Holographic display system and method for generating holograms by compensating for aberrations

Abstract

Holographic display systems and methods for generating holograms by compensating for aberrations of a holographic display device are provided. The holographic display system can include a holographic display device and a hologram generation device. The hologram generation device can generate a hologram by using a kernel that is generated by modeling each aberration corresponding to each hologram plane patch to compensate for the aberrations.

Description

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2021-0036806, filed on March 22, 2021, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a holographic display system and method for generating holograms by compensating for aberrations in a holographic display device. Background Technology

[0004] Holography is a technique for recording three-dimensional images by utilizing the interference phenomenon that occurs when a beam of light reflected from an object meets a reference beam. A hologram is a record of the interference pattern from a hologram. Holography can be classified into analog holography and digital holography. Analog holography refers to the technique of directly recording the interference pattern between the object beam and the reference beam. Digital holography refers to the technique of generating the interference pattern between the object beam and the reference beam using digital processing.

[0005] Computer-generated holography (CGH) is a type of digital holography. In CGH, holograms are generated by computing interference patterns. Three-dimensional images are then reconstructed by displaying the holograms using a holographic display device.

[0006] Due to optical aberrations in holographic display devices, the quality of three-dimensional images may degrade, and therefore, methods to prevent this degradation are needed. Summary of the Invention

[0007] A holographic display system and method are provided for generating holograms by compensating for aberrations in a holographic display device. A computer-readable recording medium is provided on which a program for executing the method in a computer is recorded. The technical task to be solved is not limited to the above, and other technical tasks may also exist.

[0008] Other aspects will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the exemplary embodiments presented in this disclosure.

[0009] According to one aspect of this disclosure, a method for generating a hologram is provided, the method comprising: generating a kernel by modeling aberrations corresponding to hologram plane blocks of a hologram plane; generating a mask corresponding to the hologram plane blocks of the hologram plane; obtaining hologram blocks by spatially filtering the hologram using the mask; obtaining a first image block by propagating the hologram blocks using the kernel; and updating the hologram based on a comparison between the first image block and a second image block.

[0010] The generation of kernels may include: modeling aberrations corresponding to holographic plane blocks using Zernike polynomials; and generating each kernel based on Zernike polynomials.

[0011] Modeling the aberrations corresponding to each of the Chanek polynomials can include determining the Chanek coefficients for at least one holographic plane block within the holographic plane block by interpolating the Chanek coefficients modeled for neighboring holographic plane blocks within the holographic plane block.

[0012] The generation of the kernel may include: generating a partitioned holographic plane block by dividing at least one of the holographic plane blocks; and generating the kernel based on the partitioned holographic plane block.

[0013] Kernel generation may include: generating a merged holographic plane block by merging at least two holographic plane blocks; and generating one kernel from the kernels based on the merged holographic plane block.

[0014] The generation of the mask may include generating at least one mask comprising a pass region and a remaining cut-off region corresponding to the corresponding holographic plane block.

[0015] The generation of the mask may further include: generating at least one mask in which the edge regions of the region have different pixel values ​​than the center region of the region.

[0016] The generation of the mask may further include: generating at least one mask, wherein a first edge region of the through region adjacent to the cutoff region has a different pixel value than the center region of the through region, and a second edge region of the through region not adjacent to the cutoff region has the same pixel value as the center region of the through region.

[0017] Obtaining the first image block may include obtaining the first image block by propagating hologram blocks in parallel.

[0018] Updating the hologram may include: determining a loss function based on the intensity difference between a first image block and a second image block; and updating the hologram to optimize the loss function.

[0019] Holographic planar segmentation is the spatial segmentation of the holographic plane.

[0020] The second image block is a reference image block obtained from the storage device.

[0021] According to another aspect of this disclosure, a non-transient computer-readable recording medium is provided having thereon recorded a computer program for performing a method for generating a hologram, the method comprising: generating a kernel by modeling aberrations corresponding to hologram plane blocks of a hologram plane; generating a mask corresponding to hologram plane blocks of a hologram plane; obtaining hologram blocks by spatially filtering the hologram using the mask; obtaining a first image block by propagating the hologram blocks using the kernel; and updating the hologram based on a comparison between the first image block and a second image block.

[0022] According to another aspect of this disclosure, a holographic display system is provided, comprising: a light source configured to emit light to reproduce a holographic image; an optical system configured to spatially focus the holographic image; a processor configured to generate a hologram configured to reproduce the holographic image; and a spatial light modulator configured to modulate light based on the hologram, wherein the processor is configured to: generate a kernel by modeling each aberration corresponding to each holographic plane block of the holographic plane; generate masks corresponding to the holographic plane blocks of the holographic plane, respectively; obtain holographic blocks by spatially filtering the hologram using the masks; obtain a first image block by propagating the holographic blocks using the kernels; and update the hologram based on a comparison between the first image block and a second image block.

[0023] The processor can be further configured to perform aberration modeling corresponding to holographic plane blocks using Zanek polynomials, and for each of the generating kernels based on Zanek polynomials.

[0024] The processor can be further configured to determine the Chanek coefficients for at least one holographic plane block in the holographic plane block by interpolating the Chanek coefficients modeled for neighboring holographic plane blocks in the holographic plane block.

[0025] The processor can be further configured to generate partitioned holographic plane blocks by dividing at least one of the holographic plane blocks, and to generate kernels based on the partitioned holographic plane blocks.

[0026] The processor can be further configured to generate a merged holographic plane block by merging at least two holographic plane blocks in the holographic plane block, and to generate a core in the core based on the merged holographic plane block in the holographic plane block.

[0027] The processor can be further configured to generate at least one mask including a pass region corresponding to the corresponding holographic plane block and a remaining cut-off region.

[0028] The processor can be further configured to generate at least one mask in which the edge regions of the region have pixel values ​​different from those of the center region of the region.

[0029] The processor can be configured to obtain the first image block by propagating hologram blocks in parallel.

[0030] The processor can be further configured to determine a loss function based on the intensity difference between the first image block and the second image block, and update the hologram to optimize the loss function.

[0031] According to another aspect of this disclosure, a holographic display apparatus is provided, comprising: a memory storing one or more instructions; and a processor configured to execute one or more instructions to: generate one or more kernels corresponding to one or more holographic plane blocks of a holographic plane; generate one or more masks corresponding to one or more holographic plane blocks; obtain one or more holographic blocks by applying one or more masks to a hologram; obtain one or more image blocks by propagating the holographic blocks based on one or more kernels; and update the hologram based on a comparison between one or more image blocks and one or more reference image blocks. Attached Figure Description

[0032] The above and other aspects, features, and advantages of certain embodiments of this disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0033] Figure 1 This is a schematic block diagram illustrating a holographic display system according to an example embodiment;

[0034] Figure 2 This is a cross-sectional view of an example of the aberrations in the illustrated optical system;

[0035] Figure 3A The illustration shows a method for generating a hologram by compensating for aberrations in a holographic display device, according to an example embodiment.

[0036] Figure 3B The illustration shows a hologram and hologram blocks based on an example embodiment;

[0037] Figure 4 The illustration shows a pattern formed by aberrations on a holographic plane segment according to an example embodiment;

[0038] Figure 5A The illustration shows the merging of holographic planar blocks according to an example embodiment;

[0039] Figure 5B The diagram illustrates the division of the hologram plane into blocks according to an example embodiment;

[0040] Figure 6 The diagram illustrates a mask according to an example embodiment;

[0041] Figure 7A and Figure 7B The illustration shows a mask for blurring according to an example embodiment;

[0042] Figure 8 The illustration shows an optimized loop for generating a hologram by compensating for aberrations in a holographic display device, according to an example embodiment.

[0043] Figure 9 The figure illustrates a flowchart of a method for generating a hologram by compensating for aberrations in a holographic display device, according to an example embodiment.

[0044] Figure 10 The illustration shows a flowchart, according to an embodiment, of a method for generating a hologram by compensating for aberrations of a holographic display device, including an example optimized loop; and

[0045] Figure 11A and Figure 11B The illustration shows experimental results of a method for generating holograms by compensating for aberrations in a holographic display device, according to an example embodiment. Detailed Implementation

[0046] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein the same reference numerals refer to the same elements throughout. In this respect, exemplary embodiments may take different forms and should not be considered as limited to the description set forth herein. Therefore, the following description of exemplary embodiments is solely for the purpose of explaining aspects by reference to the accompanying drawings. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. For example, the expression “at least one” modifies the entire list of elements without modifying any individual element in the list, such as when preceding the list of elements.

[0047] Widely used, generic terms are chosen to describe the exemplary embodiments. However, such terms may change depending on the intent of those skilled in the art, precedents, the emergence of new technologies, etc. Furthermore, in some cases, the applicant may arbitrarily choose terms, and in such cases, the meaning of the terms will be specifically described in the relevant sections. Therefore, the terms used in the specification should be defined based on their meanings and the overall description of the specification, rather than simply by their names.

[0048] In the example embodiments, terms such as “comprising” and “including” should not be construed as including all of the various components or operations described herein, and it should be understood that certain components or operations may be excluded, or additional components or operations may be included.

[0049] In the following description, exemplary embodiments will be specifically described with reference to the accompanying drawings. However, the exemplary embodiments may be implemented in many different forms and should not be regarded as limited to the examples described herein.

[0050] Figure 1 This is a block diagram schematically illustrating a holographic display system 100 according to an example embodiment.

[0051] A holographic display system 100 according to an example embodiment may include a holographic display device 110 and a hologram generation device 120. The holographic display device 110 may include a light source 111, an optical system 112, and a spatial light modulator 113. Additionally, the hologram generation device 120 may include a processor 121 and a memory 122.

[0052] The holographic display system 100 can be configured to generate holograms and reproduce holographic images based on a hologram plane HP located on a spatial light modulator 113, a reference plane RP located in the observer's pupil, and an image plane IP on which the holographic image is located.

[0053] The holographic display device 110 can be configured to display a holographic image on an image plane IP based on a hologram provided from the hologram generation device 120. The image plane IP may include multiple layers.

[0054] Light source 111 can be configured to emit light to reproduce a holographic image. Light source 111 may include a laser diode or a light-emitting diode, but this disclosure is not limited thereto. For example, according to an example embodiment, light source 111 may include an array of multiple light sources. According to another example embodiment, light source 111 may include both a laser diode and a light-emitting diode.

[0055] Optical system 112 can be configured to spatially focus a holographic image. Optical system 112 can be configured to spatially focus the reconstructed light L formed by modulation by spatial light modulator 113. For example, optical system 112 can be configured to focus the reconstructed light L on a reference plane RP.

[0056] Optical system 112 may include a fixed-focus optical system with a fixed focal length or a zoom optical system with a variable focal length. According to an example embodiment, optical system 112 may include a combination of a fixed-focus optical system and a zoom optical system. Additionally, optical system 112 may include refractive lens elements or diffractive lens elements. According to an example embodiment, optical system 112 may include a combination of refractive lens elements and diffractive lens elements.

[0057] Spatial light modulator 113 can be configured to modulate light based on a hologram. Spatial light modulator 113 can form a hologram for modulating light by refraction based on a hologram provided from hologram generation device 120. Spatial light modulator 113 may include an amplitude modulator and / or a phase modulator.

[0058] The hologram generating apparatus 120 can be configured to generate holograms. The hologram generating apparatus 120 can be configured to generate holograms based on computer-generated holograms (CGH). The hologram generating apparatus 120 can be configured to generate holograms by compensating for aberrations in the holographic display apparatus 110. Specifically, the hologram generating apparatus 120 can be configured to generate holograms by compensating for aberrations in the optical system 112.

[0059] Processor 121 can be configured to generate holograms. Processor 121 can be implemented by an array of multiple logic gates and can be implemented by a combination of a general-purpose microprocessor and memory, in which a program executable in the general-purpose microprocessor is stored.

[0060] Processor 121 can generate masks corresponding to spatial blocks of the hologram plane, each representing a spatial block of the hologram plane HP. Processor 121 can generate a kernel by modeling each aberration corresponding to each hologram plane block. Processor 121 can obtain hologram blocks by spatially filtering the hologram using the masks. Processor 121 can obtain image blocks by propagating the hologram blocks to the image plane using the kernels. Processor 121 can update the hologram based on comparisons between image blocks and predetermined image blocks. For example, a kernel can refer to a function used to measure similarity by monitoring the diffusion of aberrations corresponding to hologram plane blocks, but this application is not limited thereto.

[0061] Memory 122 may be configured to store holograms and / or programs executed by processor 121. Memory 122 may include random access memory (RAM) (such as dynamic random access memory (DRAM) and static random access memory (SRAM)), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), CD-ROM, Blu-ray disc or other optical disc storage devices, hard disk drive (HDD), solid-state drive (SSD), or flash memory. Additionally, it may include other external storage devices accessible by hologram generating apparatus 120.

[0062] Figure 2 This is a cross-sectional view of an example of the aberrations of the illustrated optical system 112.

[0063] Holographic display devices may have aberrations. Here, aberrations can refer to all optical aberrations that may occur due to the wave characteristics of light and / or the holographic display device. For example, aberrations may include spherical aberration, astigmatism, coma, distortion, and / or field curvature, but this disclosure is not limited thereto.

[0064] For example, due to spherical aberration, the focal positions of diffracted light L1, L2, and L3 in optical system 112 may differ. Since holographic images may be reproduced in a blurred state due to aberrations, methods to compensate for these aberrations are needed.

[0065] Figure 3A The illustration shows a method for generating a hologram by compensating for aberrations in a holographic display device, according to an example embodiment.

[0066] In operation 311, the processor can generate a kernel. Aberrations in a holographic display device cannot appear uniformly on the hologram plane. To model aberrations more accurately, it is necessary to model each aberration corresponding to each block of the hologram plane. According to the example embodiment, a block of the hologram plane is a spatial block of the hologram plane. For this purpose, the processor can generate a kernel that allows modeling of aberrations corresponding to each block of the hologram plane separately. Zernike polynomials can be used for aberration modeling. Aberration modeling can be performed with high precision by dividing the space for modeling.

[0067] In operation 312, the processor can generate masks. The processor can generate masks corresponding to the planar blocks of the hologram.

[0068] In operation 313, the processor can mask the hologram. That is, in operation 313, the processor can apply the mask generated in operation 312 to the hologram. Based on the masking of the hologram, holographic blocks corresponding to the planar blocks of the hologram can be generated. (See reference) Figure 3B For example, hologram blocks 323 can be generated by filtering hologram 321 with mask 322.

[0069] refer to Figure 3A In operation 314, the processor can reflect aberrations and propagate hologram blocks. Aberrations corresponding to hologram planar blocks can be modeled in the kernel. Therefore, by propagating hologram blocks using the kernel, aberrations corresponding to hologram planar blocks can be reflected and the hologram blocks can be propagated. Due to the propagation of hologram blocks, image blocks can be generated.

[0070] In operation 315, the processor can update the hologram. The processor can update the hologram based on a comparison between an image block and a reference image block. The reference image block can be a predetermined image block. According to an example embodiment, the reference image block can be pre-stored in a storage device and retrieved from the storage device during the comparison. The predetermined image block can be generated by spatially dividing the predetermined image. The predetermined image can be spatially divided in the same way as the hologram plane. A loss function can be used to update the hologram. In an example embodiment, the loss function can be determined from the difference in intensity between the image block and the predetermined image block. The updated hologram can be used to perform repeated operations 313 to 315 to optimize the loss function.

[0071] Figure 4 The illustration shows a pattern formed by aberrations on a holographic plane segment according to an example embodiment.

[0072] The hologram plane 400 can be divided into hologram plane blocks. Figure 4 The illustration shows a hologram plane 400 divided into 5x5 arrays of hologram plane blocks. Hologram plane 400 can be divided into various numbers and sizes of hologram plane blocks.

[0073] The aberrations of the holographic display device cannot affect the hologram plane 400 uniformly in space. As a result, different patterns may appear in each hologram plane segment as light propagates from each point source to each hologram plane segment.

[0074] The processor can generate kernels that model aberrations corresponding to the holographic plane blocks respectively. For example, the processor can generate kernels that model aberrations corresponding to holographic plane block 411 and kernels that model aberrations corresponding to holographic plane block 412.

[0075] The processor can use Zanek polynomials to model the aberrations corresponding to the holographic plane blocks, and generate a kernel based on each Zanek polynomial. In an embodiment, the kernel can be modeled as shown in Equation 1 below.

[0076] Equation 1

[0077] h i =B(r)W i

[0078] In equation 1, h i Let B(r) represent the kernel corresponding to the i-th holographic plane block, where B(r) represents the function of the basic wavefront modeling optical propagation, r represents the propagation distance, and W iThis represents a function that models the wavefront caused by the aberrations corresponding to the i-th holographic plane block. For example, in the case of optical propagation of spherical waves, B(r) can be modeled as exp(jkr) / r. Here, "exp" refers to the exponent.

[0079] The wavefront function W of the aberration i It can be modeled as Equation 2 below.

[0080] Equation 2

[0081] W i =exp(jπ∑α j Z j )

[0082] In Equation 2, α represents the Zanek coefficients, Z represents the Zanek polynomial, and j represents the index of the Zanek polynomial. The index of the Zanek polynomial can be determined by various standards. For example, the OSA / ANSI index, Fringe index, Noll index, Wyant index, etc., can be used as the index of the Zanek polynomial.

[0083] Table 1 shows various examples of Zanek polynomials indexed by OSA / ANSI.

[0084] Table 1

[0085]

[0086] In Table 1, Let denot azimuth, and ρ denote radial distance. Wavefronts with more complex shapes can be modeled by using higher indices to form Zanek polynomials.

[0087] The processor can be configured to determine the indices and / or coefficients of the Zanek polynomials using a program that analyzes aberrations. Alternatively, the processor can generate the kernel by obtaining the indices and / or coefficients of the Zanek polynomials from user input.

[0088] The processor can determine the Zanek coefficients for at least one holographic plane block by interpolating the Zanek coefficients already modeled for neighboring holographic plane blocks. For example, the processor can determine the Zanek coefficients for holographic plane block 414 by interpolating the Zanek coefficients for holographic plane blocks 413 and 415, which are adjacent to holographic plane block 414. Obtaining the Zanek coefficients via interpolation reduces computation time. Furthermore, obtaining the Zanek coefficients via interpolation based on spatial adjacency does not reduce the accuracy of aberration modeling.

[0089] Figure 5A The illustration shows the merging of holographic planar blocks according to an example embodiment.

[0090] The processor can generate a merged hologram plane block by merging multiple hologram plane blocks.

[0091] The processor can generate a merged holographic plane block by merging at least two holographic plane blocks. For example, the processor can generate a merged holographic plane block 510 by merging holographic plane blocks 511, 512, 513, and 514 that have relatively small aberrations.

[0092] The processor can generate kernels corresponding to the merged hologram plane blocks 510.

[0093] As the number of holographic planar blocks increases, more parallel processing may be required. Reducing the number of holographic planar blocks by merging two or more blocks can decrease the load on parallel processing. Furthermore, merging holographic planar blocks by considering the level of aberrations can maintain the accuracy of aberration modeling.

[0094] Figure 5B The illustration shows the division of the hologram plane into blocks according to an embodiment.

[0095] The processor can generate partitioned hologram plane blocks by dividing the hologram plane into blocks.

[0096] The processor can generate divided holographic plane blocks by dividing at least one holographic plane block. For example, the processor can generate divided holographic plane blocks 521, 522, 523, and 524 by dividing holographic plane block 520, which has relatively large aberrations.

[0097] The processor can generate kernels corresponding to the divided holographic plane blocks 521, 522, 523, and 524, respectively. Aberration modeling can be performed with high precision by dividing the space for modeling.

[0098] Figure 6 The illustration shows masks 621 to 623 according to an example embodiment.

[0099] The processor can generate masks corresponding to the holographic plane blocks respectively. For example, the processor can generate a mask 621 corresponding to holographic plane block 611 of holographic plane 600, a mask 622 corresponding to holographic plane block 612, and a mask 623 corresponding to holographic plane block 613.

[0100] The mask 621 may include a through region 621a corresponding to a block of the hologram plane and a remaining cutoff region 621b. According to an example embodiment, the mask 621 may be a binary mask in which the through region 621a has a pixel value of 1 and the cutoff region 621b has a pixel value of 0, but this disclosure is not limited thereto.

[0101] Figure 7A and Figure 7B The illustration shows masks 710 and 720 for blurring according to an example embodiment.

[0102] refer to Figure 7A The mask 710 can be configured to filter the hologram, allowing hologram blocks to have soft edges. For example, a soft edge can refer to a method for removing boundaries between image blocks to be combined later by adjusting the pixel values ​​of edge regions corresponding to the boundaries between hologram blocks, but this application is not limited to this. To this end, in an example embodiment, the mask 710 can have different pixel values ​​for the edge region 711a and the center region 711b of the region 711. For example, the pixel value of the edge region 711a can be 0.8, and the pixel value of the center region 711b can be 1.

[0103] Except for reference Figure 7A In addition to the given description, various filtering methods can be used for mask 710 to filter the hologram to allow hologram blocks to have soft edges.

[0104] By using hologram blocks with soft edges, the boundary lines between image blocks can be removed when combining image blocks generated from hologram blocks.

[0105] refer to Figure 7B Mask 720 can be configured to filter the hologram, allowing hologram blocks adjacent to another hologram block to have soft edges. Edge regions 721b of the adjacent cutoff region 722 of region 721 correspond to the boundaries between blocks and therefore may need to be blurred; however, edge regions 721a of the region 721 that do not correspond to the boundaries between blocks may not need to be blurred. Therefore, in embodiments of mask 720, edge regions 721b of the adjacent cutoff region 722 may have different pixel values ​​than the central region 721c, and edge regions 721a of the non-adjacent cutoff region 722 may have the same pixel values ​​as the central region 721c. For example, the pixel value of edge regions 721b of the adjacent cutoff region 722 may be 0.8, and the pixel values ​​of edge regions 721a of the non-adjacent cutoff region 722 and the central region 721c may be 1.

[0106] Figure 8 The illustration shows an optimized loop for generating a hologram by compensating for aberrations in a holographic display device, according to an example embodiment.

[0107] Before executing the optimization loop, the processor can generate N cores (h) corresponding to the holographic plane blocks. i ) and N masks (M iAdditionally, the processor can generate holograms with randomized phase and amplitude data.

[0108] In the optimization loop, the processor can use a mask (M) i )Covering Hologram And generate N hologram blocks

[0109] The processor can divide the hologram into blocks N image blocks (f) are generated by propagating from the holographic plane HP to the image plane IP. i Image blocks can be obtained by propagating hologram blocks in parallel. Alternatively, image blocks can be obtained by propagating hologram blocks sequentially. Propagation can be performed using hologram blocks. and kernel (h i The convolution operation is performed in the kernel (h). i Modeling the aberrations corresponding to the planar blocks of the hologram, and then using kernel-based (h) i ) Transmission of hologram blocks It can reflect the aberrations corresponding to the hologram planar blocks respectively, and then the hologram blocks can be propagated.

[0110] The processor can update the hologram To optimize image segmentation (f i The loss function is defined by the difference between the image block and the reference image block. The reference image block can be a predefined image block (P). i Pre-defined image blocks (P) i This can be obtained by spatially dividing a predetermined image in the same way as the holographic plane HP. Alternatively, it can be obtained by using a mask (M). i Obtaining a predetermined image block (P) by masking a predetermined image. i ).

[0111] The loss function can be derived from image segmentation (f i ) and predefined image blocks (P i The difference in intensity of the image blocks is defined. The loss function can be derived from the image blocks (f...). i ) and predefined image blocks (P i The root mean square definition of the difference in intensity of the loss function. In an embodiment, the loss function can be defined as Equation 3 below.

[0112] Equation 3

[0113]

[0114] In Equation 3, L represents the loss function. This represents the intensity of the image block, and This indicates the intensity of a predetermined image block.

[0115] In this embodiment, the hologram can be updated based on the following equation 4.

[0116] Equation 4

[0117]

[0118] In equation 4, b represents an arbitrary constant. This is because the kernel (h) is formed using the Zanek polynomial. i Therefore, the loss function can be distinguished. Thus, the hologram can be updated based on Equation 4.

[0119] Figure 9 The illustration is a flowchart of a method for generating a hologram by compensating for aberrations in a holographic display device, according to an example embodiment.

[0120] In Operation 910, the processor can generate a kernel by modeling each aberration of each holographic plane block corresponding to a spatial block of the holographic plane. The processor can generate the kernel using Zanek polynomials.

[0121] The processor can merge or divide holographic plane blocks based on the level of aberration. For example, the level of aberration can be determined from the magnitude of the Chanek coefficients. As another example, the level of aberration can be determined from the user's visual judgment. The processor can generate kernels corresponding to merged holographic plane blocks and kernels corresponding to divided holographic plane blocks.

[0122] In operation 920, the processor can generate masks corresponding to the holographic planar blocks respectively. The masks can include through regions and remaining cut-off regions corresponding to the holographic planar blocks. Additionally, masks can be generated in which the edge regions of the through regions have different pixel values ​​than the center regions of the through regions, allowing the holographic blocks to have soft edges.

[0123] In Operation 930, the processor can obtain hologram blocks by using a mask to spatially filter the hologram.

[0124] In Operation 940, the processor can obtain image blocks by propagating hologram blocks using the kernel. The processor can propagate the hologram blocks from the hologram plane to the image plane through convolution operations between the kernel and the hologram blocks. Because aberrations are modeled in the kernel, the hologram blocks can be propagated to reflect these aberrations.

[0125] In Operation 950, the processor can update the hologram based on a comparison between the image patch and the reference image patch. The processor can determine a loss function based on the intensity difference between the image patch and the reference image patch, and update the hologram to optimize the loss function.

[0126] Figure 10 The illustration is a flowchart of a method for generating a hologram by compensating for aberrations of a holographic display device, according to an example embodiment, including optimized loops.

[0127] Before executing optimization loop 1030, in operation 1010, the processor can generate the mask and kernel. In operation 1020, the processor can initialize the hologram. The hologram can be initialized with arbitrary phase and amplitude data.

[0128] In operation 1031, the processor can obtain hologram blocks. The processor can obtain hologram blocks by dividing the hologram using mask space.

[0129] In operation 1032, the processor can obtain image blocks. The processor can obtain image blocks by propagating hologram blocks using the kernel.

[0130] In operation 1033, the processor can determine the loss function. For example, the processor can determine the root mean square of the intensity difference between an image patch and a predetermined image patch as the loss function.

[0131] In operation 1034, the processor can update the hologram. The processor can update the hologram to optimize the loss function.

[0132] In operation 1035, the processor can determine that the optimization is complete. The processor can determine the completion of the optimization based on the value of the loss function. According to an example embodiment, the processor can determine the completion of the optimization when the value of the loss function meets a reference value. Alternatively, the processor can determine the completion of the optimization based on the number of iterations of optimization loop 1030. According to an example embodiment, the processor can determine the completion of the optimization when the number of iterations of optimization loop 1030 meets a reference number.

[0133] Figure 11A and Figure 11B The illustration shows experimental results of a method for generating holograms by compensating for aberrations in a holographic display device, according to an embodiment.

[0134] In the experiment, a light source with a wavelength of 532 nm, a reference image 1110 with 512x512 pixels, and a spatial light modulator with a pixel pitch of 3.6 μm were used. Additionally, in the experiment, the propagation distance was set to 8 mm, and the hologram plane was spatially divided into a 5x5 array. According to the example embodiment, the reference image 1110 is a predetermined image.

[0135] Figure 11A The illustration shows reference image 1110, hologram 1120 generated according to the method of the example embodiment to compensate for aberrations of the holographic display device, and holographic image 1130 reproduced from hologram 1120. Figure 11B The figure shows a graph of the peak signal-to-noise ratio (PSNR) of the holographic image 1130 based on the number of iterations of the optimization loop.

[0136] refer to Figure 11A and Figure 11B A high-quality holographic image 1130 is obtained that is virtually indistinguishable from the reference image 1110. Furthermore, by using holographic blocks generated via filtering to have soft edges, no boundary lines are generated between image blocks in the holographic image 1130. The quality of the holographic image 1130 can also be supported by PSNR.

[0137] Example embodiments may also be implemented in the form of a computer-readable recording medium that includes computer-executable commands (such as computer modules). A computer-readable recording medium can be any available medium accessible by a computer, and includes volatile and non-volatile media, and divisible and indivisible media. Additionally, a computer-readable recording medium can include both computer storage media and communication media. Computer storage media can include volatile and non-volatile media, and divisible and indivisible media, implemented by any method or technology for storing information (such as computer-readable commands, data structures, program modules, or other data). Communication media typically include other data such as modulated data signals, such as computer-readable commands, data structures, program modules, or other transmission mechanisms, and also includes any information transmission medium.

[0138] Furthermore, in this disclosure, "unit" may refer to a hardware component, such as a processor or circuit, and / or a software component executed by a hardware component (such as a processor).

[0139] The above description of this disclosure is provided by way of example only, and those skilled in the art to which this disclosure pertains will understand that the embodiments can be readily modified into other specific forms without altering the technical concept or essential technical features of this disclosure. Therefore, it should be understood that the embodiments described above are provided by way of example in each aspect and therefore do not limit this disclosure. For example, each component described as a single type of component can be implemented in a distributed manner, and similarly, components described as distributed can be implemented in an integrated manner.

[0140] The scope of this disclosure is not limited to the specific description of the exemplary embodiments, and therefore, this disclosure can be regarded as including all modifications or adaptations derived from the meaning and scope of the claims and their equivalent concepts.

[0141] It should be understood that the exemplary embodiments described herein are for descriptive purposes only and are not intended to be limiting. The description of features or aspects within each exemplary embodiment should be typically considered as other similar features or aspects that can be used in other exemplary embodiments. Although one or more exemplary embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of protection as defined by the following claims.

Claims

1. A method for compensating for aberrations generated by a holographic display device when generating a hologram to reproduce a holographic image, the method comprising: Initialize the computer-generated hologram; Generate masks corresponding to the holographic plane blocks of the holographic plane; Holographic blocks are obtained by spatial filtering of the computer-generated hologram using the mask. For each hologram block, a kernel is generated by modeling the aberration corresponding to that hologram planar block; The first image block is obtained by propagating each hologram block using the corresponding kernel; and The hologram is updated based on a comparison between the first image block and a reference image block retrieved from a memory corresponding to the hologram to be reproduced.

2. The method as described in claim 1, in, The generation of the kernel includes: The aberrations corresponding to the planar blocks of the hologram are modeled using Zanek polynomials; and Each of the kernels is generated based on each of the Zanek polynomials.

3. The method as described in claim 2, in, Modeling the aberrations corresponding to each of the Zaynek polynomials for the holographic plane block includes determining Zaynek coefficients for at least one holographic plane block by interpolating Zaynek coefficients modeled for neighboring holographic plane blocks within the holographic plane block.

4. The method as described in claim 1, in, The generation of the kernel includes: The partitioned holographic plane blocks are generated by dividing at least one of the holographic plane blocks; and The kernel is generated based on the holographic plane block division of the above division.

5. The method as described in claim 1, in, The generation of the kernel includes: A merged holographic plane block is generated by merging at least two holographic plane blocks from the holographic plane block; and The kernel within the kernel is generated based on the merged hologram planar blocks.

6. The method as described in claim 1, in, The generation of the mask includes generating at least one mask comprising a pass region corresponding to a corresponding holographic plane block and a remaining cut-off region.

7. The method as described in claim 6, in, The generation of the mask further includes: generating at least one mask in which the edge regions of the passage area have pixel values ​​different from those of the center region of the passage area.

8. The method as described in claim 6, in, The generation of the mask further includes: generating at least one mask, wherein a first edge region of the through region adjacent to the cutoff region has a different pixel value than the center region of the through region, and a second edge region of the through region not adjacent to the cutoff region has the same pixel value as the center region of the through region.

9. The method as described in claim 1, in, The first image block is obtained by propagating the hologram blocks in parallel.

10. The method as described in claim 1, in, The update of the hologram includes: A loss function is determined based on the intensity difference between the first image block and the reference image block; and The hologram is updated to optimize the loss function.

11. The method of claim 1, wherein, The hologram planar blocks are spatial blocks of the hologram plane.

12. A non-transitory computer-readable recording medium having a computer program recorded thereon for performing the method of any of the preceding claims.

13. A holographic display system, comprising: A light source, configured to emit light to reproduce a holographic image; The optical system is configured to spatially focus a holographic image; A processor configured to compensate for aberrations in the holographic display system when generating a computer-generated hologram to reproduce the holographic image; and A spatial light modulator, configured to modulate light based on the hologram, The processor is configured as follows: Initialize the computer-generated hologram; Generate masks corresponding to the holographic plane blocks of the holographic plane; Holographic blocks are obtained by spatial filtering of the computer-generated hologram using the mask. For each hologram block, a kernel is generated by modeling each aberration corresponding to that hologram planar block; The first image block is obtained by propagating each hologram block using the corresponding kernel; and The hologram is updated based on a comparison between the first image block and a reference image block retrieved from a memory corresponding to the hologram to be reproduced.

14. The holographic display system as described in claim 13, in, The processor is further configured to perform modeling of the aberrations corresponding to the hologram plane blocks using Zanek polynomials, and to generate each of the kernels based on each of the Zanek polynomials.

15. The holographic display system as described in claim 14, in, The processor is further configured to determine the Chanek coefficients for at least one holographic plane block in the holographic plane block by interpolating the Chanek coefficients modeled for neighboring holographic plane blocks in the holographic plane block.

16. The holographic display system as described in claim 13, in, The processor is further configured to generate a partitioned hologram plane block by dividing at least one of the hologram plane blocks, and to generate the kernel based on the partitioned hologram plane block.

17. The holographic display system as described in claim 13, in, The processor is further configured to generate a merged holographic plane block by merging at least two holographic plane blocks among the holographic plane blocks, and to generate a kernel within the kernel based on the merged holographic plane block among the holographic plane blocks.

18. The holographic display system as described in claim 13, in, The processor is further configured to generate at least one mask including a pass region corresponding to a corresponding holographic plane block and a remaining cut-off region.

19. The holographic display system as described in claim 18, in, The processor is further configured to generate at least one mask in which the edge regions of the passed region have pixel values ​​different from those of the center region of the passed region.

20. The holographic display system as described in claim 13, in, The processor is configured to obtain the first image block by propagating the hologram blocks in parallel.

21. The holographic display system as described in claim 13, in, The processor is further configured to determine a loss function based on the intensity difference between the first image block and the reference image block, and to update the hologram to optimize the loss function.

22. A holographic display device, comprising: Memory, which stores one or more instructions; and A processor configured to execute one or more instructions to perform the method of any one of claims 1-11.

Images