KR20120138227A - Apparatus and method for generating hologram - Google Patents

Abstract

PURPOSE: A hologram generating apparatus and a method thereof are provided to implement real time video hologram generation by using a lockup table having small amount of a memory. CONSTITUTION: A two-dimensional PFP(Principle Fringe Pattern) reconstructing unit(110) reconstructs a two-dimensional PFP about a depth plane obtained from a target by using one-dimensional sub PFPs(Principle Fringe Patterns) stored in an LUT(LookUp Table). A hologram information generator(120) generates hologram information by using a pre-CGH(pre-Computer Graphic Hologram) pattern. A hologram generator(130) generates a hologram related to the target by using the generating hologram information. [Reference numerals] (110) Two-dimensional PFP reconstructing unit; (120) Hologram information generator; (130) Hologram generator; (140) Power source unit; (150) Main control unit

Description

Apparatus and method for generating hologram

The present invention relates to a hologram generating device and method. More specifically, the present invention relates to a hologram generating apparatus and method using a look-up table (LUT).

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 a method of observing holography produced using a laser, and it is possible to feel the same stereoscopic image as the real one without wearing 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.

The present invention has been made to solve the above problems, and an object of the present invention is to propose a hologram generating apparatus and method using a look-up table with reduced memory capacity. Technical problems other than the present invention will be easily understood through the following description.

The present invention has been made to achieve the above object, a two-dimensional PFP for restoring the two-dimensional PFP for each depth plane obtained from the target using the one-dimensional sub-Principal Fringe Pattern (PFP) stored in the look-up table Restoring unit; A hologram information generation unit generating hologram information using a pre-computer graphic hologram (CGH) pattern based on the restored two-dimensional PFP; And a hologram generator for generating a hologram related to the target by using the generated hologram information.

Preferably, the 2D PFP reconstructor uses a PFP having one variable or a preselected trigonometric function as the 1D sub PFP when restoring the 2D PFP.

Preferably, the 2D PFP reconstruction unit determines the size or area of the 2D PFP to be reconstructed and restores the 2D PFP based on the determined size or area.

Preferably, the 2D PFP reconstructor uses the coordinates of the boundary point, the spacing between pixels in the 3D video, and the resolution of the 3D video when determining the size of the 2D PFP to be reconstructed.

Preferably, the hologram information generation unit, a point selection unit for selecting at least two points in the reconstructed two-dimensional PFP; A position change PFP acquisition unit which acquires a two-dimensional PFP that is moved by coordinates one of the selected points; A PFP combiner for combining the obtained two-dimensional PFPs when the two-dimensional PFPs which are moved relative to all selected points are obtained; And a CGH pattern-based hologram information generator for generating the hologram information by extracting a pre-CGH pattern having a predetermined size from the combined two-dimensional PFPs.

Preferably, the CGH pattern-based hologram information generator extracts a pre CGH pattern including all the selected points as the pre CGH pattern having the predetermined size.

Preferably, the hologram generating apparatus further includes a lookup table generator that separates each two-dimensional PFP into a plurality of one-dimensional sub-PFPs and generates the look-up table using the separated one-dimensional sub-PFPs.

Preferably, the hologram generating apparatus further includes a three-dimensional information extraction unit for extracting the three-dimensional information of the target, and extracts the depth information and the brightness information of the target as the three-dimensional information.

Preferably, the hologram generating apparatus further includes a boundary point coordinate extraction unit for extracting coordinates of the boundary point located in each depth plane based on the depth information.

In addition, the present invention is a two-dimensional PFP reconstruction step for reconstructing the two-dimensional PFP for each depth plane obtained from the target by using the one-dimensional sub PFP (Principle Fringe Pattern) stored in the lookup table; Hologram information generation step of generating hologram information using a pre-computer graphic hologram (CGH) pattern based on the reconstructed two-dimensional PFP; And a hologram generation step of generating a hologram related to the target by using the generated hologram information.

Preferably, the two-dimensional PFP reconstruction step uses a PFP having one variable or a preselected trigonometric function as the one-dimensional sub-PFP when restoring the two-dimensional PFP.

Preferably, the step of restoring the two-dimensional PFP determines the size or area of the two-dimensional PFP to be restored and restores the two-dimensional PFP based on the determined size or area.

Preferably, the 2D PFP reconstruction step uses the coordinates of the boundary point, the spacing between pixels in the 3D video, and the resolution of the 3D video when determining the size of the 2D PFP to be reconstructed.

Advantageously, the step of generating hologram information comprises: a point selecting step of selecting at least two points in the reconstructed two-dimensional PFP; A position change PFP obtaining step of obtaining a positionally shifted two-dimensional PFP by coordinate shifting one of the selected points; A PFP combining step of combining the obtained two-dimensional PFPs when the two-dimensional PFPs which are moved relative to all selected points are obtained; And generating the hologram information by extracting a pre CGH pattern having a predetermined size from the combined two-dimensional PFPs.

Preferably, the CGH pattern-based hologram information generating step extracts a pre CGH pattern including all the selected points as a pre CGH pattern corresponding to the predetermined size.

Preferably, prior to the 2D PFP reconstruction step, a step of generating a lookup table that separates each 2D PFP into a plurality of 1D sub PFPs and generates the lookup table using the separated 1D sub PFPs. Include.

Preferably, a three-dimensional information extraction step between the look-up table generation step and the two-dimensional PFP reconstruction step, extracting the three-dimensional information of the target and extracting the depth information and the brightness information of the target with the three-dimensional information; It includes more.

Preferably, the method further includes a boundary point coordinate extraction step for extracting coordinates of boundary points located in each depth plane based on the depth information between the three-dimensional information extraction step and the two-dimensional PFP reconstruction step.

According to the present invention, the following effects can be obtained by proposing a hologram generating apparatus and method using a lookup table having a reduced memory capacity. First, real-time video hologram playback becomes possible. Second, it becomes possible to generate a three-dimensional image in real time.

1 is a block diagram schematically showing a hologram generating device according to a preferred embodiment of the present invention.
FIG. 2 is a block diagram illustrating in detail the internal configuration of the hologram information generating unit illustrated in FIG. 1.
3 is a block diagram schematically illustrating a configuration added to the hologram generating device illustrated in FIG. 1.
4 is a reference diagram for explaining a method of acquiring 3D information using a holography technique.
5 is a conceptual diagram of a hologram generating method according to an embodiment of the present invention.
6 illustrates a pair of 1-D sub-PFPs and a 2-D PFP recovered using the same.
7 illustrates a brightness image and a depth image obtained from a car image.
8 is a graph showing the time taken for 2-D PFP recovery according to the resolution of the PFP.
9 is a conceptual diagram illustrating a procedure for minimizing the size of 2-D PFP.
FIG. 10 is a diagram illustrating 2-D PFP with outer coordinates extracted and recovered.
11 is a conceptual diagram illustrating a hologram generation procedure using the proposed method.
12 illustrates a reconstructed image of a hologram pattern generated using the proposed method.
13 is a graph showing the memory size in each scheme according to the hologram parameter.
14 is a flowchart illustrating a hologram generating method according to a preferred embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the 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 "have" 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. 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 block diagram schematically showing a hologram generating device according to a preferred embodiment of the present invention. According to FIG. 1, the hologram generating apparatus 100 includes a two-dimensional PFP (Principle Fringe Pattern) restoring unit 110, a hologram information generating unit 120, a hologram generating unit 130, a power supply unit 140, and a main control unit 150. ).

The 2D PFP reconstructor 110 restores the 2D PFP for each depth plane obtained from the target by using 1D sub PFPs stored in the lookup table.

When the 2D PFP restoration unit 110 restores the 2D PFP, the 2D PFP restoration unit 110 may use a PFP having one variable or a PFP including a preselected trigonometric function as a 1D sub-PFP.

The 2D PFP restoration unit 110 may determine the size or area of the 2D PFP to be restored and restore the 2D PFP based on the determined size or area. In this case, when determining the size of the 2D PFP to be restored, the 2D PFP reconstructor 110 may use the coordinates of the boundary point, the spacing between the pixels in the 3D image, and the resolution of the 3D image.

The hologram information generation unit 120 performs a function of generating hologram information using a pre-computer graphic hologram (CGH) pattern based on the restored two-dimensional PFP.

As illustrated in FIG. 2, the hologram information generating unit 120 includes a point selector 121, a position change PFP obtainer 122, a PFP combiner 123, and a CGH pattern-based hologram information generator 124. It may include. FIG. 2 is a block diagram illustrating in detail the internal configuration of the hologram information generating unit illustrated in FIG. 1.

The point selector 121 selects at least two points in the restored two-dimensional PFP.

The position change PFP acquisition unit 122 performs a function of acquiring a positionally shifted two-dimensional PFP by coordinate shifting one of the selected points.

The PFP combiner 123 performs a function of combining the obtained two-dimensional PFPs when the two-dimensional PFPs which are moved relative to all selected points are obtained.

The CGH pattern-based hologram information generator 124 extracts a pre-CGH pattern having a predetermined size from the combined two-dimensional PFPs to generate hologram information. The CGH pattern-based hologram information generator 124 may extract a pre CGH pattern including all points selected as a pre CGH pattern having a predetermined size.

The hologram generator 130 generates a hologram related to the target by using the generated hologram information.

The power supply unit 140 performs a function of supplying power to each component constituting the hologram generating device 100.

The main controller 150 performs a function of controlling the overall operation of each component constituting the hologram generating device 100.

As illustrated in FIG. 3, the hologram generating apparatus 100 may further include a lookup table generator 160, a 3D information extractor 170, and a boundary point coordinate extractor 180. 3 is a block diagram schematically illustrating a configuration added to the hologram generating device illustrated in FIG. 1.

The lookup table generator 160 performs a function of generating a lookup table. The lookup table generator 160 may divide each two-dimensional PFP into a plurality of one-dimensional sub-PFPs and generate a lookup table using the separated one-dimensional sub-PFPs.

The 3D information extractor 170 performs a function of extracting 3D information of the target. The 3D information extractor 170 may extract depth information and brightness information of the target as 3D information of the target.

The boundary point coordinate extractor 180 performs a function of extracting coordinates of the boundary point located in each depth plane based on the depth information.

Next, the hologram generating apparatus 100 described with reference to FIGS. 1 to 3 will be described with reference to one embodiment. 4 is a reference diagram for explaining a method of acquiring 3D information using a holography technique. The following description refers to FIG. 4.

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. In this case, 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. In this case, the unmodified reference wave interferes with the object wave and the generated interference fringe is stored on the screen. Films in which such interference fringes are stored are called holograms.

A computer generated hologram (CGH) pattern is generated by computer calculation by (x, y, z) coordinate values and intensity values (a) of pixels. CGH is used for 3D holographic image acquisition. 4 shows a geometric calculation model of the hologram. Hereinafter, the hologram will be described, but the present invention is not limited thereto.

The hologram is located on the xy plane 430 and the p th point of the object is located at (x _p , y _p , z _p ) 410. 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 superposition of the object waves as shown in Equation 1 below.

Where p represents a point constituting an object (object point), and N is the total number of points constituting the object. a _p represents the intensity of the object wave and k is a wave vector, defined as k = 2π / λ. λ is the wavelength of light in free space. r _p represents the oblique distance between the p th object point and the point (x, y, 0) in the hologram, and is defined by Equation 2 below.

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

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) in the hologram plane is represented by Equation 4 as an interference pattern between the object wave O (x, y) and the reference wave R (x, y).

In Equation 4, ① represents the intensity of the reference wave, ② represents the intensity of the object wave. ③ denotes an interference pattern between an object wave and a reference wave partially including 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 ③, I (x, y) can be expressed as follows.

That is, in the conventional ray tracing method, a hologram pattern can be generated by Equation 5. However, as shown in Equation 5, the equation for generating the hologram pattern is quite complicated, which makes it difficult to generate in real time.

In order to solve this problem, a method of using a lookup table that generates a hologram by calling each element fringe pattern according to a three-dimensional image to be created in advance by creating an element fringe pattern that can represent all points in an arbitrary object space is proposed. 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. Therefore, in the following, the vertical and horizontal degree of discretization is set to 150 micron.

In the method using a lookup table, an element fringe pattern must be generated 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 by Equation 6 using Equation 5.

Here, r _p is a distance between the pth point and (x, y, 0), as given by Equation 2.

In this method, the lookup table is a set of fringe patterns for each point (x _p , y _p , z _p ) that you have made, rather than calculating the fringe pattern for each point as necessary when calculating the hologram, as shown in Equation 5. Calculate using 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.

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.

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 significantly reduces memory requirements.

In the N-LUT method, an element fringe pattern must also be generated 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.

Where r _p is the distance between the pth point and (x, y, 0) as given by Equation 2. Therefore, in the newly proposed N-LT method, only the element fringe pattern (hereinafter, referred to as the reference element fringe pattern) for the depth direction of the object is calculated and stored. When one depth direction of the object is determined, the object existing on the plane The element fringe patterns of the points move the previously stored reference element fringe pattern to each object point to calculate the fringe pattern 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) may be finally expressed as in Equation (9).

By using the N-LUT method, a hologram pattern can be generated and restored at high speed. However, it was still difficult to apply this method to videos because of the large amount of data.

The present invention proposes a new method that can significantly reduce the memory capacity while maintaining the performance of the existing N-LUT technique for high-speed hologram generation. 5 is a conceptual diagram of a hologram generating method according to an embodiment of the present invention. According to FIG. 5, the proposed method can be divided into five parts as follows.

1. Generation of N-LUT using 1-D sub-PFP (510)

2. Extracting 3D Information from the Object to be Generated (520)

3. Extract the outer coordinates for each depth plane from the object (530) and 2-D PFP recovery (540) from the 1-D sub-PFP using this information

4. Hologram Generation Using Recovered 2-D PFP (550)

5. 3D Image Reconstruction from Generated CGH Patterns (560)

Each part (1.-5.) Is demonstrated below.

1. Generation of N-LUT using 1-D sub-PFP

In the proposed method, the hologram is generated using 2-D PFP recovered from 1-D sub-PFP by using the trigonometric function. As shown in Equation 10, 2-D PFP can be separated into four terms of 1-D sub-PFP by using the characteristics of the trigonometric function.

Δx = xx _p and Δy = y-yp here. As can be seen in the first line of Equation 10, 2-D PFP is a function of two variables x and y. Therefore, both variables are affected. But on the third line, each term is a function of only one variable, x or y. Therefore, given four functions, each with only one variable, it is possible to recover 2-D PFP using it.

Also, if you look at the first and second term in the third line of Equation 10, it is the same cos function and only the variables are different. Therefore, if you have only one cos function, you can use it with both terms. The third term and the fourth term are also the same sin function and differ only in the variables. So if you only have one sin function, you can use two terms. As a result, having only two sin and cos functions recovers the 2-D PFP used for hologram generation.

6 shows each 1-D sub-PFP consisting of sin and cos functions, and 2-D PFP recovered using it. In Figure 6 (a) represents 1-D sine sub-PFP, (b) represents 1-D cosine sub-PFP. (c) shows recovered 2-D PFP.

The proposed method stores a pair of 1-D sub-PFPs instead of 2-D PFPs, which significantly reduces the memory usage. For example, in the conventional method, if the size of the 2-D PFP is 1,024 × 1,024, the memory capacity of the 2-D PFP becomes 1,024 × 1,024 × 8 bits = 1 MB. However, the proposed method requires two 1 × 1,024 1-D sub-PFPs, resulting in a memory size of 2 × 1 × 1,024 × 8 bits = 2 KB. Therefore, we can see that the proposed method has 512 times less memory than the conventional method.

2. Extracting 3D Information from Objects

In the next step, brightness information and depth information are extracted from a three-dimensional object for which a hologram is to be generated. 7 illustrates brightness information and depth information extracted for the car image, respectively. In FIG. 7, (a) shows a brightness image, and (b) shows a depth image.

3. Outer coordinate extraction of input image and recovery of 2-D PFP using this information

In the existing N-LUT method, holograms are generated using a 2-D PFP made in advance. In this case, the 2-D PFP has a region that is not used at the time of hologram creation because of a predetermined size. The proposed method recovers 2-D PFP using 1-D sub-PFP and then generates hologram using it, so recovery time of 2-D PFP affects hologram generation time. Therefore, when recovering the 2-D PFP, only the area to be used without restoring the entire area of the 2-D PFP can shorten the time required for hologram generation.

8 shows the time taken to recover according to the resolution of the PFP when recovering to 2-D PFP using the 1-D sub-PFP. This shows that the recovery time increases exponentially as the resolution of the PFP increases. Therefore, proper size of the required PFP can reduce the time required for 2-D PFP recovery.

For example, four points (A (x ₁ , y ₁ , z ₁ ), B (x ₂ , y ₂ , z ₁ ) and C (x ₃ , A method of generating a hologram using a conventional N-LUT technique when an object consisting of y ₃ , z ₁ ) and D (x ₄ , y ₄ , z ₁ )) is shown in FIG. 9. 9 is a diagram illustrating a procedure for minimizing the size of 2-D PFP. In FIG. 9, (a) represents an object composed of four points existing in one depth plane, and (b) represents an area selected to represent each point. (c) shows repaired 2-D PFP and (d) shows CGH production procedure.

As shown in (b) of FIG. 9, region I, which is centered on A ′ (x ₁ × disc, y ₁ × disc, z ₁ ), is extracted to calculate the hologram for point A. Similarly, regions II, III, and IV are extracted to calculate the holograms for points B, C, and D. Finally, if each extracted region is added together as shown in FIG. 9 (d), the final hologram can be obtained.

As mentioned earlier, the entire area of the 2-D PFP can be used to generate holograms. However, the higher the resolution of the PFP, the longer the time required to recover the 2-D PFP, so it is necessary to minimize the size of the recovered 2-D PFP. 10 (c) shows a 2-D PFP recovered by minimizing the size and may be expressed as follows.

Where h _x and h _y represent the horizontal and vertical resolution of the hologram, and disc represents the interval between each point of the reconstructed hologram image. Also, x _leftmost , x _rightmost , y _top and y _bottom represent the outer coordinates of each direction in which the object exists in the corresponding depth plane of the input image.

FIG. 10A illustrates extraction of outer coordinates of information of an arbitrary depth plane from the input image of FIG. 7. (B) and (c) of FIG. 10 show 2-D PFP recovered using the minimization technique and 2-D PFP recovered using the minimization technique, respectively. As can be seen in Figure 10 it can be seen that the proposed method is much smaller than the conventional method.

4. Generation of Hologram Using Recovered 2-D PFP

11 shows a procedure for generating holograms for four object points respectively present in two depth planes using the proposed method. Only two recovered 2-D PFPs are used in the sample of FIG. 11 since there are only two depth planes. That is, as shown in FIG. 11B, a 2-D PFP centered on (0,0, z ₁ ) and a restored 2-D PFP centered on (0,0, z ₂ ) are used. The two 2-D PFPs are then moved from the center to calculate holograms for each point.

That is, to calculate Point A (-x ₁ , y ₁ , z ₁ ), the recovered 2-D PFP corresponding to z ₁ as shown in FIG. 11 (c) is -x ₁ in the horizontal direction and y in the vertical direction. ₁ thereby moves. Likewise, each 2-D PFP is moved to perform hologram operations on Points B, C, and D. Finally, adding all the 2-D PFPs that have moved and extracting the predetermined size of the hologram generates the hologram for the last four points.

11 illustrates a hologram generation procedure using the proposed method. In FIG. 11, (a) shows an input image present in each depth plane, and (b) shows a 2-D PFP that has been minimized and recovered. (c) shows the shift with respect to the position of the input point of the recovered 2-D PFP, and (d) shows the sum of the four 2-D PFPs that have moved. (e) shows the final generated hologram pattern.

5. Restoration of 3D Objects from Holograms

The image reconstructed in two depth planes using the proposed method of FIG. 12 is shown. In FIG. 12, (a) shows an image reconstructed by focusing on a rear wheel part of a vehicle, and (b) shows an image reconstructed by focusing on a front wheel of a car. If you look at it, you can see that it is well restored in three dimensions to each focus.

- specifications required for each method by holographic memory space

The proposed method can achieve the same hologram generation effect with less memory space than the existing LUT and N-LUT method. Fig. 13 shows the angle according to the size of the input 3D image (see (a)), the size of the hologram (see (b)), the number of depth planes (see (c)), and the pixel size of the hologram (see (d)). Represents a memory space in the method. In this case, the input 3D image has a size of 100 × 100 × 100, the hologram size and the pixel size are 1,000 × 1,000 and 10 μm, and the viewing distance is 500 mm, respectively.

13, (a) and (b) show the required memory capacities in the respective methods according to the size of the input image and the hologram. As the resolution of the input image and the hologram increases, the required memory capacity increases exponentially, reaching TB level in the LUT method and GB level in the N-LUT method. However, there is little increase in the proposed method. In the proposed method, the required memory capacity is increased but it remains at MB level.

(C) in Fig. 13 shows the required memory capacity in each method according to the number of depth planes. This shows that in all methods, the required memory capacity increases linearly as the number of depth planes increases. However, the LUT method reaches TB level and the N-LUT method reaches GB level, but the proposed method stays at MB level.

In FIG. 13, (d) shows a required memory capacity according to the hologram pixel size. In the LUT method, the pixel size and the required memory capacity are independent. However, in the N-LUT method, the smaller the pixel size is, the greater the number of pixels to be moved, and when the pixel size is smaller, the required memory capacity is increased exponentially and reaches TB level. In the proposed method, however, the smaller the pixel size, the larger the required memory capacity. However, the N-LUT method uses 2D-PFP to increase the required memory capacity to square, but the proposed method uses 1D-PFP to linearly increase the required memory capacity. Therefore, in the proposed method, it can be seen that the required memory capacity is still at MB level.

Next, a hologram generating method of the hologram generating device will be described. 14 is a flowchart illustrating a hologram generating method according to a preferred embodiment of the present invention. The following description refers to FIGS. 1 to 3 and 14.

First, the 2D PFP restoration unit 110 restores the 2D PFP for each depth plane obtained from the target by using 1D sub PFP (Principle Fringe Patterns) stored in the lookup table (S10).

In operation S10, the 2D PFP restoration unit 110 may use a PFP having one variable or a PFP including a preselected trigonometric function as a 1D sub PFP when restoring the 2D PFP.

In operation S10, the 2D PFP restoration unit 110 may determine the size or region of the 2D PFP to be restored and restore the 2D PFP based on the determined size or region. In this case, the 2D PFP reconstructor 110 may use the coordinates of the boundary point, the spacing between the pixels in the 3D video, and the resolution of the 3D video when determining the size of the 2D PFP to be reconstructed.

After the step S10, the hologram information generation unit 120 generates hologram information using a pre-computer graphic hologram (CGH) pattern based on the restored two-dimensional PFP (S20).

Step S20 may be specifically performed as follows. First, the point selector 121 selects at least two points in the restored two-dimensional PFP. Thereafter, the position-changing PFP obtaining unit 122 coordinates one of the selected points to obtain the position-shifted two-dimensional PFP. Then, the PFP combining unit 123 combines the obtained two-dimensional PFPs when the position-shifted two-dimensional PFPs are acquired for all selected points. Thereafter, the CGH pattern-based hologram information generator 124 extracts a pre-CGH pattern having a predetermined size from the combined two-dimensional PFPs to generate hologram information. The CGH pattern-based hologram information generator 124 may extract a pre CGH pattern including all points selected as a pre CGH pattern having a predetermined size.

After the step S20, the hologram generator 130 generates a hologram related to the target by using the generated hologram information (S30).

Meanwhile, the lookup table generator 160 may generate the lookup table before the step S10 (S1). The lookup table generator 160 may divide each two-dimensional PFP into a plurality of one-dimensional sub-PFPs and generate a lookup table using the separated one-dimensional sub-PFPs.

Meanwhile, the 3D information extractor 170 may extract 3D information of the target between steps S1 and S10 (S2). The 3D information extractor 170 may extract depth information and brightness information of the target as 3D information of the target.

Meanwhile, the boundary point coordinate extractor 180 may extract the coordinates of the boundary point located in each depth plane based on the depth information between steps S2 and S10.

It will be apparent to those skilled in the art that various modifications, substitutions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. . The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: hologram generating device 110: two-dimensional PFP recovery unit
120: hologram information generation unit 121: point selection unit
122: position change PFP acquisition unit 123: PFP coupling unit
124: CGH pattern-based hologram generator 130: hologram generator
140: power supply unit 150: main control unit
160: lookup table generation unit 170: 3D information extraction unit
180: boundary point coordinate extraction unit

Claims (18)

A two-dimensional PFP reconstruction unit for reconstructing the two-dimensional PFP for each depth plane obtained from the target by using one-dimensional sub PFPs (Principle Fringe Patterns) stored in the lookup table;
A hologram information generation unit generating hologram information using a pre-computer graphic hologram (CGH) pattern based on the restored two-dimensional PFP; And
Hologram generator for generating a hologram associated with the target by using the generated hologram information
Hologram generating device comprising a. The method of claim 1,
And the two-dimensional PFP reconstructor uses a PFP having one variable or a preselected trigonometric function as the one-dimensional sub-PFP when restoring the two-dimensional PFP. The method of claim 1,
And the 2D PFP reconstructor determines the size or area of the 2D PFP to be reconstructed and restores the 2D PFP based on the determined size or area. The method of claim 3, wherein
And the 2D PFP reconstructor uses the coordinates of the boundary point, the spacing between pixels in the 3D video, and the resolution of the 3D video when determining the size of the 2D PFP to be reconstructed. The method of claim 1,
The hologram information generation unit,
A point selector for selecting at least two points in the reconstructed two-dimensional PFP;
A position change PFP acquisition unit which acquires a two-dimensional PFP that is moved by coordinates one of the selected points;
A PFP combiner for combining the obtained two-dimensional PFPs when the two-dimensional PFPs which are moved relative to all selected points are obtained; And
CGH pattern-based hologram information generating unit for generating the hologram information by extracting a pre-CGH pattern of a predetermined size from the combined two-dimensional PFPs
Hologram generating device comprising a. The method of claim 5, wherein
And the CGH pattern-based hologram information generator extracts a pre CGH pattern including all the selected points as a pre CGH pattern corresponding to the predetermined size. The method of claim 1,
A lookup table generator which separates each 2D PFP into a plurality of 1D sub PFPs and generates the lookup table using the separated 1D sub PFPs.
Hologram generating device further comprising a. The method of claim 1,
Three-dimensional information extraction unit for extracting the three-dimensional information of the target, extracting the depth information and the brightness information of the target with the three-dimensional information
Hologram generating device further comprising a. The method of claim 8,
Boundary point coordinate extraction unit for extracting coordinates of the boundary point located in each depth plane based on the depth information
Hologram generating device further comprising a. A two-dimensional PFP reconstruction step of reconstructing the two-dimensional PFP for each depth plane obtained from the target by using one-dimensional sub-Principle Fringe Patterns (PFPs) stored in the lookup table;
Hologram information generation step of generating hologram information using a pre-computer graphic hologram (CGH) pattern based on the reconstructed two-dimensional PFP; And
Hologram generation step of generating a hologram associated with the target by using the generated hologram information
Hologram generation method comprising a. 11. The method of claim 10,
The two-dimensional PFP reconstruction step is a hologram generation method, characterized in that for reconstructing the two-dimensional PFP using a PFP having one variable or a preselected trigonometric function as the one-dimensional sub-PFP. 11. The method of claim 10,
The 2D PFP reconstruction step may include determining a size or area of the 2D PFP to be reconstructed and reconstructing the 2D PFP based on the determined size or area. 13. The method of claim 12,
The 2D PFP reconstruction step may include using the coordinates of the boundary point, the spacing between pixels in the 3D video, and the resolution of the 3D video when determining the size of the 2D PFP to be reconstructed. 11. The method of claim 10,
The hologram information generating step,
A point selection step of selecting at least two points in the reconstructed two-dimensional PFP;
A position change PFP obtaining step of obtaining a positionally shifted two-dimensional PFP by coordinate shifting one of the selected points;
A PFP combining step of combining the obtained two-dimensional PFPs when the two-dimensional PFPs which are moved relative to all selected points are obtained; And
CGH pattern-based hologram information generation step of generating the hologram information by extracting a pre-CGH pattern of a predetermined size from the combined two-dimensional PFPs
Hologram generation method comprising a. 15. The method of claim 14,
The generating of the CGH pattern-based hologram information includes extracting a pre-CGH pattern including all the selected points as a pre-CGH pattern corresponding to the predetermined size. 11. The method of claim 10,
A lookup table generation step of dividing each two-dimensional PFP into a plurality of one-dimensional sub-PFPs and generating the look-up table using the separated one-dimensional sub-PFPs
Hologram generation method characterized in that it further comprises. 11. The method of claim 10,
3D information extraction step of extracting the 3D information of the target, extracting the depth information and the brightness information of the target with the 3D information
Hologram generation method characterized in that it further comprises. The method of claim 17,
A boundary point coordinate extraction step of extracting coordinates of a boundary point located in each depth plane based on the depth information
Hologram generation method characterized in that it further comprises.

Images