Projection system and image uniformity compensation method thereof

Abstract

To provide a projection system and a video image uniformity coefficient compensation method thereof.SOLUTION: A method includes steps of: projecting a test image onto a projection surface by a projection device; performing measurement at the projection surface by a plurality of color measurement devices to acquire a plurality of test color data corresponding respectively to a plurality of measurement positions; forming an estimation image by using the plurality of test color data; updating uniformity coefficient compensation information of each pixel on the basis of a target value and each pixel information of the estimation image; and performing compensation to an initial image on the basis of the uniformity coefficient compensation information to generate a uniformity image, and projecting the uniformity image by the projection device.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to projection technology, and in particular to a projection system and its image uniformity compensation method. [Background technology]

[0002] A projection device is a display device for generating a large-sized screen. When a projection device projects an image, an illumination light beam from a light source can be projected onto a light valve after being dispersed and shaped into a light shape. For example, an illumination system of a projection device can uniformly project an illumination light beam onto a light valve using a lens array or a light integration rod. The light valve then converts the illumination light beam into an image light beam in a reflection or transmission manner and provides the image light beam to a projection lens, which then projects the image light beam onto a projection surface (e.g., a screen or a wall surface) to form an image. As can be seen, the light beam needs to be projected via several reflection and refraction paths, which may cause the projection screen finally formed on the projection surface to have non-uniformity in brightness or chromaticity. The most common screen non-uniformity is that the central area of ​​the projection screen is relatively bright, but the peripheral area of ​​the projection screen is relatively dark, or there is a difference (discomfort) between the color representation of the peripheral area of ​​the projection screen and the color representation of the central area.

[0003] Generally speaking, the length of the path that the light beam takes from the light source to the projection surface, the deterioration of internal elements for uniforming the illumination light beam, and other factors can cause the projection screen to have non-uniform luminance or chromaticity. In addition, since the projection screens projected by different projectors also have differences in luminance or chromaticity, when multiple projectors stitch together the projection screens, obvious differences in luminance or chromaticity may occur at the stitched portions of the projection screens. In other words, the stitched screens produced by stitching together the projection screens produced by multiple projectors also have non-uniform luminance or chromaticity.

[0004] Note that the "Background Art" section is intended only to aid in understanding the present invention, and therefore the contents disclosed in the "Background Art" section may include techniques not known to those skilled in the art. Therefore, the contents disclosed in the "Background Art" section do not mean that the contents or the problems that one or more embodiments of the present invention are intended to solve were already known to those skilled in the art prior to the filing of the present invention. Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS An object of the present invention is to provide a projection system and an image uniformity compensation method capable of improving chromaticity or luminance nonuniformity on a projection screen.

[0006] Other objects and advantages of the present invention can be further understood from the technical features disclosed in the present invention. [Means for solving the problem]

[0007] According to an embodiment of the present invention, there is provided a method for image uniformity compensation, which is used in a projection system including a projection device, and includes the following steps: projecting a test image onto a projection surface by the projection device; performing measurements on the projection surface by a plurality of color measurement devices when projecting the test image, obtaining a plurality of test color data respectively corresponding to a plurality of measurement positions; forming an estimated image using the plurality of test color data; updating uniformity compensation information for each pixel based on a target value and each pixel information of the estimated image; performing compensation on an initial image based on the uniformity compensation information to generate a uniformed image; and projecting the uniformed image by the projection device.

[0008] According to another embodiment of the present invention, a projection system is provided, which includes a projection device, a plurality of color measurement devices, and a calculation device. The projection device projects a test image onto a projection surface. The plurality of color measurement devices are disposed on the projection surface, and the calculation device is connected to the projection device and the plurality of color measurement devices. When the projection device projects the test image, the plurality of color measurement devices perform measurements on the projection surface, and the calculation device obtains a plurality of test color data respectively corresponding to a plurality of measurement positions. The calculation device forms an estimated image using the plurality of test color data, and updates uniformity compensation information for each pixel according to a target value and each pixel information of the estimated image. The calculation device performs compensation on the initial image based on the uniformity compensation information to generate a uniformized image, and then projects the uniformized image by the projection device.

[0009] As described above, in the embodiment of the present invention, a plurality of color measurement devices can measure the actual projection result on the projection plane, and an estimated image can be formed based on the measurement result. Then, based on each pixel information and a target value of the estimated image, uniformity compensation information corresponding to each pixel position is generated, in which the target value is also determined by the measurement result. Thus, in the embodiment of the present invention, the initial image is adjusted using the uniformity compensation information before projection, so that the projection screen on the projection plane can have uniform brightness and chromaticity.

[0010] In order to make the above-mentioned features and advantages of the present invention more apparent, the present invention will now be described in detail with reference to the accompanying drawings, in which: FIG. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 illustrates a projection system according to one embodiment of the present invention. [Diagram 2] 4 is a flowchart of an image uniformity compensation method according to an embodiment of the present invention. [Diagram 3] 4 is a flowchart of determining uniformity compensation information according to an embodiment of the present invention. [Figure 4]11A and 11B are diagrams illustrating color space component distributions of a projected screen before and after modification according to an embodiment of the present invention. [Diagram 5] 4 is a flowchart of uniformity compensation using multiple sets of sub-uniformity compensation information according to an embodiment of the present invention. [Figure 6A] FIG. 1 illustrates a projection system according to one embodiment of the present invention. [Figure 6B] FIG. 1 illustrates a projection system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The above and other technical contents, features, functions and effects of the present invention will become more apparent from the following detailed description of preferred embodiments based on the accompanying drawings. Note that the directional terms used in the following embodiments, such as up, down, left, right, front, back, etc., are merely the directions in the accompanying drawings. Therefore, the directional terms used are only for the purpose of explaining the present invention, and are not intended to limit the present invention.

[0013] 1 is a diagram showing a projection system according to an embodiment of the present invention, the projection system 10 includes a projection device 110, a plurality of color measurement devices 120_1 to 120_13, and a calculation device .

[0014] The projection device 110 can project an image provided by the computing device 130 onto a projection surface S1, which may be a liquid crystal projector (LCP), a digital light processing (DLP) projector, a liquid crystal on silicon (LCOS) projection display device, etc. In this embodiment, the projection device 110 may further include a light source module, an optical module, a lens module, related optical and circuit control elements, etc. The projection surface S1 may be a flat or curved surface, such as a wall, a flat screen, a spherical screen, etc., but the present invention is not limited thereto.

[0015] The color measuring devices 120_1-120_13 may be attached to a plurality of measuring positions on the projection surface S1, and may be instruments for measuring color information, such as a chromaticity illuminometer, a spectrometer, etc. Generally speaking, the color measuring devices 120_1-120_13 can be attached to the projection surface S1 and face the projection device 110 to perform measurements, and output chromaticity coordinates after the measurements, and these chromaticity coordinates may be CIE 1931 chromaticity coordinates, CIE 1976 chromaticity coordinates, CIE RGB chromaticity coordinates, etc., but the present invention is not limited thereto.

[0016] In FIG. 1, 13 color measurement devices 120_1 to 120_13 are used as an example for explanation, but the present invention does not limit the number of color measurement devices. The number of color measurement devices may be five, nine, etc. However, in order to form an estimated image based on the measurement results by the color measurement devices, the number of color measurement devices is preferably at least one. Furthermore, the present invention does not limit the measurement positions of the color measurement devices, and may be appropriately designed based on actual needs.

[0017] The computing device 130 is connected to the projection device 110 and the plurality of color measurement devices 120_1-120_13, and includes at least a memory and at least one processor connected to the memory. The computing device 130 may be a computing-capable computer-controlled system such as a desktop computer, a laptop, a work station, an industrial computer, a server, etc. The memory may be any non-transient, volatile or non-volatile data storage device that is used to store cache data, persistent data, compiler code for performing the functions of the computing device 130. The processor may be a Field Programmable Array (FPGA), a Programmable Logic Device (PLD), an Application Specific Integrated Circuits (ASIC), other similar devices, or a combination of these devices. The processor may be a Central Processing Unit (CPU) or other programmable general-purpose or special-purpose microprocessor, a Digital Signal Processor (DSP), a Graphics Processing Unit (GPU), or other similar device, or a combination of these devices.

[0018] Fig. 2 is a flow chart of a method for compensating image uniformity in an embodiment of the present invention, and the steps of the method shown in Fig. 2 can be implemented by each element of the projection system 10 in Fig. 1. Please refer to Fig. 1 and Fig. 2 at the same time. Hereinafter, the steps of the method for compensating image uniformity according to this embodiment will be described with reference to each element of the projection system 10 in Fig. 1.

[0019] In step S201, a test image (not shown) is projected onto a projection surface S1 by the projection device 110. Specifically, the computing device 130 provides a test image to the projection device 110, and the projection device 110 projects the test image onto the projection surface S1.

[0020] In step S202, when the projection device 110 projects a test image, the multiple color measurement devices 120_1 to 120_13 perform measurements on the projection surface S1, and the calculation device 130 obtains multiple test color data corresponding to multiple measurement positions. Generally speaking, it is preferable that the color measurement devices 120_1 to 120_13 are distributed over the entire projection surface S1. As shown in FIG. 1, the color measurement devices 120_1, 120_5, 120_9, and 120_13 are installed at the four corners of the projection surface S1, and the color measurement devices 120_2 to 120_4, 120_6 to 120_8, and 120_10 to 120_12 are installed in a square shape on the projection surface S1. Based on this, the color measurement devices 120_1 to 120_13 can perform color measurements at different measurement positions on the projection surface S1, and then output test color data corresponding to these measurement positions to the calculation device 130, and these test color data correspond to the chromaticity coordinates of a specific color space.

[0021] In step S203, the calculation device 130 forms an estimated image using a plurality of test color data. More specifically, these test color data can be regarded as sampling data obtained by sampling different pixels of a projection screen, and the calculation device 130 can estimate the estimated image based on the size of the projection image (i.e., the resolution of the projection image) and the test color data at different measurement positions. In one embodiment, the calculation device 130 may form the estimated image by a linear or nonlinear interpolation method. Taking FIG. 1 as an example, when the resolution of the projection image is M*N, the calculation device 130 can form an estimated image having an image size of M*N based on 13 test color data (i.e., 13 pixel information) from the color measurement devices 120_1 to 120_13. More specifically, the calculation device 130 can generate an estimated image having M*N pixels by performing an interpolation process on each color space component to obtain each pixel value component of each pixel in the estimated image.

[0022] In step S204, the calculation device 130 updates the uniformity compensation information of each pixel according to the predetermined target value and each pixel information of the estimated image. The uniformity compensation information of each pixel is a compensation gain value, which may be between 0 and 1. Specifically, the initial setting value of the uniformity compensation information of each pixel may be preset to, for example, "1". The calculation device 130 can determine how to update the uniformity compensation information from the set value to another value by comparing each color space component of each pixel in the estimated image with the target value. In other words, if the resolution of the projected image is M*N, the calculation device 130 updates 3*M*N compensation gain values ​​of three color space components corresponding to M*N pixels, respectively, that is, the three color space components (e.g., red, green, and blue) of each pixel in the estimated image have corresponding compensation gain values.

[0023] Then, in step S205, the projection device 110 performs compensation on the initial image based on the uniformity compensation information to generate a uniform image, and then projects the uniform image by the projection device 110. In other words, if the resolution of the projection image is M*N, the projection device 110 can obtain a uniform image by adjusting each color space component of M*N pixels in the initial image using 3*M*N compensation gain values. More specifically, the projection device can multiply the corresponding color space components of the corresponding pixels on the initial image by the 3*M*N compensation gain values. In other words, in the embodiment of the present invention, the three color space components of each pixel in the initial image are attenuated to different degrees, so that the projection screen projected by the projection device 110 based on the uniform image can have uniform brightness and chromaticity. It should be noted that the uniformity compensation information formed in steps S201 to S204 can be recorded in the processing circuit of the projection device 110, so that the projection device 110 can perform the correction process and then perform compensation on the initial image from the computing device 130 or other image source device to project a uniformized image. In this way, the projection result generated by the projection device 110 based on the uniformized image has no luminance or chromaticity non-uniformity.

[0024] In one embodiment, the calculation device 130 determines the uniformity compensation information by comparing a target value with each pixel information in the estimated image, and the target value is determined based on the actual projection screen before compensation correction. In one embodiment, the calculation device 130 can further use an iterative calculation method to more accurately generate uniformity compensation information for compensating for the image uniformity. Hereinafter, an embodiment will be given to describe in detail how to generate the uniformity compensation information.

[0025] Fig. 3 is a flow chart of an image uniformity compensation method in an embodiment of the present invention, and the method steps shown in Fig. 3 can be realized by each element of the projection system 10 in Fig. 1. Please refer to Fig. 1 and Fig. 3 at the same time. Hereinafter, the steps of generating uniformity compensation information in this embodiment will be described in detail with reference to each element of the projection system 10 in Fig. 1. Note that the following description will be given taking the case where the resolution of the projected image on the projection screen is M*N as an example.

[0026] In addition, in the embodiment of the present invention, the computing device 130 can generate corresponding uniformity compensation information for different test luminances. The test luminances may be 100%, 75%, 50%, 25%, 0%, etc., and may be designed according to actual needs. When generating corresponding uniformity compensation information for a certain test luminance, the computing device 130 can provide an original test image corresponding to the certain test luminance to the projection device 110 for projection, so as to generate the uniformity compensation information corresponding to the certain test luminance.

[0027] First, in step S301, the calculation device 130 obtains an original test image corresponding to a test luminance. In step S302, the projection device 110 projects the original test image corresponding to the test luminance onto the projection surface S1. Specifically, the calculation device 130 provides the projection device 110 with an original test image (i.e., a white screen, a black screen, or a gray screen corresponding to the test luminance) in which each pixel information is the same and corresponds to the test luminance, and allows the projection device 110 to project the original test image onto the projection surface S1. For example, when the test luminance is 100%, the R value, the G value, and the B value of each pixel in the original test image are all 256 (normalized to 1). When the test luminance is 50%, the R value, the G value, and the B value of each pixel in the original test image are all 128 (normalized to 0.5).

[0028] In step S303, when the projection device 110 projects the original test image, the multiple color measurement devices 120_1-120_13 perform measurements on the projection surface S1, and the calculation device 130 obtains multiple original color data corresponding to multiple measurement positions. The original color data is a chromaticity coordinate. Although the pixel values ​​of each pixel in the original test image are all the same, there may be differences in the measurement results of the color measurement devices 120_1-120_13 at different measurement positions on the projection surface S1 due to differences in the length of the optical transmission path, deterioration of the projection optical elements, etc.

[0029] In addition, in one embodiment, the color measurement devices 120_1-120_13 can output a plurality of color measurement values ​​corresponding to a first color space after measurement, for example, X, Y, and Z values ​​of the CIE 1931 color space. Since the calculation device 130 and the projection device 110 perform the projection operation in the CIE RGB color space, the calculation device 130 converts the plurality of color measurement values ​​corresponding to the first color space measured by the plurality of color measurement devices 120_1-120_13 into a plurality of original color data corresponding to a second color space based on a color transformation matrix. That is, the calculation device 130 converts the color measurement values ​​(X, Y, and Z) output by the color measurement devices 120_1-120_13 into a plurality of original color data corresponding to a second color space. i ,Yi ,Z i ) i=1~13 The original color data (R i ,G i ,B i ) i=1~13 where i is the index value of the measurement position.

[0030] In the above, the first color space is the CIE 1931 color space and the second color space is the CIE RGB color space. However, the present invention is not limited to the first color space and the second color space, and may be appropriately designed according to actual needs. In addition, since the definition of white light is different for different environmental light sources, in the embodiment of the present invention, the color transformation matrix for converting the color measurement value of the first color space into multiple original color data of the second color space may also be designed based on the color temperature of different light sources, but the present invention is not limited thereto. However, for the convenience of explanation, the following description will still be given by taking the example of the first color space being the CIE 1931 color space and the second color space being the CIE RGB color space. That is, the measurement values ​​output by the color measuring devices 120_1 to 120_13 are in CIE 1931 chromaticity coordinates, and the calculation device 130 converts the CIE 1931 chromaticity coordinates output by the color measuring devices 120_1 to 120_13 into CIE RGB chromaticity coordinates before carrying out the subsequent processes.

[0031] In step S304, the calculation device 130 obtains the target value by obtaining the minimum value from the multiple color space component values ​​of the multiple original color data. In this embodiment, the calculation device 130 can obtain 13 original color data, and each of the 13 original color data has three color space component values, namely, R value, G value, and B value. That is, in the example shown in FIG. 1, the calculation device 130 can obtain 13 R values, 13 G values, and 13 B values ​​corresponding to 13 measurement positions, and obtain the minimum value from these 39 values ​​as the target value. That is, the target value T=min i=1~13 (R i ,G i ,B i), where i is an index value of the measurement position. In this embodiment, all the test color data acquired by the measurement of the color measurement devices 120_1 to 120_13 are adjusted to approach the target value T, thereby making it possible to achieve the objectives of uniform luminance and white balance on the projection screen.

[0032] In step S305, the calculation device 130 adjusts the original test video using the uniformity compensation information to generate a test video. When the first modification process is performed, the uniformity compensation information corresponding to each pixel may be preset to 1. That is, in the first modification process, the original test video is the same as the test video. Then, when the first iterative modification process is performed after the first modification process, some of the uniformity compensation information is updated to a value smaller than 1 by the first modification process, and the test video in the first iterative modification process is generated by the calculation device 130 by adjusting the original test video based on the updated uniformity compensation information, so that the test video in the first iterative modification process is different from the original test video. Based on this, when the second iterative modification process is performed after the first iterative modification process, some uniformity compensation information is updated again by the first iterative modification process, and the test image in the second iterative modification process is generated by the computing device 130 by adjusting the test image in the first iterative modification process based on the updated uniformity compensation information, so the test image in the second iterative modification process is different from the original test image and the test image in the first iterative modification process. If the original test image I is (I r n ,I g n ,I b n ) n=1~(M*N) The uniformity compensation information is expressed as (β r n ,β g n ,β b n ) n=1~(M*N)where n is the pixel index, the test image P is expressed as (P r n ,P g n ,P b n ) n=1~(M*N) Of these, P r n =I r n *β r n ;P g n =I g n *β g n ;P b n =I b n *β b n It is.

[0033] In step S306, the projection device 110 projects a test image onto the projection surface S1. As can be seen from the above, the projection device 110 projects different test images onto the projection surface S1, which are generated through multiple iterative correction processes, and calculates corresponding uniformity compensation information after each test image projection.

[0034] In step S307, when the test image is projected, the multiple color measurement devices 120_1-120_13 perform measurements on the projection plane S1 to obtain multiple test color data corresponding to multiple measurement positions, respectively. The multiple test color data are RGB color data. As in step S303, the calculation device 130 converts the multiple color measurement values ​​corresponding to the first color space obtained by the measurements of the multiple color measurement devices 120_1-120_13 into multiple test color data corresponding to the second color space, based on the color transformation matrix. When the test image is projected, the calculation device 130 converts the color measurement values ​​(X k ,Y k ,Z k ) k=1~13 The test color data (R k ,G k ,Bk ) k=1~13 where k is the index value of the measurement position.

[0035] In step S308, the calculation device 130 determines whether the difference between the maximum and minimum values ​​of the multiple color space components of the multiple test color data is smaller than a tolerance threshold value (a predetermined threshold value). This step is used to determine whether the iterative correction is to be continued. In this embodiment, the calculation device 130 can determine whether to stop updating the uniformity compensation information based on the color measurement result. Specifically, in the example shown in FIG. 1, the calculation device 130 can obtain multiple test color data corresponding to 13 measurement positions in step S307, and these test color data include 13 R values, 13 G values, and 13 B values. The calculation device 130 obtains the minimum and maximum values ​​from the 39 values, and determines whether the difference between the maximum and minimum values ​​is smaller than a tolerance threshold value. The magnitude of the tolerance threshold value can be appropriately set based on the actual application.

[0036] Conversely, when the difference is equal to or greater than the allowable threshold (the judgment result of step S308 is "NO"), it means that the screen uniformity of the current compensated projection result is not permitted, that is, the current screen uniformity is judged to be non-uniform, and the calculation device 130 decides to continue updating the uniformity compensation information. In step S309, the calculation device 130 performs an interpolation process using a plurality of measurement positions and a plurality of color space components of the test color data to obtain each pixel information of the estimated image, thereby forming an estimated image. Specifically, these measurement positions correspond to different pixel coordinate positions, respectively, and the calculation device 130 performs an interpolation process based on these pixel coordinate positions and the corresponding test color data to obtain each pixel information of the estimated image. The interpolation process may be thin-plate spline interpolation, other linear or nonlinear interpolation methods. More specifically, the calculation device 130 performs an interpolation process for each spatial color component of the test color data and the corresponding measurement positions in order to obtain each pixel component value of each pixel of the estimated image in order. When the estimated image J is (J r n ,J g n ,J b n ) n=1~(M*N) The computing device 130 calculates the test color data (R k ,G k ,B k ) k=1~13 Color space component R in 1 ~R 13 The pixel component value (J r n ) n=1~(M*N) Similarly, the computing device 130 can obtain the test color data (R k ,G k ,B k ) k=1~13 Color space component G in 1 ~G 13 The pixel component value (J g n ) n=1~(M*N)Similarly, the computing device 130 can obtain the test color data (R k ,G k ,B k ) k=1~13 Color space component B in 1 ~B 13 The pixel component value (J b n ) n=1~(M*N) You can also get:

[0037] In step S310, the calculation device 130 generates adjustment coefficient information for each pixel based on the ratio between the target value and the pixel component value of each pixel in the estimated image and the convergence coefficient. Specifically, the calculation device 130 can determine the adjustment coefficient information for each pixel by comparing the target value T with each pixel in the estimated image J. Note that the adjustment coefficient information for each pixel similarly includes three adjustment coefficients corresponding to the three color space components. When the adjustment coefficient information is (α r n ,α g n ,α b n ) n=1~(M*N) In this case, the calculation device 130 can obtain the adjustment coefficient information by the following formulas (1) to (3) in order.

[0038] α r n =(C+T) / (C+J r n ) Formula(1) α g n =(C+T) / (C+J g n ) Formula(2) α b n =(C+T) / (C+J b n ) Formula(3) Wherein, n is a pixel index, C is a convergence coefficient, and T is a target value. However, the formulas (1) to (3) are merely examples, and the calculation device 130 can also calculate the adjustment coefficient information according to other convergence formulas.

[0039] In step S311, the calculation device 130 updates the uniformity compensation information based on the adjustment coefficient information. The calculation device 130 can update the uniformity compensation information by multiplying the adjustment coefficient information by the uniformity compensation information. r n ,β g n ,β b n ) n=1~(M*N) and the adjustment coefficient information is (α r n ,α g n ,α b n ) n=1~(M*N) Then, the updated uniformity compensation information is (β r n *α r n ,β g n *α g n ,β b n *α b n ) n=1~(M*N) It is.

[0040] After step S311, return to step S305, and use the updated uniformity compensation information to adjust the original test image again to form a test image, thereby performing the next iterative modification process. In other words, steps S305 to S311 are repeatedly executed by the computing device 130 until the test image in a certain iterative modification process satisfies the condition of step S308. Note that, when steps S305 to S311 are repeatedly executed, the test color data obtained by the measurements of the color measuring devices 120_1 to 120_13 gradually converge to the target value, and the uniformity compensation information also gradually converges.

[0041] More specifically, after step S307, if the difference between the maximum value and the minimum value of the multiple color space components of the multiple test color data is smaller than the allowable critical value (if the judgment result of step S308 is "yes"), it means that the screen uniformity of the current compensated projection result is acceptable, and the calculation device 130 decides to stop updating the uniformity compensation information. In step S312, the calculation device 130 provides the uniformity compensation information to the projection device 110, and the projection device 110 can store the uniformity compensation information in, for example, a processing circuit of a DSP or other storage element. Thereby, the projection device 110 can improve the projection quality by adjusting the initial image provided by the image source device based on the uniformity compensation information in the processing circuit.

[0042] FIG. 4 is a diagram showing the color space component distribution of the projection screen before and after correction in an embodiment of the present invention. As shown in FIG. 4, when performing uniformity correction without using uniformity compensation information in the embodiment of the present invention, even if the projection device 110 receives a white image in which each pixel value is the same, there is a non-uniform phenomenon in the R value distribution 41, the G value distribution 42, and the B value distribution 43 of the projection screen actually projected on the projection surface. In addition, the non-uniform distribution of the R value distribution 41, the G value distribution 42, and the B value distribution 43 not only causes a non-uniformity in the luminance of the screen, but also makes the chromaticity non-uniformity visible on the actual projection screen. In contrast, after performing uniformity correction using the uniformity compensation information in the embodiment of the present invention, the R value distribution 44, the G value distribution 45, and the B value distribution 46 of the actual projection screen are uniform distributions, so that the actual projection screen can exhibit a state of uniform luminance and uniform chromaticity. As can be seen, the embodiment of the present invention achieves the purpose of making the entire projection screen uniform by compressing the contrast of the screen.

[0043] However, since the luminance actually appearing on the projection screen and the luminance of the input image do not necessarily have a linear relationship, the calculation device 130 can further generate multiple sets of sub-uniformity compensation information corresponding to multiple test luminances by repeatedly executing the process shown in Fig. 3 based on different test luminances (for example, five test luminances of 100%, 75%, 50%, 25%, or 0%). After generating all the corresponding sub-uniformity compensation information for different test luminances, the calculation device 130 can further perform an interpolation process on the multiple sets of sub-uniformity compensation information to generate sub-uniformity compensation information corresponding to other luminances, and then process the images with different luminances.

[0044] 5 is a flow chart of uniformity compensation using multiple sets of sub-uniformity compensation information in one embodiment of the present invention. The method steps shown in FIG. 5 may be implemented in each element of the projection system 10 in FIG. 1. Please refer to FIG. 1 and FIG. 5 simultaneously. The following description will be made with reference to each element of the projection system 10 in FIG. 1.

[0045] In step S501, the calculation device 130 performs an interpolation process on the sub-uniformity compensation information associated with the test luminance. In step S502, the projection device 110 generates a uniformized image by performing compensation on the initial image based on the interpolation result of the interpolation process. In other words, in one embodiment, the uniformity compensation information may include a plurality of sub-uniformity compensation information associated with a plurality of test luminances, and the calculation device 130 can derive sub-uniformity compensation information associated with other luminances based on the plurality of sub-uniformity compensation information generated after actually performing an iterative correction process. In this way, the projection device 110 can generate a uniformized image by adjusting the initial image based on the sub-uniformity compensation information corresponding to different luminances. For example, if the grayscale value (i.e., luminance) of one pixel in the initial image is L1, the projection device 110 can obtain the uniformity compensation gain value of the pixel by looking up the sub-uniformity compensation information corresponding to the luminance L1. In addition, if the grayscale value (i.e., luminance) of another pixel in the initial image is L2, the projection device 110 can also obtain the uniformity compensation gain value of the other pixel by looking up the sub-uniformity compensation information corresponding to the luminance L2.

[0046] In addition, in the embodiment of the present invention, uniformity correction may be further performed on the plurality of projection devices. FIG. 6A and FIG. 6B are diagrams showing a projection system in an embodiment of the present invention. As shown in FIG. 6A and FIG. 6B, the projection system 20 includes a projection device 110, a plurality of color measurement devices 120_1-120_13, a calculation device 130, and a projection device 140. The projection device 110, the plurality of color measurement devices 120_1-120_13, and the calculation device 130 in FIG. 6A and FIG. 6B are the same as those in FIG. 1, so detailed description thereof is omitted here. The projection system 20 further includes a projection device 140. The projection device 140 and the projection device 110 may cause a chromaticity difference or a luminance difference between the projection screens generated by both devices due to various causes. That is, even if the projection device 140 and the projection device 110 receive the same pixel information, there exists a color difference between the two projection screens generated by both devices in terms of the human eye.

[0047] In one embodiment, the computing device 130 can generate corresponding uniformity compensation information for the projection device 140 and the projection device 110, respectively, and the projection device 140 and the projection device 110 can adjust the input images based on their respective uniformity compensation information, so that the chromaticity and luminance of the projection screens of the two devices are consistent, which is beneficial for the two projection devices to stitch the projection screens.

[0048] First, as shown in FIG. 6A, the projection device 110 projects an original test image corresponding to a test luminance onto the projection plane S1. When the projection device 110 projects the original test image, the multiple color measuring devices 120_1-120_13 perform measurements on the projection plane S1 to obtain multiple first original color data corresponding to multiple measurement positions. Refer to FIG. 6B again. Next, the projection device 140 is used instead of the projection device 110, and the original test image corresponding to the test luminance is projected onto the projection plane S1 by another projection device 140 further included in the projection system 20. When the other projection device 140 projects the original test image, the multiple color measuring devices 120_1-120_13 perform measurements on the projection plane S1 to obtain multiple second original color data corresponding to multiple measurement positions.

[0049] Also, after obtaining a plurality of first original color data and a plurality of second original color data for the projection device 110 and the projection device 140, respectively, the calculation device 130 can obtain a target value by obtaining a minimum value from a plurality of color space component values ​​of the plurality of first original color data and a plurality of color space component values ​​of the plurality of second original color data. For example, for the projection device 110, the calculation device 130 can obtain 13 R values, 13 G values, and 13 B values ​​corresponding to 13 measurement positions. For the projection device 140, the calculation device 130 can similarly obtain 13 R values, 13 G values, and 13 B values ​​corresponding to 13 measurement positions. Then, the calculation device 130 finds a minimum value from the 78 values ​​as the target value of the projection device 110 and the projection device 140.

[0050] Then, the calculation device 130 and the projection device 110 can obtain uniformity compensation information of the projection device 110 by performing an iterative correction process (for example, steps S305 to S312 in FIG. 3) based on the target value. Then, the calculation device 130 and the projection device 140 can obtain uniformity compensation information of the projection device 140 by performing an iterative correction process (for example, steps S305 to S312 in FIG. 3) based on the target value. In this way, the projection device 140 and the projection device 110 can adjust the input image based on their own uniformity compensation information so that the chromaticity and luminance of the projection screens of both projection devices are consistent. In another embodiment, the projection system may include multiple projection devices, i.e., is not limited to two.

[0051] From the above, in the embodiment of the present invention, the compensation gain value can be determined for each color space component by measuring the real color information of the image on the projection surface. Based on this, regardless of the cause of the non-uniformity of the luminance or chromaticity on the projection screen, the projection device adjusts the input image using the uniformity compensation information in the embodiment of the present invention, and then the luminance non-uniformity and / or chromaticity non-uniformity on the projection screen generated by the projection device can be improved, thereby improving the projection quality. In addition, in the embodiment of the present invention, the corresponding uniformity compensation information can be further generated for a curved projection surface, thereby preventing the occurrence of the non-uniformity of the luminance on the projection screen due to the curved projection surface.

[0052] Furthermore, in the embodiment of the present invention, since the color measurement device performs measurements directly on the projection surface, there is no need to consider the effects of camera correction and errors caused by the camera itself, as compared with the technology of correcting by taking pictures of the projection screen with a camera. In other words, compared with correcting using information taken by a camera, the test color data obtained in the embodiment of the present invention is closer to the actual situation, so that the brightness non-uniformity of the image can be more accurately compensated for, thereby further improving the display quality of the projection device.

[0053] The present invention has been disclosed above based on the preferred embodiment described above, but the preferred embodiment described above is not intended to limit the present invention, and a person skilled in the art may make minor modifications and adaptations to the present invention without departing from the technical spirit and scope of the present invention, and therefore the scope of protection of the present invention is based on the scope of the attached claims. In addition, it is not necessary for any embodiment or claim of the present invention to achieve all of the objectives, advantages or features disclosed in the present invention. In addition, a part of the abstract and the title of the invention are only intended to assist in searching the literature, and are not intended to limit the technical scope of the present invention. In addition, the terms "first", "second", etc., referred to in the specification or claims are only intended to name an element or distinguish other embodiments or scopes, and are not intended to limit the upper or lower limits on the quantity of elements. [Explanation of symbols]

[0054] 10, 20: Projection system 110, 140: Projection device 120_1~120_13: Color) Measuring device 130: Computing device S1: Projection surface 41, 44: Distribution of R values 42, 45: Distribution of G values 43, 46: Distribution of B values S201~S205, S301~S312, S501~S502: Steps.

Claims

1. 1. A method for compensating image uniformity for use in a projection system including a projection device, comprising: The projection device projects a test image onto a projection surface; When the test image is projected, a plurality of color measurement devices respectively measure the test image at a plurality of measurement positions on the projection plane, and obtain a plurality of test color data respectively corresponding to the plurality of measurement positions in the test image, each of the plurality of test color data including three color space components; determining whether a difference between a maximum value and a minimum value of a plurality of color space components of the plurality of test color data in the test image is less than a tolerance threshold value; determining to stop updating uniformity compensation information when the difference is less than the tolerance threshold; determining to continue updating the uniformity compensation information if the difference is greater than or equal to the tolerance threshold; forming an estimated image using the three color space components of each of the plurality of test color data; Update the uniformity compensation information of each pixel according to a target value and each pixel information of the estimated image, the uniformity compensation information of each pixel being three compensation gain values ​​respectively corresponding to the three color space components of each pixel; and a step of performing compensation for three color space components of each pixel corresponding to an initial image based on the three compensation gain values ​​of each pixel of the estimated image to generate a uniform image, and projecting the uniform image using the projection device.

2. 2. The image uniformity compensation method according to claim 1, comprising: The projection device projects an original test image corresponding to a test luminance onto the projection surface; When the original test image is projected, the plurality of color measurement devices perform measurements on the projection surface to obtain a plurality of original color data corresponding to the plurality of measurement positions; and The image uniformity compensation method further includes obtaining the target value by obtaining a minimum value from a plurality of color space component values ​​of the plurality of original color data.

3. 3. The image uniformity compensation method according to claim 2, further comprising the steps of: updating the uniformity compensation information of each pixel based on the target value and information of each pixel of the estimated image, generating adjustment coefficient information for each pixel based on a ratio between the target value and a pixel component value of each pixel in the estimated image and a convergence coefficient; and The method for image uniformity compensation includes updating the uniformity compensation information based on the adjustment factor information.

4. 2. The image uniformity compensation method according to claim 1, comprising: Before the step of the projection device projecting the test image onto the projection surface, Obtaining an original test image corresponding to the test luminance; and The method for image uniformity compensation further includes adjusting the original test image using the uniformity compensation information to generate the test image.

5. 2. The image uniformity compensation method according to claim 1, comprising: The step of forming the estimated image using the plurality of test color data includes: and performing an interpolation process using the plurality of measurement positions and a plurality of color space components of the test color data to obtain pixel information of the estimated image, thereby forming the estimated image.

6. 2. The image uniformity compensation method according to claim 1, comprising: The step of obtaining the plurality of test color data corresponding to the plurality of measurement positions by the plurality of color measurement devices on the projection surface when the test image is projected includes: A method for compensating for image uniformity, comprising: converting a plurality of color measurement values ​​corresponding to a first color space measured by the plurality of color measurement devices into the plurality of test color data corresponding to a second color space based on a color transformation matrix.

7. 2. The image uniformity compensation method according to claim 1, comprising: The method for image uniformity compensation, wherein the plurality of test color data is RGB color data.

8. 2. The image uniformity compensation method according to claim 1, comprising: The uniformity compensation information includes a plurality of sub-uniformity compensation information associated with a plurality of test luminances, and the step of generating a uniformed image by performing compensation on the initial image based on the uniformity compensation information includes: performing an interpolation process on the sub-uniformity compensation information associated with the test luminance; and The image uniformity compensation method includes a step of performing compensation on the initial image based on an interpolation result generated by an interpolation process to generate a uniform image.

9. 1. A method for image uniformity compensation for a projection system including a projection device and another projection device, comprising: The projection device projects a test image onto a projection surface; When the test image is projected, a plurality of color measurement devices perform measurements on the projection surface to obtain a plurality of test color data respectively corresponding to a plurality of measurement positions; generating an estimated image using the plurality of test color data; Update uniformity compensation information for each pixel based on the target value and each pixel information of the estimated image; and generating a uniformed image by performing compensation on an initial image based on the uniformity compensation information, and projecting the uniformed image using the projection device; The image uniformity compensation method includes: The projection device projects an original test image corresponding to a test luminance onto the projection surface; When the original test image is projected by the projection device, the plurality of color measurement devices perform measurements on the projection surface to obtain a plurality of first original color data corresponding to the plurality of measurement positions; said another projection device projects said original test image corresponding to said test luminance onto said projection surface; When the original test image is projected by the other projection device, the plurality of color measurement devices perform measurements on the projection plane to obtain a plurality of second original color data corresponding to the plurality of measurement positions; and The method for image uniformity compensation further includes obtaining the target value by obtaining a minimum value from a plurality of color space component values ​​of the plurality of first original color data and a plurality of color space component values ​​of the plurality of second original color data.

10. 1. A projection system including a projection device, a plurality of color measurement devices, and a computing device, The projection device projects a test image onto a projection surface; the plurality of color measurement devices are mounted on the projection surface; the computing device is connected to the projection device and to the plurality of color measurement devices; When the projection device projects the test image, the plurality of color measurement devices respectively measure the test image at a plurality of measurement positions on the projection plane, the calculation device obtains a plurality of test color data respectively corresponding to the plurality of measurement positions in the test image, each of the plurality of test color data including three color space components; the computing device determines whether a difference between a maximum value and a minimum value of a plurality of color space components of the plurality of test color data in the test image is less than a tolerance threshold value; If the difference is smaller than the threshold, the computing device determines to stop updating the uniformity compensation information; if the difference is equal to or greater than the threshold, the computing device determines to continue updating the uniformity compensation information; the calculation device forms an estimated image using the three color space components of each of the plurality of test color data, and updates the uniformity compensation information of each pixel based on a target value and each pixel information of the estimated image, the uniformity compensation information of each pixel being three compensation gain values ​​respectively corresponding to the three color space components of each pixel; The calculation device performs compensation on three color space components of each pixel corresponding to an initial image based on the three compensation gain values ​​of each pixel of the estimated image to generate a uniformed image, and the projection device projects the uniformed image.

11. 11. The projection system of claim 10, The projection device projects an original test image corresponding to a test luminance onto the projection surface; When the projection device projects the original test image, the plurality of color measurement devices perform measurements on the projection plane, and the calculation device obtains a plurality of original color data corresponding to the plurality of measurement positions from the plurality of color measurement devices; The calculation device obtains the target value by obtaining a minimum value from a plurality of color space component values ​​of the plurality of original color data.

12. 12. A projection system according to claim 11, The calculation device generates adjustment factor information for each pixel based on a ratio between the target value and a pixel component value of each pixel in the estimated image and a convergence factor, and updates the uniformity compensation information based on the adjustment factor information.

13. 11. The projection system of claim 10, A projection system, wherein before the projection device projects the test image onto the projection surface, the computing device obtains an original test image corresponding to a test luminance, and adjusts the original test image using the uniformity compensation information to generate the test image.

14. 11. The projection system of claim 10, The calculation device performs an interpolation process using the plurality of measurement positions and the plurality of color space components of the test color data to obtain pixel information of the estimated image, thereby forming the estimated image.

15. 11. The projection system of claim 10, The calculation device converts a plurality of color measurements measured by the plurality of color measurement devices, corresponding to a first color space, into the plurality of test color data corresponding to a second color space based on a color transformation matrix.

16. 11. The projection system of claim 10, A projection system, wherein the plurality of test color data is RGB color data.

17. 11. The projection system of claim 10, a projection system, the projection system including: a projection system in which the uniformity compensation information includes a plurality of sub-uniformity compensation information associated with a plurality of test luminances; and the computing device performs an interpolation process on the sub-uniformity compensation information associated with the test luminances; and performs compensation on the initial image based on an interpolation process result generated by the interpolation process to generate a uniformed image.

18. 1. A projection system including a projection device, another projection device, a plurality of color measurement devices, and a computing device, The projection device projects a test image onto a projection surface; the plurality of color measurement devices are mounted on the projection surface; the computing device is connected to the projection device and to the plurality of color measurement devices; When the projection device projects the test image, the plurality of color measurement devices perform measurements on the projection plane, and the calculation device obtains a plurality of test color data respectively corresponding to a plurality of measurement positions; the computing device forms an estimated image using the plurality of test color data, and updates uniformity compensation information for each pixel based on a target value and information about each pixel of the estimated image; the computing device performs compensation on an initial image based on the uniformity compensation information to generate a uniformed image; and the projection device projects the uniformed image. When the projection device projects an original test image corresponding to a test luminance onto the projection surface, the plurality of color measurement devices perform measurements on the projection surface, and the calculation device obtains a plurality of first original color data corresponding to the plurality of measurement positions; When the other projection device projects the original test image corresponding to the test luminance onto the projection plane, the plurality of color measurement devices perform measurements on the projection plane, and the calculation device obtains a plurality of second original color data corresponding to the plurality of measurement positions; The calculation device obtains the target value by obtaining a minimum value from a plurality of color space component values ​​of the plurality of first original color data and a plurality of color space component values ​​of the plurality of second original color data.

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