A method and system for enhancing holographic photography display effect

Abstract

The present application relates to the field of image processing technology, and specifically to a method and system for enhancing the display effect of holographic photography, the method comprising: acquiring a digital holographic image; obtaining the holographic image focusing degree of each pixel point; then obtaining the holographic background pixel point and the holographic focus pixel point; obtaining the difference between the low pixel interval and the high pixel interval; calculating the holographic low pixel compensation parameter and the holographic high pixel compensation parameter of the digital holographic standard image; then obtaining the target amplitude balanced image; optimizing the iterative process of the holographic background pixel point and the holographic focus pixel point based on the target amplitude balanced image, and obtaining a pure phase hologram. The present application enhances the display effect of the holographic image.

Description

Technical Field

[0001] The present application relates to the field of image processing technology, and in particular to a method and system for enhancing holographic photography display effects. Background Art

[0002] Holographic display technology has extensive research value and application prospects due to its unique characteristics that can meet the requirements of the human visual system, and is often used in industrial and commercial scenarios. Computer-generated holographic display technology can obtain coherent fringes through numerical calculations, generate computational holograms of scenes or objects, and use spatial light modulators to load and reconstruct fringes, overcoming the complexity of preparing holograms by optical methods, unstable performance, and storage difficulties, greatly reducing the difficulty of realizing holographic display.

[0003] At present, it is difficult to achieve simultaneous modulation of amplitude and phase due to the modulation characteristics of spatial light modulators. Therefore, when using spatial light modulators for holographic display, it is necessary to encode the complex amplitude of the object light wave into an amplitude-type or phase-type computational hologram. The GS algorithm reduces the error until the design requirements are met by iterating and updating the respective constraints in the two planes of the digital holographic standard image and the pure phase hologram. However, the loss of amplitude information caused by the GS algorithm leads to the inaccuracy of the pure phase hologram, which makes the pixels with higher and lower amplitudes in the hologram introduce larger errors when reconstructing the hologram, thus affecting the quality of the reconstructed image and reducing the display effect of the hologram. How to reduce the errors of pure phase holograms in the optical reconstruction process and further improve the quality of the reconstructed image is a problem that needs to be solved urgently. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide a method and system for enhancing the display effect of holographic photography. The technical solutions adopted are as follows:

[0005] In a first aspect, an embodiment of the present application provides a method for enhancing a holographic photography display effect, the method comprising the following steps:

[0006] Acquire a digital holographic image; obtain the focusing degree of the holographic image of each pixel based on the amplitude information of the pixel points and the distance between the pixel points in the digital holographic image;

[0007] Based on the amplitude information and phase information of the pixel points in the digital holographic image and the focusing degree of the holographic image, the holographic background pixel points and the holographic focus pixel points in the digital holographic standard image are obtained;

[0008] Based on the difference between the normalized amplitude information and the quartile in the digital holographic standard image, the low pixel interval difference and the high pixel interval difference are obtained;

[0009] Based on the normalized amplitude information, the low pixel interval difference and the high pixel interval difference in the digital holographic standard image, a holographic low pixel compensation parameter and a holographic high pixel compensation parameter of the digital holographic standard image are obtained;

[0010] Based on the holographic low pixel compensation parameter and the holographic high pixel compensation parameter, combined with the normalized amplitude information in the digital holographic standard image, a target amplitude balanced image is obtained;

[0011] The iterative process of optimizing the holographic background pixels and holographic focus pixels is based on the target amplitude equalization image to obtain a pure phase hologram.

[0012] Furthermore, the method for acquiring the focusing degree of the holographic image is:

[0013] Extracting amplitude information of corresponding pixel points in the digital holographic image to form a digital holographic amplitude image;

[0014] For each pixel point in the digital holographic amplitude image, a window with a side length of a preset length is taken as the holographic focusing window of each pixel point with the pixel point as the center;

[0015] Obtaining the distance between each corner point and the central pixel point in the holographic focusing window as a first distance, and recording the sum of the first distance and a preset adjustment factor as a corner point discrete weight;

[0016] Calculating the focus concentration of each corner point based on the discrete weight of the corner point, wherein the focus concentration is negatively correlated with the discrete weight of the corner point;

[0017] According to the number of corner points in the holographic focusing window and the focus concentration of each corner point, the focus of the holographic image of each pixel is obtained, and the focus of the holographic image is positively correlated with the focus concentration and the number of corner points respectively.

[0018] Furthermore, the step of obtaining the holographic background pixel points and the holographic focus pixel points in the digital holographic standard image includes:

[0019] Normalizing the amplitude information of the pixels in the digital holographic image, using the normalized amplitude information as the normalized amplitude information of the pixels, and using the image composed of the pixels constructed by the normalized amplitude information and the phase information as the digital holographic standard image;

[0020] The holographic image focusing degree of each pixel in the digital holographic standard image is taken as input, and the Otsu threshold method is used to output the focusing degree threshold; the pixel points whose holographic image focusing degree is less than or equal to the focusing degree threshold are taken as holographic background pixel points, and the pixel points whose holographic image focusing degree is greater than the focusing degree threshold are taken as holographic focus pixel points.

[0021] Furthermore, the method for obtaining the low pixel interval difference and the high pixel interval difference is:

[0022] Obtain the quartiles of the normalized amplitude information of all pixels in the digital holographic standard image;

[0023] The mean of the normalized amplitude information of all pixels in the digital holographic standard image is taken as the first normalized mean, and the absolute value of the difference between the first normalized mean and the first quartile is calculated as the low pixel interval difference; the absolute value of the difference between the first normalized mean and the third quartile is calculated as the high pixel interval difference.

[0024] Furthermore, the method for obtaining the holographic low pixel compensation parameters is:

[0025] Calculating the product of the first quartile of the normalized amplitude information of the digital holographic standard image and the low pixel interval difference as a first product, and determining the holographic low pixel compensation parameter based on the first product; wherein the first product and the holographic low pixel compensation parameter are negatively correlated;

[0026] The sum of the low pixel compensation reference index and the preset holographic compensation parameter adjustment factor is calculated as the first compensation sum value, and the product of the first compensation sum value and the preset holographic low pixel basic compensation parameter is used as the holographic low pixel compensation parameter.

[0027] Furthermore, the method for obtaining the holographic high pixel compensation parameters is:

[0028] Calculate the product of the third quartile of the normalized amplitude information of the digital holographic standard image and the high pixel interval difference as the second product, and calculate the result of an exponential function with a natural constant as the base and a negative value of the second product as the exponent as the high pixel compensation reference index;

[0029] The sum of the high pixel compensation reference index and the preset holographic compensation parameter adjustment factor is calculated as the second compensation sum value, and the product of the second compensation sum value and the preset holographic high pixel basic compensation parameter is used as the holographic high pixel compensation parameter.

[0030] Furthermore, the method for acquiring the target amplitude equalization image is:

[0031] When the normalized amplitude information of the pixel in the digital holographic standard image is less than the holographic low pixel compensation parameter, the gray value of the pixel corresponding to the target amplitude equalization image is 0;

[0032] When the normalized amplitude information of the pixel in the digital holographic standard image is greater than the holographic high pixel compensation parameter, the corresponding target amplitude equalization image pixel grayscale value is 1;

[0033] When the normalized amplitude information of the pixel point in the digital holographic standard image is greater than or equal to the holographic low pixel compensation parameter and less than or equal to the holographic high pixel compensation parameter, the absolute value of the difference between the normalized amplitude information of the pixel point of the digital holographic standard image and the holographic low pixel compensation parameter is taken as the first absolute value of the difference, the absolute value of the difference between the holographic low pixel compensation parameter and the holographic high pixel compensation parameter is taken as the second absolute value of the difference, and the rounded-up value of the ratio of the first absolute value of the difference to the second absolute value of the difference is taken as the grayscale value of the pixel point in the corresponding target amplitude equalization image.

[0034] Furthermore, the iterative process of the holographic background pixel points and the holographic focus pixel points includes:

[0035] The iterative process of the iterative algorithm is divided into a pre-iteration part and a post-iteration part;

[0036] For the pre-iteration part of the holographic background pixels and the holographic focus pixels, the grayscale values ​​of the pixels of the target amplitude equalization image are used as new amplitude constraints;

[0037] For the post-iteration part of the holographic background pixels, the gray value of the digital holographic standard image is used as the amplitude constraint condition;

[0038] For the post-iteration part of the holographic focus pixel point, the ratio of the grayscale value of the pixel point of the digital holographic standard image to the amplitude constraint condition of the previous algorithm iteration is used as the first constraint ratio, and the calculation result of the exponential function with the first constraint ratio as the base and the normalized holographic image focusing degree as the exponent is used as the amplitude constraint condition of each holographic focus pixel point in the current iteration.

[0039] Furthermore, the pure phase hologram is an image obtained by pre-iteration and post-iteration of holographic background pixels and holographic focus pixels.

[0040] In a second aspect, an embodiment of the present application further provides a holographic photography display effect enhancement system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of any one of the above-mentioned methods when executing the computer program.

[0041] This application has at least the following beneficial effects:

[0042] According to the number and distribution of corner points of the holographic focusing window in the digital holographic image, the focusing degree of the holographic image is calculated, and the pixels of the corresponding digital holographic standard image are divided into holographic background pixels and holographic focus pixels, so as to improve the compensation of holographic focus pixels in subsequent processing. By analyzing the distribution of the grayscale histogram of the digital holographic standard image, the adaptive holographic low pixel compensation parameters and holographic high pixel compensation parameters are calculated, and the pixels of the digital holographic standard image are divided into low grayscale area, medium grayscale area and high grayscale area, so as to improve the compensation effect of pixels with lower and higher grayscale values. The GS algorithm is divided into two parts: pre-iteration and post-iteration. In the pre-iteration, the adjusted grayscale value of the digital holographic standard image is used as the amplitude constraint condition of the GS algorithm. According to the compensation of the grayscale on both sides of the grayscale histogram of the digital holographic standard image, the protection of the amplitude information of the digital holographic standard image in the iteration process is enhanced, so as to obtain a higher quality pure phase hologram. In the post-iteration, the amplitude constraint condition of the holographic focus pixel is iteratively optimized to reduce the loss of amplitude information in the process of converting the digital holographic standard image into a pure phase hologram. By adopting the improved GS algorithm, the error generated in the reconstruction process of pure phase holograms is fundamentally reduced. By distinguishing the holographic background pixels and holographic focus pixels in the digital holographic standard image, the additional calculation amount is reduced, and a more accurate pure phase hologram is generated, thereby enhancing the display effect of the holographic image. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 A flowchart of a method for enhancing holographic photography display effects provided in one embodiment of the present application;

[0045] Figure 2 A flow chart for obtaining a pure phase hologram provided for one embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following is a detailed description of a holographic photography display effect enhancement method and system proposed in accordance with the present application, its specific implementation, structure, features and effects, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0047] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0048] The following is a detailed description of a method and system for enhancing holographic photography display effects provided by the present application in conjunction with the accompanying drawings.

[0049] See also Figure 1 , which shows a flowchart of a method for enhancing holographic photography display effects provided by an embodiment of the present application, the method comprising the following steps:

[0050] Step S1, collect the digital image in the holographic photography, and record the digital image obtained by the holographic photography as a digital holographic image. Among them, the holographic image is a complex-valued image, which reconstructs the three-dimensional shape of the object by recording the interference pattern of light waves. When two light waves meet, they will produce an interference pattern, which records the phase and amplitude information of the light waves reflected or transmitted by the object, that is, the holographic image carries both the amplitude information and the phase information of the object.

[0051] Step S2, according to the number and distribution of corner points in the digital holographic image, calculate the focusing degree of the holographic image, and divide the pixels of the corresponding digital holographic standard image into holographic background pixels and holographic focus pixels. By analyzing the distribution of the grayscale histogram of the digital holographic standard image, calculate the adaptive holographic low pixel compensation parameters and holographic high pixel compensation parameters. According to the division of different pixels, adjust the grayscale histogram of the digital holographic standard image. Divide the iterative process of the GS algorithm into two parts, pre-iteration and post-iteration, and improve the GS algorithm. Use the improved GS algorithm to process the digital holographic standard image to complete the conversion of the pure phase hologram.

[0052] Digital holographic images are limited by the modulation characteristics of spatial light modulators, making it difficult to achieve simultaneous modulation of amplitude and phase.

[0053] The pixels in the digital holographic image carry both the amplitude information and phase information of the object, where the amplitude information is the grayscale value of each pixel in the digital holographic image. The grayscale values ​​of the corresponding pixels in the digital holographic image are extracted to form a grayscale image, which is recorded as the digital holographic amplitude image.

[0054] For each pixel point in the digital holographic amplitude image, a window with a side length of W is taken as the holographic focusing window of each pixel point, with the pixel point as the center. In this embodiment, the value of W is 15. The pixel points in each holographic focusing window are used as the input of the Harris corner point detection algorithm, and the number of corner points in the holographic focusing window and the position of each corner point are output.

[0055] Furthermore, in order to analyze the amount of information contained in the pixel points in the digital holographic image and calculate the focusing degree of the holographic image, the method for obtaining the focusing degree of the holographic image is as follows:

[0056] The distance between each corner point and the central pixel point in the holographic focusing window is obtained as the first distance, and the sum of the first distance and the preset adjustment factor is recorded as the discrete weight of the corner point. In this embodiment, Manhattan distance is selected as the distance metric, and the implementer can select it according to the actual situation; the value of the preset adjustment factor is 1.

[0057] Secondly, the focus concentration of each corner point is calculated based on the discrete weight of the corner point, and the focus concentration is negatively correlated with the discrete weight of the corner point. The focus concentration reflects the concentration degree of the corner points in the holographic focus window to the center pixel of the window.

[0058] It should be noted that the negative correlation relationship can be a subtraction relationship, a division relationship, etc., which can be determined according to actual conditions and will not be elaborated in this application.

[0059] Specifically, the present application proposes an embodiment in which the inverse of the square of the discrete weight of the corner point is used as the focus concentration.

[0060] Furthermore, the present application proposes another embodiment, in which the calculation result of an exponential function with a natural constant as the base and a negative value of the corner point discrete weight as the exponent is used as the focusing concentration.

[0061] The closer the corner point is to the central pixel in the holographic focusing window, the greater the concentration of the corner point on the central pixel, the greater the focus concentration of the window, and the greater the amount of information contained in the corresponding window.

[0062] Furthermore, according to the number of corner points in the holographic focusing window and the focus concentration of each corner point, the focus of the holographic image of each pixel is obtained, and the focus of the holographic image is positively correlated with the focus concentration and the number of corner points respectively.

[0063] It should be noted that the positive correlation relationship may be an idempotent relationship of multiplication, addition, or exponential function, which may be determined based on actual conditions and will not be elaborated in this application.

[0064] Specifically, the present application proposes an embodiment, which, for the holographic focusing window of each pixel point, calculates the sum of the focus concentrations of all corner points in the holographic focusing window as a first sum value, and calculates the product of the first sum value and the number of corner points in the holographic focusing window as the focusing degree of the holographic image of each pixel point.

[0065] Furthermore, the present application proposes another embodiment, which calculates the calculation result of an exponential function with a natural constant as the base and the number of corner points in the holographic focusing window as the exponent, and calculates the product of the first sum and the calculation result as the focusing degree of the holographic image of each pixel point.

[0066] For each pixel in the digital holographic amplitude image, the holographic image focusing degree of each pixel reflects the amount of image information in the holographic focusing window centered on each pixel. The more corner points there are in the holographic focusing window, the richer the image details in the window, the more image information it contains, and the central pixel of the window needs to be additionally compensated when it is converted into a pure phase hologram. On the other hand, the greater the focusing concentration of the window, the more concentrated the corner points in the window, the greater the probability that the central pixel of the holographic focusing window is in the focusing area of ​​the digital holographic image, and the greater the focusing degree of the holographic image.

[0067] Furthermore, in order to use the GS algorithm to iterate the amplitude information and phase information of the pixel points in the digital holographic image and obtain the enhanced holographic image, the present application normalizes the amplitude information of the pixel points in the digital holographic image, uses the normalized amplitude information as the normalized amplitude information of the pixel points, and uses the image composed of the pixel points composed of the normalized amplitude information and phase information as the digital holographic standard image. Among them, the normalized amplitude information is the normalized grayscale value, and the holographic image focusing degree of each pixel point of the digital holographic standard image is the same as the holographic image focusing degree of the pixel point at the corresponding position of the digital holographic image.

[0068] The holographic image focusing degree of each pixel in the digital holographic standard image is used as input, and the Otsu threshold method is used to output the focusing degree threshold. The pixel points whose holographic image focusing degree is less than or equal to the focusing degree threshold are used as holographic background pixel points, and the pixel points whose holographic image focusing degree is greater than the focusing degree threshold are used as holographic focus pixel points.

[0069] The focus area of ​​the digital holographic standard image contains the main information of the image, while the image quality of the blurred area is low and the amount of image information contained is small, so the compensation for it can be reduced in subsequent processing. Therefore, the pixels in the digital holographic standard image are divided into holographic background pixels and holographic focus pixels. Different iterative methods are used for the two parts of pixels, sacrificing the reconstruction quality of the holographic background pixels and enhancing the image quality of the holographic focus pixels.

[0070] During the reconstruction process, the range of variation of the phase information of each pixel is limited, which means that pixels with higher and lower pixel values ​​are more difficult to accurately reconstruct than pixels with medium pixel values. After reconstruction, there will be more pixels in the middle value range than pixels on both sides of the grayscale value interval.

[0071] The grayscale histogram of the digital holographic standard image is obtained. The method for obtaining the grayscale histogram is a well-known technique and will not be described in detail here.

[0072] Furthermore, the loss of pixels on both sides of the grayscale histogram can be compensated in advance by extreme value enhancement. The pixel distribution of each image is different. The pixels on both sides of the grayscale histogram of a high-contrast image will account for a larger proportion than those of a low-contrast image. Based on this feature, the holographic low-pixel compensation parameters and the holographic high-pixel compensation parameters are calculated as follows:

[0073] The quartiles of the normalized amplitude information of all pixels in the digital holographic standard image are obtained; wherein the method for obtaining the quartiles is a well-known technology and will not be described in detail here.

[0074] The mean of the normalized amplitude information of all pixels in the digital holographic standard image is taken as the first normalized mean, and the difference between the first normalized mean and the first quartile is calculated as the low pixel interval difference; the difference between the first normalized mean and the third quartile is calculated as the high pixel interval difference.

[0075] The low pixel interval difference and the high pixel interval difference reflect the number of lower and higher gray value pixels on both sides of the gray histogram. When the number of pixels on both sides of the gray histogram is more, the low pixel interval difference and the high pixel interval difference are smaller.

[0076] Furthermore, the product of the first quartile of the normalized amplitude information of the digital holographic standard image and the low pixel interval difference is calculated as the first product, and the calculation result of an exponential function with a natural constant as the base and a negative value of the first product as the exponent is calculated as a low pixel compensation reference index.

[0077] Further, based on the low pixel compensation reference index, the holographic low pixel compensation parameter is obtained, the sum of the low pixel compensation reference index and the preset holographic compensation parameter adjustment factor is calculated as the first compensation sum value, and the product of the first compensation sum value and the preset holographic low pixel basic compensation parameter is used as the holographic low pixel compensation parameter. In this embodiment, the value of the preset holographic compensation parameter adjustment factor is 1, and the value of the preset holographic low pixel basic compensation parameter is 0.25.

[0078] Furthermore, the product of the third quartile of the normalized amplitude information of the digital holographic standard image and the high pixel interval difference is calculated as the second product, and the calculation result of an exponential function with a natural constant as the base and a negative value of the second product as the exponent is calculated as a high pixel compensation reference index.

[0079] Further, based on the high pixel compensation reference index, the holographic high pixel compensation parameter is obtained, the sum of the high pixel compensation reference index and the preset holographic compensation parameter adjustment factor is calculated as the second compensation sum value, and the product of the second compensation sum value and the preset holographic high pixel basic compensation parameter is used as the holographic high pixel compensation parameter. In this application, the value of the preset holographic high pixel basic compensation parameter is 0.85.

[0080] The GS algorithm is improved according to the holographic low pixel compensation parameters and the holographic high pixel compensation parameters. When the number of pixels on both sides of the grayscale histogram is greater, a higher holographic low pixel compensation parameter and a lower holographic high pixel compensation parameter are set to improve the compensation of pixels on both sides of the grayscale histogram and reduce the error introduced when converting the digital holographic standard image into a pure phase hologram.

[0081] On the one hand, when the first quartile of the digital holographic standard image is smaller and the third quartile is larger, the more pixels there are on both sides of the grayscale histogram of the digital holographic standard image, the larger the corresponding holographic low pixel compensation parameter is, and the smaller the holographic high pixel compensation parameter is. On the other hand, the smaller the difference between the low pixel interval and the high pixel interval, the larger the corresponding holographic low pixel compensation parameter is, and the smaller the corresponding holographic high pixel compensation parameter is.

[0082] Furthermore, in order to enhance the compensation for pixels with low grayscale values ​​and high grayscale values, the digital holographic standard image needs to be further adjusted.

[0083] According to the holographic low pixel compensation parameters and holographic high pixel compensation parameters obtained by the above calculation, the pixel point area of ​​the digital holographic standard image is divided into a low grayscale area, a medium grayscale area and a high grayscale area, and the grayscale values ​​of different areas are adjusted according to different rules, and the target amplitude balanced image is output. The grayscale values ​​of the pixel points of the target amplitude balanced image are calculated, and the method for obtaining the target amplitude balanced image is:

[0084] When the normalized amplitude information of a pixel in the digital holographic standard image is less than the holographic low pixel compensation parameter, the pixel is located in the low grayscale area, and the grayscale value of the pixel in the corresponding target amplitude equalization image is 0; when the normalized amplitude information of a pixel in the digital holographic standard image is greater than the holographic high pixel compensation parameter, the pixel is located in the high grayscale area, and the grayscale value of the pixel in the corresponding target amplitude equalization image is 1. When the normalized amplitude information of a pixel in the digital holographic standard image is greater than or equal to the holographic low pixel compensation parameter and less than or equal to the holographic high pixel compensation parameter, the absolute value of the difference between the normalized amplitude information of the pixel in the digital holographic standard image and the holographic low pixel compensation parameter is taken as the first absolute value of the difference, the absolute value of the difference between the holographic low pixel compensation parameter and the holographic high pixel compensation parameter is taken as the second absolute value of the difference, and the rounded-up value of the ratio of the first absolute value of the difference to the second absolute value of the difference is taken as the grayscale value of the pixel in the corresponding target amplitude equalization image.

[0085] In order to better reproduce the defects of pixels on both sides of the grayscale histogram, the grayscale values ​​of pixels on both sides of the grayscale histogram are compensated when the digital holographic standard image is converted into a pure phase hologram.

[0086] The target amplitude equalization image is used as the amplitude constraint condition for subsequent GS algorithm iterations to compensate for the pixel loss in low-grayscale and high-grayscale areas in advance and improve the accuracy of hologram reconstruction.

[0087] Specifically, the holographic background pixels and the holographic focus pixels in the digital holographic standard image are processed separately.

[0088] The GS algorithm is improved, and the iteration process of the GS algorithm is divided into a pre-iteration part and a post-iteration part. The total number of iterations of the GS algorithm is set to N, the number of pre-iterations is set to M, in this embodiment, N is 50, M is 12, and the remaining number of iterations is used as the post-iteration part.

[0089] For holographic background pixels, since they are relatively blurred and contain little image information, merging and iterating with holographic focus pixels will affect the enhancement effect of holographic focus pixels. Since both the holographic background pixels and the holographic focus pixels with lower and higher grayscale values ​​need to be grayscale compensated, the two pixels are subjected to the same iterative processing in the pre-iteration part, that is, the grayscale values ​​of the pixels of the target amplitude equalization image are used as the new amplitude constraint conditions, and the GS algorithm is used for iteration.

[0090] In the iterative process of the post-iteration part, for the holographic background pixel, the gray value of the digital holographic standard image is used as the amplitude constraint condition, and the phase obtained in the pre-iteration is used as the initial phase value before the post-iteration part starts to iterate; for the holographic focus pixel, the new amplitude constraint condition of the current holographic focus pixel is calculated according to the amplitude constraint condition of the previous iteration. The method for obtaining the new amplitude constraint condition is:

[0091] The focusing degree of the holographic image of all pixels is normalized.

[0092] For each holographic focal pixel, the ratio of the grayscale value of the pixel of the digital holographic standard image to the amplitude constraint of the previous GS algorithm iteration is used as the first constraint ratio, and the calculation result of the exponential function with the first constraint ratio as the base and the normalized holographic image focusing degree as the exponent is used as the amplitude constraint of each holographic focal pixel in the current iteration.

[0093] According to the above steps, the amplitude constraint conditions of the focal pixels of the post-iteration partial hologram in each iteration process are calculated.

[0094] According to the above iterative process, the amplitude information and phase information of the holographic background pixel points and the holographic focus pixel points in the digital holographic standard image are iterated to obtain a pure phase hologram. The pure phase hologram acquisition flow chart is as follows: Figure 2 shown.

[0095] Since the holographic focus pixels contain more image information, their amplitude constraints are continuously optimized during the iteration process to improve the enhancement effect of the hologram after reconstruction.

[0096] Since the GS algorithm will gradually average the amplitude constraints during the iteration process, the amplitude information in the holographic focus pixel will be lost. Therefore, the grayscale value of the pixel in the digital holographic standard image is used as the reference. The larger the amplitude constraint of the previous iteration, the smaller the amplitude constraint of the current calculation. At the same time, the amplitude constraint is adjusted with the holographic image focusing degree of each pixel as the index. The greater the holographic image focusing degree, the more information the digital holographic standard image contains, and the greater the adjustment of the amplitude constraint, which reduces the loss of amplitude information in the process of converting the digital holographic standard image into a pure phase hologram.

[0097] Step S3, reconstructing the digital holographic standard image according to the acquired pure phase hologram.

[0098] The pure phase hologram obtained by the improved GS algorithm is loaded into the spatial light modulator, the hologram is reconstructed and displayed, and the holographic display effect is enhanced.

[0099] Based on the same inventive concept as the above method, an embodiment of the present application also provides a holographic photography display effect enhancement system, including a memory, a processor, and a computer program stored in the memory and running on the processor, and when the processor executes the computer program, the steps of any one of the above-mentioned holographic photography display effect enhancement methods are implemented.

[0100] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0101] The various embodiments in the present application are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0102] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for enhancing holographic display effects, characterized in that: The method comprises the following steps: Acquire a digital holographic image; obtain the focusing degree of the holographic image of each pixel based on the amplitude information of the pixel points and the distance between the pixel points in the digital holographic image; Based on the amplitude information and phase information of the pixel points in the digital holographic image and the focusing degree of the holographic image, the holographic background pixel points and the holographic focus pixel points in the digital holographic standard image are obtained; Based on the difference between the normalized amplitude information and the quartile in the digital holographic standard image, the low pixel interval difference and the high pixel interval difference are obtained; Based on the normalized amplitude information, the low pixel interval difference and the high pixel interval difference in the digital holographic standard image, a holographic low pixel compensation parameter and a holographic high pixel compensation parameter of the digital holographic standard image are obtained; Based on the holographic low pixel compensation parameter and the holographic high pixel compensation parameter, combined with the normalized amplitude information in the digital holographic standard image, a target amplitude balanced image is obtained; The iterative process of optimizing the holographic background pixels and holographic focus pixels is based on the target amplitude equalization image to obtain a pure phase hologram.

2. A method for enhancing holographic display effects as claimed in claim 1, characterized in that: The method for acquiring the focusing degree of the holographic image is as follows: Extracting amplitude information of corresponding pixel points in the digital holographic image to form a digital holographic amplitude image; For each pixel point in the digital holographic amplitude image, a window with a side length of a preset length is taken as the holographic focusing window of each pixel point with the pixel point as the center; Obtaining the distance between each corner point and the central pixel point in the holographic focusing window as a first distance, and recording the sum of the first distance and a preset adjustment factor as a corner point discrete weight; Calculating the focus concentration of each corner point based on the discrete weight of the corner point, wherein the focus concentration is negatively correlated with the discrete weight of the corner point; According to the number of corner points in the holographic focusing window and the focus concentration of each corner point, the focus of the holographic image of each pixel is obtained, and the focus of the holographic image is positively correlated with the focus concentration and the number of corner points respectively.

3. A method for enhancing holographic display effects as claimed in claim 1, characterized in that: The step of obtaining holographic background pixel points and holographic focus pixel points in the digital holographic standard image includes: Normalizing the amplitude information of the pixels in the digital holographic image, using the normalized amplitude information as the normalized amplitude information of the pixels, and using the image composed of the pixels constructed by the normalized amplitude information and the phase information as the digital holographic standard image; The holographic image focusing degree of each pixel in the digital holographic standard image is taken as input, and the Otsu threshold method is used to output the focusing degree threshold; the pixel points whose holographic image focusing degree is less than or equal to the focusing degree threshold are taken as holographic background pixel points, and the pixel points whose holographic image focusing degree is greater than the focusing degree threshold are taken as holographic focus pixel points.

4. A method for enhancing holographic display effects as claimed in claim 3, characterized in that: The method for obtaining the low pixel interval difference and the high pixel interval difference is: Obtain the quartiles of the normalized amplitude information of all pixels in the digital holographic standard image; The mean of the normalized amplitude information of all pixels in the digital holographic standard image is taken as the first normalized mean, and the absolute value of the difference between the first normalized mean and the first quartile is calculated as the low pixel interval difference; the absolute value of the difference between the first normalized mean and the third quartile is calculated as the high pixel interval difference.

5. A method for enhancing holographic display effects as claimed in claim 4, characterized in that: The method for obtaining the holographic low pixel compensation parameters is: Calculating the product of the first quartile of the normalized amplitude information of the digital holographic standard image and the low pixel interval difference as a first product, and determining the holographic low pixel compensation parameter based on the first product; wherein the first product and the holographic low pixel compensation parameter are negatively correlated; The sum of the low pixel compensation reference index and the preset holographic compensation parameter adjustment factor is calculated as the first compensation sum value, and the product of the first compensation sum value and the preset holographic low pixel basic compensation parameter is used as the holographic low pixel compensation parameter.

6. A method for enhancing holographic display effects as claimed in claim 5, characterized in that: The method for obtaining the holographic high pixel compensation parameters is: Calculate the product of the third quartile of the normalized amplitude information of the digital holographic standard image and the high pixel interval difference as the second product, and calculate the result of an exponential function with a natural constant as the base and a negative value of the second product as the exponent as the high pixel compensation reference index; The sum of the high pixel compensation reference index and the preset holographic compensation parameter adjustment factor is calculated as the second compensation sum value, and the product of the second compensation sum value and the preset holographic high pixel basic compensation parameter is used as the holographic high pixel compensation parameter.

7. A method for enhancing holographic display effects as claimed in claim 1, characterized in that: The method for obtaining the target amplitude equalization image is: When the normalized amplitude information of the pixel in the digital holographic standard image is less than the holographic low pixel compensation parameter, the gray value of the pixel corresponding to the target amplitude equalization image is 0; When the normalized amplitude information of the pixel in the digital holographic standard image is greater than the holographic high pixel compensation parameter, the corresponding target amplitude equalization image pixel grayscale value is 1; When the normalized amplitude information of the pixel point in the digital holographic standard image is greater than or equal to the holographic low pixel compensation parameter and less than or equal to the holographic high pixel compensation parameter, the absolute value of the difference between the normalized amplitude information of the pixel point of the digital holographic standard image and the holographic low pixel compensation parameter is taken as the first absolute value of the difference, the absolute value of the difference between the holographic low pixel compensation parameter and the holographic high pixel compensation parameter is taken as the second absolute value of the difference, and the rounded-up value of the ratio of the first absolute value of the difference to the second absolute value of the difference is taken as the grayscale value of the pixel point in the corresponding target amplitude equalization image.

8. A method for enhancing holographic display effects as claimed in claim 1, characterized in that: The iterative process of the holographic background pixel points and the holographic focus pixel points includes: The iterative process of the iterative algorithm is divided into a pre-iteration part and a post-iteration part; For the pre-iteration part of the holographic background pixels and the holographic focus pixels, the grayscale values ​​of the pixels of the target amplitude equalization image are used as new amplitude constraints; For the post-iteration part of the holographic background pixels, the gray value of the digital holographic standard image is used as the amplitude constraint condition; For the post-iteration part of the holographic focus pixel point, the ratio of the grayscale value of the pixel point of the digital holographic standard image to the amplitude constraint condition of the previous algorithm iteration is used as the first constraint ratio, and the calculation result of the exponential function with the first constraint ratio as the base and the normalized holographic image focusing degree as the exponent is used as the amplitude constraint condition of each holographic focus pixel point in the current iteration.

9. A method for enhancing holographic display effects as claimed in claim 1, characterized in that: The pure phase hologram is an image obtained by pre-iteration and post-iteration of holographic background pixel points and holographic focus pixel points.

10. A holographic photography display effect enhancement system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of a method for enhancing holographic photography display effects as described in any one of claims 1-9 are implemented.

Images