CN114114676A - Scattering screen parameter optimization method, scattering screen and readable storage medium - Google Patents

Scattering screen parameter optimization method, scattering screen and readable storage medium Download PDF

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Publication number
CN114114676A
CN114114676A CN202010862348.7A CN202010862348A CN114114676A CN 114114676 A CN114114676 A CN 114114676A CN 202010862348 A CN202010862348 A CN 202010862348A CN 114114676 A CN114114676 A CN 114114676A
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light
scattering screen
scattering
projector
cost function
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不公告发明人
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Chengdu Idealsee Technology Co Ltd
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Chengdu Idealsee Technology Co Ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0012—Optical design, e.g. procedures, algorithms, optimisation routines
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/54—Accessories
    • G03B21/56—Projection screens
    • G03B21/60—Projection screens characterised by the nature of the surface
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/54—Accessories
    • G03B21/56—Projection screens
    • G03B21/60—Projection screens characterised by the nature of the surface
    • G03B21/602—Lenticular screens
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B35/00—Stereoscopic photography
    • G03B35/18—Stereoscopic photography by simultaneous viewing
    • G03B35/20—Stereoscopic photography by simultaneous viewing using two or more projectors

Abstract

The invention discloses a scattering screen parameter optimization method, a scattering screen and a readable storage medium, wherein the method is applied to optical field display, and equipment for realizing the optical field display comprises a projector array and the scattering screen; the method comprises the following steps: constructing a cost function about the brightness difference variable; the number of the pixel points is related to N deflection angles of the N regions; optimizing the cost function according to a preset optimization algorithm, and determining a minimum value of the cost function; determining an optimized deflection angle according to the minimum value of the cost function; and the N deflection angles corresponding to the minimum values are the optimized deflection angles. The scheme is used for relieving the problem that the brightness of projection pictures which can be observed in different observation areas is not uniform in light field display in the prior art.

Description

Scattering screen parameter optimization method, scattering screen and readable storage medium
Technical Field
The invention relates to the field of light field display, in particular to a scattering screen parameter optimization method, a scattering screen and a readable storage medium.
Background
The light field display refers to a display mode of reconstructing light rays emitted by an object through projectors, as shown in fig. 1A, each projector constructs light rays emitted by each point on the object in different directions, and if enough projectors project enough light rays, it is equivalent to constructing light rays emitted by a plurality of points forming the surface of the object in different directions. Therefore, when the human eyes receive the light rays emitted by the projector at different angles, the human eyes can feel that the human eyes can observe objects from different angles, and the light field display in the real sense is realized.
To realize real light field display, on one hand, because a large number of projectors are needed for projection and a large number of data processing are needed, in the actual light field display, the field of view in the vertical direction is sacrificed, and only the light rays emitted by the object in the horizontal direction are reconstructed. Therefore, in the light field display, the light rays are scattered at a large angle in the vertical direction, so that the observer can observe a complete picture at different heights. On the other hand, because the projector has a certain physical size, the light reconstructed in the horizontal direction has a certain interval, i.e. the observer can see discontinuous pictures, therefore, the light needs to be scattered at a small angle in the horizontal direction in the light field display, so that the observer can see continuous pictures.
At present, the problems of light field display are many, for example: the number of projectors is large, the data operation amount is large, the resolution is low, and the like, and uneven brightness of a projection picture observed in different observation areas is also one of the problems to be solved.
Disclosure of Invention
The invention aims to provide a scattering screen parameter optimization method, a scattering screen and a readable storage medium, which are used for relieving the problem of uneven brightness of projection pictures observed in different observation areas in light field display in the prior art.
In order to achieve the above object, a first aspect of the embodiments of the present invention provides a method for optimizing parameters of a scattering screen, which is applied to optical field display, where an apparatus for implementing the optical field display includes a projector array and a scattering screen, light emitted from the projector array enters human eyes after being scattered by the scattering screen, the scattering screen is divided into N regions, the N regions are set to be non-uniform deflection angles, and N is a positive integer; the method comprises the following steps:
constructing a cost function about the brightness difference variable; the brightness difference variable is used for indicating the difference value between the number of pixel points which can be received by human eyes at the target viewpoint and the number of pixel points which can be received by the human eyes at the reference viewpoint; the number of the pixel points is related to N deflection angles of the N regions;
optimizing the cost function according to a preset optimization algorithm, and determining a minimum value of the cost function;
determining an optimized deflection angle according to the minimum value of the cost function; and the N deflection angles corresponding to the minimum values are the optimized deflection angles.
Optionally, the method for calculating the brightness of the picture that can be received by human eyes at the target viewpoint/reference viewpoint includes:
calculating the number of pixel points which can be received by human eyes at the target viewpoint/the reference viewpoint; and the number of the pixel points is used for representing the brightness of the picture.
Optionally, the method for calculating the number of pixel points that can be received by human eyes at the target viewpoint/the reference viewpoint includes:
aiming at each pixel point emitted by a projector, calculating the spot position and spot size of the pixel point projected on the scattering screen;
calculating a light scattering angle of the light spot in a preset direction according to the size of the light spot, and a deflection angle and a scattering angle of an area where the light spot is located, wherein the preset direction is a horizontal direction or a vertical direction;
judging whether the light scattered by the light spot of the pixel point through the scattering screen can enter human eyes positioned at the target viewpoint/reference viewpoint or not according to the light scattering angle and the position of the target viewpoint/reference viewpoint;
calculating the number of pixel points which are emitted by each projector and can be received by human eyes at the target viewpoint/reference viewpoint;
and calculating the total number of the pixel points which can be received by human eyes at the target viewpoint/the reference viewpoint according to the number of the pixel points of each projector.
Optionally, the reference viewpoint is a viewpoint directly facing the center of the scattering screen.
Optionally, the preset optimization algorithm is one of a genetic algorithm, a particle swarm algorithm, or a steepest descent method.
Optionally, optimizing the cost function according to a preset optimization algorithm includes:
initializing a population, wherein the population comprises M individuals, the information of each individual is used for indicating the respective deflection angle of the N areas, and M is a positive integer;
calculating a cost function for each of the individuals;
judging whether a preset condition for stopping optimization calculation is met;
if yes, determining an extreme value of the cost functions of the M individuals;
if not, iterating the M individuals according to the preset optimization algorithm.
Optionally, the condition for stopping the optimization calculation is at least one of the following:
the times of the optimized calculation reach the set times;
the average value of the cost functions of the M individuals is smaller than a preset threshold value;
the cost function of at least one of the M individuals is smaller than a preset threshold value.
Optionally, when the preset optimization algorithm is a genetic algorithm, iterating the M individuals according to the preset optimization algorithm includes:
calculating an adaptation value for each of the individuals; wherein the adaptive value of the individual refers to a value of a cost function of the individual;
reselecting M individuals from the population based on the adaptive value of each individual and a preset selection algorithm;
and carrying out cross variation on the reselected M individuals to generate a next generation of population.
A second aspect of the embodiments of the present invention provides a diffuser screen, which is applied to an optical field display device, where the optical field display device further includes a projector array, light emitted from the projector array enters human eyes after being scattered by the diffuser screen, the diffuser screen includes N regions, the N regions are set to have non-uniform deflection angles, and N is a positive integer.
Optionally, the diffuser screen includes a micro lens array and a prism array; or the diffuser screen comprises a horizontal cylindrical lens array, a vertical cylindrical lens array and a prism array.
A third aspect of embodiments of the present invention provides a computer-readable storage medium, having stored thereon a computer program, which, when executed by a processor, causes the processor to perform the method according to the first aspect.
A fourth aspect of the embodiments of the present invention provides a light field display method applied to a light field display device, where the light field display device includes a projector array and a scattering screen, and light emitted from the projector array enters human eyes after being scattered by the scattering screen, and the method includes:
emitting light corresponding to the image to be projected through the projector array;
when the light rays are incident to different areas of the scattering screen, the light rays are subjected to non-uniform deflection through the different areas of the scattering screen, so that the light rays are uniformly distributed in an observable area of the light field display equipment after passing through the scattering screen; the scattering screen is divided into N areas, the N areas have non-uniform deflection angles, and N is a positive integer.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
in the scheme of the embodiment of the invention, the cost function related to the brightness difference variable is optimized, so that the difference value between the brightness of the picture received at the target viewpoint and the brightness of the picture received at the reference viewpoint is small, and the more uniform the brightness of the picture is when the difference value between the brightness of the picture received at different viewpoints is smaller, therefore, the group of deflection angle parameters corresponding to the minimum value of the cost function is set as the deflection angle of each area of the scattering screen, so that the problem that the brightness of the projection picture which can be observed in different observation areas is not uniform in light field display in the prior art can be solved, and the technical effect of improving the brightness uniformity of the projection picture displayed in the light field is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without any creative effort:
FIG. 1A is a schematic view of a light field display;
FIGS. 1B-1C are schematic diagrams of projector stripes;
FIG. 1D is a schematic diagram of the light path of light through a diffuser screen;
FIG. 2 is a flowchart of a method for optimizing parameters of a diffuser screen according to an embodiment of the present invention;
fig. 3 is a schematic light path diagram of a plurality of pixel point light rays emitted by the projector according to the embodiment of the present invention;
fig. 4 is a schematic flowchart of an iterative method based on a preset optimization algorithm according to an embodiment of the present invention;
FIG. 5 is a schematic flow chart of a population iteration method based on a genetic algorithm according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a microlens array according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a lenticular lens array according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1B-1D, the spatial light field device includes a projector array and a diffuser screen disposed in the light exit direction of the projector array, and the user is typically positioned to look at the other side of the diffuser screen, as shown by the human eye position in fig. 1D. The scattering screen can be a plane scattering screen or a curved surface scattering screen. After light projected by the projector passes through the scattering screen, the direction of the light is not changed, but the light is scattered along the x direction at a small angle and is scattered along the y direction at a large angle. Thus, for each ray exiting the projector, it will be scattered into a vertical bar after passing through the projector, as shown by the gray portion in fig. 1B. When the human eyes are located at a certain position, for each projector, light beams within a certain angle range enter the human eyes after being scattered by the scattering screen. The effect is that human eyes see the vertical bars with certain width on the scattering screen, and a complete picture is spliced by the vertical bars.
In the embodiment of the present invention, the projector in the projector array may be an LCD (Liquid Crystal Display) projector, a DLP (Digital Light processing) projector, an LCOS (Liquid Crystal on Silicon) projector, or an optical fiber scanning projector.
The inventor of the present invention found that, when implementing the light field display scheme, since the projection angle of each projector is limited, the range of light emitted from a single projector cannot cover all the viewing angles in the space, obviously, the middle area near the center of the projector array (or the center of the diffuser) can be covered by more projector light, resulting in a brighter image seen by the user in the middle area near the center of the projector array, and a darker image seen by the user in the edge area far from the center of the projector array, and the brightness of the projection image received by different viewing areas is not uniform.
To alleviate the above-mentioned problem of uneven projection brightness, an embodiment of the present invention provides a method for optimizing parameters of a diffuser, please refer to fig. 2, and fig. 2 is a flowchart of the method for optimizing parameters of a diffuser according to the embodiment of the present invention, which includes the following steps.
In step 201, a cost function for the brightness difference variable is constructed. Wherein the brightness difference variable is used to indicate a difference between the brightness of the picture receivable by the human eye at the target view point and the brightness of the picture receivable by the human eye at the reference view point.
In the embodiment of the invention, the brightness of the picture is related to N deflection angles of the N areas; the deflection angles of the N areas are changed, correspondingly, the number of pixel points which can be received by human eyes at different viewpoints is changed, and the brightness of the picture is different, so that the brightness of the picture can be represented by the number of the pixels. At a certain viewpoint, the more the number of pixels that can be received, the brighter the picture, otherwise, the less the number of received pixels, the darker the picture, and when the difference between the numbers of pixels received at different viewpoints is smaller, the more uniform the picture brightness is, therefore, the minimum value of the cost function can be obtained by optimizing the constructed cost function, and then, the optimal set of deflection angles corresponding to the minimum value is selected to be set as the deflection angles of the scattering screen, so that the brightness of the picture received at different viewpoints is more uniform.
Step 202, optimizing the cost function according to a preset optimization algorithm, and determining a minimum value of the cost function. The preset optimization algorithm may be a genetic algorithm, a particle swarm algorithm, a steepest descent method, or the like.
Step 203, determining an optimized deflection angle according to the minimum value of the cost function; and the N deflection angles corresponding to the minimum values are the optimized deflection angles.
Therefore, in the scheme, the cost function is optimized, so that the difference value between the number of the pixel points received at the target viewpoint and the brightness of the picture received at the reference viewpoint is very small, and then the deflection angle parameter corresponding to the minimum value is set as the deflection angle of each area of the scattering screen, so that the problem that the brightness of the projection picture which can be observed in different observation areas is not uniform in light field display in the prior art is solved, and the technical effect of improving the brightness uniformity of the projection picture displayed in the light field is realized.
Next, how to construct the cost function will be explained.
In the embodiment of the invention, the cost function is a function related to the brightness difference variable. At a certain viewpoint, the more the number of pixels that can be received, the brighter the picture, otherwise, the less the number of pixels that are received, the darker the picture, and when the difference between the numbers of pixels received at different viewpoints is smaller, the more uniform the picture brightness, therefore, the brightness difference can be represented by the pixel number difference, and the cost function can be set to the pixel number difference.
As shown in fig. 3, the target viewpoint is the position E of the observer/human eye, and Eu and Ep are the edges of the pupil of the human eye. The number of target viewpoints may be one or more; when a plurality of viewpoints are set, the difference between the number of pixels that can be received at the viewpoints and the number of pixels that can be received at the reference viewpoints can be calculated respectively, and the sum of the sub cost functions corresponding to the plurality of viewpoints is taken as the total cost function. In the embodiment of the present invention, the number of the target viewpoints may be selected and set according to factors such as an application scenario and a size of a spatial environment, and a value of the target viewpoints may be 1 to 10, 1 to 20, or more, which is not limited in the present invention.
In the embodiment of the present invention, as shown in fig. 3, S1 to Sn are pixel positions (spot positions) projected on the diffuser by the projector, and the method for calculating the number of pixels that can be received by human eyes at the target viewpoint includes the following steps.
And step 1, calculating the spot position and spot size of a single pixel point emitted by the projector on the scattering screen. The spot size is Ds ═ Dp × tan (fp/L), where Dp is the size of a single pixel point emitted by the projector, fp is the focal length of the projection lens of the projector, and L is the distance from the projector to the center of the diffuser (if the projectors are arranged along a circular arc with the center of the circle at the center of the diffuser, then L is the radius of the circular arc where the projector array is located). According to the position of the projector, a light equation of the central light PP1 of the pixel point can be obtained, if S1 is the intersection point of the light PP1 and the scattering screen, the intersection point position S1 is the position of the light spot, wherein the position of the projector is the position of the projector in a coordinate system established by taking the center of the scattering screen as an origin.
And 2, dividing a common display area of the scattering screen. Taking the horizontal direction (X direction) as an example, the common display area is divided into Ms dots at equal intervals, and the distance between adjacent dots is made equal to or slightly smaller than Ds. Assuming that the size of the common display area is Ls, the point at the position of-Ls/2 is the first point S1(S1 is the intersection point of the light PP1 and the scattering screen), and then-Ls/2 + Ls/Ms is the coordinates of the second point, and the coordinates of each point after the common display area is divided can be calculated in turn.
And step 3, S1 is a first point, Sn is an nth point, and the range of the size of the light spot (Siu, Sid) of each projector pixel on the scattering screen is (-0.5 × Ds + x (i), 0.5 × Ds + x (i)), wherein x (i) is the position of the ith division point, and i is a positive integer less than or equal to n.
And 4, calculating the scattering angle of the light spot. Considering only the X direction, assuming that the projector is located at (xp, zp), the diffuser is located at a plane where z is 0, the projector projects onto the common display area, the angle of the principal ray of the X (i) th point is θ i arctan ((X (i) -xp)/(0-zp)), and after the rays corresponding to the two edges of the X (i) th spot exit from the diffuser, the angles of the ray scattering are θ i1 ═ θ i- θ p 0.5+ θ s + θ z, and θ i2 ═ θ i + θ p 0.5+ θ s + θ z, where the beam divergence angle is θ p, i.e., the divergence angle of the rays of the individual pixels projected by the projector, the diffuser scattering angle is θ s, and the deflection angle is θ z.
Referring to fig. 5, please continue to refer to fig. 5, where E is the pupil position of the observer, the pupil position of the observer is calculated, and only the horizontal direction is considered, the position of the eyes of the observer is (xe, ze), where the position of the eyes of the observer is the position of the eyes of the observer in the coordinate system established by using the center of the diffuser screen as the origin, and the pupil size is De, and the pupil range of the human eye is represented as (xe-0.5 De, xe +0.5 De) by the horizontal position of the pupil edge (Eu, Ep).
And 6, calculating whether the light spot can enter the human eye, as shown in fig. 5, when the ith light spot in the common display area is spread to the distance ze of the human eye, the light spot range (Piu, Pid) is (-0.5 × Ds + x (i) + ze × tan (θ i1), 0.5 × Ds + x (i) + ze × tan (θ i2), if the range is overlapped with the pupil range of the human eye, the human eye can see the light spot, the light beam indicating the pixel point can enter the human eye, and if the range is not overlapped with the pupil range of the human eye, the light beam indicating the pixel point cannot enter the human eye.
According to the method from the step 1 to the step 6, the number of pixels which can enter human eyes among all the pixels (including S1 to Sn) projected by the projector can be calculated, and then the number of pixels which can be received at the target viewpoint projected by a single projector can be calculated. Then, according to the number of pixel points which can be received at the target viewpoint and are emitted by each projector in the projector array, the total number of pixel points which can be received by human eyes at the target viewpoint is calculated.
In the embodiment of the present invention, the reference viewpoint and other viewpoints in the observation region may also be calculated by the above method.
In the embodiment of the invention, the reference viewpoint can select an intermediate viewpoint, namely a viewpoint facing the center of the scattering screen, the position of the reference viewpoint in a coordinate system established by taking the center of the scattering screen as an origin can be represented as (0, 0, Le) (Le is the vertical distance between an observer and the scattering screen), and the number N of pixels of all projectors which can be received at the intermediate viewpoint is calculated0Calculating the number N of pixels observable by the observer at other positionsnThen the brightness difference variable can be represented as N0-NnSince the number of pixels that can be seen by the observer at the center is the largest, N is the number of pixels that can be seen by the observer at the center0-Nn≥0。
Next, an optimization process of the cost function in the embodiment of the present invention is described by taking a preset optimization algorithm as an example of a genetic algorithm. As shown in fig. 4, the following steps are included.
Step 401, initializing a population. The population comprises M individuals, the information of each individual is used for indicating the respective deflection angle of the N areas, namely, one individual corresponds to a group of possible deflection angle optimization parameters, and M, N are positive integers.
In the embodiment of the present invention, the number of the deflection angles included in each individual is the same as the number of the different deflection angle regions of the scattering screen, for example: dividing the scattering screen into 16 regions, and determining the deflection angles of the 16 regions, wherein each individual comprises deflection angle information of the 16 regions; another example is: the scattering screen is divided into 24 areas, the deflection angles of the 24 areas need to be determined, and then each individual includes the deflection angle information of the 24 areas. The number of individuals in the population can be set as desired to strike a balance between ensuring accuracy and reducing the number of calculations as much as possible. In the embodiment of the present invention, the number of individuals in a population is 150 for example.
In the genetic algorithm, it is necessary to encode the deflection angle information in an individual, and a binary encoding method, a floating point encoding method, or a symbol encoding method may be used for encoding. In the embodiment of the present invention, binary coding is taken as an example for description.
Assuming that the optimized range of the deflection angle of the diffuser is-1 ° to 1 °, if each angle has an 8-bit code length, the optimized range of the angle of-1 ° to 1 ° may be divided into 256, and the code length corresponding to the deflection angle of 16 regions is 128(8 × 16 — 128). And (2) randomly initializing the code of each individual, namely randomly initializing each individual into a binary number of 128 bits, wherein the number of the individuals in the population is 150, generating 150 binary numbers of 128 bits after random initialization, namely generating 150 individuals, and the chromosome length of each individual is 128 bits.
Step 402, calculating a cost function for each of the individuals.
In the embodiment of the invention, the cost function is a function related to the brightness difference variable. And calculating pixel point difference values of each target viewpoint and the reference viewpoint when the deflection angle of the scattering screen is set as the deflection angle information corresponding to each individual according to the deflection angle information of each individual, so as to obtain the value of the cost function corresponding to each individual. The method for calculating the cost function has been described in the embodiment corresponding to fig. 3, so for the brevity of the description, the detailed description is omitted here.
And step 403, judging whether a preset condition for stopping iterative computation is met.
In an embodiment of the present invention, the condition for stopping the iterative computation is at least one of the following: the times of the optimized calculation reach the set times; or the average value of the cost functions of the M individuals is smaller than a preset threshold value; or the cost function of at least one of the M individuals is smaller than a preset threshold value. If yes, go to step 404, otherwise go to step 405.
And step 404, determining minimum values of the cost functions of the M individuals, and determining the optimized deflection angle according to the minimum values of the cost functions. And the N deflection angles in the individuals corresponding to the extreme values are the optimized deflection angles. That is, when the condition for stopping the iterative computation is satisfied, the individual corresponding to the minimum cost function at that time is recorded, and N deflection angles in the individual are used as the optimized deflection angles.
And 405, iterating the M individuals according to a preset optimization algorithm to generate a next generation population. And then returns to continue to step 402.
Next, the iteration of the population is described by taking a genetic algorithm as an example, and the iteration of the M individuals according to the genetic algorithm includes the following steps, as shown in fig. 5.
Step 501, calculating the adaptive value of each individual in the population; in performing the deflection angle optimization, the cost function value of each individual may be calculated as an adaptive value of the individual by regarding the brightness difference variable.
Then, step 502 is executed, and individual selection copying is performed according to the adaptive value and the preset selection algorithm of each individual; in embodiments of the invention, individuals may be selected using Roulette Wheel Selection (Roulette Wheel Selection), and the probability that each individual is selected to remain is
Figure RE-GDA0002813529300000091
Wherein f isiAn adaptation value for each individual. Then, a population of the same number of individuals is generated according to the selection method. In other embodiments, the preset Selection algorithm may also use random competitive Selection (stored competition), optimal reservation Selection (optimal Value Selection), expected Value Selection (expected Value Selection), and the like, which is not limited in this disclosure.
And 503, carrying out cross variation on the reselected M individuals to generate a next generation population. The chromosomes of each individual have been described in the foregoing examples. When cross mutation is carried out, two individuals are exchanged with binary chromosomes of random length at corresponding positions according to a certain probability, namely chromosome crossing is realized; and inverting the chromosome of the individual with a certain probability, namely changing 0 into 1 and changing 1 into 0, so as to realize chromosome mutation.
As shown in table 1, in the optimization process, assuming that the diffuser screen is divided into 11 regions in the horizontal direction, the deflection angles corresponding to the 11 regions at different positions after optimization are shown in table 1. Accordingly, the diffuser screen may be set according to the deflection angle shown in table 1.
TABLE 1
Figure BDA0002648559780000101
Based on the same inventive concept, an embodiment of the present invention further provides a diffuser screen, which is applied to a light field display device, the light field display device further includes a projector array, light emitted from the projector array enters human eyes after being scattered by the diffuser screen, the diffuser screen includes N regions, the N regions are set to be non-uniform deflection angles, N is a positive integer, and the diffusion angles of the N regions are set according to the diffuser screen parameter optimization method in the foregoing embodiment. Various changes and specific examples in the foregoing method for optimizing the parameters of the diffuser screen in the embodiments of fig. 2 to 5 are also applicable to the diffuser screen in this embodiment, and those skilled in the art can clearly know the implementation method of the diffuser screen in this embodiment through the foregoing detailed description of the method for optimizing the parameters of the diffuser screen, so that the detailed description is omitted here for brevity of the description.
In the embodiment of the present invention, two possible diffuser screen configurations are explained. In light field display, the scattering screen is required to have horizontal small-angle scattering, vertical large-angle scattering and deflection angle. In practical application, the function can be realized by two scattering screens, and also can be realized by three scattering screens.
As shown in fig. 6, the diffuser screen is a microlens structure plus a prism array. Each micro lens on the scattering screen scatters light of one pixel point emergent from the projector, and the prism deflects light of each pixel point emergent from the projector.
As shown in fig. 7, the diffuser is a diffuser formed by two cylindrical lens arrays, the left lens realizes large-angle vertical scattering, the right lens realizes small-angle horizontal scattering, and the prism array realizes light deflection.
Corresponding directional scattering screens with deflection angles can be designed according to the deflection angles and the positions in the table 1, so that the brightness uniformity of a projection picture is realized.
An embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the processor is caused to execute the method in the foregoing embodiment.
The embodiment of the invention also provides a light field display method, which is applied to light field display equipment, wherein the light field display equipment comprises a projector array and a scattering screen, light emitted by the projector array enters human eyes after being scattered by the scattering screen, and the method comprises the following steps:
emitting light corresponding to the image to be projected through the projector array;
when the light rays are incident to different areas of the scattering screen, the light rays are subjected to non-uniform deflection through the different areas of the scattering screen, so that the light rays are uniformly distributed in an observable area of the light field display equipment after passing through the scattering screen; the scattering screen is divided into N areas, the N areas have non-uniform deflection angles, and N is a positive integer.
Various changes and specific examples in the foregoing method for optimizing parameters of a diffuser screen in the embodiments of fig. 2 to fig. 7 are also applicable to the method for displaying a light field in the present embodiment, and those skilled in the art can clearly know the method for implementing the method for displaying a light field in the present embodiment through the foregoing detailed description of the method for optimizing parameters of a diffuser screen, so that details are not described herein again for the sake of brevity of the description.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
in the scheme of the embodiment of the invention, the cost function about the brightness difference variable is optimized, so that the difference between the number of the pixel points received at the target viewpoint and the number of the pixel points received at the reference viewpoint is small, and the image brightness is more uniform when the difference between the number of the pixel points received at different viewpoints is smaller, therefore, the group of deflection angle parameters corresponding to the minimum value of the cost function is set as the deflection angle of each area of the scattering screen, so that the problem of uneven brightness of the projection image which can be observed in different observation areas in the light field display in the prior art can be solved, and the technical effect of improving the brightness uniformity of the projection image displayed in the light field is realized.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations where mutually exclusive features and/or steps are present.
Any feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.
The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.

Claims (12)

1. A scattering screen parameter optimization method is applied to optical field display, and equipment for realizing the optical field display comprises a projector array and a scattering screen, wherein light rays emitted by the projector array enter human eyes after being scattered by the scattering screen; the method comprises the following steps:
constructing a cost function about the brightness difference variable; the brightness difference variable is used for indicating the difference value between the brightness of the picture which can be received by human eyes at the target viewpoint and the brightness of the picture which can be received by the human eyes at the reference viewpoint; the brightness of the picture is related to N deflection angles of the N areas;
optimizing the cost function according to a preset optimization algorithm, and determining a minimum value of the cost function;
determining an optimized deflection angle according to the minimum value of the cost function; and the N deflection angles corresponding to the minimum values are the optimized deflection angles.
2. The method of claim 1, wherein the method of calculating the brightness of the picture that can be received by human eyes at the target viewpoint/reference viewpoint comprises:
calculating the number of pixel points which can be received by human eyes at the target viewpoint/the reference viewpoint; and the number of the pixel points is used for representing the brightness of the picture.
3. The method of claim 1, wherein the method of calculating the number of pixel points that can be received by the human eye at the target viewpoint/reference viewpoint comprises:
aiming at each pixel point emitted by a projector, calculating the spot position and spot size of the pixel point projected on the scattering screen;
calculating a light ray scattering angle of the light spot in a preset direction according to the size of the light spot, and a deflection angle and a scattering angle of an area where the light spot is located, wherein the preset direction is a horizontal direction or a vertical direction;
judging whether the light of the light spots of the pixel points after being scattered by the scattering screen can enter human eyes positioned at the target viewpoint/reference viewpoint or not according to the light scattering angle and the position of the target viewpoint/reference viewpoint;
calculating the number of pixel points which are emitted by each projector and can be received by human eyes at the target viewpoint/reference viewpoint;
and calculating the total number of the pixel points which can be received by human eyes at the target viewpoint/the reference viewpoint according to the number of the pixel points of each projector.
4. The method of claim 1, wherein the reference viewpoint is a viewpoint directly opposite to a center of the diffuser screen.
5. The method of claim 1, wherein the pre-set optimization algorithm is one of a genetic algorithm, a particle swarm algorithm, or a steepest descent method.
6. The method of claim 5, wherein optimizing the cost function according to a predetermined optimization algorithm comprises:
initializing a population, wherein the population comprises M individuals, the information of each individual is used for indicating the respective deflection angle of the N areas, and M is a positive integer;
calculating a cost function for each of the individuals;
judging whether a preset condition for stopping optimization calculation is met;
if yes, determining an extreme value of the cost functions of the M individuals;
if not, iterating the M individuals according to the preset optimization algorithm.
7. The method of claim 6, wherein the condition to stop the optimization computation is at least one of:
the times of the optimized calculation reach the set times;
the average value of the cost functions of the M individuals is smaller than a preset threshold value;
the cost function of at least one of the M individuals is smaller than a preset threshold value.
8. The method of claim 6, wherein when the preset optimization algorithm is a genetic algorithm, iterating the M individuals according to the preset optimization algorithm comprises:
calculating an adaptation value for each of the individuals; wherein the adaptive value of the individual refers to a value of a cost function of the individual;
reselecting M individuals from the population based on the adaptive value of each individual and a preset selection algorithm;
and carrying out cross variation on the reselected M individuals to generate a next generation of population.
9. The scattering screen is applied to light field display equipment, the light field display equipment further comprises a projector array, and light rays emitted by the projector array enter human eyes after being scattered by the scattering screen.
10. A diffuser screen according to claim 9, wherein the diffuser screen comprises a microlens array and a prism array; or the diffuser screen comprises a horizontal cylindrical lens array, a vertical cylindrical lens array and a prism array.
11. A computer-readable storage medium, having stored thereon a computer program which, when executed by a processor, causes the processor to perform the method of any one of claims 1-8.
12. A light field display method is applied to a light field display device, the light field display device comprises a projector array and a scattering screen, and light rays emitted by the projector array enter human eyes after being scattered by the scattering screen, and the method comprises the following steps:
emitting light corresponding to the image to be projected through the projector array;
when the light rays are incident to different areas of the scattering screen, the light rays are subjected to non-uniform deflection through the different areas of the scattering screen, so that the light rays are uniformly distributed in an observable area of the light field display equipment after passing through the scattering screen; the scattering screen is divided into N areas, the N areas have non-uniform deflection angles, and N is a positive integer.
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