KR100912074B1 - Improved stereo-image optical topometer - Google Patents

Abstract

The present invention relates to a skin measurement apparatus using a stereoscopic image. The skin measurement apparatus corrects the existing skin measurement system in three aspects to enable more scientific and objective three-dimensional surface measurement. The skin measurement apparatus measures the level of the light amount provided to the measurement area, and adjusts the brightness level of the light source according to the measured level, so that a constant light amount is always provided to the measurement area. In addition, the skin measuring apparatus obtains an image using the highest point of the replica plate as a zero disparity, and obtains a degree of variance using an uncrossed variation, thereby enabling accurate image acquisition. In addition, the skin measurement apparatus undergoes a calibration and correction process of the camera, thereby enabling accurate depth information extraction from an image obtained from a converging camera model.

According to the present invention, it is possible to derive more scientific and objective results in determining the severity of atopic dermatitis, in which minute changes should be detected.

Stereoscopic image, skin measurement, light source, calibration, correction

Description

Improved stereo-image optical topometer using stereoscopic image

1 is a block diagram showing an overall skin measurement apparatus according to a preferred embodiment of the present invention.

2 is a cross-sectional view sequentially illustrating a process of acquiring an image of a measurement area in a skin measurement apparatus according to an exemplary embodiment of the present invention.

FIG. 3 is a photograph for explaining a process of setting a relatively thin film type (thin type) and a relatively thick film type (thick type) at the time of fabricating a replica plate in order to examine the effectiveness of the image acquisition method according to the present invention. admit.

FIG. 4 is a diagram exemplarily illustrating a left image and a right image acquired by an image acquisition method of a skin measurement apparatus according to an exemplary embodiment of the present invention.

FIG. 5 illustrates a case where a degree of variance is obtained for an image obtained by using a zero disparity as the lowest point of the simulation plate according to a conventional image acquisition method, and then 3D reconstruction.

FIG. 6 illustrates a result of reconstructing an image acquired for a thin type of a replica plate according to an image acquisition method of the present invention, and FIG. 7 illustrates a thick film type of a replica plate according to an image acquisition method of the present invention. This is a 3D reconstructed image of (thick type) in the same way.

8 are left and right images obtained for a calibration rig produced according to a preferred embodiment of the present invention, and FIG. 9 shows 49 control points as a world coordinate for the calibration rig according to the present invention. 10 shows image coordinates designated by pixel values of control points for each of left and right images.

(A) of FIG. 11 is an epipolar line in left and right images before correction and (b) is an epipolar line in left and right images after correction according to the present invention.

FIG. 12 is a photograph illustrating three-dimensional reconstructed images using a disparity map before and after camera correction.

FIG. 13 is a diagram illustrating an intersecting state between two planes including the vertical and horizontal axes of the image coordinates and the focal plane.

<Explanation of symbols for the main parts of the drawings>

10: skin measurement device

100: Microscope

110: light source

120: light amount regulator

130: light receiving element

132: light quantity measuring unit

140: the first camera

142: second camera

150: computer

The present invention relates to a skin measurement apparatus using a three-dimensional image, and more specifically, to provide a standardized light source, and to measure the fine epidermis by acquiring an accurate image without error according to the thickness of the copying plate and through camera calibration and correction. The present invention relates to a skin measurement apparatus using a stereoscopic image.

According to a recent study, the prevalence of atopic dermatitis among children under 6 years of age in Seoul is 41.7%, and atopic dermatitis is rapidly increasing. In addition, many kinds of therapeutics and ameliorators are being developed and commercially available. However, there are few scientific studies that are the basis for objectifying and quantifying the efficacy of drugs in clinical evaluation of skin diseases. As a method for evaluating atopic dermatitis, there is a visual evaluation method such as SCORAD index which is used in the clinic, and as a medical evaluation method, the moisture content, water content of the stratum corneum layer using corneometer, D-Squame, evaporimeter, pH-meter, spectrophotometer, etc. There is a method of measuring the degree of evaporation, skin elasticity, skin color, and the like. Recently, a method of evaluating the severity of atopic dermatitis by measuring the change of the skin surface condition has been used to objectify the severity of atopic dermatitis. The methods include the use of a surface profilometer, image analysis ( morphological measurements using image analysis, density measurements, and methods using laser profilometers. However, these methods have a problem that it is difficult to accurately quantify the three-dimensional surface state of the skin in that it is based on the inappropriateness of the skin surface state measurement principle and two-dimensional data. Accordingly, the recent invention using stereo images has been proposed as a new solution.

The method of using stereoscopic images is the first method used to measure the depth of the crater on the lunar surface of Apollo, a US space program. It is applied to dermatology and cosmetic engineering to measure the morphological characteristics of skin.

This is because the object cannot be perceived in three dimensions with one eye, but when the image of the object is recognized by both eyes, the difference between the two eyes can be analyzed in the cerebrum to feel the three-dimensional sense of the object and the perspective can be accurately recognized. . Based on this principle, when stereo matching is performed from a pair of images acquired by two CCD cameras on the same object, a distance difference occurs between the two images, which is called disparity. Depth information is embedded in the concept of variation, so that not only the X-axis and the Y-axis but also the Z-axis can be measured to obtain three-dimensional information. By using this, it is possible to quantitatively measure the three-dimensional morphological characteristics of the biological surface.

In order to measure the morphological characteristics of the skin in this way, skin wrinkle replicas should be prepared. The material of the replica board is mainly made of silicon rubber with fine grain structure. Resin and catalyzer are mixed and attached to the desired area. The reason for using a replica plate without measuring the skin directly is that it can take advantage of the spatial and temporal ease of the measurement and the fixing. However, in the case of measuring using a three-dimensional image using a replica plate, there is a problem that an error due to the thickness other than the wrinkles that occur during the production of the replica plate rather than the skin wrinkle portion.

In addition, conventional stereo image systems have been measured assuming a standard static model or a non-convergence model due to the complexity of calculation. The position where disparity of left and right images does not occur in a stereoscopic image system is called zero disparity. In using a stereoscopic camera, the zero shift is an infinite point. However, in reality, as the possibility of convergence model is raised due to mechanical disparity for zero disparity, there is a problem that an error occurs in the existing measurement method.

Lastly, unlike a system using a general camera, the measurement of the microscopic surface of the skin requires the use of a light source together with a microscope. However, there is a problem that the amount of light distortion is followed in the image acquisition using the light source. This has the same problem of light quantity distortion in the case of equipment that uses a light source such as D-Squame and Skin Color Distribution Analyzer (SCDA) system.

Accordingly, the present applicant intends to propose a method of presenting and establishing a more accurate and scientific evaluation method by improving the existing problems in the three aspects of the method of measuring the three-dimensional shape of the skin surface.

An object of the present invention for solving the above problems is to provide a skin measurement apparatus that can always obtain a stereoscopic image according to the standardized amount of light by having a light source that can provide a constant amount of light irrespective of time and space. .

It is another object of the present invention to provide a skin measurement apparatus having an image acquisition method in which the replica plates manufactured at the same site are all three-dimensionally reconstructed in the same shape.

It is still another object of the present invention to correct stereoscopic images using a correction algorithm for making a pair of corresponding epipolar lines parallel and colinear with one of the horizontal scanning lines of the image, and extracting displacements from the corrected images. The present invention provides a skin measurement apparatus having a camera calibration and correction method that enables a three-dimensional restoration of a replica plate accurately.

Skin measurement apparatus according to a feature of the present invention for achieving the above technical problem,

Microscope,

A light source providing light of a predetermined frequency band,

A light receiving element which detects light provided from the light source to the measurement region of the object and converts the light into an electrical signal;

A light quantity measuring unit outputting a level of light quantity according to an electrical signal provided from the light receiving element;

A light source controller for adjusting the level of the light source according to the level of the light quantity output by the light quantity measuring unit;

First and second cameras respectively acquiring left and right images of the measurement area enlarged through the microscope;

And a computer for analyzing a measurement area using the left and right images acquired by the first and second cameras, and provided to the measurement area of the object before acquiring an image using the first and second cameras. By detecting the level of the amount of light, and adjusting the level of the light source according to the level of the detected amount of light to correct the light source, the surface of the living body is measured using a stereoscopic image obtained by always providing a constant amount of light to the measurement region of the object.

When the skin measurement apparatus having the above-described characteristics is applied to skin surface measurement, left and right images are acquired by matching the highest point of the simulated plate manufactured for the measurement area of the skin surface with zero disparity, A disparity map using an uncrossed disparity is created for the left and right images, and an image transformation calculation is performed on the variance according to Equation 1, and an image of a measurement area of the skin surface is obtained. It is desirable to obtain.

The skin measurement apparatus having the above-described feature performs calibration for the first and second cameras using a calibration rig, and the calibration process obtains internal and external parameters of the first and second cameras, Calculate the camera matrices for the first and second cameras using the internal and external parameters, the calibration rig having each side connected at 174.2 ° and having 49 points per side, It is desirable to calibrate to measure the human surface.

The skin measurement apparatus having the above-described feature calculates a corrected camera matrix by correcting the calculated camera matrices for the first and second cameras using a correction algorithm, and uses the corrected camera matrix to calculate an image. And detecting a disparity using the corrected image, wherein the correction algorithm includes a pair of corresponding epipolar lines for the left and right images among the horizontal scan lines of the image. It is desirable to have an algorithm that is parallel to one and collinear.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the surface measurement apparatus according to a preferred embodiment of the present invention.

1 is a block diagram showing an overall skin measurement apparatus according to a preferred embodiment of the present invention. Referring to FIG. 1, the skin measuring apparatus 10 may include a microscope 100, a light source 110, a light amount controller 120, a light receiving element 130, a light amount measuring unit 132, and a first camera 140. And a second camera 142 and a computer 150.

The light source 110 provides light of a predetermined frequency band to a region of interest (ROI) of an object.

The light receiving element 130 detects an amount of light provided from a light source to a region of interest (ROI) of an object, converts the light into an electrical signal, and provides the light amount to the light quantity measuring unit 132. The light receiving element 130 of the skin measurement apparatus according to the present invention uses a photodiode. In particular, in the case of using a tungsten lamp or the like as a light source, the PIN photodiode has a high light absorption coefficient and high sensitivity in the visible light region, and is therefore suitable for use as a light receiving element.

The light quantity measuring unit 132 preferably uses a multimeter, and measures the level of the electrical signal provided from the light receiving element 130 to display the measured value through the instrument panel or the display unit.

The light source controller 120 is preferably composed of 8 bits to use a digital light controller (Digital Light Controller) that can adjust the light source to 256 levels. Therefore, the light source controller 120 adjusts the level of the light source according to information input from the outside.

In general, a CCD camera is used as the first and second cameras. The first and second cameras acquire left and right images of the surface of the object through the microscope.

According to the present invention, the skin measuring apparatus having the above-described configuration accurately measures the level of light provided by the light source to the surface of the measurement object through the light receiving element and the light amount measuring unit, and finely adjusts the light source controller according to the level of the measured light amount. By adjusting the output of the light source quantitatively, the light source can be operated as a standardized light source that can always provide a constant level of light. The skin measurement apparatus according to the present invention can increase the quantitative objectivity of a stereo image system by using a standardized light source as described above.

 New acquisition method

In the conventional image grab method by the SOT, the depth of skin wrinkles is measured using information from a zero disparity without a depth information to a direction having a positive disparity. However, it was confirmed that the skin miter plate used in the measurement of skin wrinkles may form different skin shapes at different thicknesses, so that even the images of the same area may cause different measurement values. In order to solve such a problem, conventionally, the wrinkles of the deepest part of the area to be measured were guessed, and the image was acquired after setting them to zero disparity. However, in the present invention, the left and right images are obtained by adjusting the peak of the replica plate to zero disparity for more accurate measurement, and the variance using uncrossed disparity is obtained for the obtained images, thereby obtaining the same region. The simulated plates produced in can all be three-dimensionally restored to the same shape.

When the depth of the skin wrinkle is measured using the skin measurement apparatus using the stereoscopic image, a replica is produced for the skin. When applying the imitation plate to the system using the existing stereoscopic image, if the zero disparity is set to the infinite point or the lowest point of the object, the thickness of the imitation plate itself, in addition to the depth of the wrinkle portion, even at the same measurement site Since the information of is extracted, there is a problem of inducing different values. Therefore, the present invention proposes a solution by making the position of the zero disparity the highest point of the simulation plate. As described above, when the image is acquired with the zero disparity as the highest point, since the variation has a negative value, an uncrossed disparity map is obtained and then the calculation process of Equation 1 is performed.

Value of disparity = The highest value in uncrossed disparity-The another value in uncrossed disparity

2 is a cross-sectional view sequentially illustrating a process of acquiring an image of a measurement area in a skin measurement apparatus according to an exemplary embodiment of the present invention. Referring to Figure 2, (a) is a process for producing a replica plate in the skin, (b) is a process for obtaining a zero point variation as the highest point of the wrinkles for the produced replica plate. Since the degree of variance obtained by using the acquired images of the image is in the negative direction, the degree of variance in the form of (c) of FIG. 2 is obtained. Therefore, the non-crossed variation in which the height part of the replica board formed by the depth part of a wrinkle becomes negative form is created. Extraction of the depth value of the skin using the same is not the value of the depth of the skin wrinkles produced on the replica plate, on the contrary, only the depth values of the skin wrinkles come out. Therefore, only the depth value of pure skin wrinkles can be extracted as shown in (d) through the image conversion calculation as shown in Equation (1).

FIG. 3 is a photograph for explaining a process of setting a relatively thin film type (thin type) and a relatively thick film type (thick type) at the time of fabricating a replica plate in order to examine the effectiveness of the image acquisition method according to the present invention. admit. (A) of FIG. 3 is a photograph of a region of a measurement region (ROI: Region Of Interest), and (b) is of 30 simulation plates prepared by the same person for the same region of the measurement region of (a). (C) is a photograph of a thin film type and a thick film type selected from the 30 simulated plates produced. Through Figure 3, even if the same person to produce a replica plate at the same site it can be seen that the thickness of the replica plate itself is different.

After the above-described two types of replica plates undergo a light calibration process, a left image and a right image are acquired by a stereo image system, and a disparity map is obtained. 4 is a diagram exemplarily illustrating the acquired left image and right image.

FIG. 5 illustrates a case in which a degree of variance is obtained for an image obtained by using a zero disparity as the lowest point of the simulation plate according to a conventional image acquisition method, and then 3D reconstruction is performed. Both the thin film type and the thick film type are hard to find clearly in the shape of the measurement site, and the depth extraction is expected to be problematic. This is because blurring occurs in the image due to poor focusing, making it difficult to match left and right images. In order to solve this problem, there was a prior invention in which an image was acquired by focusing on zero disparity. However, there is a problem in that the position of the zero disparity is unclear and the depth below it is ignored or the depth information is extracted from the uncrossed disparity.

6 shows the result of reconstructing the image acquired according to the image acquisition method of the present invention. FIG. 6A illustrates an image obtained by obtaining a disparity map after obtaining an image using zero disparity as the highest point of the simulation plate in a thin type, and then reconstructing the image in three dimensions. In the actual copying board, as shown in (c) of FIG. 3, both ends and the central part of the copying board are raised, and in the form of wrinkles therebetween, while in FIG. It is in the form of, and the wrinkles of the skin is not in the form of a replica plate, but in the form of the actual skin. This is a result of the positional change of zero disparity. FIG. 6B is a reconstructed image after the calculation process of Equation 1 is performed. This can be confirmed that it is restored to the same form as the actual copying board.

7 is a 3D image reconstructed by the same method as the thick type (thick type). Similarly, it can be seen that the image of FIG. 7 (a) has been restored to a negative form rather than an actual copying plate, and it can be seen that it has been correctly restored as shown in FIG.

Comparing FIG. 6 (b) and FIG. 7 (b), any of the thin film type or the thick film type of the simulated plate manufactured at the same site, only the measured position is slightly moved, and the three-dimensional restoration is performed in the same shape. It can be seen that. By comparing the foregoing with those of FIGS. 5A and 5B, it can be seen that the method according to the present invention is an improved method. 6 and 7, it can be seen that the replica plates produced at the same site by the image acquisition method of the present invention can be three-dimensionally restored to almost the same shape.

Camera calibration method

In the case of the conventional convergent camera model, since the optical axis looks at the same point, a large amount of matching pixels can be obtained from the left and right images than the parallel camera model, but it is very difficult to process because the geometric difference between the obtained two images is severe. There is this.

However, in the present invention, by using a correction algorithm for making a pair of corresponding epipolar lines parallel to and parallel to one of the horizontal scan lines of the image, precise depth information using a stereo camera is used. In the field of dermatology where computation is needed, disparity extraction using calibrated images can be an important solution.

As in the case of the actual skin application, it was confirmed that the applied correction algorithm can show a good result for extracting the depth information from the image obtained from the converging camera model.

The skin measurement apparatus according to the present invention enables camera calibration and correction to be used in the measurement of minute areas.

Camera calibration refers to the process of creating a projection equation that can connect the two-dimensional objects in space with known coordinate values and when they are acquired as images. In this case, the obtained projection equation is used as camera coordinates, and for this, a process of calculating internal and external parameters of the camera is required.

Calibration measurement equipment is for conveniently setting well-defined three-dimensional coordinates. The measuring equipment is located in the world coordinate system W and defines its own world coordinate system like three-dimensional coordinates whose characteristics are easy to understand. The camera sees this feature and can obtain two-dimensional coordinates.

The device according to the invention first builds a calibration rig for camera calibration and calibration. First, the calibration rig is connected at an angle of about 174.2˚ on one side of 3.2mm × 6.4mm, and draws a total of 49 points by drawing the minimum thickness of 7 horizontally and 3 vertically at 0.8mm intervals per side. Make.

8 are left and right images acquired for a calibration rig produced according to a preferred embodiment of the present invention, and FIG. 9 is 49 control points as a world coordinate for the calibration rig according to the present invention. ). The axes are set by calculating the angle and length of the two sides of the calibration rig, and the center of the axes is selected as the 25th control point. Image coordinates are designated as pixel values for each control point in each of the left and right images as shown in FIG. 10.

Using the pixel coordinates in the image corresponding to the world coordinates using the 49 spatial calibration rigs described above, internal and external parameters of the camera before correction are calculated to obtain camera matrices that are the perspective projection matrix (PPM).

Here, an intrinsic parameter is a necessary element for representing the conversion characteristic in the camera. In fact, the image on the retinal plane is sampled by the CCD array, and the result is converted into an analog video signal. The video signal is sampled again by a frame grabber mounted on a computer. It is stored in a frame buffer. Thus, the final coordinate values of the image we get are the pixel coordinates, not the coordinates on the retinal plane. The internal parameter is a necessary element for representing the conversion characteristic inside the camera as described above.

The extrinsic parameter may be defined as a set of geometric elements representing a transformation between an unknown camera coordinate system and a known world coordinate system, such as the position and orientation of the camera. The world coordinate system refers to a known spatial coordinate system required for converting points in three-dimensional space into a camera coordinate system. The conversion equation from the world coordinate system to the camera coordinate system can be expressed using a parallel translation vector (t, translation vector) representing a relative position between the origin of each coordinate system, and a rotation matrix (R) representing an amount of rotation of each coordinate axis. In other words, the camera coordinate system uses a known world coordinate system and information of the image to determine the position and orientation. Accordingly, the 3D motion vector t determines the position of the origin of each of the camera coordinate system and the world coordinate system, and R, which is a 3 × 3 rotation matrix, is an orthogonal matrix taking corresponding coordinate axes of the two coordinate systems.

The calibration camera matrices for the first and second cameras are calculated using the internal and external parameters calculated as described above. Since a detailed description of the process of calculating the camera matrix is well known in the art, the description thereof will be omitted.

Correction method

Rectification reduces the computational countermeasures of common two-dimensional search problems to one-dimensional search problems, typically along horizontal raster lines in the corrected image. The basic principle of correction is to define new camera matrices (PPMs) such that the baseline includes the focal plane. At this time, the epipole is infinity, so the epipolar lines are parallel. Correct correction means that the epipolar lines must be horizontal and the corresponding points must have the same vertical coordinate value.

The new camera matrices (PPMs) both have the same orientation but different positions. The position of the focal point is the same as the old camera, whereas the orientation changes only because the two cameras rotate around the focal point in such a way that the focal plane is on the same plane and contains the baseline. In order to simplify the algorithm, we will set the corrected PPMs to have the same internal parameters as the old camera. The resulting corrected PPMS only differs in focus. So if you think of a pair of new cameras, you can think of them as one camera moved along the X axis in the camera coordinate system. Thus, in the corrected image, the image plane is coplanar and parallel to the baseline.

If the coordinate of W in the world coordinate system is w = (x, y, z) and the coordinate of M in the image coordinate is m = (u, v) , then the homogeneous or projective of W, M is expressed by Equation 2 Same as

에서

으로의 변환은 메트릭스

에 의해 주어진다.And

in

Conversion to metrics

Is given by

Here, lambda is an arbitrary scale factor.

A camera designed by perspective projection matrix (PPM) can be decomposed as shown in Equation 4 using QR factorization, and the position and orientation of the camera (external parameter) can be converted from the camera coordinate system to the world coordinate system. It consists of a 3x3 rotation matrix R which represents, and a parallel vector t.

Here matrix A depends on internal parameters.

PPM can be written as in Equation 6.

Equation 3 can be written as Equation 7 by removing the proportional element again.

이 된다. 또한, 영상 좌표의 수직(

), 수평(

) 축의 두 개의 평면은 영상 평면과 각각 교차한다. C(optical center)는 이 세평면의 교차이다. 그러므로 c(principle point)의 좌표는 수학식 8과 같다.FIG. 13 is a diagram illustrating an intersecting state between two planes including the vertical and horizontal axes of the image coordinates and the focal plane. As shown in FIG. 13, the focal plane F is parallel to the image plane R and includes a focal center C, and the points on the F are projected to infinity. therefore

Becomes You can also use the vertical (

), Horizontal (

The two planes of the) axis intersect the image plane, respectively. C (optical center) is the intersection of these three planes. Therefore, the coordinate of c (principle point) is expressed by Equation 8.

이기 때문에, 이 선의 식은 수학식 10과 같은 형태로 쓸 수 있다. The image line through point M in the image is line MC. The set of 3D points

Because of this, the equation of this line can be written in the form of Equation (10).

Now let's consider the new PPMs. Equation 11 can be obtained from equations (4) and (9).

The focal points C ₁ and C ₂ are given from the old optical center calculated from Equation 8, and the rotation matrix R is newly calculated so that two PPMs are equally applied. In addition, the internal parameters of matrix A are the same in the two PPMs and can be arbitrarily selected. If R is defined in the form of a column vector, Equation 12 is used.

의 영상평면에서

의 영상평면으로의 변환함수를 계산하여야 한다. 3×3 matrix

으로 주어지는 동일직선상의 변환을 찾는다. 같은 결과를 오른쪽 영상에 적용한다. 3차원 좌표 w에 대해 수학식 13과 같이 쓸 수 있다.Now, to correct the left image,

On the image plane

Calculate the transform function of the image plane. 3 × 3 matrix

Find the colinear transformation given by. The same result is applied to the right image. For three-dimensional coordinate w can be written as Equation 13.

Now, the equation of the image line can be expressed by equation (10) as shown in equation (14).

Is a proportional element.

When transform T ₁ is applied to the original left image to produce a corrected image, the pixels of the corrected image correspond to non-integer positions on the original plane. Therefore, the corrected image is obtained by applying interpolation to obtain an image that can be used in the present invention.

FIG. 11A is an epipolar line in left and right images before correction and (b) is an epipolar line in left and right images after correction according to the present invention. 11, before the correction, the epipole was formed as the epipolar lines converged in the left and right images, but after the correction according to the present invention, the epipole lines were parallel and the epipole was infinity. have.

  FIG. 12A is a left and right stereoscopic image of a skin replica plate at a calibration control point position, and FIG. 12C is a three-dimensional image based on variance extracted after camera calibration and rectification from the image of FIG. The wrinkles in the rectangular zone in the image of (a) can be clearly restored when compared with (b).

Although the present invention has been described above with reference to preferred embodiments thereof, this is merely an example and is not intended to limit the present invention, and those skilled in the art do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications which are not illustrated above in the scope are possible. And differences relating to such modifications and applications should be construed as being included in the scope of the invention as defined in the appended claims.

The skin measurement apparatus according to the present invention complements the stereo-image optical topometer (SOT) using the conventional stereo image concept in three aspects to enable more scientific and objective three-dimensional surface measurement.

Medical imaging equipment that uses a conventional microscope is followed by the use of a light source. As such, the image acquired by the conventional measuring apparatus may have a different result of shading or distortion depending on the amount of light depending on the intensity of the light source, so that a consistent amount of light is supplied to all measurement objects. Analogue light source control by subjective judgment, which is a conventional usage, may result in different result values from the same measurement object when the measurement time, space and researcher are different.

Therefore, the present invention uses a photodiode (OHDP42CB, OPTO H i TEC, Japan) and with quantitative measurement by the current quantity of light, a digital light source regulator (Digital Light Controller) of a 8bit designed for the present invention using a light-receiving element It is possible to supply a constant amount of light regardless of space-time.

In addition, according to the present invention, by controlling the amount of light in 256 steps with a digital light controller, it is possible to provide a stable light source to the system, thereby achieving the accuracy of the measurement of the surface of the living body.

On the other hand, the skin measurement apparatus according to the present invention is a correction algorithm for making a pair of corresponding epipolar lines parallel and collinear with one of the horizontal scanning lines of the image. Was used. Using this correction algorithm, the coordinates were calculated as world coordinates, and the camera parameters were found by solving the relationship with the image coordinates of the obtained left and right images. Subsequent rectification confirmed that the epipole was at infinity and all epipolar lines were corrected to be parallel to each other. In addition, better reproducibility was confirmed in the three-dimensional restoration of the skin than before camera calibration and correction according to the present invention.

In particular, it has been suggested that the skin measurement apparatus according to the present invention can be approached more scientifically and objectively in determining the degree of severity of atopic dermatitis, which requires the discrimination of minute changes.

In order to verify the effect of the skin measurement apparatus according to the present invention, a study was applied to verify the efficacy of atopic dermatitis improving moisturizer for 20 people with atopic disease, and as a result, the method and the improved invention A study on the medical effectiveness of the method according to the present invention was performed to find the superiority of the skin measurement apparatus according to the present invention.

Among the methods for evaluating the severity of the control group and the treatment group, the SCORAD (Severity Scoring of Atopic Dermatitis) index evaluation method and the stereo-image optical topometer (SOT), and the improved SOT for evaluating the medical efficacy of the present invention. Each was evaluated in the skin measurement apparatus according to the present invention.

The SCORAD (Severity Scoring of Atopic Dermatitis) index evaluation method is calculated as shown in Equation 16 according to the method proposed by The European Task Force on Atopic Dermatitis.

RES (Reference Evaluation Systems: 0-103) =

Extent / 5 (0-20; 19.4%) + 3.5 * Intensity ( 0-63; 61.2%) + Objective symptoms (0-20; 19.4%)

Extent measures the distribution of the patient's lesions from 0 to 100 using the “rule of nine”. Intensity measures each of the six items (erythema, edema / papulation, oozing / crust, excoriation, lichenification, and dryness). Scores from 0 to 3 were assigned to a total of 18 points, and the value was calculated by substituting Equation 5.

The SCORAD index evaluation method and the existing SOT, the result value by the improved SOT according to the present invention used a statistical processing program (NCSS, NCSS Inc., Kaysville, Utah, USA). The statistical significance test was performed using the Student T-test and GLM ANOVA to see the change according to the application period of the basic moisturizer (control) and the moisturizer containing the active ingredient (treatment group), and P <0.05 was statistically significant. Considered.

In the conventional SCORAD index, the GLM ANOVA test did not confirm the improvement of atopic dermatitis in both treatment and control groups. However, the existing SOT was found to be statistically significant in the six variance coefficients of S _a , S _q , S _z , SL , SA , and SV to improve atopic dermatitis. For Ta other systems in the present invention is an improved _{SOT S a (Arithmetic Mean Deviation of} the Surface), S q (Root-Mean-Square Deviation of the Surface), S z (Ten Point Height of the Surface) in the treatment group in , S _ds (Density of Summit of the Surface), S _td (Texture Direction of the Surface) and SA (Three Dimensional Area) showed statistically significant and decreased effect of improving atopic dermatitis. Judging. In addition, the system according to the present invention showed a decrease in shape while having a more stable form than the numerical reduction of the existing SOT, it was shown that more accurate quantitative measurement than the conventional SOT.

In addition, the comparison result using the coefficient of variation (Coefficient Of Variation) of the existing SOT and the system according to the present invention, it was confirmed that the coefficient of variation of the system according to the present invention appears less than the previous SOT.

From the above results, it was confirmed that the stereo image system (stereo image system) using the stereo image concept is a method for scientific and objective evaluation of the severity of atopic dermatitis. As restoration was possible, it was confirmed that quantitative analysis was possible than the existing system.

Claims (10)

Microscope; A light source for providing light of a predetermined frequency band; A light receiving element that detects light provided from the light source to the measurement region of the object and converts the light into an electrical signal; A light quantity measuring unit outputting a level of light quantity according to an electrical signal provided from the light receiving element; A digital light source controller for adjusting the level of the light source according to the level of the light quantity output by the light quantity measuring unit; First and second cameras respectively acquiring left and right images of the measurement area enlarged through the microscope; A computer for analyzing a measurement area by using left and right images acquired by the first and second cameras; And detecting the level of the amount of light provided to the measurement region of the object before acquiring the image using the first and second cameras, and adjusting the level of the light source according to the detected amount of light to correct the light source. And a skin measurement apparatus configured to measure a surface of a living body using a stereoscopic image obtained by always providing a constant amount of light to a measurement area of an object. The skin measuring device according to claim 1, wherein the light receiving element is a photodiode, and the light quantity measuring unit is a multimeter. delete The method of claim 1, wherein when the skin measurement apparatus is applied to skin surface measurement, left and right images are obtained by matching the highest point of the replica plate manufactured for the measurement area of the skin surface with zero disparity, A disparity map using an uncrossed disparity is created for the acquired left and right images, and an image of a measurement area of the skin surface is obtained by performing image transformation calculation on the disparity. Skin measurement device. The skin measurement apparatus according to claim 4, wherein the light source is corrected before acquiring the left and right images of the replica plate. The apparatus of claim 1, wherein the skin measurement apparatus performs calibration of the first and second cameras using a calibration rig, and the calibration process obtains internal and external parameters of the first and second cameras, And derive a camera matrix for the first and second cameras using the internal and external parameters. 7. The skin measurement apparatus of claim 6, wherein the calibration rig is 174.2 ° connected to each side and has 49 points per side, so that the skin measurement apparatus is calibrated to measure the human body surface. The apparatus of claim 6, wherein the skin measuring apparatus calculates a corrected camera matrix according to a correction algorithm by using camera matrices for the first and second cameras, and corrects an image by using the corrected camera matrix. And detecting a disparity using the corrected image. The correction algorithm includes a pair of corresponding epipolar lines on one of the horizontal scanning lines of the image for the left and right images. A skin metrology device, characterized in that it is an algorithm that makes it parallel and collinear. The method according to claim 6, wherein the internal parameter is a parameter representing a conversion characteristic in a camera for converting coordinate values of an image plane into pixel coordinate values, and the external parameter indicates conversion between unknown camera coordinates and a known world coordinate system. A skin metrology device, characterized in that it is a set of geometric elements represented. The method of claim 8, wherein the correction algorithm receives a pair of stereoscopic images and camera matrices for the first and second cameras, converts the coordinates of the camera coordinate system into coordinates of the world coordinate system, and converts the coordinates of the world coordinate system into a world coordinate system. skin measurement device, characterized in that for correcting the images by creating a transformation matrix that converts the coordinates into coordinates of the image coordinate system.

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