflected is reflected back, and a method of observing the light that is transmitted. In the vein biometry technique, when the reflected or transmitted light is observed, a lot of light is absorbed by the hemoglobin in the place where the vein is located, and the vein pattern can be observed when the vein is not located.

As described above, the multi-spectral technique can be used to image blood vessels. Existing devices using blood vessel information transmit light of a wavelength suitable for acquisition of blood vessel information, receive reflected or transmitted signals, acquire blood vessel information do. Some equipment uses light at 750nm and other equipment uses light at 700nm-1000nm to obtain vascular information. However, in order to transmit and receive light having such a specific wavelength band, special equipment is required. When such a special equipment is used for vein imaging, the use of the equipment is restricted, the mobility is low, and the cost is high. These disadvantages limit the extent to which vascular information can be applied and are currently used only in limited fields such as vein biometrics for access control.

On the other hand, if it is possible to acquire vascular information through a general camera, it is good in mobility, easy to use, and low cost, which overcomes the disadvantages of conventional vascular imaging devices. Since most of the recently introduced mobile devices support camera functions, applications using mobile devices become possible. Therefore, the embodiments of the present invention described below introduce technical means for acquiring blood vessel image using a general RGB camera.

FIG. 1 is a diagram illustrating a blood vessel imaging process using an RGB camera proposed by embodiments of the present invention. As described above, when blood vessel information can be acquired using a general camera, techniques are useful in various applications And it can be said to have great advantages such as low cost, good mobility and convenient use. For this purpose, it is necessary to extract the blood vessel data from the RGB image acquired by the general camera 110. Estimation of the reflection spectrum from the RGB image can be regarded as estimation of the low-dimensional data as high-dimensional data. The embodiments of the present invention can be applied to a technique of estimating the reflection spectrum using a small number of band information . In order to estimate the low-dimensional data as high-dimensional data, various techniques can be utilized. In order to estimate the reflection spectrum from the RGB data, the Wiener estimation method is used as an example.

The output v _i (i = R, G, B) of the RGB camera can be expressed by the following equation (1).

Where _{f i (λ) (i =} R, G, B) are red, green, and characteristics of the filter for passing a signal of a blue band, E (λ) is the spectrum, S (λ) of the light source is the camera's sensitivity, r ( represents a reflection spectrum of the object to be photographed.

는 3×k 행렬이며, 광원의 스펙트럼 E, 그리고 카메라 감도 S 는 각각 k×1, 1×k 행렬이다.In order to simplify expression (1), a vector and a matrix can be expressed by the following equation (2), and t denotes a transposition of a matrix. Here, the camera output v is a 3 × 1 matrix with three values of R, G, and B, and the reflection spectrum r is a k × 1 matrix with k spectral information. The spectral characteristic matrix of R, G, and B filters

Is a 3 × k matrix, the spectrum E of the light source, and the camera sensitivity S are k × 1, 1 × k matrices, respectively.

Solving Equation (2), the estimated reflection spectrum matrix can be expressed as Equation (3).

을 가장 작게 해 주는 행렬 G^-1는 아래의 수학식 4와 같이 나타낼 수 있다. 여기서

는 앙상블 평균을 나타낸다.Now, using the Wiener estimation technique, the error of the actual reflection spectral matrix r and the estimated reflection spectral matrix r _est

The matrix G ^-1 that minimizes the matrix G ^-1 can be expressed by Equation (4) below. here

Represents an ensemble average.

In Equation (4), R _rv is a correlation matrix of the camera output v and the reflection spectrum r, and R _vv is an autocorrelation matrix of the camera output v.

The estimated output to the camera using a matrix G ^-1 obtained through a process such as v = reflected spectrum from _{^{[RGB] t r est = [}} λ 1 λ 2 ... _{k-1 [} lambda] _k can be estimated as shown in the following Equation (5).

To obtain the ensemble data described in Equation (4), reflection spectra and RGB data are obtained from various sample colors as shown in FIG. At this time, spectral cameras can be used to acquire reflection spectrum data, and RGB cameras can be used to acquire RGB data. The estimated matrix G ^-1 is calculated using the RGB data and the actual reflection spectrum obtained from the sample color. The estimation matrix G ^-1 calculated by this process reflects the characteristics of the light source, the sensitivity of the camera, and the characteristics of the filter when acquiring the ensemble data. Therefore, the RGB image acquired in the same environment can estimate the reflection spectrum using the pre-calculated estimation matrix G ^-1 . In other words, it is preferable that the process of FIG. 1 to 120 is performed separately beforehand. In the blood vessel imaging process proposed by the embodiments of the present invention, only the estimation matrix calculated through 120 process can be utilized.

Now, the reflection spectrum 130 is estimated using the estimation matrix G ^-1 from the RGB data photographed through the RGB camera 110 with respect to the region where the blood vessel image is to be observed, and the blood vessel image 140 < / RTI >

As we have seen so far, we can estimate the reflection spectrum from the RGB image using the Wiener estimation technique and suggest that it can be improved through the reflection spectrum estimation.

FIG. 2 is a flowchart illustrating a method of imaging a blood vessel in a living body according to an embodiment of the present invention, and sequentially shows the idea of FIG.

In step S210, the blood vessel imaging apparatus acquires an RGB image of a target living body using an RGB camera.

In step S220, the blood vessel imaging apparatus previously calculates an estimation factor for spectrum estimation from the image data including a plurality of sample colors. Herein, the blood vessel imaging apparatus acquires real reflection spectral data from the sample color in advance using a spectroscopic camera, obtains RGB data from the sample color in advance using an RGB camera, and outputs the actual reflection spectrum data and the RGB data The estimation factor is calculated to minimize the error between the actual reflection spectrum and the reflection spectrum to be estimated.

As described in detail with reference to FIG. 1 and Equation 3 to Equation 4, this estimation factor is a correlation matrix of the camera output and the reflection spectrum and an auto-correlation matrix of the camera output, . ≪ / RTI > The camera output may be set in consideration of characteristics of a filter for passing signals of red, green, and blue bands, a spectrum of a light source, a sensitivity of a camera, and a reflection spectrum of a subject to be photographed.

In step S230, the blood vessel imaging apparatus estimates a reflection spectrum image from the RGB image using the estimated factor. That is, the reflection spectrum can be estimated by reflecting the estimated factor into the RGB image as shown in Equation (5).

In step S240, the blood vessel imaging device generates an image in which blood vessels in the living body are visually displayed according to the degree of reflection of light corresponding to the blood vessel from the estimated reflection spectrum image. A more specific visualization method will be described later with reference to FIG. 3 to FIG. 4B.

FIG. 3 is a comparative diagram for explaining a result of increasing the contrast of the blood vessel image in the blood vessel imaging method according to the embodiment of the present invention, wherein (a) is the image before the increase in contrast, and (b) The following image is exemplified.

The blood vessel images obtained using the method described above are difficult to observe the blood vessels visually as shown in FIG. 3 (a) due to the low contrast. Therefore, an additional process is required to make the blood vessel visible as shown in FIG. 3 (b) through appropriate image processing.

To this end, in one embodiment of the present invention, the process of visually displaying blood vessels in a living body comprises the steps of adjusting the contrast and brightness of a blood vessel image using histogram stretching from the estimated reflection spectrum image .

In order to use the proposed technology regardless of the location, it is necessary to extract only the hand or arm and analyze it. For this purpose, a region of interest is set at the center of the observation screen and a user places his / her hand or arm in the region of interest. The size of the area of interest is divided into five parts, horizontal and vertical, to obtain sufficient data with less inconvenience to the user.

FIGS. 4A and 4B are diagrams for explaining a process of setting a region of interest in the blood vessel image of FIG. 3 and extending the histogram using the region of interest, respectively, and set the region of interest as shown in FIG. The signal in the region of interest is assumed to be a mixture of the reflected signal from the skin and the reflected signal from the blood vessel.

The histogram of the signal intensity in the region of interest is shown in FIG. 4 (b), and the minimum value of the signal intensity is 97 and the maximum value of the signal intensity is 116 in the range from 0 to 255. As can be seen from the histogram distribution, the signal is concentrated within a very narrow range and the image has low contrast. Therefore, the contrast and brightness were adjusted through histogram stretching.

Since the brightness of the skin may be varied depending on the surrounding environment and image acquisition conditions during image acquisition, such as light source, background, and camera angle, the signal within the region of interest may be analyzed for each frame to find the maximum and minimum values. Respectively. When acquiring the image, we gave a 40% margin when choosing the minimum value considering the shadow part or less light and relatively dark part. The selected minimum and maximum values are linearly mapped from 0 to 180 to enhance the contrast and adjust the brightness to an appropriate level. This histogram extension can be expressed as Equation (6) below.

In Equation (6), data _in and data _out represent the data before and after the histogram expansion, respectively, max _in is the maximum value of the signal in the region of interest before the histogram expansion, and min _in is the 40% margin of the minimum value of the signal in the region of interest This indicates a quasi-value. max _out and max _in represent the maximum and minimum values of the data after histogram expansion. Max _out and max _in were set to 180 and 0, respectively, so that the contrast of the skin was increased and the brightness was adjusted to an appropriate level.

As a result of performing the histogram expansion, it can be confirmed that the image of FIG. 4 (a) is higher than that of FIG. 4 (b) and the image of the blood vessel is well visible and the image of darkness is brightly adjusted. By analyzing and adjusting the data distribution of skin and blood vessels in this way, it was optimized.

In summary, in a blood vessel imaging method according to an embodiment of the present invention, a blood vessel imaging apparatus sets a region of interest including only a signal reflected from a skin and a signal reflected from a blood vessel in the previously estimated reflection spectral image, The histogram expansion is preferably performed for the region of interest set. The histogram expansion may be performed by detecting a maximum value and a minimum value of the signal intensity for each frame of the estimated reflection spectrum image, linearly mapping the detected maximum value and minimum value, It is preferable to increase the degree of the above.

Furthermore, the histogram extension has the advantage of enhancing the contrast, but the disadvantage is that the noise existing before the histogram expansion can be emphasized through the histogram expansion. Therefore, it is desirable to remove the noise using a two-dimensional average filter and a median filter after histogram expansion. It can be seen from the experiment that the noise that is emphasized in the histogram extended image before the filter is taken can be reduced significantly in the image taken by the filter.

As described above, the embodiments of the present invention can be obtained by using a general camera having advantages such as good mobility, low cost, and convenient use. Using the obtained camera, it is useful for a venous puncture navigator, Can be expected to be used.

Among them, the first application that can be considered is the venous puncture navigator. A venous puncture is a direct stabbing of the vein using an injection needle. It is performed primarily from the elbow to the wrist, or through the back of the hand. Although venous puncture is very common in the hospital such as venous blood sampling and intravenous injection, it is known that the pain is greater than the subcutaneous or intramuscular injection and the probability of failure is higher than that of other injections. Especially in children and newborns, the puncture site is limited, and venous puncture is difficult due to small venous blood vessels.

FIG. 5 is a block diagram illustrating a vascular puncture guiding apparatus 500 using in vivo blood vessel imaging according to an exemplary embodiment of the present invention. Referring to FIG. 5, The method of the present invention will be described only in the case of a blood vessel puncture.

The RGB camera 510 is a means for acquiring an RGB image of a living body intended to puncture a blood vessel, and can take a blood vessel puncture image in real time as shown in FIG.

The image processing unit 520 previously calculates an estimation factor for spectrum estimation from the image data including a plurality of sample colors, estimates a reflection spectrum image from the RGB image using the estimation factor, An image in which blood vessels in a living body are visually displayed is generated according to the degree of reflection of light corresponding to the blood vessel from the image.

The image processing unit 520 acquires real reflection spectral data from the sample color in advance using a spectral camera, acquires RGB data from the sample color in advance using an RGB camera, and outputs the actual reflection spectral data and the RGB It is preferable to use the data to calculate an estimation factor that minimizes the error between the actual reflection spectrum and the reflection spectrum to be estimated. In addition, the image processing unit 520 generates an image in which the blood vessel in the living body is visually displayed by adjusting the contrast and brightness of the blood vessel image using the histogram expansion from the estimated reflection spectrum image, It is preferable that the maximum value and the minimum value of the signal intensity are detected every frame of the reflected spectrum image and the detected maximum value and minimum value are linearly mapped to increase the contrast of the skin.

Finally, the display unit 530 displays the generated blood vessel image. Here, the image processor 520 generates a puncture guide line for the blood vessel near the skin where the needle touches the needle for the blood vessel puncture, and emphasizes and displays it in real time through the display unit 530, thereby allowing the operator to perform a more convenient blood vessel puncture .

In the case of real-time delivery of the blood vessel imaging technique using the conventional camera, it can help to select and treat the puncture site by making the blood vessel more visible. In addition, since it is possible to visualize blood vessels that are difficult to observe with the naked eye, it can be very helpful for the venous puncture of elderly, children, and severe patients who can not find veins. The use of this technique as a navigator for venous puncture can reduce the time required for venous puncture and increase the efficiency, thereby reducing the cost of intravenous puncture and reducing the failure rate of venous puncture to increase patient satisfaction. In addition, since it does not irradiate a separate light source using a general camera, it has an advantage that it can be used safely in any part of the body. Most of all it is much more economical than purchasing a separate device that uses near infrared rays to receive and receive NIR because it uses a normal RGB imaging device.

On the other hand, a second application field of a blood vessel image using a general camera relates to a biometric technique using a hand blood vessel. Biometrics is used for authentication by using information of specific parts of the body. It is useful for security because there is no risk of loss or theft and it is difficult to counterfeit. Body parts used for biometrics include fingerprints, veins, face, and voice. With the rapid increase in the use of smart mobile devices, security in mobile devices has become more prominent. Biometrics technology has been attracting attention as a technology to solve the security problem of mobile devices because it guarantees simple and high security.

Among the various biometric technologies, the vascular recognition technology of the palm or finger has a lower recognition rate than other biometric technologies and has the advantages of less rejection and higher security because it is non-contact type. Currently, hand blood vessel visualization studies and hand vascular biometrics commercialization devices acquire blood vessel information by irradiating light of a specific wavelength and sensing the light. Therefore, in order to use the hand-blood vessel biometric technology in a mobile device, there is a weak point that a light source emitting near-infrared light and a sensor capable of receiving a near-infrared light signal are additionally required.

On the other hand, when acquiring hand vein information through a general camera, it can be applied to a mobile device having a built-in camera without adding hardware. A smart mobile device having a built-in camera can replace the data acquisition device of the existing blood vessel recognition system.

6 is a block diagram illustrating an apparatus 600 for authenticating a user using blood vessel imaging in vivo according to an exemplary embodiment of the present invention. Referring to FIG. 6, And only the outline of the configuration for user authentication is mainly described.

The RGB camera 610 is a means for acquiring an RGB image of a target living body of a user to be authenticated.

The image processor 620 may previously calculate an estimation factor for spectrum estimation from image data including a plurality of sample colors, estimate a reflection spectrum image from the RGB image using the estimation factor, An image in which blood vessels in a living body are visually displayed is generated according to the degree of reflection of light corresponding to the blood vessel from the image.

The image processing unit 620 acquires real reflection spectral data from the sample color in advance using a spectral camera, acquires RGB data from the sample color in advance using an RGB camera, and outputs the actual reflection spectral data and the RGB Data can be used to calculate an estimation factor that minimizes the error between the actual reflection spectrum and the reflection spectrum to be estimated. In addition, the image processor 620 generates an image in which the blood vessel in the living body is visually displayed by adjusting the contrast and brightness of the blood vessel image using the estimated spectral image from the estimated reflected spectrum image, It is preferable that the maximum value and the minimum value of the signal intensity are detected every frame of the reflected spectrum image and the detected maximum value and minimum value are linearly mapped to increase the contrast of the skin.

The authentication processing unit 630 stores the blood vessel image of the authenticated user in advance, compares the blood vessel image generated by the image processing unit and the blood vessel image of the previously stored authentication user, and outputs the authentication result according to the matching. That is, the user can easily authenticate the user by using only the normal RGB camera by checking the database about the vascular spirituality stored in advance and checking whether there is an authentication user matching the blood vessel image generated through the image processing unit 620.

According to the embodiments of the present invention described above, it is possible to generate reliable blood vessel images from images obtained using a general RGB camera, thereby enabling the distribution of blood vessels from skin images without any time or place without special optical / And can be used as a guide device for a venous puncture in real time utilizing the same, and can also be utilized as a user authentication device utilizing a blood vessel image.

Meanwhile, the embodiments of the present invention can be embodied as computer readable codes on a computer readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored.

Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device and the like, and also a carrier wave (for example, transmission via the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the present invention can be easily deduced by programmers skilled in the art to which the present invention belongs.

The present invention has been described above with reference to various embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

110: RGB camera
500: vascular puncture guiding device 510: RGB camera
520: image processor 530:
600: User authentication device 610: RGB camera
620: Image processor 630: Authentication processor

Claims (17)

A method for imaging blood vessels in a living body,
Acquiring an RGB image of a target living body using an RGB camera;
Predicting an estimation factor for spectrum estimation from image data including a plurality of sample colors;
Estimating a reflection spectrum image from the RGB image using the estimation factor; And
Adjusting the contrast and brightness of the blood vessel image using histogram stretching from the estimated reflection spectrum image to generate an image in which blood vessels in the living body are visually displayed according to the degree of reflection of light corresponding to the blood vessel; Methods of inclusion. The method according to claim 1,
The step of calculating the estimation factor in advance includes:
Obtaining actual reflection spectral data from the sample color in advance using a spectroscopic camera;
Obtaining RGB data from the sample color in advance using an RGB camera; And
And calculating an estimation factor for minimizing an error between an actual reflection spectrum and a reflection spectrum to be estimated using the actual reflection spectrum data and the RGB data. 3. The method of claim 2,
The estimation factor may be calculated by:
Correlation matrix of the camera output and the reflection spectrum and an auto-correlation matrix of the camera output. The method of claim 3,
Wherein the camera output comprises:
A characteristic of a filter for passing signals of red, green, and blue bands, a spectrum of a light source, a sensitivity of a camera, and a reflection spectrum of an object to be photographed. The method according to claim 1,
Wherein the spectral estimation is performed using Wiener estimation. delete The method according to claim 1,
Setting an area of interest including only a signal reflected from the skin and a signal reflected from the blood vessel in the estimated reflected spectrum image,
Wherein the histogram extension is performed for the set region of interest. The method according to claim 1,
The histogram extension may include:
Detecting a maximum value and a minimum value of the signal intensity for each frame of the estimated reflection spectrum image and linearly mapping the detected maximum value and minimum value to increase the contrast of the skin by extending the interval, Way. The method according to claim 1,
The step of generating an image in which the blood vessels in the living body are visually displayed,
And removing noise from the histogram extended image using a two-dimensional average filter and a median filter. A computer-readable recording medium storing a program for causing a computer to execute the method according to any one of claims 1 to 5 and 7 to 9. A vascular puncture guide apparatus using vascular imaging in vivo,
An RGB camera for acquiring an RGB image of a subject to be punctured;
Estimating an estimation factor for spectrum estimation from image data including a plurality of sample colors, estimating a reflection spectrum image from the RGB image using the estimation factor, and estimating a reflection spectrum image from the estimated reflection spectrum image using histogram expansion An image processor for generating an image in which a blood vessel in a living body is visually displayed according to a degree of reflection of light corresponding to a blood vessel by adjusting a contrast and brightness of the blood vessel image; And
And a display unit for displaying the generated blood vessel image. 12. The method of claim 11,
Wherein the image processing unit comprises:
And generates a puncture guide line for a blood vessel near a skin contacting the needle for a blood vessel puncture, and emphasizes and displays it in real time through the display unit. 12. The method of claim 11,
Wherein the image processing unit comprises:
Acquiring real reflection spectral data from the sample color in advance using a spectral camera, acquiring RGB data from the sample color in advance using an RGB camera, and using the actual reflection spectrum data and the RGB data, And calculates an estimation factor for minimizing the error of the reflection spectrum to be estimated. 12. The method of claim 11,
The histogram extension may detect a maximum value and a minimum value of the signal intensity for each frame of the estimated reflection spectrum image and linearly map the detected maximum value and minimum value to increase the contrast of the skin by expanding the interval. . A user authentication apparatus using in vivo blood vessel imaging,
An RGB camera for acquiring an RGB image of a target living body of a user to be authenticated;
Estimating an estimation factor for spectrum estimation from image data including a plurality of sample colors, estimating a reflection spectrum image from the RGB image using the estimation factor, and estimating a reflection spectrum image from the estimated reflection spectrum image using histogram expansion An image processor for generating an image in which a blood vessel in a living body is visually displayed according to a degree of reflection of light corresponding to a blood vessel by adjusting a contrast and brightness of the blood vessel image; And
And an authentication processor for previously storing the blood vessel image of the authenticated user and comparing the blood vessel image generated by the image processor with the blood vessel image of the authentication user stored in advance and outputting the authentication result according to the matching. 16. The method of claim 15,
Wherein the image processing unit comprises:
Acquiring real reflection spectral data from the sample color in advance using a spectral camera, acquiring RGB data from the sample color in advance using an RGB camera, and using the actual reflection spectrum data and the RGB data, And calculates an estimation factor for minimizing the error of the reflection spectrum to be estimated. 16. The method of claim 15,
The histogram extension may detect a maximum value and a minimum value of the signal intensity for each frame of the estimated reflection spectrum image and linearly map the detected maximum value and minimum value to increase the contrast of the skin by expanding the interval. .

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