Pattern image output method, projector, and program

Abstract

To suppress execution time for executing the phase shift method.SOLUTION: A pattern image output method is provided, comprising using the phase shift method to output a first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pattern image output method, a projector, and a program. [Background technology]

[0002] Conventionally, a technique has been used in which a projected image projected on a projection surface and a captured image obtained by capturing the projected image are associated with each other by image processing using a phase shift method.

[0003] In the technology disclosed in Patent Document 1, first, the lighting control device causes the projection device to project a stripe pattern whose brightness changes periodically in a first direction onto the projection area. The lighting control device also acquires a captured image from a camera that captured the projection image. The lighting control device associates the projection image with the captured image for the first direction using a phase shift method. Next, the lighting control device causes the projection device to project a stripe pattern whose brightness changes periodically in a second direction perpendicular to the first direction onto the projection area. Similarly, the lighting control device acquires a captured image from the camera that captured the projection image. The lighting control device associates the projection image with the captured image for the second direction using a phase shift method. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-271580 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, when using patterns with different phases, it is necessary to execute the phase shift method as many times as the number of patterns. As a result, the execution time for executing the phase shift method increases, and convenience is reduced. [Means for solving the problem]

[0006] A pattern image output method according to one embodiment of the present invention is a pattern image output method that outputs a first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period, which are used in a phase shift method.

[0007] Furthermore, a projector according to one embodiment of the present invention includes an optical device and at least one processor, and the at least one processor controls the optical device to output a first pattern image used in a phase shift method, the first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period.

[0008] Furthermore, a program according to one embodiment of the present invention is a program that causes a computer to execute a process of outputting a first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period, which are used in a phase shift method. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing the configuration of a projector 10 according to a first embodiment. [Diagram 2] 4 is a flowchart showing the operation of the projector 10. [Diagram 3] FIG. 4 is a diagram showing an example of a pattern image. [Figure 4] FIG. 4 is a diagram showing an example of a pattern image. [Diagram 5] FIG. 4 is a diagram showing an example of a pattern image. [Figure 6] FIG. 4 is a diagram showing an example of a pattern image. [Figure 7] FIG. 4 is a diagram showing an example of a pattern image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a pattern image output method, a projector, and a program according to the embodiment will be described with reference to the drawings. In each drawing, the dimensions and scale of each part are appropriately different from the actual ones. In addition, since the embodiments described below are preferred specific examples, various technically preferable limitations are attached, but the scope of the present disclosure is not limited to these forms unless otherwise specified in the following description to limit the present disclosure.

[0011] 1: First embodiment 1-1: Configuration of the embodiment 1 is a block diagram showing the configuration of a projector 10 according to the first embodiment. The configuration of the projector 10 will be described below with reference to FIG.

[0012] The projector 10 includes a projection device 11, an imaging device 12, a processing device 13, a storage device 14, and a communication device 15. The elements of the projector 10 are connected to each other by one or more buses for communicating information. Furthermore, each element of the projector 10 is composed of one or more devices, and some elements of the projector 10 may be omitted.

[0013] The projection device 11 is a device that projects a projection image onto a projection surface such as a screen or a wall. The projection device 11 includes, for example, a light source, a liquid crystal panel, and a projection lens, modulates light from the light source using the liquid crystal panel, and projects the modulated light onto a projection surface such as a screen or a wall through the projection lens. In particular, in this embodiment, the projection device 11 projects a pattern image generated by a pattern generation unit 131 described later onto the projection surface. The projection device 11 is an example of an "optical device." Note that, in the above, a transmissive liquid crystal light valve or a reflective liquid crystal light valve may be used as the liquid crystal panel. In addition, a digital mirror device that modulates light emitted from a light source by controlling the emission direction of incident light for each micromirror as a pixel may be used. In addition, the configuration is not limited to a configuration having multiple light modulation devices for each color light, and a configuration in which multiple color lights are modulated in a time-division manner by one light modulation device may be used.

[0014] The imaging device 12 captures a display image that is displayed by being projected onto the projection surface by the projection device 11. The imaging device 12 also outputs the captured image to the processing device 13. In particular, in this embodiment, the imaging device 12 captures a pattern image that is projected onto the projection surface by the projection device 11, and outputs the captured pattern image to the processing device 13. The imaging device 12 may be a normal digital camera or an image sensor.

[0015] The processing device 13 is a processor that controls the entire projector 10, and is composed of, for example, a single chip or multiple chips. The processing device 13 is composed of, for example, a central processing unit (CPU) including an interface with peripheral devices, an arithmetic unit, and a register. Note that some or all of the functions of the processing device 13 may be realized by hardware such as a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The processing device 13 executes various processes in parallel or sequentially. The processing device 13 is an example of a "computer."

[0016] The storage device 14 is a recording medium readable by the processing device 13, and stores a plurality of programs including the control program PR1 executed by the processing device 13. The control program PR1 may be transmitted from another device that manages the projector 10 via a communication network (not shown). The storage device 14 may be configured with at least one of, for example, a Read Only Memory (ROM), an Erasable Programmable ROM (EPROM), an Electrically Erasable Programmable ROM (EEPROM), and a Random Access Memory (RAM). The storage device 14 may be called a register, a cache, a main memory, or a primary storage device.

[0017] The communication device 15 is hardware serving as a transmitting / receiving device for communicating with other devices. In particular, in this embodiment, the communication device 15 is also called, for example, a network device, a network controller, a network card, or a communication module.

[0018] The processing device 13 functions as a pattern generation unit 131, a projection control unit 132, an imaging control unit 133, a first acquisition unit 134, a frequency analysis unit 135, a correspondence relationship generation unit 136, a measurement value calculation unit 137, a correction value calculation unit 138, a second acquisition unit 139, and an image correction unit 140 by reading and executing the control program PR1 from the memory device 14.

[0019] The pattern generating unit 131 generates a pattern image used in the phase shift method. The pattern image will be described in detail below.

[0020] When performing the phase shift method according to this embodiment, the number of shifts is set to N. That is, in the phase shift method according to this embodiment, the projection device 11 sequentially projects N pattern images. The imaging device 12 captures the N pattern images that are sequentially projected. The processing device 13 acquires multiple phase values ​​by performing frequency analysis on the time change in brightness in the N captured images. Projecting a pattern image by the projection device 11 is an example of "outputting a pattern image".

[0021] In this specification, the coordinate system on the liquid crystal panel of the projection device 11 is referred to as the "panel coordinate system." A number of arbitrary phase values ​​that change continuously with respect to the coordinates (x, y) on the panel coordinate system are expressed as θ1=g1(x, y), θ2=g2(x, y), . . . , θ r =g r In this case, the amplitude of the projection pattern in the pattern image projected for n=0, 1, . . . , N-1 is determined by the following formula (1). f(x,y,n)=A1cos(θ1+2πn / N)+A2cos(θ2+4πn / N)+···+A r cos(θ r +2rπn / N) Formula (1) Here, A1, A2, , A r is an arbitrary constant that determines the brightness of an image showing a brightness distribution corresponding to each trigonometric function, which is superimposed in a pattern image corresponding to the above formula (1). Note that the number of captured pattern images, i.e., the number of shifts N, when the number of trigonometric functions added in f(x, y, n) is r, may be N=2r+1 or more. Specifically, if the imaging device 12 captures N=2r+1 or more pattern images, the frequency analysis unit 135 described later executes a discrete Fourier transform to obtain phase values ​​θ1, θ2,...θ r can be calculated.

[0022] That is, the pattern image generated by the pattern generating unit 131 includes a first brightness distribution based on a first period and a second brightness distribution based on a second period. This pattern image is an example of a "first pattern image." Also, as described above, this first pattern image is based on a function obtained by adding together multiple trigonometric functions corresponding to different frequencies in the time direction.

[0023] Each of the 2r+1 or more pattern images has r brightness distributions, and among the r brightness distributions, at least one brightness distribution corresponding to the same period has a different brightness at the same coordinate.

[0024] The projection control unit 132 causes the projection device 11 to project the pattern image generated by the pattern generation unit 131 onto the projection surface.

[0025] The imaging control unit 133 causes the imaging device 12 to capture the pattern image projected onto the projection surface.

[0026] The first acquisition unit 134 acquires, from the imaging device 12, a captured image obtained by capturing a pattern image.

[0027] The frequency analysis unit 135 performs a frequency analysis on the data indicating the captured image acquired by the first acquisition unit .

[0028] In this specification, the coordinate system in the captured image is referred to as the "camera coordinate system." The frequency analysis unit 135 performs a discrete Fourier transform on the time change in brightness of the coordinates (X, Y) in the camera coordinate system of N captured images obtained by capturing N pattern images that are projected sequentially. Specifically, the frequency analysis unit 135 performs a discrete Fourier transform on the time change in brightness of the coordinates (X, Y) in the captured image that accompanies the sequential projection of the N pattern images. As a result, the frequency analysis unit 135 calculates phase values ​​θ1, θ2,...θ r Specifically, among the discrete Fourier transformed values, the components corresponding to frequencies ±2π / N represent the phase value θ1. Similarly, the components corresponding to frequencies ±4π / N represent the phase value θ2. The components corresponding to frequencies ±2πr / N represent the phase value θr Represents.

[0029] In the phase shift method according to Patent Document 1, only one phase value can be measured each time the phase shift method is executed. On the other hand, in the phase shift method according to the present embodiment, the pattern generation unit 131 generates a pattern image in which the amplitude of the projection pattern is determined by a formula in which multiple trigonometric functions with different time frequencies are added. The frequency analysis unit 135 can calculate multiple phase values ​​each time the phase shift method is executed by frequency analyzing the pattern image. In other words, the frequency analysis unit 135 can extract multiple frequency components in one execution of the phase shift method, and therefore can calculate multiple phase values. As a result, the pattern generation unit 131 can simultaneously project, for example, a pattern image for phase unwrapping in addition to a normal pattern image. The definition of "phase unwrapping" will be described later. In addition, the frequency analysis unit 135 can simultaneously measure, for example, coordinate values ​​in both the x direction and the y direction. As a result, the frequency analysis unit 135 can significantly reduce the execution time for executing the phase shift method and the calculation time by the frequency analysis unit 135.

[0030] The correspondence generating unit 136 generates a correspondence between the coordinates (X, Y) in the camera coordinate system in the captured image and the coordinates (x, y) in the panel coordinate system, based on the coordinates (X, Y) in the captured image and the multiple phase values ​​calculated by the frequency analysis unit 135. As described above, the multiple phase values ​​that change continuously with respect to the coordinates (x, y) on the panel coordinate system are θ1=g1(x, y), θ2=g2(x, y), . . ., θ r =g r The phase values ​​θ1, θ2, . . . , θ r Based on this, the coordinates (x, y) in the panel coordinate system can be calculated. Furthermore, as described above, multiple phase values ​​θ1, θ2, . . . , θ ris calculated by performing a discrete Fourier transform on the time change in brightness of coordinates (X, Y) in the camera coordinate system. Therefore, the correspondence generating unit 136 can generate a correspondence between the coordinates (X, Y) in the camera coordinate system and the coordinates (x, y) in the panel coordinate system. The x direction in the panel coordinate system is an example of a "first axis." The y direction in the panel coordinate system is an example of a "second axis."

[0031] The measurement value calculation unit 137 calculates various measurement values ​​using the captured image acquired by the first acquisition unit 134 and the correspondence between the camera coordinate system and the panel coordinate system generated by the correspondence generation unit 136. The "captured image" here is not limited to the above-mentioned pattern image, and includes, for example, captured images generated by capturing an image of the projection surface by the imaging device 12 during geometric correction of the projector 10, during color correction of the projection image, and during normal use. In addition, the "measurement value" here may be, for example, one or more of the three-dimensional shape of the projection surface, the parallax between the projection lens of the projection device 11 and the imaging device 12, and color unevenness on the liquid crystal panel.

[0032] A correction value calculation unit 138 calculates various correction values ​​based on the measurement values ​​calculated by the measurement value calculation unit 137. The correction values ​​are used, for example, for the above-mentioned geometric correction or for correcting color unevenness in a projected image.

[0033] The second acquisition unit 139 acquires an image that is viewed by a user of the projector 10 during normal use from an external device via the communication device 15. The external device is composed of various image output devices such as a personal computer or a tablet DVD (Digital Versatile Disc) player.

[0034] Image correction unit 140 corrects the image acquired by second acquisition unit 139 by setting various correction values ​​calculated by correction value calculation unit 138 in a correction circuit. Image correction unit 140 also outputs the corrected image to projection control unit 132. Projection control unit 132 causes projection device 11 to project the image acquired from image correction unit 140 during normal use.

[0035] 1-2: Operation of the embodiment 2 is a flowchart showing the operation of the projector 10. The operation of the projector 10 will be described below with reference to FIG.

[0036] In step S11, the processing device 13 functions as a pattern generating unit 131. The processing device 13 generates a pattern image used in the phase shift method.

[0037] In step S12, the processing device 13 functions as the projection control unit 132. The processing device 13 causes the projection device 11 to project the pattern image generated in step S11 onto the projection surface.

[0038] In step S13, the processing device 13 functions as an imaging control unit 133. The processing device 13 causes the imaging device 12 to capture the pattern image projected onto the projection surface by the projection device 11. The processing device 13 also functions as a first acquisition unit 134. The processing device 13 acquires, from the imaging device 12, a captured image obtained by capturing the pattern image.

[0039] In step S14, if the processing device 13 has projected and photographed all the pattern images (YES in S14), the processing device 13 executes the process of step S15. In step S14, if the processing device 13 has not yet finished projecting and photographing all the pattern images (NO in S14), the processing device 13 executes the process of step S11.

[0040] In step S15, the processing device 13 functions as a frequency analysis unit 135. The processing device 13 performs a discrete Fourier transform on the data indicating the captured image acquired by the first acquisition unit 134 in the time direction.

[0041] In step S16, the processing device 13 functions as a frequency analysis unit 135. Based on the result of the discrete Fourier transform in step S15, the processing device 13 calculates phase values ​​θ1, θ2, . . . θ corresponding to each pixel at the coordinates (X, Y) in the camera coordinate system. r Calculate.

[0042] In step S17, the processing device 13 functions as the correspondence relationship generating unit 136. The processing device 13 converts the multiple phase values ​​θ1, θ2, . . . , θ r The processing device 13 calculates the coordinate values ​​(x, y) in the panel coordinate system from the coordinate values ​​(X, Y) in the camera coordinate system and the coordinate values ​​(x, y) in the panel coordinate system.

[0043] In step S18, the processing device 13 functions as the measurement value calculation unit 137. The processing device 13 calculates various measurement values ​​using the captured image acquired by the first acquisition unit 134 and the correspondence relationship generated in step S17.

[0044] In step S19, the processing device 13 functions as the correction value calculation unit 138. The processing device 13 calculates various correction values ​​based on the measurement values ​​calculated in step S18.

[0045] In step S20, the processing device 13 functions as the image correction unit 140. The processing device 13 corrects the image acquired from the external device by setting the various correction values ​​calculated in step S19 in a correction circuit.

[0046] 1-3: Example In the following, a specific example will be described in which the processing device 13 generates a correspondence relationship between the camera coordinates and the panel coordinates, and performs geometric correction or color correction of the projector 10 using the generated correspondence relationship.

[0047] First, the pattern generating unit 131 generates a pattern image. When generating the pattern image, the pattern generating unit 131 determines four phase values ​​corresponding to coordinates (x, y) in the panel coordinate system by functions defined by the following formulas (2) to (5). θ1=2πx / T Formula (2) θ2=2πy / S Equation (3) θ3=2πx / W Formula (4) θ4=2πy / H Formula (5) In the above formulas (2) to (5), T is the period in the x direction corresponding to the normal phase shifting method. S is the period in the y direction corresponding to the normal phase shifting method. W is the horizontal resolution of the liquid crystal panel. H is the vertical resolution of the liquid crystal panel.

[0048] Here, θ1 and θ2 are the same phase values ​​as those used in the normal phase shift method. In order to improve the detection accuracy of the phase shift method, it is better that the period T and period S are small. However, due to the periodicity of trigonometric functions, when the period T and period S are small, areas having the same phase value are generated in multiple coordinates of the panel coordinate system. In order to make different phase values ​​correspond one-to-one to different coordinates, the pattern generation unit 131 in this embodiment uses a phase value θ3 defined by a formula (4) using a horizontal resolution W corresponding to the entire length of the liquid crystal panel in the x direction instead of the period T in formula (2) in combination with θ1 and θ2. In addition, the pattern generation unit 131 further uses a phase value θ4 defined by a formula (5) using a vertical resolution H corresponding to the entire length of the liquid crystal panel in the y direction instead of S in formula (3). In addition to the phase values ​​θ1 and θ2, the use of phase values ​​θ3 and θ4 corresponding to a period longer than the phase values ​​θ1 and θ2 is referred to as "phase unwrapping" in this specification. The pattern generating unit 131 uses phase values ​​θ3 and θ4 in addition to phase values ​​θ1 and θ2, so that different phase values ​​correspond one-to-one to different coordinates in the panel coordinate system. Formula (2) is an example of a "first brightness distribution", Formula (3) is an example of a "second brightness distribution", Formula (4) is an example of a "third brightness distribution", and Formula (5) is an example of a "fourth brightness distribution". Period T is an example of a "first period", period S is an example of a "second period", horizontal resolution W is an example of a "third period", and vertical resolution H is an example of a "fourth period".

[0049] Since there are r=4 types of phase values, the number of shifts N in the phase shift method executed in this embodiment, i.e., the number of captured pattern images, is N=2r+1=9 or more. The amplitude of the projection pattern at coordinates (x, y) on the panel coordinate system is determined by the following formula (6) for pattern number n=0, 1, . . . , N-1. f(x,y,n)=cos(θ1+2πn / N)+cos(θ2+4πn / N)+cos(θ3+6πn / N)+cos(θ4+8πn / N) Formula (6) The projection device 11 sequentially projects N pattern images having a projection pattern determined by the above formula (6). The imaging device 12 captures the N pattern images that are sequentially projected. Note that (a) to (i) in FIG. 3 are an example of N=9 pattern images. In the example shown in FIG. 3, W=8T and H=5S. However, W=8T and H=5S are merely an example. W may be any multiple of T, and H may be any multiple of S. Furthermore, W is not limited to an integer multiple of T, and H is not limited to an integer multiple of S.

[0050] The pattern image in this embodiment is an image obtained by adding together an image showing a first brightness distribution having a first period along a first axis, an image showing a second brightness distribution having a second period along a second axis perpendicular to the first axis, an image showing a third brightness distribution having a period larger than the first period along the first axis, and an image showing a fourth brightness distribution having a period larger than the second period along the second axis.

[0051] The frequency analysis unit 135 performs frequency analysis on the captured images of the N pattern images. The brightness of the pixel located at the coordinates (X, Y) in the camera coordinate system in the captured image is expressed as a0, a1, . . . , a N-1 Since the brightness of a captured image is proportional to the brightness of the subject, the brightness a n is expressed by the following equation (7).

number

[0052] The frequency analysis unit 135 analyzes these N a n The values ​​obtained by performing the discrete Fourier transform on the values ​​of b0, b1, . . ., b N-1 The discrete Fourier transform is expressed by the following formulas (8) and (9).

number

[0053] Due to the nature of the Fourier transform, each b n satisfies the following formulas (10) to (15). (However, when N=9, b5=b N―4 It is.)

number

[0054] Therefore, phase values ​​θ1, θ2, θ3, and θ4 for each frequency are obtained based on b1, b2, b3, and b4 after the Fourier transform. Furthermore, the x coordinate on the panel coordinate system corresponding to the pixel at the coordinate (X, Y) on the camera coordinate system is calculated from the above formulas (2) and (4). Similarly, the y coordinate on the panel coordinate system corresponding to the pixel at the coordinate (X, Y) on the camera coordinate system is calculated from the above formulas (3) and (5).

[0055] As an example, specific examples of calculated values ​​are shown below. The horizontal resolution of the liquid crystal panel is W=1920, and the vertical resolution is H=1200. The period in the x direction corresponding to the normal phase shift method is T=1920 / 8=240, and the period in the y direction is S=1200 / 5=240. The number of shifts, i.e., the number of captured pattern images, is N=9, and the projection device 11 sequentially projects the nine pattern images exemplified in FIG. 3, and the imaging device 12 sequentially captures these projected images.

[0056] Assume that pixel values ​​a0, a1,..., a8 of nine captured images at coordinates (X,Y) on the camera coordinate system are as follows: These values ​​are obtained by capturing the change in brightness at the position of coordinates (x,y)=(633,490) on the panel coordinate system using the imaging device 12. a0=140,a1=211,a2=189,a3=179,a4=264,a5=219,a6=152,a7=109,a8=224

[0057] When these values ​​are subjected to a discrete Fourier transform, b1, b2, b3, and b4 become the following values.

number

[0058] each b i The real part is cosθ i A constant multiple of , the imaginary part is -sinθ i Since θ1, θ2, θ3, and θ4 are constant multiples of θ1, θ2, θ3, and θ4, the following values ​​are obtained by using inverse trigonometric functions: θ1=3.999589···[rad] θ2=0.263357···[rad] θ3=2.846996···[rad] θ4=2.580158···[rad]

[0059] When the original x and y coordinates are calculated backwards from each of the phase values ​​θ1, θ2, θ3, and θ4, x1, y2, x3, and y4 become the following values. x1=152.773070···+T×k y2=10.059534···+S×l x3=869.978096... y4=492.773891...

[0060] Each of x1 and y2 has an ambiguity of integer multiples of +T and +S. In other words, the values ​​of x1 and y2 are not uniquely determined. This ambiguity is due to the periodicity of the projection pattern. On the other hand, the values ​​of x3 and y4 are uniquely determined because the period of the projection pattern matches the resolution of the LCD panel. However, since the spatial phase change of x3 and y4 is gradual, they are susceptible to noise and have large errors. In fact, (x3, y4) is shifted by one pixel or more from the true value (873, 490). Therefore, x3 and y4 are used in phase unwrapping to resolve the ambiguity of x1 and y2.

[0061] x3=869.978096···, and y4=492.773891···, respectively. T×3≦x3≦T×4 S×2≦y4≦S×3 Since x1, y2 must also be within these ranges. Therefore, x1=152.773070···+T×3=872.773070··· y2=10.059534···+S×2=490.059534··· It becomes.

[0062] The error of (x1, y2) from the true value (873, 490) is within one pixel, indicating that the coordinates (x, y) on the panel coordinate system were measured with high precision.

[0063] Through the above calculations, the correspondence generating unit 136 can obtain the correspondence between the coordinates (X, Y) on the camera coordinate system and the coordinates (x, y) on the panel coordinate system.

[0064] After the correspondence between the camera coordinate system and the panel coordinate system is generated, the image correction unit 140 can perform geometric correction, for example, based on the parallax between the projection lens of the projection device 11 and the imaging device 12, and by applying a technology related to a stereo camera to perform three-dimensional measurement of the projection surface. Alternatively, the image correction unit 140 can measure color unevenness on the liquid crystal panel and perform color correction. The image correction unit 140 can execute various corrections including these geometric corrections and color corrections.

[0065] 2: Variations The present disclosure is not limited to the above-described embodiments. Specific modified embodiments are exemplified below.

[0066] 2-1: Variation 1 In the above embodiment, the pattern generation unit 131 generates N pattern images whose amplitude of the projection pattern is determined by the formula (1). However, the pattern generation unit 131 may generate a moving image as the pattern images represented by a formula that generalizes the formula (1).

[0067] Specifically, multiple phase values ​​are expressed as θ1, θ2, . . . , θ r In addition, the time frequencies corresponding to each phase value are ω1, ω2, . . . , ω r When the time elapsed from the start of projection of the pattern image is t, the amplitude of the projection pattern is expressed by the following equation (16). f(θ1,θ2,...,θ r ,t)=A1cos(θ1+2πω1t)+A2cos(θ2+2πω2t)+···+A r cos(θ r +2πω r t) Formula (16)

[0068] The imaging device 12 intermittently captures a moving image of the pattern image expressed by the formula (16) projected by the projection device 11 at arbitrary intervals.

[0069] The frequency analysis unit 135 performs frequency analysis, for example, a Fourier transform, on the brightness change of each pixel in the captured image to obtain the respective frequencies ω1, ω2, . . . , ω r The phase values ​​θ1, θ2, . . . , θ r can be calculated. Note that for each frequency ω1, ω2, ω r When the frequency ω is an integer multiple of a certain frequency ω0, the frequency analysis unit 135 can execute the above method.

[0070] 2-2: Variation 2 In the above embodiment, the pattern generating unit 131 composites four phase values ​​θ1, θ2, θ3, and θ4. In other words, a pattern image showing the amplitude of the projection pattern is generated by a formula obtained by adding trigonometric functions corresponding to each of the four phase values ​​θ1, θ2, θ3, and θ4. However, the combination of composite phase values ​​may be different from this.

[0071] For example, the pattern generation unit 131 may separately combine θ1 and θ2 used for accurate coordinate value detection and θ3 and θ4 for phase unwrapping. If multiple types of trigonometric functions, each corresponding to a different phase value, are combined, the contrast per trigonometric function decreases, making coordinate value detection more susceptible to noise. Therefore, by reducing the number of phase values ​​combined by the pattern generation unit 131, it is possible to ensure the accuracy of coordinate value detection by the frequency analysis unit 135 and to shorten the operation time.

[0072] First, the amplitude of the projection pattern contained in the fine pattern image for detecting accurate x and y coordinates is given by the following equation (17). f(x,y,n)=cos(2πx / T+2πn / N)+cos(2πy / S+4πn / N) Formula (17) The first term on the right side of equation (17) is an example of an image showing a first luminance distribution, and the second term on the right side of equation (17) is an example of an image showing a second luminance distribution.

[0073] Since the number of types of phase values ​​to be synthesized is r=2, the number of captured pattern images N may be N=2r+1=5 or more. Note that (a) to (e) in FIG. 4 are an example of N=5 pattern images corresponding to formula (17). The pattern image may be created based on formula (17), or may be created by adding an image created based on the first term on the right side of formula (17) and an image created based on the second term on the right side of formula (17).

[0074] The amplitude of the projection pattern contained in the gradual pattern image for performing phase unwrapping is given by the following equation (18). f(x,y,n)=cos(2πx / W+2πn / N)+cos(2πy / H+4πn / N) Formula (18) The first term on the right side of equation (18) is an example of an image showing a third luminance distribution, and the second term on the right side of equation (18) is an example of an image showing a fourth luminance distribution.

[0075] 5(a) to (e) are examples of N=5 pattern images corresponding to formula (18). The pattern images may be created based on formula (18), or may be created by adding together an image created based on the first term on the right side of formula (18) and an image created based on the second term on the right side of formula (18).

[0076] The first pattern image in this modification 2, i.e., the pattern image corresponding to formula (17), is an image obtained by adding together an image showing a first brightness distribution having a first period along a first axis and an image showing a second brightness distribution having a second period along a second axis perpendicular to the first axis. Also, the second pattern image in this modification 2, i.e., the pattern image corresponding to formula (18), is an image obtained by adding together an image showing a third brightness distribution having a period larger than the first period along the first axis and an image showing a fourth brightness distribution having a period larger than the second period along the second axis.

[0077] As described above, in the present modified example 2, the frequency analysis unit 135 can obtain four phase values ​​θ1, θ2, θ3, and θ4 by performing the phase shift method twice.

[0078] 2-3: Variation 3 Alternatively, the pattern generating unit 131 may combine the phase values ​​related to the x direction with each other and the phase values ​​related to the y direction with each other. The amplitude of the projection pattern when the phase value for accurately measuring the x coordinate and the phase value for phase unwrapping are combined is represented by the following formula (19). f(x,n)=cos(2πx / T+2πn / N)+cos(2πx / W+4πn / N) Formula (19) The first term on the right side of equation (19) is an example of an image showing a first luminance distribution, and the second term on the right side of equation (19) is an example of an image showing a second luminance distribution.

[0079] 6(a) to 6(e) are examples of N=5 pattern images corresponding to formula (19). The pattern images may be created based on formula (19), or may be created by adding together an image created based on the first term on the right side of formula (19) and an image created based on the second term on the right side of formula (19).

[0080] The same is true for the y direction.

[0081] The pattern image in this modification 3, i.e., the pattern image corresponding to formula (19), is an image obtained by adding together an image showing a first brightness distribution having a first period along a first axis and an image showing a second brightness distribution having a period along the first axis larger than the first period.

[0082] As described above, in the present modification 3, the frequency analysis unit 135 can simultaneously perform accurate detection of the x coordinate and phase reconnection. Similarly, in the present modification 3, the frequency analysis unit 135 can simultaneously perform accurate detection of the y coordinate and phase reconnection.

[0083] 2-4: Variation 4 In the phase shift method, generally, the accuracy is improved by shortening the period of the trigonometric function in the spatial direction and increasing the number of shifts. Therefore, as an example, the pattern generating unit 131 may synthesize a phase value with a short period in order to detect a coordinate value with higher accuracy, in addition to the phase value for accurately measuring the x coordinate and the phase value for phase unwrapping. Here, if the period F is an arbitrary value shorter than the period T, the amplitude of the projection pattern is expressed by the following formula (20). f(x,n)=cos(2πx / F+2πn / N)+cos(2πx / T+4πn / N)+cos(2πx / W+6πn / N) Formula (20) The first term on the right side of formula (20) is an example of a third luminance distribution. The second term on the right side of formula (20) is an example of a first luminance distribution. The third term on the right side of formula (20) is an example of a second luminance distribution.

[0084] Since the number of types of phase values ​​to be synthesized is r=3, the number of captured pattern images N may be N=2r+1=7 or more. Note that (a) to (g) in FIG. 7 are an example of N=7 pattern images corresponding to formula (20). The pattern image may be created based on formula (20), or may be created by adding an image created based on the first term on the right side of formula (20), an image created based on the second term on the right side of formula (20), and an image created based on the third term on the right side of formula (20).

[0085] The same is true for the y direction.

[0086] The pattern image in this fourth modification, i.e., the pattern image corresponding to formula (20), is an image obtained by adding together an image showing a first brightness distribution having a first period along a first axis, an image showing a second brightness distribution having a period along the first axis that is larger than the first period, and an image showing a third brightness distribution having a period along the first axis that is smaller than the first period.

[0087] As described above, in the present modification 4, the frequency analysis unit 135 can simultaneously perform more accurate detection of the x coordinate and phase reconnection. Similarly, in the present modification 4, the frequency analysis unit 135 can simultaneously perform more accurate detection of the y coordinate and phase reconnection.

[0088] 2-5: Variation 5 In the above embodiment, the function of the processing device 13 included in the projector 10 may be realized by an external device of the projector 10. The external device is specifically a personal computer, a tablet, or the like. For example, the external device may execute a function corresponding to the pattern generating unit 131 among the functional blocks of the processing device 13, transmit a pattern image generated by the external device to the projector 10, and the projector 10 may acquire the pattern image transmitted from the external device. Furthermore, the function of the processing device 13 included in the projector 10 may be realized as an application that can be distributed via a communication network (not shown). The external device is an example of a "computer." Transmitting a pattern image generated by the external device to the projector 10 is an example of "outputting a pattern image."

[0089] 2-6: Variation 6 In the above embodiment, the pattern generating unit 131 generates a pattern image. However, instead of including the pattern generating unit 131, the processing device 13 may acquire a pattern image stored in the storage device 14.

[0090] 2-7: Variation 7 In the above embodiment, the projector 10 has the built-in imaging device 12, but the imaging device 12 may be an external device of the projector 10. The imaging device 12 as an external device of the projector 10 may be communicably connected to the projector 10 via an interface such as a USB, for example.

[0091] 3: Summary of this disclosure The following is a summary of this disclosure. (Additional Note 1) A pattern image output method for outputting a first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period, used in a phase shift method.

[0092] According to the above-mentioned method for outputting a pattern image, the first pattern image includes a first brightness distribution based on a first period and a second brightness distribution based on a second period. Therefore, when using patterns with different periods, the projector can reduce the execution time for executing the phase shift method compared to a method of executing the phase shift method for each of a plurality of patterns. As a result, the convenience for the user is improved.

[0093] (Supplementary Note 2) A method for outputting a pattern image according to Supplementary Note 1, wherein the first brightness distribution has the first period along a first axis, the second brightness distribution has the second period along a second axis perpendicular to the first axis, and the first pattern image is an image obtained by adding together an image showing the first brightness distribution and an image showing the second brightness distribution.

[0094] With the above-described pattern image output method, the projector can detect the coordinate values ​​in the first axis direction and the coordinate values ​​in the second axis direction by performing the phase shift method once, by using a pattern image having a valid brightness distribution in each of the first axis direction and the second axis direction.

[0095] (Supplementary Note 3) The pattern image output method of Supplementary Note 1, further outputting a second pattern image obtained by adding an image showing a third brightness distribution having a period larger than the first period along a first axis and an image showing a fourth brightness distribution having a period larger than the second period along a second axis perpendicular to the first axis.

[0096] By the above-mentioned pattern image output method, an image showing a third brightness distribution having a period larger than the first period along the first axis and an image showing a fourth brightness distribution having a period larger than the second period along the second axis are added in the second pattern image. Therefore, the projector can improve the detection accuracy of the coordinate values ​​in the first axis direction and the coordinate values ​​in the second axis direction by executing the phase shift method once.

[0097] (Supplementary Note 4) The method for outputting a pattern image of Supplementary Note 1, wherein the first brightness distribution has the first period along a first axis, the second brightness distribution has a period along the first axis that is larger than the first period, and the first pattern image is an image obtained by adding an image showing the first brightness distribution and an image showing the second brightness distribution.

[0098] With the above-described pattern image output method, the first brightness distribution has a first period along the first axis, and the second brightness distribution has a period along the first axis that is larger than the first period. Therefore, the projector can detect accurate coordinate values ​​by using a pattern image having a brightness distribution that is effective for one axis.

[0099] (Supplementary Note 5) The pattern image output method of any one of Supplementary Note 1 and Supplementary Note 4, wherein the first brightness distribution has the first period along a first axis, the second brightness distribution has a period along the first axis that is larger than the first period, and the first pattern image is an image obtained by adding together an image showing the first brightness distribution, an image showing the second brightness distribution, and an image showing a third brightness distribution having a period along the first axis that is smaller than the first period.

[0100] With the above pattern image output method, the first brightness distribution has a first period along the first axis, the second brightness distribution has a period along the first axis that is larger than the first period, and the third brightness distribution has a period along the first axis that is smaller than the first period. This allows the projector to further improve the detection accuracy of coordinate values ​​along one axis.

[0101] (Supplementary Note 6) The method for outputting a pattern image according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the first brightness distribution has the first period along a first axis, the second brightness distribution has the second period along a second axis perpendicular to the first axis, and the first pattern image is an image obtained by adding together an image showing the first brightness distribution, an image showing the second brightness distribution, an image showing a third brightness distribution having a period along the first axis larger than the first period, and an image showing a fourth brightness distribution having a period along the second axis larger than the second period.

[0102] According to the above pattern image output method, in addition to the image showing the first brightness distribution and the image showing the second brightness distribution, an image showing a third brightness distribution having a period along the first axis larger than the first period, and an image showing a fourth brightness distribution having a period along the second axis larger than the second period are added to the first pattern image. Therefore, the projector can further improve the detection accuracy of the coordinate values ​​in the first axis direction and the coordinate values ​​in the second axis direction by performing the phase shift method once.

[0103] (Supplementary Note 7) The method for outputting a pattern image according to any one of Supplementary Note 1 to Supplementary Note 6, wherein, when r is an integer equal to or greater than 2, 2r+1 pattern images including the first pattern image are output in sequence, each of the 2r+1 pattern images has r brightness distributions, and among the r brightness distributions, at least one brightness distribution corresponding to the same period has a different brightness at the same coordinate.

[0104] By the above pattern image output method, 2r+1 pattern images including a first pattern image are output in sequence. Also, the 2r+1 pattern images have different brightness at the same coordinates in at least one brightness distribution corresponding to the same period. Therefore, when using pattern images with different phases, the projector can reduce the execution time for executing the phase shift method compared to a method of increasing the number of patterns to improve accuracy. As a result, user convenience is improved.

[0105] (Supplementary Note 8) A method for outputting a pattern image according to any one of Supplementary Note 1 to Supplementary Note 7, wherein, for coordinates (x, y) on a panel, two phase values ​​are θ1=g1(x, y) and θ2=g2(x, y), the number of shifts is N, and A1 and A2 are arbitrary constants, the amplitude f(x, y, n) of the n=0, ..., N-1th projection pattern includes at least A1cos(θ1+2πn / N) as a term corresponding to the first brightness distribution, and A2cos(θ2+4πn / N) as a term corresponding to the second brightness distribution.

[0106] By the above-mentioned method for outputting a pattern image, the amplitude f(x,y,n) of the projection pattern includes A1cos(θ1+2πn / N) as a term corresponding to the first brightness distribution, and A2cos(θ2+4πn / N) as a term corresponding to the second brightness distribution. Here, θ1=g1(x,y) and θ2=g2(x,y). Therefore, the projector can further improve the detection accuracy of the coordinate values ​​in the first axis direction and the coordinate values ​​in the second axis direction by performing the phase shift method once.

[0107] (Supplementary Note 9) A projector including an optical device and at least one processor, wherein the at least one processor controls the optical device to output a first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period, for use in a phase shifting method.

[0108] With the above projector, the first pattern image includes a first brightness distribution based on a first period and a second brightness distribution based on a second period. Therefore, when using pattern images with different phases, the execution time for executing the phase shift method can be reduced compared to a method of increasing the number of patterns to improve accuracy. As a result, user convenience is improved.

[0109] (Appendix 10) A program for causing a computer to execute the steps of: outputting a first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period, for use in a phase shift method.

[0110] With the above program, the first pattern image includes a first brightness distribution based on the first period and a second brightness distribution based on the second period. Therefore, when using pattern images with different phases, the projector can reduce the execution time for executing the phase shift method compared to a method of increasing the number of patterns to improve accuracy. As a result, user convenience is improved. [Explanation of symbols]

[0111] 10...projector, 11...projection device, 12...imaging device, 13...processing device, 14...storage device, 15...communication device, 131...pattern generation unit, 132...projection control unit, 133...imaging control unit, 134...first acquisition unit, 135...frequency analysis unit, 136...correspondence relationship generation unit, 137...measurement value calculation unit, 138...correction value calculation unit, 139...second acquisition unit, 140...image correction unit, PR1...control program

Claims

1. A first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period, which are used in the phase shift method, is output. How to output the pattern image.

2. the first brightness distribution has the first period along a first axis; the second brightness distribution has the second period along a second axis perpendicular to the first axis; The first pattern image is an image obtained by adding together an image showing the first brightness distribution and an image showing the second brightness distribution. The pattern image output method according to claim 1 .

3. further outputting a second pattern image obtained by adding together an image showing a third brightness distribution along a first axis, the third brightness distribution having a period greater than the first period, and an image showing a fourth brightness distribution along a second axis perpendicular to the first axis, the fourth brightness distribution having a period greater than the second period; The pattern image output method according to claim 1 .

4. the first brightness distribution has the first period along a first axis; the second brightness distribution has a period along the first axis that is greater than the first period; The first pattern image is an image obtained by adding together an image showing the first brightness distribution and an image showing the second brightness distribution. The pattern image output method according to claim 1 .

5. the first brightness distribution has the first period along a first axis; the second brightness distribution has a period along the first axis that is greater than the first period; The first pattern image is an image showing the first brightness distribution; an image showing the second brightness distribution; an image showing a third brightness distribution having a period along the first axis that is smaller than the first period; is the image obtained by adding The pattern image output method according to claim 1 .

6. the first brightness distribution has the first period along a first axis; the second brightness distribution has the second period along a second axis perpendicular to the first axis; The first pattern image is an image showing the first brightness distribution; an image showing the second brightness distribution; an image showing a third brightness distribution having a period along the first axis that is greater than the first period; an image showing a fourth brightness distribution having a period along the second axis that is greater than the second period; is the image obtained by adding The pattern image output method according to claim 1 .

7. where r is an integer equal to or greater than 2, sequentially outputting 2r+1 pattern images including the first pattern image; Each of the 2r+1 pattern images is having r brightness distributions, Among the r brightness distributions, at least one brightness distribution corresponding to the same period has a different brightness at the same coordinate. The pattern image output method according to claim 1 .

8. For coordinates (x, y) on the panel, two phase values ​​are expressed as θ １ = g1(x, y), θ ２ = g ２ (x, y), the number of shifts is N, and A １ and A ２ When is an arbitrary constant, the amplitude f(x, y, n) of the n-th projection pattern (n=0, . . . , N-1) is expressed as a term corresponding to at least the first brightness distribution, A １ cos(θ １ +2πn / N), and as a term corresponding to the second brightness distribution, A ２ cos(θ ２ +4πn / N) The pattern image output method according to claim 1 .

9. an optical device; at least one processor; The at least one processor A projector that outputs a first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period, used in a phase shift method, by controlling the optical device.

10. outputting a first pattern image including a first brightness distribution based on a first period and a second brightness distribution based on a second period, which are used in the phase shift method; A program that a computer runs.

Images