A View-Field Enhancement 3D Light Field Display Method Based on Composite Lenses and Aperiodic Coding

Abstract

This invention discloses a view-enhanced 3D light field display method based on compound lenses and aperiodic encoding, relating to the field of 3D display technology. The method includes a display device and a compound lens array. The compound lens array is located in front of and parallel to the display device, and comprises several compound lens units. Each compound lens unit includes a first lens and a second lens arranged sequentially from the object side to the image side. The object side of the first lens is planar, and the image side is convex. The object side of the second lens is concave, and the image side is convex. This invention not only improves the overall performance of the system but also enhances image quality while reducing hardware costs, thereby enhancing the view area of ​​the 3D light field display system.

Description

Technical Field

[0001] This invention relates to the field of three-dimensional display technology, and more specifically to a view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic coding. Background Technology

[0002] Because 2D display technology can only present the intensity and color of light in an image, and the scene it displays is merely a two-dimensional plane, 2D displays can no longer meet people's needs. 3D display technology overcomes the shortcomings of 2D displays, presenting information such as the amplitude, color, and direction of light, showcasing a scene with complete spatial depth information. Due to these characteristics, 3D display technology has great application prospects in fields such as medicine and education.

[0003] The size of the viewing area is a crucial parameter for evaluating a 3D light field display system. A larger viewing area allows the system to carry more information, enabling viewers to see 3D objects from more angles. In a 3D light field display system, light control devices introduce aberrations into the image. Some of these aberrations cause light rays to shift, resulting in a deviation between the actual and ideal viewpoint positions. The size of the viewing area of ​​a 3D light field display system is affected by this viewpoint shift. As the viewing area increases, the viewpoint shift becomes more severe, and the uneven distribution of viewpoints becomes more pronounced. This reduces the effective viewing area of ​​the system, making it impossible to achieve the initially set target viewing area size, resulting in information loss and waste.

[0004] In existing technologies, common solutions involve improving light control devices or using advanced optical components to directly reduce aberrations in the system, thereby minimizing viewpoint shift and enhancing the viewing area. However, hardware optimization is often constrained by physical limitations, such as cost, size, and optical materials, which may limit the flexibility or efficiency of the solution. Another approach is to use special encoding algorithms to compensate for aberrations, which can overcome hardware limitations to some extent and achieve a uniform distribution of viewpoints, but is also limited by algorithm accuracy and computational performance. Moreover, software methods typically rely on the initial image quality acquired by the hardware; if the base image quality is poor, the effectiveness of software optimization will be limited. Optimizing aberrations solely at the hardware or software level has inherent limitations and makes it difficult to achieve high-quality 3D light field display effects. Summary of the Invention

[0005] To address the aforementioned shortcomings in the prior art, the present invention provides a view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic coding, which solves the problem of view-area loss in three-dimensional light field display caused by aberrations in the prior art.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] A method for enhancing the view area of ​​a three-dimensional light field display based on composite lenses and aperiodic encoding is provided, which includes the following steps:

[0008] Load the aperiodic encoded composite image through the display device;

[0009] By suppressing optical aberrations through a composite lens array, light rays incident at different angles are deflected to exit at different angles, displaying different parallax maps at different angles, thereby forming a three-dimensional display light field;

[0010] The composite lens array is located in front of and parallel to the display device. The composite lens array includes several composite lens units. Each composite lens unit includes a first lens and a second lens arranged sequentially from the object side to the image side. The object side of the first lens is a plane and the image side is a convex surface. The object side of the second lens is a concave surface and the image side is a convex surface.

[0011] Furthermore, the encoding method for aperiodic coded composite graphs includes the following steps:

[0012] Obtain the offset function of the principal ray after passing through the compound lens array;

[0013] Based on the offset function, the offset distance of the sub-pixel under each compound lens unit is obtained;

[0014] Adding the offset distance to the synthetic image encoding yields the aperiodic encoding of the synthetic image.

[0015] Furthermore, the specific method for obtaining the offset function of the principal ray after passing through the compound lens array includes the following steps:

[0016] By performing optical path tracing based on the compound lens array, the distribution map of the principal ray after passing through the compound lens array is obtained. This map is then compared with the distribution map under ideal conditions to obtain the coordinates of different positions under ideal conditions and the corresponding offset coordinates.

[0017] Ideally, the coordinates at different positions and the corresponding offset coordinates are fitted with a distortion model to obtain the offset function.

[0018] Furthermore, based on the offset function, the specific method for obtaining the offset distance of sub-pixels under each compound lens unit includes the following steps:

[0019] The distance from the sub-pixel to the center of the corresponding compound lens unit is obtained based on the sub-pixel's position, the intercept of the compound lens unit, and the lens placement tilt angle.

[0020] Divide the distance from the sub-pixel to the center of the corresponding compound lens unit by the focal length of the compound lens unit to obtain the distance normalization value, and then input it into the offset function.

[0021] Multiply the result of inputting the distance normalization value into the offset function by the focal length of the compound lens unit to obtain the offset sub-pixel coordinates;

[0022] The offset distance of a subpixel is obtained by subtracting its offset coordinates from the distance from the subpixel to the center of the corresponding compound lens unit.

[0023] Furthermore, the specific method for adding the offset distance to the synthetic image encoding to obtain the aperiodic encoding of the synthetic image includes the following steps:

[0024] sub-pixels The number of offset subpixels is obtained by dividing the offset distance by the subpixel width and rounding up or down.

[0025] sub-pixels The result of adding the x-coordinate to the number of offset sub-pixels is used as the sub-pixel. Offset coordinates, and sub-pixels The information corresponding to the viewpoint map before the offset is encoded into sub-pixels. In the sub-pixel at the offset coordinate position;

[0026] By traversing all sub-pixels, the aperiodic code of the synthesized image is obtained.

[0027] Furthermore, an aperture stop is provided on the object-side surface of the first lens; within the same compound lens unit, the constraint relationship between the distance d from the aperture stop to the image-side surface of the second lens and the radius of curvature r1 of the image-side surface of the second lens is: 0.9 <d / r1<1.1。

[0028] Furthermore, the object-side surface of the second lens and the image-side surface of the first lens are both spherical; the image-side surface of the second lens is aspherical.

[0029] Furthermore, the constraint relationship between the radius of curvature r1 of the image-side surface of the second lens and the radius of curvature r2 of the object-side surface of the second lens is: 0.8 <r2 / r1<1.2。

[0030] Furthermore, the distance from the display device to the compound lens array is equal to the focal length of the compound lens array.

[0031] Furthermore, the image from the first lens and the second lens are cemented together.

[0032] The beneficial effects of this invention are as follows: This invention effectively reduces the aberrations of the system and improves the display quality of the system by using a composite lens array; further fine adjustment is performed through an aperiodic coding algorithm to correct the viewpoint offset, achieve a uniform distribution of viewpoints, and reduce the loss of viewing area caused by aberrations; based on the combination of the above hardware and algorithms, not only can the overall performance of the system be improved, but also the image quality can be improved while reducing hardware costs, thereby enhancing the viewing area of ​​the three-dimensional light field display system. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the system structure used in this embodiment;

[0034] Figure 2 A schematic diagram comparing the viewpoint offset distance caused by a compound lens array and a traditional light control device;

[0035] Figure 3 A schematic diagram of the encoding after adding an offset distance to the sub-pixels. Detailed Implementation

[0036] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0037] The view-area enhancement three-dimensional light field display method based on compound lenses and aperiodic coding includes the following steps:

[0038] A1. Load the aperiodic encoded composite image through the display device;

[0039] A2. By suppressing optical aberrations through a composite lens array, light rays incident at different angles are deflected to different angles and emitted at different angles, displaying different parallax maps at different angles, thereby forming a three-dimensional display light field.

[0040] like Figure 1 As shown, the compound lens array is located in front of and parallel to the display device. The compound lens array includes several compound lens units. Each compound lens unit includes a first lens and a second lens arranged sequentially from the object side to the image side. The object side of the first lens is a plane and the image side is a convex surface. The object side of the second lens is a concave surface and the image side is a convex surface.

[0041] In this embodiment, the display device includes a light-emitting unit, and the light-emitting unit includes a plurality of sub-pixels. The display device can be a liquid crystal display, an LED display, an OLED display, etc. An aperture stop is provided on the object side surface of the first lens; in order to achieve the effect of suppressing distortion, the placement position of the aperture stop needs to be as close as possible to the center of the sphere of the lens. At this time, the principal ray of the incident light is parallel to the normal of the incident surface, and the principal ray of the incident light does not refract but passes straight through the lens, achieving the suppression of distortion. In the same compound lens unit, the constraint relationship between the distance d from the aperture stop to the image side surface of the second lens and the radius of curvature r1 of the image side surface of the second lens is: 0.9 < d / r1 < 1.1. The object side surface of the second lens and the image side surface of the first lens are both spherical surfaces; the image side surface of the second lens is an aspherical surface. The field curvature of the lens is related to the optical power of the lens. When the field curvature is 0, the sum of the optical powers of the compound lens array is also 0. Therefore, to reduce the field curvature, a combination of thin lenses with positive and negative optical powers is needed to make the sum of their optical powers as close to 0 as possible. In this embodiment, the radius of curvature of the image side surface and the object side surface of the second lens needs to be as equal as possible to make the optical power of the lens system close to 0. The constraint relationship between the radius of curvature r1 of the image side surface of the second lens and the radius of curvature r2 of the object side surface of the second lens is: 0.8 < r2 / r1 < 1.2. The first lens and the second lens are both made of glass materials. The image of the first lens and the second lens are glued together. The distance from the display device to the compound lens array is equal to the focal length of the compound lens array.

[0042] The compound lens array deflects the light emitted from the sub-pixels of the display device and emits it at different angles, displays different parallax maps at different angles, and enables the system to form a three-dimensional display light field. At the same time, the aperture stop on the object side of the compound lens array can limit the incident angle of the incident light, making the principal ray of the incident light parallel to the normal of the incident surface, and the principal ray of the incident light does not refract but directly enters, thereby achieving the effect of suppressing distortion, reducing the offset between the actual viewpoint position and the ideal viewpoint position, making the actual viewing area size closer to the ideal viewing area size, and the first lens and the second lens can suppress other optical aberrations of the system, improving the display quality of the three-dimensional light field display system.

[0043] Exemplarily, referring to Figure 2 , in the case of not using the aperiodic coding algorithm, compared with the traditional light control device, the offset distance of the viewpoint of the compound lens array has been reduced from to , and the offset of the viewpoint has been significantly improved. However, it is difficult for the compound lens array to completely eliminate the influence of distortion on the three-dimensional light field display system, and there is still a small offset between the actual viewpoint position and the ideal viewpoint position. At this time, the aperiodic coding algorithm is adopted to optimize the aberrations that are difficult to eliminate by the compound lens array at the software level, achieve the uniform distribution of the viewpoints of the three-dimensional light field display system, and achieve the effect of view area enhancement.

[0044] In this embodiment, the encoding method (aperiodic encoding algorithm) for the aperiodic encoded composite graph includes the following steps:

[0045] S1. Obtain the offset function of the principal ray after passing through the compound lens array;

[0046] S2. Based on the offset function, obtain the offset distance of the sub-pixels under each compound lens unit;

[0047] S3. Add the offset distance to the composite image encoding to obtain the aperiodic encoding of the composite image.

[0048] The offset is mainly caused by the distortion of the compound lens array. The light emitted from the display device, after passing through the compound lens array, cannot exit in the ideal direction, resulting in a deviation between the actual viewpoint position constructed by the light-emitting unit and the ideal viewpoint position. Furthermore, this deviation is not a fixed value but increases with the increase of the incident angle of the main ray, thus leading to an uneven distribution of the actual viewpoint position and weakening the effective range of the viewing area. Therefore, in step S1, the specific method for obtaining the offset function of the main ray after passing through the compound lens array includes the following steps:

[0049] S1-1. Perform optical path tracing based on the compound lens array to obtain the distribution map of the principal ray after passing through the compound lens array. Compare this distribution map with the distribution map under ideal conditions to obtain the coordinates of different positions under ideal conditions. and the corresponding offset coordinates ;

[0050] S1-2, coordinates and coordinates The offset function is obtained by fitting the distortion model using the Brown algorithm (Brown distortion model).

[0051] For example, the obtained offset function is shown below:

[0052]

[0053]

[0054]

[0055] in, For distance, The radial distortion coefficient is... The tangential distortion coefficients are typically fitted to the radial distortion coefficients in Brown's algorithm. Furthermore, the three-dimensional light field display system in this embodiment only constructs viewpoints in the horizontal direction and has no vertical parallax. Therefore, in this embodiment, the offset function can be simplified to:

[0056] .

[0057] In step S2, the specific method for obtaining the offset distance of each sub-pixel under the compound lens unit based on the offset function includes the following:

[0058] The distance from the sub-pixel to the center of the corresponding compound lens unit is obtained based on the sub-pixel's position, the intercept of the compound lens unit, and the lens placement tilt angle. At this time, the coordinates of the sub-pixel relative to the center of the compound lens unit are: ;

[0059] The offset function obtained based on the Brown algorithm is modeled in a normalized camera coordinate system. Points in the normalized coordinate system only retain orientation information and ignore depth. Therefore, to convert pixel coordinates to normalized coordinates, the distance from the sub-pixel to the compound lens unit needs to be correlated. In this embodiment, the distance from the sub-pixel to the compound lens unit is the focal length. There is a relation Substituting the above relationship into the offset function yields the offset normalized sub-pixel coordinates. ;

[0060] The offset sub-pixel coordinates can be obtained by converting the normalized coordinates (the result of inputting the distance normalization value into the offset function) into sub-pixel coordinates (multiplied by the focal length of the compound lens unit): ;

[0061] Subtracting the offset sub-pixel coordinates from the distance from the sub-pixel to the center of the corresponding compound lens unit yields the sub-pixel offset distance, expressed as: .

[0062] In step S3, the method for adding the offset distance to the synthetic image encoding to obtain the aperiodic encoding of the synthetic image includes the following steps:

[0063] S3-1, Subpixel The number of offset subpixels is obtained by dividing the offset distance by the subpixel width and rounding up or down.

[0064] S3-2, Subpixel The result of adding the x-coordinate to the number of offset sub-pixels is used as the sub-pixel. Offset coordinates, and sub-pixels The information corresponding to the viewpoint map before the offset is encoded into sub-pixels. In the sub-pixel at the offset coordinate position;

[0065] S3-3. Traverse all sub-pixels to obtain the aperiodic encoding of the synthesized image.

[0066] like Figure 3 As shown, without adding an offset distance, the image coordinates of sub-pixel 1 are... At this time, the sub-pixel corresponds to the first A viewpoint map. In this embodiment, the offset distance of the sub-pixels obtained according to the above steps. and subpixel width When using floor function, there is a relation. ,in, This represents the number of offset sub-pixels. This indicates rounding down. That is, the image coordinates of sub-pixel 2 after offset are... The corresponding viewpoint diagram The corresponding information is encoded into coordinates. After traversing each sub-pixel, the aperiodic code of the synthesized image is obtained. Finally, the synthesized image processed by the aperiodic encoding algorithm is loaded into the display device.

[0067] For example, when m is 1, the information corresponding to the viewpoint map of sub-pixel 1 is encoded into sub-pixel 2. When m is 2, the information corresponding to the viewpoint map of sub-pixel 1 is encoded into sub-pixel 3.

[0068] In summary, this invention uses a combination of a composite lens array and an aperiodic coding algorithm to correct the viewpoint offset, thereby achieving a uniform distribution of viewpoints and enhancing the viewing area of ​​the three-dimensional light field display.

Claims

1. A method for viewing area enhancement of three-dimensional light field display based on compound lenses and aperiodic encoding, characterized in that, Includes the following steps: Load the aperiodic encoded composite image through the display device; By suppressing optical aberrations through a composite lens array, light rays incident at different angles are deflected to exit at different angles, displaying different parallax maps at different angles, thereby forming a three-dimensional display light field; The composite lens array is located in front of and parallel to the display device. The composite lens array includes several composite lens units. Each composite lens unit includes a first lens and a second lens arranged sequentially from the object side to the image side. The object side of the first lens is a plane and the image side is a convex surface. The object side of the second lens is a concave surface and the image side is a convex surface. The encoding method for aperiodic coded composite graphs includes the following steps: Obtain the offset function of the principal ray after passing through the compound lens array; Based on the offset function, the offset distance of the sub-pixel under each compound lens unit is obtained; Adding the offset distance to the synthetic image encoding yields the aperiodic encoding of the synthetic image.

2. The view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic encoding according to claim 1, characterized in that, The specific method for obtaining the offset function of the principal ray after passing through the compound lens array includes the following steps: By performing optical path tracing based on the compound lens array, the distribution map of the principal ray after passing through the compound lens array is obtained. This map is then compared with the distribution map under ideal conditions to obtain the coordinates of different positions under ideal conditions and the corresponding offset coordinates. Ideally, the coordinates at different positions and the corresponding offset coordinates are fitted with a distortion model to obtain the offset function.

3. The view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic encoding according to claim 1, characterized in that, The specific method for obtaining the offset distance of sub-pixels under each compound lens unit based on the offset function includes the following steps: The distance from the sub-pixel to the center of the corresponding compound lens unit is obtained based on the sub-pixel's position, the intercept of the compound lens unit, and the lens placement tilt angle. Divide the distance from the sub-pixel to the center of the corresponding compound lens unit by the focal length of the compound lens unit to obtain the distance normalization value, and then input it into the offset function. Multiply the result of inputting the distance normalization value into the offset function by the focal length of the compound lens unit to obtain the offset sub-pixel coordinates; The offset distance of a subpixel is obtained by subtracting its offset coordinates from the distance from the subpixel to the center of the corresponding compound lens unit.

4. The view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic encoding according to claim 1, characterized in that, The specific method for adding the offset distance to the synthetic image encoding to obtain the aperiodic encoding of the synthetic image includes the following steps: sub-pixels The number of offset subpixels is obtained by dividing the offset distance by the subpixel width and rounding up or down. sub-pixels The result of adding the x-coordinate to the number of offset sub-pixels is used as the sub-pixel. Offset coordinates, and sub-pixels The information corresponding to the viewpoint map before the offset is encoded into sub-pixels. In the sub-pixel at the offset coordinate position; By traversing all sub-pixels, the aperiodic code of the synthesized image is obtained.

5. The view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic encoding according to claim 1, characterized in that, An aperture stop is provided on the object-side surface of the first lens; within the same compound lens unit, the constraint relationship between the distance d from the aperture stop to the image-side surface of the second lens and the radius of curvature r1 of the image-side surface of the second lens is: 0.9 <d / r1<1.1。 6. The view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic encoding according to claim 1, characterized in that, The object side of the second lens and the image side of the first lens are both spherical; the image side of the second lens is aspherical.

7. The view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic encoding according to claim 1, characterized in that, The constraint relationship between the radius of curvature r1 of the image-side surface of the second lens and the radius of curvature r2 of the object-side surface of the second lens is: 0.8 <r2 / r1<1.2。 8. The view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic encoding according to claim 1, characterized in that, The distance from the display device to the compound lens array is equal to the focal length of the compound lens array.

9. The view-area enhancement three-dimensional light field display method based on composite lenses and aperiodic encoding according to claim 1, characterized in that, The image from the first lens and the second lens are cemented together.

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