KR101021127B1 - Method for generating computer generated hologram using look-up table and spatial redundancy, and Apparatus thereof - Google Patents

Abstract

Disclosed are a method and apparatus for calculating a computer-generated hologram using spatial redundancy of a lookup table and an image. The method of calculating the hologram according to the present invention includes calculating one reference element fringe pattern with respect to each point spaced by the same distance from the reference point of the hologram plane of the target object, wherein the reference element fringe pattern is determined by the angle of the target object from the reference point. Storing according to the distance of the point, calculating identity data representing the sameness of each point in the input image and adjacent points, calculating an n-point element fringe pattern obtained by synthesizing the n reference element fringe patterns; And calculating hologram information by matching the n-point element fringe pattern to n consecutive identical points identified from the identity data. In the present invention, the memory required for the hologram calculation has a small effect.

Hologram, lookup table, spatial redundancy.

Description

Method for generating computer generated hologram using spatial redundancy of lookup table and image and its device {Method for generating computer generated hologram using look-up table and spatial redundancy, and Apparatus approx}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram calculation method, and more particularly, to a computer-generated hologram calculation method and apparatus using a lookup table and spatial redundancy.

Recently, researches on 3D image and image reproduction technology are being actively conducted, and it is expected that the next generation display will be developed as a new concept of realistic image media that raises the level of visual information. In addition, the demand for 3D images is increasing because 3D images are more realistic, natural, and closer to the reality that humans feel.

Among the 3D image related technologies, the holography method is a method in which a viewer observes a virtual image of a virtual image while looking at the holography at a certain distance away from the front of the holography.

The holography method is to observe the holography produced using a laser and feel the same stereoscopic image as the real one without attaching special glasses. Therefore, the holography method is known to be the most ideal way to feel the three-dimensional image without the fatigue and excellent stereoscopic feeling.

Generally, a ray-tracing method that calculates the diffraction of light is mainly used when calculating the hologram pattern. In this case, the target object is regarded as a set of points and the hologram pattern for each point is calculated and added. However, this method has a problem that it is difficult to reproduce in real time due to a large amount of computation.

In order to overcome this problem, a method of calculating a hologram using a look-up table (LUT) has been proposed. This method calculates all the element fringes of all points for the possible area in advance, and then, when calculating the hologram, retrieves and sums the element fringes corresponding to the point of the object to enable real-time processing. However, this method has a problem in that as the size of the object area increases, the number of element fringes required increases, and thus the size of the lookup table becomes too large.

To solve this problem, a new look-up table (N-LUT) method is proposed, which can dramatically reduce the memory capacity of the look-up table while maintaining the high-speed hologram calculation as in the conventional look-up table method. It became. The method includes a hologram calculation and playback method performed by a computer-generated hologram calculation and playback device, comprising: calculating one reference element fringe pattern for each point of a target object spaced the same distance from the reference point of the hologram plane; Recording the reference element fringe pattern in a look-up table according to the distance of each point of the object from the reference point; Calculating computer-generated hologram information by shifting the reference element fringe pattern with respect to each point of the target object located on the same plane as the distance corresponding to the reference element fringe pattern; And reconstructing the computer-generated hologram information to enable computer-generated hologram calculation and reproduction using a look-up table including the step of reproducing the 3D image. However, this method also increases the resolution of the image to be calculated, which increases the number of points to be calculated, which increases the computation time, making it difficult to apply practically.

The present invention provides a method and apparatus for calculating a computer-generated hologram using a lookup table capable of real-time video hologram reproduction and temporal redundancy.

Technical problems other than the present invention will be easily understood through the following description.

According to an aspect of the present invention, to solve the conventional problems as described above, calculating one reference element fringe pattern for each point spaced by the same distance from the reference point of the hologram plane of the target object; Storing the reference element fringe pattern according to a distance of each point of the object from the reference point; Calculating identity data representing whether the points of the input image and the adjacent points are the same; calculating an n-point element fringe pattern obtained by synthesizing the n reference element fringe patterns; And calculating hologram information by matching the n-point element fringe pattern to n consecutive identical points identified from the identity data, wherein n is a natural number.

According to another aspect of the invention a fringe calculation unit for calculating one reference element fringe pattern for each point of the target object spaced by the same distance from the reference point of the hologram plane; A look-up table for storing the reference element fringe pattern according to a distance of each point of a target object from the reference point; An identity analyzer for calculating identity data representing whether the points of the input image and the adjacent points are the same; And a point fringe calculator configured to calculate an n-point element fringe pattern obtained by synthesizing the n reference element fringe patterns. And a hologram calculator configured to calculate hologram information by matching the n-point element fringe pattern to n consecutive identical points identified from the identity data, wherein n is a natural number.

The computer-generated hologram calculation method and apparatus using the lookup table and the spatial redundancy according to the present invention have the effect of real-time hologram calculation.

In addition, the method and apparatus for calculating a computer-generated hologram using the lookup table and the spatial redundancy according to the present invention have a small effect on the memory required for the hologram calculation.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

In the following description of the present invention with reference to the accompanying drawings, the same components are denoted by the same reference numerals regardless of the reference numerals, and redundant explanations thereof will be omitted. In the following description of the present invention, if it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, before describing the preferred embodiments of the present invention in detail, a general principle and system for obtaining three-dimensional information using holography techniques will be described.

1 is a diagram illustrating a 3D information acquisition method using a holography technique according to an embodiment of the present invention.

The principle of the hologram is to split the beam from the laser into two, so that one beam shines directly on the screen and the other beam shines on the object. At this time, a light beam that directly shines on the screen is called a reference wave, and a light beam that shines on an object is called an object wave.

The object wave is the light reflected from each surface of the object, so the phase difference is different depending on the distance from the object surface to the screen. At this time, the unmodified reference wave interferes with the object wave, and the calculated interference fringe is stored on the screen. Films in which such interference fringes are stored are called holograms.

The computer generated hologram (CGH) is abbreviated as 'CGH'. The pattern is calculated by computer calculation by the ( x , y , z ) coordinate values and the intensity values I of the pixels. CGH is used for 3D holographic image acquisition. Figure 1 shows the geometric calculation model of the hologram. Hereinafter, the description will be made based on the CGH, but the present invention is not limited thereto.

The hologram is located on the x - y plane 130 and the p th point of the object is located at ( x _p , y _p , z _p ) 110. a _p and Φ _p represent the strength and phase of the points, respectively, and these are calculated by the computer

The complex amplitude O ( x , y ) in the hologram can be obtained by the superposition of the object waves as shown in equation (1) below.

(1)

(One)

Where p is the point constituting the object (object point), and N is the total number of points constituting the object. a _p represents the intensity of the object wave, k is a wave vector, and k = 2 π / λ . λ is the wavelength of light in free space. exp ( jωt ) is not included in equation (1). r _p represents the oblique distance between the pth object point and the point ( x , y , 0) in the hologram, and is defined by Equation (2) below.

(2)

(2)

In addition, the complex amplitude R ( x , y ) of the reference wave, which is a plane wave, is given by Equation (3) below.

(3)

(3)

Where a _R and θ _R represent the intensity of the reference wave and the incident angle of the reference wave, respectively. The overall lattice intensity I ( x , y ) at the hologram plane is represented by equation (4) as the interference pattern between the object wave O ( x , y ) and the reference wave R ( x , y ).

(4)

(4)

는 기준파의 세기를 나타내고, 두 번째 부분인

은 물체파의 세기를 나타낸다. 세 번째 부분

은 홀로그램 정보를 부분적으로 포함하고 있는 물체파와 기준파 사이의 간섭 패턴을 의미하며, 물체파의 공간 위치에 따른 위상 정보를 포함하고 있다.The first part of equation (4)

Represents the strength of the reference wave, the second part

Represents the intensity of the object wave. Third part

Denotes an interference pattern between the object wave and the reference wave partially including the hologram information, and includes phase information according to the spatial position of the object wave.

In the following equation (5), since hologram information is included only in the third part, I ( x , y ) can be expressed as follows.

(5)

(5)

That is, in the conventional ray tracing method, the hologram pattern can be calculated by Equation (5). However, as shown in Equation (5), the equation for calculating the hologram pattern is quite complicated, which makes it difficult to calculate in real time.

In order to solve this problem, an element fringe pattern that can represent all points in an arbitrary object space is created in advance and stored in a look-up table, and each element fringe pattern is imported to calculate a hologram according to the 3D image to be calculated. A method using an up table has been proposed.

Before describing such components, first, an aspect of the embodiment of the present invention will be described as follows. In general, image space is not discrete. However, since the capabilities of the human visual system are limited, resolution can be selected without degrading the image. At this time, the degree of discretization should be small enough not to be perceived by the human eye so that two consecutive points can be recognized as continuous points without being separated. For example, humans recognize two points with a distance of 3 milliradians as one point. Therefore, if the image is viewed at a distance of 500 mm, a point with an interval of 500 mm × 0.003 = 150 microns or less is recognized as one point. Hereinafter, an embodiment according to the present invention will be described by setting the degree of vertical and horizontal discretization to 150 micron.

In the method using the lookup table, the element fringe pattern must be calculated in advance. This is an element fringe pattern T ( x , y ; x _p , y _p , z _p ) having a reference brightness that can represent each point, which can be expressed as in Equation (6) using Equation (5).

(6)

(6)

Where r _p is the distance between the pth point and ( x , y , 0), given by Eq. (2).

This way, when calculating the hologram, a lookup is a set of fringe patterns for each point ( x _p , y _p , z _p ) that you create, rather than calculating the fringe pattern for each point as needed (Eq. (5)). Calculations are made using tables. Therefore, in the lookup table method, the hologram information I ( x , y ) is finally given as in Equation (7), where N represents the number of object points.

(7)

(7)

In the method using the lookup table, the element fringe pattern calculated in advance for all possible points of the object image brought a tremendous speed increase in hologram synthesis. However, the biggest drawback of this approach is that the amount of pre-calculated element fringe patterns is so large that the memory of the LT to store them is greatly increased. For example, in the LT method, if the object space is 100 (width) × 100 (length) × 100 (depth), and each element fringe pattern has a capacity of 1 MB, the memory capacity of the entire lookup table is 1 MB × 100 × 100 × 100 = 1 TB is required.

In order to solve these problems, N-LUT, a new type of lookup table that can drastically reduce the memory capacity of the lookup table while maintaining the fast calculation speed as in the conventional lookup table method, has been proposed. Techniques have been proposed. That is, in the N-LUT method, only the element fringe pattern for the depth direction of the object is calculated and stored. When the depth direction of the object is determined, the element fringe patterns of the object points existing on the surface are pre-calculated and stored by moving the element fringe pattern of the depth stored to the respective object points to the left and right to calculate and sum the fringe patterns. The hologram pattern in the depth plane is calculated. In the same way, the hologram pattern for the whole object is calculated by summing up all the holograms in all the object depth planes. Therefore, the existing lookup table method requires the storage of element fringe patterns for object points in all directions, such as horizontal, vertical, and depth. However, the proposed N-LUT method requires only preliminary storage of element fringe patterns for the object depth direction. This greatly reduces memory requirements.

In the N-LUT method, the element fringe pattern must also be calculated in advance. That is, each element fringe pattern T ( x , y ; z _p ) becomes a Fresnel zone plate of a reference intensity for each depth and can be expressed as follows.

(8)

(8)

Where r _p is the distance between the pth point and ( x , y , 0), given by Eq. (2). Therefore, in the newly proposed N-LT method, only the element fringe pattern for the depth direction of the object is calculated and stored. When one depth direction of the object is determined, the element fringe patterns of the object points existing on the surface are stored in advance. By moving the element fringe pattern of depth to each object point, the fringe pattern is calculated to calculate the hologram pattern in the depth plane. In the same way, each hologram is calculated and summed in all object depth planes to calculate the hologram pattern for the whole object. Therefore, in the lookup table method, the hologram information I ( x , y ) can be finally expressed as in Equation (9).

(9)

(9)

Using the N-LUT method, the hologram pattern can be calculated and restored at high speed. However, this method also has a problem that when the resolution of the image to be calculated increases, the number of points to be calculated increases, which increases the computational complexity.

2 is a diagram illustrating a hologram calculating apparatus according to an embodiment of the present invention, FIG. 3 is a diagram showing a brightness image and a depth image according to an embodiment of the present invention, and FIG. 4 is an embodiment of the present invention. FIG. 5 is a diagram illustrating an element fringe pattern for three points, and FIG. 5 is a diagram illustrating a reference element fringe pattern and an n-point element fringe pattern according to an embodiment of the present invention.

Referring to FIG. 2, the hologram calculating device includes an extractor 210, an identity analyzer 220, a fringe calculator 230, a point fringe calculator 240, a lookup table 250, and a hologram calculator 260. It consists of.

The extractor 210 extracts a brightness image and a depth image. The brightness image represents brightness of an image represented by a general two-dimensional image. The depth image is an image representing depth information of the brightness image. The brightness image and the depth image are output as shown in FIG. 3. The extractor 210 synthesizes the brightness image and the depth image in a predetermined format and outputs the input image to the identity analyzer 220.

The identity analyzer 220 extracts identity data based on spatial redundancy from the 3D image. In a typical image, adjacent pixels have similar brightness values. That is, a general image has spatial redundancy. In the 3D image, adjacent pixels have similar brightness and depth values. In addition, for some areas there are points with the same brightness and depth values. The identity analyzer 220 calculates the sameness data extracted by grouping the same brightness and depth values. For example, the identity analysis unit 220 compares the brightness and the depth value of the point A (0,0,0) and the point B (1,0,0) present in the three-dimensional coordinates, if the point A, Generate identity data indicating identity of B. In addition, the identity analysis unit 220 may analyze the identity of three or more consecutive points as well as two points. The identity analyzer 220 outputs the calculated identity data to the point fringe calculator 240 and the hologram calculator 260.

The fringe calculator 230 calculates a reference element fringe pattern for the target object. As described above by illustrating Equation (9), the fringe calculator 230 calculates a reference element fringe pattern required when using the N-LUT method and outputs the fringe pattern as a lookup table.

The point fringe calculator 240 receives the identity data and the reference element fringe pattern to calculate an n-point element fringe pattern. The n-point element fringe pattern is an element fringe pattern capable of expressing a hologram pattern of n consecutive points. Hereinafter, the n-point element fringe pattern will be described in detail with reference to FIG. 4.

An n-point element fringe pattern capable of calculating hologram patterns corresponding to several points at one time can be obtained as shown in FIG. 4. Given an element fringe pattern 420 for a point, assuming the distance between adjacent points is d , and creating a three-point element fringe pattern for three adjacent points 410, an element fringe pattern for a point 420 is shifted according to the position of each point. That is, the element fringe pattern 432 shifted by d to express a point separated by d from the element fringe pattern 431 at the original position, and by 2 d to express a point separated by 2 d The shifted element fringe pattern 433 is calculated. When the three element fringe pattern is added, a three-point element fringe pattern 440 capable of representing three neighboring points is calculated.

Therefore, the n -point element fringe pattern T _n ( x , y ; z _p ) that can represent n consecutive points can be finally expressed as in Equation (10).

(10)

10

In the above, it is assumed that the element fringe pattern for three adjacent points is calculated. The two-point element fringe pattern 520 and the three-point element fringe pattern 530 generated using the reference element fringe pattern 510 in the above-described manner are shown in FIG. 5.

Referring back to FIG. 2, the point fringe calculator 240 calculates an n-point element fringe pattern and outputs the n-point element fringe pattern to the lookup table 250.

The lookup table 250 is a space for storing one reference element fringe pattern and an n-point element fringe pattern for each point of the target object spaced by the same distance from the reference point of the hologram plane. The reference element fringe pattern of the lookup table 250 can be calculated from the above equation (8). At this time, the lookup table 250 outputs the reference element fringe pattern and the n-point element fringe pattern to the hologram calculator 260. The lookup table 250 then transmits the reference element fringe pattern and the hologram calculator 260 to the hologram calculator 260. Outputs the n-point element fringe pattern.

The hologram calculator 260 calculates a hologram by receiving a reference element fringe pattern, identity data, and an n-point element fringe pattern. FIG. 6 is a diagram illustrating a method of calculating a hologram pattern using spatial redundancy data and an element fringe pattern with respect to the calculated n points. Referring to FIG. Referring to FIG. 6, six point light sources are illustrated in the input image 610 according to an embodiment of the present invention. The image 620 of the z ₁ depth plane consists of ( -x ₁ , y ₁ , z ₁ ) and two neighboring points therefrom, and the image 650 of the z ₂ depth plane is ( x ₂ , -y _2). , z ₂ ) and two neighboring points from it. In the composite image 640 of the z ₁ depth plane of the shifted reference element fringe pattern, since the position of the reference point light source A is at (− x ₁ , y ₁ , z ₁ ), the hologram calculating unit 260 has a depth of z _1. Shift the element fringe pattern for three points at- x ₁ and y _{1 in the} x and y directions, respectively. Looking at the composite image 660 of the z ₂ depth plane of the shifted reference element fringe pattern, since the position of the reference point light source D is at ( x ₁ , − y ₁ , z ₁ ), the hologram calculating unit 260 performs z _2. Shift the element fringe pattern for three points in depth by x ₁ and- y _{1 in the} x and y directions, respectively. Subsequently, the hologram calculator 260 synthesizes the shifted reference element fringe pattern and the n-point element fringe pattern to calculate CGH. In addition, the hologram calculating unit 260 calculates hologram information using CGH as shown in Equation (9).

Hereinafter, a hologram calculation method using a lookup table and spatial redundancy will be described with reference to FIG. 7. In this case, for the sake of clarity, each functional unit constituting the hologram calculating device will be collectively described as a 'hologram calculating device'. In the following hologram calculation process, portions overlapping with the description of the hologram calculation device will be omitted for clarity.

7 is a diagram illustrating a hologram calculation process according to an embodiment of the present invention.

In operation 710, the hologram calculating apparatus calculates a reference element fringe pattern with reference to the input image. The reference element fringe pattern is an element fringe pattern stored in the look-up table 250 in the above-described N-LUT method, and is an element fringe pattern in the depth direction of the object.

In operation 720, the hologram calculating apparatus stores the reference element fringe pattern in the lookup table.

In operation 730, the hologram calculating apparatus calculates identity data of the input image. That is, the hologram calculating device calculates the sameness data extracted by grouping the points having the same brightness and the same depth value.

In operation 740, the hologram calculating apparatus calculates an n-point element fringe pattern using the identity data and the reference element fringe pattern.

In operation 750, the hologram calculating apparatus calculates CGH by matching the reference element fringe pattern, the identity data, and the n-point element fringe pattern to each point of the target object, and calculates the hologram information through the CGH. Hereinafter, a detailed description of step 750 will be made with reference to FIG. 8.

8 is a diagram illustrating a process of calculating hologram information by matching a reference element fringe pattern and an n-point element fringe pattern according to an embodiment of the present invention.

In step 810, the hologram calculating apparatus matches the reference element fringe pattern to points that are not identical in succession on the identity data, and sets n to 1. Where n is any natural number.

In step 820, the hologram calculating device increases n by one.

In step 830, the hologram calculating apparatus determines whether there are n or more consecutive identical points in the sameness data.

If there are n or more consecutive identical points, the hologram calculating apparatus matches the n-point element fringe pattern to n consecutive identical points in step 840. Subsequently, the hologram calculating apparatus performs the process from step 820.

If there are no n or more consecutive identical points, the hologram calculating device calculates the hologram information using the CGH in step 850. The hologram calculation method using CGH was described above with reference to equation (9).

In the above-described process of calculating the hologram information, the element fringe patterns are matched by determining the order based on the number of consecutive identical points, but the element fringe patterns may be matched in the order of the coordinates of the target object. At this time, the n-point element fringe pattern may be stored in the lookup table.

The above-described hologram calculating device and method has an effect of lowering the computational complexity for hologram calculation. Hereinafter, the effect of the hologram calculation device according to an embodiment of the present invention will be described with reference to the table. The table below compares the number of calculation points for the calculation of the hologram according to the above-described method.

Calculated object points Number of spatially redundant data of the test 3-D object Conventional method (1-point) Proposed method
(2-point) Proposed method
(3-point) Proposed method
(4-point) 1-point 78,726 51,828 50,004 49,491 2-point - 13,449 8,697 8,508 3-point - - 3,776 2,337 4-point - - - 1,302 Total 78,726 65,277 62,477 61,638 Reduction ratio (%) 100 82.9 79.4 78.3

The 1-point element fringe pattern represents a conventional method using an N-LUT. In this case, a total of 78,726 points must be calculated to produce a hologram. In comparison, when the two-point element fringe pattern or the four-point element fringe pattern is used, the calculation amounts of points of 82.9%, 79.4%, and 78.3% are respectively shown.

The table below compares the calculation time of the hologram according to the above-described method.

N-LUT method Proposed method 2-point 3-point 4-point Average computation time for one object point ( ms ) 11.76
(100%) 9.53
(81.0%) 9.16
(77.9%) 9.05
(77.0%)

In the case of the conventional N-LUT method, the average time for calculating a point takes 11.76 ms, and in the case of using the 2-point element fringe pattern, the average time for calculating a point is 9.53 ms, compared to the conventional method. It takes 81%. The three-points resulted in 9.16ms and 9.05ms in the 4-points, resulting in 77.9% and 77.0%, respectively. Therefore, the hologram calculation method according to an embodiment of the present invention has the effect of reducing the computational complexity compared to the conventional N-LUT method.

The computer-generated hologram calculation and reproduction method using the lookup table and the spatial redundancy according to the embodiment of the present invention may be performed in combination with a predetermined device, for example, a mobile communication terminal, after being stored in a recording medium. Here, the recording medium may be a magnetic or optical recording medium such as a hard disk, a video tape, a CD, a VCD, a DVD, or a database of a client or server computer built offline or online.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and changes can be made. In particular, the analysis of spatial redundancy may be performed in various ways such as horizontal direction, vertical direction, diagonal direction, and block unit. In the case of the n-point element fringe pattern, the hologram may be calculated in advance, and the 1-point element fringe pattern may be made, and the n-point element fringe pattern may be made when necessary to calculate the hologram.

1 is a view showing a three-dimensional information acquisition method using a holography technique according to an embodiment of the present invention.

2 is a diagram illustrating a hologram calculating device according to an embodiment of the present invention.

3 illustrates a brightness image and a depth image according to an embodiment of the present invention.

4 illustrates an element fringe pattern for three points in accordance with one embodiment of the present invention.

5 illustrates a reference element fringe pattern and an n-point element fringe pattern according to an embodiment of the present invention.

FIG. 6 illustrates a method of calculating a hologram pattern using spatial redundancy data and an element fringe pattern for the calculated n points according to an embodiment of the present invention. FIG.

7 is a diagram illustrating a hologram calculation process according to an embodiment of the present invention.

8 is a diagram illustrating a process of calculating hologram information by matching a reference element fringe pattern and an n-point element fringe pattern according to an embodiment of the present invention.

Claims (8)

Calculating one reference element fringe pattern for each point spaced by i and d from the reference point of the hologram plane of the object; Storing the reference element fringe pattern according to a distance of each point of the object from the reference point; Calculating identity data representing whether the points of the input image and the adjacent points are the same; calculating an n-point element fringe pattern obtained by synthesizing the n reference element fringe patterns; And Calculating hologram information by matching the n-point element fringe pattern to n consecutive identical points identified from the identity data, And n is a natural number, i is a natural number equal to or greater than 1 and less than or equal to n, and d is a predetermined real number. The method of claim 1, The reference element fringe pattern is calculated by the following equation.

Where p is any natural number ,

Is the reference element fringe pattern, r _p is the distance between the p point and ( x , y , 0), k is 2 π divided by λ , λ is the wavelength of light in the air, θ _R is the reference wave and the object The angle between waves, Φ _p is the phase value of the object wave at the p- th point of the object. The method of claim 2, The n-point element fringe pattern is calculated by the following equation.

here

Is the n-point element fringe pattern. The method of claim 3, And the hologram information is calculated by the following equation.

Here, I is hologram information, a _p is the intensity value of the object wave of the p-th point of the target object, N is the total number of points constituting the target object. A fringe calculator configured to calculate one reference element fringe pattern for each point spaced by i and d from a reference point of the hologram plane of the object; A look-up table for storing the reference element fringe pattern according to a distance of each point of a target object from the reference point; An identity analyzer for calculating identity data representing whether the points of the input image and the adjacent points are the same; And a point fringe calculator configured to calculate an n-point element fringe pattern obtained by synthesizing the n reference element fringe patterns; And A hologram calculator configured to calculate hologram information by matching the n-point element fringe pattern to n consecutive identical points identified from the identity data, And n is a natural number, i is a natural number equal to or greater than 1 and less than or equal to n, and d is a predetermined real number. The method of claim 5, And the reference element fringe pattern is calculated by the following equation.

Where p is Any natural number ,

Is the reference element fringe pattern, r _p is the distance between the p point and ( x , y , 0), k is 2 π divided by λ , λ is the wavelength of light in the air, θ _R is the reference wave and the object Angle between waves, Φ _p is Phase value of the object wave at the p- th point of the target object. The method of claim 6, And the n-point element fringe pattern is calculated by the following equation.

here

Is the n-point element fringe pattern. The method of claim 7, wherein And the hologram information is calculated by the following equation.

Here, I is hologram information, a _p is the intensity value of the object wave of the p-th point of the target object, N is the total number of points constituting the target object.

Images