Method for determining spherical wave initial phase coefficients, hologram generation method and device

Abstract

The application provides a method for determining a spherical wave initial phase coefficient, a hologram generation method and equipment. The method comprises: setting a cyclic calculation rule of the spherical wave initial phase coefficient; cyclically calculating the spherical wave initial phase coefficient according to the cyclic calculation rule; in each calculation process, comprising: forming a hologram of a sample image based on the initial phase coefficient in the current calculation process; obtaining a reconstructed image of the hologram and a spectrum of the reconstructed image; determining a main peak position in the spectrum; and after the cyclic calculation is terminated, taking the initial phase coefficient in the calculation process corresponding to the maximum distance between the main peak position and the center spectrum as the initial phase coefficient of the spherical wave. The initial phase coefficient of the spherical wave determined by the above method considers the speckle size and periodic characteristics of the reconstructed image, so that when a hologram is added to an input image using the initial phase coefficient of the spherical wave for initial phase calculation, the speckle and high-frequency artifact noise phenomena in the reconstructed image can be suppressed, and the visual perception of the reconstructed image is improved.

Description

Technical Field

[0001] This application relates to the field of computational holography, and more specifically, to a method for determining the initial phase coefficient of a spherical wave, a method for generating holograms based on spherical waves, an electronic device, and a readable storage medium. Background Technology

[0002] Currently, most AR / VR display devices use "pseudo-3D" display technology based on binocular parallax. Prolonged use of such devices can cause visual fatigue such as blurriness and dizziness, and in severe cases, may even cause irreversible damage to the visual system. To address these issues, computational holography, which can realistically reproduce 3D scenes with depth information, has become a research hotspot in recent years.

[0003] Computational holography uses hologram generation algorithms, such as the Gerchberg-Saxton algorithm (GS algorithm), to encode information from a 3D image (RGBD image) into a phase hologram containing only phase information or an amplitude hologram containing only amplitude information. Compared to amplitude holograms, phase holograms have become the most commonly used type of hologram due to their extremely high diffraction efficiency. The phase hologram is then loaded onto a spatial light modulator (SLM), and a 3D image (i.e., a reconstructed image) can be generated in a specified space using a specific optical system. Suppressing speckle and high-frequency artifacts in the reconstructed image and improving its visual appeal is currently a hot research topic. Summary of the Invention

[0004] This application provides a method for determining the initial phase coefficient of a spherical wave, a hologram generation method, and a device that can at least partially solve the above-mentioned problems existing in related technologies.

[0005] This application provides a method for determining the initial phase coefficient of a spherical wave, comprising: setting a cyclic calculation rule for the initial phase coefficient of the spherical wave; performing cyclic calculation on the initial phase coefficient of the spherical wave according to the set cyclic calculation rule; wherein, in each calculation process, the method includes: forming a hologram of a sample image based on the initial phase coefficient of the current calculation process; obtaining a reconstructed image of the hologram and the spectrum of the reconstructed image; determining the position of the main peak in the spectrum; and after the cyclic calculation terminates, taking the initial phase coefficient of the calculation process corresponding to the maximum distance between the main peak position and the center spectrum as the initial phase coefficient of the spherical wave.

[0006] In some implementations, forming a hologram of a sample image based on the initial phase coefficients in the current calculation process includes: forming the initial phase of the spherical wave in the current calculation process based on the initial phase coefficients in the current calculation process; constructing the object plane light field distribution of the sample image by adding the formed initial phase to the sample image; and calculating the hologram of the sample image based on the constructed object plane light field distribution.

[0007] In some implementations, calculating the hologram of the sample image based on the constructed object plane light field distribution includes: calculating the phase-type hologram of the sample image using the GS algorithm based on the constructed object plane light field distribution.

[0008] In some implementations, acquiring a reconstructed image of a hologram includes acquiring an image formed by the hologram captured by an optical imaging system.

[0009] In some implementations, after determining the position of the main peak in the spectrum, each calculation process also includes: determining the distance between the position of the main peak and the center spectrum; and establishing the correspondence between the distance and the initial phase coefficient in this calculation process.

[0010] In some implementations, using the initial phase coefficient in the calculation process corresponding to the maximum distance between the main peak position and the center spectrum as the initial phase coefficient of the spherical wave includes: determining the initial phase coefficient in the calculation process corresponding to the maximum distance between the main peak position and the center spectrum based on the established correspondence; and using the determined initial phase coefficient as the initial phase coefficient of the spherical wave.

[0011] In some implementations, the grayscale value of the sample image is 255.

[0012] In some implementations, the rules for setting the cyclic calculation of the initial phase coefficient of the spherical wave include: setting the calculation formula of the initial phase coefficient of the spherical wave in the cyclic process in the form of an arithmetic sequence; and setting the maximum number of cyclic calculations as the criterion for terminating the cyclic calculation.

[0013] A hologram generation method based on spherical waves includes: determining the initial phase coefficient of a spherical wave using the method described above; forming an initial phase of the spherical wave based on the determined initial phase coefficient; constructing an object plane light field distribution of the input image by adding the initial phase of the spherical wave to the input image; and calculating a hologram of the input image based on the constructed object plane light field distribution.

[0014] A hologram generation system based on spherical waves includes:

[0015] The module for determining the initial phase coefficient is used to determine the initial phase coefficient of a spherical wave using the method described above. The module for forming the initial phase is used to form the initial phase of the spherical wave based on the determined initial phase coefficient. The module for constructing the object plane light field distribution is used to construct the object plane light field distribution of the input image by adding the initial phase of the spherical wave to the input image. The module for generating the hologram is used to generate the hologram of the input image based on the constructed object plane light field distribution.

[0016] An electronic device includes: a processor; and a memory communicatively connected to the processor, wherein the memory stores a program executable by the processor, and when the program is executed by the processor, the processor is able to execute either the method for determining the initial phase coefficient of a spherical wave as described above or the method for generating a hologram based on a spherical wave as described above.

[0017] A readable storage medium storing a computer program, which, when executed by a processor, implements either the method for determining the initial phase coefficient of a spherical wave as described above or the method for generating a hologram based on a spherical wave as described above.

[0018] The method for determining the initial phase coefficient of a spherical wave provided in at least one embodiment of this application uses the initial phase coefficient of the spherical wave as the value obtained in the calculation process when the distance between the main peak position and the center spectrum in the reconstructed image spectrum of the hologram based on the sample image is the largest. This ensures that the determined initial phase coefficient of the spherical wave is a value that takes into account the speckle size and periodicity characteristics of the reconstructed hologram image. As a result, when the spherical wave initial phase with this initial phase coefficient is added to the input image to calculate the hologram, speckle and high-frequency artifact noise in the reconstructed image of the hologram can be suppressed, thereby improving the visual quality of the reconstructed image. Attached Figure Description

[0019] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. Wherein:

[0020] Figure 1A This is a schematic diagram of the reconstructed image of the hologram obtained when a random initial phase is added to the input image according to relevant techniques;

[0021] Figure 1B yes Figure 1A A partial schematic diagram within the dashed box;

[0022] Figure 2A This is a schematic diagram of the reconstructed image of the hologram obtained when a traditional spherical wave initial phase is added to the input image according to relevant techniques;

[0023] Figure 2B yes Figure 2AA partial schematic diagram within the dashed box;

[0024] Figure 3A This is a flowchart illustrating a method for determining the initial phase coefficient of a spherical wave according to an exemplary embodiment of this application.

[0025] Figure 3B This is a schematic flowchart of a hologram generation method based on spherical waves provided according to an exemplary embodiment of this application;

[0026] Figure 4A This is a flowchart illustrating step S120 according to an embodiment of this application.

[0027] Figure 4B This is a flowchart illustrating step S121 according to an embodiment of this application;

[0028] Figure 5A This is a schematic diagram of a template image according to an embodiment of this application;

[0029] Figure 5B It is based on Figure 5A A schematic diagram of the reconstructed image of the hologram of the template image;

[0030] Figure 5C It is based on Figure 5B A schematic diagram of the spectrum of the reproduced image;

[0031] Figure 5D It is based on Figure 5C A schematic diagram of the single-sided spectrum in the horizontal direction of the center of the reproduced image;

[0032] Figure 6 This is a flowchart illustrating step S130 according to an embodiment of this application;

[0033] Figure 7A and Figure 7B This is a schematic diagram of the reconstructed image of the hologram formed by selecting the initial phase coefficients at different distances from the main peak position and the center spectrum;

[0034] Figure 8A and Figure 8B These are the reconstructed images of the holograms generated using the hologram generation method based on spherical waves proposed in this application, and their magnified local images.

[0035] Figure 9A and Figure 9B These are the reconstructed images of the holograms generated by the traditional spherical wave initial phase hologram generation algorithm and their magnified local images.

[0036] Figure 10A and Figure 10B These are the reconstructed images of holograms generated by a hologram generation algorithm based on random initial phase, and their magnified local images.

[0037] Figure 11 This is a schematic diagram of a hologram generation system based on spherical waves, an exemplary embodiment of this application;

[0038] Figure 12 This is a schematic diagram of the structure of an electronic device according to an exemplary embodiment of this application; and

[0039] Figure 13 This is a schematic diagram of the structure of an electronic device according to an exemplary embodiment of this application. Detailed Implementation

[0040] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0041] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features, especially not any order of precedence. Therefore, without departing from the teachings of this application, the first part discussed herein may also be referred to as the second part, and vice versa.

[0042] In the accompanying drawings, the thickness, dimensions, and shapes of the parts have been slightly adjusted for ease of illustration. The drawings are for illustrative purposes only and are not drawn to scale. As used herein, the terms “approximately,” “about,” and similar terms are used as expressions of approximation, not as expressions of degree, and are intended to illustrate inherent deviations in measured or calculated values ​​that will be recognized by one of ordinary skill in the art.

[0043] It should also be understood that expressions such as "comprising," "including," "having," "containing," and / or "comprising" are open-ended rather than closed-ended expressions in this specification, indicating the presence of the stated features, elements, and / or components, but not excluding the presence of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not just individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to examples or illustrations.

[0044] Unless otherwise specified, all terms used herein (including engineering and technical terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that, unless expressly stated herein, terms defined in common dictionaries shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or overly formalized meaning.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] As mentioned earlier, compared to amplitude-type holograms, phase-type holograms have become the most commonly used type of hologram at present due to their extremely high diffraction efficiency.

[0047] In existing hologram generation algorithms, adding an initial phase to the input image can effectively encode the low-frequency components in the input image into the hologram, thereby making the reconstructed image as close as possible to the input image.

[0048] Among them, random initial phase is the most common method. Taking a two-dimensional image as the input image as an example, its specific expression is as follows:

[0049]

[0050] In the formula, The initial phase is represented by the `rand()` function, which generates a random number between 0 and 1. `x` and `y` are the pixel coordinates of the two-dimensional image.

[0051] However, due to the high coherence characteristics of the laser source, the random initial phase introduces irregularly ordered granular speckle patterns into the reconstructed image, such as... Figure 1A and its local magnification Figure 1B As shown. Research has shown that using a spherical wave initial phase can reduce the difference between adjacent pixels in the initial phase, thereby achieving the goal of weakening the aforementioned speckle.

[0052] Similarly, taking a two-dimensional image as an example, the initial phase of a spherical wave can be expressed as follows:

[0053]

[0054] In the formula, The initial phase is represented by 'a', where 'a' is the initial phase coefficient of the spherical wave, and 'x' and 'y' are the corresponding pixel coordinates.

[0055] It can be seen that the above method of defining the initial phase enables the phase to change in an orderly manner from the center outwards, thereby weakening speckle.

[0056] The initial phase coefficient 'a' of a spherical wave determines the texture features of the holographic reconstruction image. However, the traditional definition of the initial phase of a spherical wave ignores this point and simply defines the value of coefficient 'a' as π / M, where M is the pixel size of the hologram.

[0057] When a traditional spherical wave initial phase is added to the input image, the resulting reconstructed hologram and its magnified local image are as follows: Figure 2A and Figure 2B As shown, while the traditional spherical wave initial phase coefficient weakens the speckle in the holographic reconstruction, it introduces numerous high-frequency artifacts, which also affect the viewing experience. In summary, random initial phase coefficients introduce speckle noise into the holographic reconstruction, while traditional spherical wave initial phase coefficients introduce high-frequency artifacts.

[0058] Based on this, an exemplary embodiment of this application provides a method for determining the initial phase coefficient of a spherical wave, comprising: setting a cyclic calculation rule for the initial phase coefficient of the spherical wave; performing cyclic calculation on the initial phase coefficient of the spherical wave according to the set cyclic calculation rule; wherein, in each calculation process, the method comprises: forming a hologram of a sample image based on the initial phase coefficient of the current calculation process; obtaining a reconstructed image of the hologram and the spectrum of the reconstructed image; determining the position of the main peak in the spectrum; and after the cyclic calculation terminates, taking the initial phase coefficient of the calculation process corresponding to the maximum distance between the main peak position and the center spectrum as the initial phase coefficient of the spherical wave. In the above-described scheme of this application, during the cyclic calculation of the initial phase coefficient of the spherical wave, the initial phase coefficient of the spherical wave is used as the initial phase coefficient of the calculation process when the distance between the main peak position and the center spectrum in the reconstructed image spectrum of the hologram based on the sample image is the largest. This makes the determined initial phase coefficient of the spherical wave a value that takes into account the speckle size and periodicity of the hologram reconstructed image. As a result, when the spherical wave initial phase with this initial phase coefficient is added to the input image to calculate the hologram, the speckle and high-frequency artifact noise in the reconstructed image of the hologram of the input image can be suppressed, and the visual quality of the reconstructed image can be improved.

[0059] In the following sections, specific examples of this solution will be described in more detail with reference to the accompanying drawings.

[0060] like Figure 3A As shown, the first embodiment of this application provides a method 1000 for determining the initial phase coefficient of a spherical wave. For example... Figure 3A As shown, the method 1000 for determining the initial phase coefficient of a spherical wave includes the following steps:

[0061] S110. Set the cyclic calculation rules for the initial phase coefficient of the spherical wave;

[0062] S120, the initial phase coefficient of the spherical wave is calculated iteratively according to the set cyclic calculation rules; wherein, in each calculation process, a hologram of a sample image is formed based on the initial phase coefficient of the current calculation process; the reconstructed image of the hologram and its spectrum are obtained; the position of the main peak in the spectrum is determined; and

[0063] S130, after the loop calculation terminates, the initial phase coefficient in the calculation process corresponding to the maximum distance between the main peak position and the center spectrum is taken as the initial phase coefficient of the spherical wave.

[0064] It should be understood that the steps shown in the method 1000 for determining the initial phase coefficient of a spherical wave are not exclusive, and other steps may be performed before, after, or between any of the steps shown. Furthermore, some of the steps described above may be performed simultaneously or in a manner different from [the steps described above]. Figure 3A The execution order is shown below. (Followed by...) Figure 3A , Figures 4A to 7B The steps S110 to S130 described above are further described.

[0065] S110

[0066] The initial phase of the spherical wave as shown in equation (2) above The expression is as follows:

[0067]

[0068] In the formula, 'a' is the initial phase coefficient of the spherical wave, and 'x' and 'y' are the corresponding pixel coordinates. The magnitude of the initial phase coefficient 'a' directly determines the speckle characteristics of the holographic reconstruction.

[0069] Optionally, in step S110, the cyclic calculation formula for the initial phase coefficient of the spherical wave is set in the form of an arithmetic sequence as follows:

[0070] a n =a0+(n-1)Δa (3)

[0071] In the formula, a n Let be the initial phase coefficient of the spherical wave in the nth calculation process, where a0 is a preset initial value, n is the number of iterations, and Δa is the step size. For example:

[0072] In the first calculation, a1 = a0;

[0073] In the second calculation, a2 = a0 + Δa;

[0074] In the third calculation, a3 = a0 + 2Δa;

[0075] And so on, in the nth calculation, an = a0 + (n-1)Δa.

[0076] Optionally, the preset initial value a0 is π / M, where M is the pixel size of the hologram.

[0077] Step S110 also determines the termination condition for the cyclic calculation of the initial phase coefficient.

[0078] In some implementations, the termination condition for the loop calculation is n > N, where N is the number of samples. N can be any positive integer greater than 1; the larger N is, the larger the search range and the more accurate the result. For example, N is any value between 10 and 10000. Alternatively, N is any value between 50 and 5000.

[0079] Therefore, the range of the initial phase coefficient a of the spherical wave in this application is a∈[a0, a0+(N-1)Δa].

[0080] It should be noted that, depending on the preset initial value and termination condition, the range of the initial phase coefficient 'a' can be from 0 to infinity.

[0081] Furthermore, although this application presents the relevant technical solutions in the form of an arithmetic sequence, the technical solutions of this application are also applicable to a set of initial phase coefficients of spherical waves determined in the form of a geometric sequence or a variable step size, and this application does not impose any restrictions on this.

[0082] S120

[0083] After determining the cyclic calculation formula and termination condition for the initial phase coefficient of the spherical wave in step S110, the initial phase coefficient of the spherical wave is cyclically calculated in step S120.

[0084] like Figure 4A As shown, each calculation process in step S120 includes the following steps in sequence:

[0085] S121. A hologram of the sample image is formed based on the initial phase coefficients in this calculation process;

[0086] S122, Obtain the reconstructed image of the hologram and the spectrum of the reconstructed image; and

[0087] S123. Determine the position of the main peak in the spectrum.

[0088] The above steps determine the position of the main peak in the spectrum of the reconstructed image of the hologram based on the sample image, so that the initial phase coefficient in the calculation process corresponding to the maximum distance between the main peak position and the center spectrum can be used as the initial phase coefficient of the spherical wave in subsequent steps.

[0089] In some implementations, such as Figure 4B As shown, step S121 includes:

[0090] S1211. The initial phase of the spherical wave in this calculation process is formed based on the initial phase coefficient.

[0091] S1212, Constructing the object plane light field distribution of the sample image by attaching the initial phase formed therefrom; and

[0092] S1213. Calculate the hologram of the sample image based on the constructed object plane light field distribution.

[0093] Specifically, after the calculation begins, when n=1, it is the first calculation process, and the initial phase coefficient a1=a0 in the first calculation process.

[0094] In step S1211, the initial phase of the spherical wave in this calculation process is formed based on the initial phase coefficient a1. In step S1212, the initial phase formed in step S1211 is added to the sample image to construct the object plane light field amplitude distribution for the sample image. Where u0 is the initial amplitude of the sample image, j 2 =-1. In some implementations, such as Figure 5A As shown, the grayscale value of the sample image is 255. A grayscale image with all grayscale values ​​of 255 represents a pure white image. The reconstructed image corresponding to a pure white image only has speckle and no other interference information. Therefore, the spectrum corresponding to the reconstructed image is relatively simple. This application uses a pure white image as the sample image, which is beneficial for selecting the initial phase coefficient of the spherical wave. In step S1213, the hologram of the sample image is calculated based on the object plane light field distribution constructed in step S1212.

[0095] Optionally, in step S1213, the phase hologram of the sample image is calculated using the GS algorithm based on the object plane light field distribution constructed in step S1212.

[0096] It should be noted here that, based on the light field distribution on the object plane, the GS algorithm is used to calculate the phase hologram of the sample image. The specific implementation process can be referred to by those skilled in the art under the guidance of this application, and will not be elaborated here.

[0097] After forming a hologram of the sample image in step S121, the reconstructed image of the hologram and the spectrum of the reconstructed image are obtained in step S122.

[0098] In some implementations, obtaining the reconstructed image of the hologram in step S122 includes receiving an image formed by the hologram captured by an optical imaging system.

[0099] Specifically, the hologram formed in step S1213 Loaded onto a spatial light modulator, and then captured by a camera, the holographic reconstruction of the sample image is recorded in a manner that produces a realistic reconstructed image through an optical imaging system. (Refer to...) Figure 5B As shown.

[0100] The above-mentioned solution of this application introduces a strategy of real-time camera-captured image reconstruction, which enables the reconstructed image of the hologram to include noise components introduced by factors such as optical system aberrations, thus ensuring the accuracy of determining the initial phase coefficient of the spherical wave. This is because in related technologies, the reconstructed image of the hologram is generally obtained through simulation, but the simulation results of the reconstructed image cannot accurately reflect its speckle characteristics. At the same time, the light propagation model used in the simulation has a certain gap with the actual optical system. Therefore, this application uses the method of real-time camera-captured image reconstruction to solve the above problems.

[0101] Continuing in step S122, the spectrum of the reconstructed image is obtained. Taking the sample image as a two-dimensional image as an example, the two-dimensional spectrum of the reconstructed image of the sample image hologram is referenced. Figure 5C As shown. It should be noted that although this application uses two-dimensional images as an example, all the methods involved in this application are equally applicable to three-dimensional images.

[0102] In step S123, the location of the main peak of the aforementioned spectrum is determined. Optionally, considering the even function characteristic of the spectrum, it is only necessary to analyze the single-sided spectrum in the central horizontal direction, such as... Figure 5C As shown within the dashed box. It should be noted that... Figure 5C The result shown is the result after taking the logarithm of the spectrum. Figure 5D This is the single-sided spectrum along the horizontal direction of the center of the holographic image. For example... Figure 5D As shown, the main peak in the spectrum is as follows Figure 5D As indicated by the asterisk (*), the definition of the main peak in this application is as follows: 1) the maximum point in the spectrum, that is, the intensity of the point is greater than the intensity of the points to the left and right; 2) the point with the greatest intensity among all the maximum points.

[0103] In some implementations, reference continues. Figure 4A As shown, after determining the position of the main peak in the spectrum in step S123, each calculation process also includes:

[0104] S124. Determine the distance between the main peak position and the center spectrum; and

[0105] S125. Establish the correspondence between the above distance and the initial phase coefficient in this calculation process.

[0106] Specifically, in the first calculation process, after determining the main peak, the distance dis1 of the main peak relative to the center spectrum can be calculated in step S124, and the correspondence between the initial phase coefficient a1 and the distance dis1 in this calculation process can be recorded in step S125. For example, (coefficient a, distance dis) data pairs can be formed and stored.

[0107] This concludes the first calculation process.

[0108] Then, the termination condition of the loop calculation is used to determine whether the loop calculation has ended. If n <= N, then n = n + 1, and return to step S120 to continue the next loop calculation. If n > N, then the loop calculation ends.

[0109] For example, after the loop calculation is completed, multiple sets of data pairs (coefficient a, distance dis) can be obtained. For instance:

[0110] The result obtained from the first iteration: (coefficient a1, distance dis1);

[0111] The result obtained from the second iteration: (coefficient a2, distance dis2);

[0112] The result obtained from the third iteration: (coefficient a3, distance dis3);

[0113] The result obtained from the nth iteration: (coefficient a) n Distance n );

[0114] ...

[0115] The result obtained from the Nth iteration: (coefficient a) N Distance N ).

[0116] S130

[0117] In step S130, the initial phase coefficient in the calculation process corresponding to the maximum distance between the main peak position and the center spectrum is taken as the initial phase coefficient of the spherical wave.

[0118] In some implementations, such as Figure 6 As shown, step S130 includes:

[0119] S131. Based on the established correspondence, determine the initial phase coefficient in the iterative calculation process corresponding to the maximum distance between the main peak position and the center spectrum; and

[0120] S132. The determined initial phase coefficient is used as the initial phase coefficient of the spherical wave.

[0121] The position of the main peak in the spectrum reflects the size and periodicity of the speckle on the reconstructed hologram image. The farther the main peak is from the center of the spectrum, the smaller the speckle size and the smaller the period, thus making the reconstructed hologram image appear more delicate.

[0122] Based on extensive experimental results, for holograms with a pixel size of 1080*1080, a suitable range for the initial phase coefficient 'a' is approximately between 150 and 200. Furthermore, the initial phase coefficient 'a' of the spherical wave determined using the method described above in this application is typically greater than 100, while the initial phase coefficient of the spherical wave determined using existing related technologies is typically less than 1. Therefore, the initial phase of the spherical wave in this application can also be referred to as the large-coefficient spherical wave initial phase.

[0123] Figure 7A and Figure 7B The reconstructed images of the holograms of the template image are shown at distances of dis = 150 lp / mm and dis = 50 lp / mm, respectively. It is easy to see that... Figure 7A The period and size of the speckle are significantly smaller than those of the medium speckle. Figure 7B The period and size of the speckle demonstrate the feasibility of the spherical wave coefficient selection method described above in this application.

[0124] The above-mentioned solution in this application has the following characteristics:

[0125] 1) When determining the initial phase coefficient of the spherical wave, using a pure white image as input can make the reconstructed image clearly show the speckle characteristics without other interfering factors, which simplifies the difficulty of spectrum analysis of the reconstructed image.

[0126] 2) By analyzing the spectral characteristics of the reconstructed image, the speckle size and periodicity are determined, which in turn guides the selection of the initial phase coefficient of the spherical wave, thereby suppressing speckle and high-frequency artifact noise in the reconstructed image of the hologram.

[0127] 3) By taking actual photos with a camera, the influence of factors such as optical system aberrations on the quality of the reproduced image can be recorded, so that the error of the actual optical system can be fully considered when selecting the initial phase coefficient of the spherical wave, thus ensuring the accuracy of the selection of the initial phase coefficient of the spherical wave.

[0128] This application also provides an exemplary second embodiment of a hologram generation method 2000 based on spherical waves, such as... Figure 3B As shown, it includes the following steps:

[0129] S210. The initial phase coefficient of the spherical wave is determined using the method for determining the initial phase coefficient of the spherical wave, and the initial phase of the spherical wave is formed based on the determined initial phase coefficient.

[0130] S220, Adding the initial phase of a spherical wave to the input image to construct the object plane light field distribution of the input image; and

[0131] S230. Calculate the hologram of the input image based on the constructed object plane light field distribution.

[0132] Specifically, according to the above-described embodiments, such as Figure 3A The method 1000 shown for determining the initial phase coefficient of a spherical wave determines the initial phase coefficient 'a' of the spherical wave, and a large coefficient spherical wave initial phase coefficient is constructed. Then, together with the input image u0, the light field distribution u of the object plane is constructed, which is expressed in the following form:

[0133]

[0134] In the formula, u0 represents the initial amplitude of the input image. The remaining parameters can be found in the explanations in Method 1000.

[0135] Then, the GS algorithm is used to calculate the hologram corresponding to the input image based on the object plane light field distribution u.

[0136] Figure 8A and Figure 8B The reconstructed images and their magnified local views of the holograms generated using the spherical wave-based hologram generation method proposed in this application are shown respectively.

[0137] To illustrate the differences between this application and related technologies, Figure 9A and Figure 9B as well as Figure 10A and Figure 10B These are the reconstructed images and their magnified local images of the holograms generated by the traditional spherical wave initial phase generation algorithm and the hologram generation algorithm based on random initial phase, respectively.

[0138] from Figure 8A and Figure 8B , Figure 9A and Figure 9B as well as Figure 10A and Figure 10B As can be seen from the data, the overall appearance of the reconstructed image corresponding to the hologram generated by this application is significantly better than that of traditional algorithms. Its speckle pattern is uniformly and periodically distributed, and the speckle size is also smaller.

[0139] This application also provides an exemplary third embodiment of a hologram generation system 3000 based on spherical waves, such as... Figure 11 As shown, it includes:

[0140] The initial phase coefficient determination module 310 is used to determine the initial phase coefficient of the spherical wave using the spherical wave initial phase coefficient determination method 1000 as described above.

[0141] The initial phase forming module 320 is used to form the initial phase of the spherical wave according to the determined initial phase coefficient;

[0142] The object plane light field distribution construction module 330 is used to attach the initial phase of the spherical wave to the input image to construct the object plane light field distribution of the input image; and

[0143] The hologram generation module 340 is used to generate a hologram of the input image based on the constructed object plane light field distribution.

[0144] The hologram generation system 3000 based on spherical waves provided in this application is used to implement, for example... Figure 3B The hologram generation method 2000 based on spherical waves is shown. Therefore, the specific implementation process of the hologram generation system 3000 based on spherical waves can refer to the above scheme, and will not be repeated here.

[0145] Furthermore, based on the above-mentioned method for determining the initial phase coefficient of spherical waves or the hologram generation method based on spherical waves, embodiments of this application also provide an electronic device, such as a server or a cloud server.

[0146] Figure 12 A schematic diagram of the structure of an electronic device according to a first exemplary embodiment of this application is shown.

[0147] like Figure 12 As shown, the electronic device includes: at least one processor 701; and a memory 702 communicatively connected to the at least one processor 701; wherein the memory stores instructions executable by the at least one processor 701, which, when executed by the at least one processor 701, enable the at least one processor 701 to perform the method for determining the initial phase coefficient of a spherical wave or the method for generating a hologram based on a spherical wave mentioned in the above embodiments. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present application described and / or claimed herein.

[0148] Figure 13 A schematic diagram of the structure of an electronic device according to a second exemplary embodiment of this application is shown.

[0149] like Figure 13As shown, the electronic device may also include, for example, an I / O interface 703, an input unit 704, an output unit 705, a communication unit 706, a read-only memory (ROM) 707, and a random access memory (RAM) 708. Specifically, the processor 701 can perform various appropriate actions and processes according to a computer program stored in the ROM 707 or a computer program loaded from the memory 702 into the RAM 708. The RAM 708 may also store various programs and data required for the operation of the electronic device. The processor 701, ROM 707, and RAM 708 are interconnected via a bus 709. The I / O interface (input / output interface) 703 is also connected to the bus 709.

[0150] Multiple components in the electronic device are connected to the I / O interface 703, including: an input unit 704, such as a keyboard, mouse, etc.; an output unit 705, such as various types of displays, speakers, etc.; a memory 702, such as a disk, optical disk, etc.; and a communication unit 706, such as a network card, modem, wireless transceiver, etc. The communication unit 706 allows the electronic device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0151] Processor 701 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 701 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 701 performs the various methods and processes described above, such as methods for determining the initial phase coefficient of spherical waves or methods for generating holograms based on spherical waves. For example, in some embodiments, methods for determining the initial phase coefficient of spherical waves or methods for generating holograms based on spherical waves can be implemented as computer software programs tangibly contained in a computer-readable storage medium, such as memory 702. In some embodiments, part or all of the computer program can be loaded and / or installed on an electronic device via ROM 707 and / or communication unit 706. When the computer program is loaded into RAM 708 and executed by processor 701, one or more steps of the methods for determining the initial phase coefficient of spherical waves or methods for generating holograms based on spherical waves described above can be performed. Alternatively, in other embodiments, the processor 701 may be configured by any other suitable means (e.g., by means of firmware) to perform a method for determining the initial phase coefficients of spherical waves or a method for generating holograms based on spherical waves.

[0152] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0153] The program code for implementing the methods of this application may be written in any combination of one or more programming languages. The program code may be packaged into a computer program product. This program code or computer program product may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by processor 701, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a computer, partially on a computer, partially on a remote computer as a standalone software package, or entirely on a remote computer or server.

[0154] For a detailed description of the electronic device and its beneficial effects, please refer to the description of the method for determining the initial phase coefficient of spherical waves or the method for generating holograms based on spherical waves, which will not be repeated here.

[0155] Furthermore, it should be noted that this application also provides a computer-readable storage medium storing a computer program executed by the aforementioned method for determining the initial phase coefficient of spherical waves or the hologram generation method based on spherical waves. The computer program includes program instructions, which, when executed by the processor, enable the execution of the aforementioned method for determining the initial phase coefficient of spherical waves or the hologram generation method based on spherical waves. Therefore, these descriptions will not be repeated here. Additionally, the beneficial effects of using the same method will not be repeated here either. For technical details not disclosed in the embodiments of the computer-readable storage medium involved in this application, please refer to the description of the method embodiments of this application.

[0156] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0157] The above description is merely an illustration of the embodiments of this application and the technical principles employed. Those skilled in the art should understand that the scope of protection involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the technical concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for determining the initial phase coefficient of a spherical wave, characterized in that, include: Define the cyclic calculation rules for the initial phase coefficient of spherical waves; The initial phase coefficient of the spherical wave is calculated cyclically according to the established cyclic calculation rules; wherein each calculation process includes: A hologram of the sample image is formed based on the initial phase coefficients obtained in this calculation process; Obtain the reconstructed image of the hologram and the spectrum of the reconstructed image; Determine the position of the main peak in the spectrum; and After the cyclic calculation terminates, the initial phase coefficient in the calculation process corresponding to the maximum distance between the main peak position and the center spectrum is taken as the initial phase coefficient of the spherical wave.

2. The determination method according to claim 1, characterized in that, The holograms of the sample images formed based on the initial phase coefficients in this calculation process include: The initial phase of the spherical wave in this calculation is formed based on the initial phase coefficient. The initial phase is attached to the sample image to construct the object plane light field distribution of the sample image; and A hologram of the sample image is formed based on the constructed object plane light field distribution.

3. The determination method according to claim 2, characterized in that, The hologram of the sample image is formed based on the constructed object plane light field distribution, including: Based on the constructed object plane light field distribution, the phase hologram of the sample image is calculated using the GS algorithm.

4. The determination method according to claim 1, characterized in that, Obtaining the reconstructed image of the hologram includes: The image formed by the hologram is acquired by the optical imaging system.

5. The determination method according to claim 1, characterized in that, After determining the position of the main peak in the spectrum, each calculation process also includes: Determine the distance between the main peak position of the spectrum and the center spectrum; and Establish the correspondence between the distance and the initial phase coefficient in this calculation process.

6. The determination method according to claim 5, characterized in that, The initial phase coefficient used in the calculation process when the distance between the main peak position and the center spectrum is maximized is taken as the initial phase coefficient of the spherical wave, including: Based on the established correspondence, the initial phase coefficient in the calculation process corresponding to the maximum distance between the main peak position and the center spectrum is determined; and The determined initial phase coefficient is used as the initial phase coefficient of the spherical wave.

7. The determining method according to any one of claims 1 to 6, characterized in that, The grayscale value of the sample image is 255.

8. The determining method according to any one of claims 1 to 6, characterized in that, The cyclic calculation rules for the initial phase coefficient of spherical waves include: The formula for calculating the initial phase coefficient of the spherical wave during the cyclic process is defined in the form of an arithmetic sequence; and Set a maximum number of iterations as the condition for terminating the loop.

9. A hologram generation method based on spherical waves, characterized in that, include: The initial phase coefficient of the spherical wave is determined using the method for determining the initial phase coefficient of the spherical wave as described in any one of claims 1 to 8. The initial phase of the spherical wave is formed based on the determined initial phase coefficient; The initial phase of the spherical wave is added to the input image to construct the object plane light field distribution of the input image; as well as A hologram of the input image is generated based on the constructed object plane light field distribution.

10. A hologram generation system based on spherical waves, characterized in that, include: The initial phase coefficient determination module is used to determine the initial phase coefficient of a spherical wave using the method for determining the initial phase coefficient of a spherical wave as described in any one of claims 1 to 8. An initial phase forming module is used to form the initial phase of the spherical wave based on the determined initial phase coefficient; The object plane light field distribution construction module is used to attach the initial phase of the spherical wave to the input image to construct the object plane light field distribution of the input image; as well as The hologram generation module is used to generate a hologram of the input image based on the constructed object plane light field distribution.

11. An electronic device, characterized in that, include: processor; as well as A memory, communicatively connected to the processor, wherein the memory stores a program executable by the processor, and when the program is executed by the processor, the processor is able to execute the method for determining the initial phase coefficient of a spherical wave according to any one of claims 1 to 8 or the method for generating a hologram based on a spherical wave according to claim 9.

12. A readable storage medium, characterized in that, The readable storage medium stores a computer program, which, when executed by a processor, implements the method for determining the initial phase coefficient of a spherical wave according to any one of claims 1 to 8 or the method for generating a hologram based on a spherical wave according to claim 9.

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