JP2014036394A - Distortion correction method of projection image and projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate correction operation of trapezoidal distortion.SOLUTION: A user specifies correction points at four corners, becoming the reference of distortion correction, on the projection image projected to a screen by an operation unit (113). A CPU (110) initially sets an initial travel as a travel for the moving operation of the correction point, and sets a smaller travel each time of the moving operation or according to the number of times of the moving operation. A CPU (110) determines deformation parameters for distortion correction from the correction point after movement, and sets the deformation parameters in an image processing unit (140). The image processing unit (140) deforms an image to be projected, by the deformation parameters from the CPU (110). An image deformed by the image processing unit (140) is displayed by liquid crystal elements (151R, 151G, 151B), and projected to a screen by a projection optical system (171).

Description

  The present invention relates to a projection image distortion correction method and a projection display apparatus, and more specifically to a projection image distortion correction method in a projection display apparatus such as a liquid crystal projector and a projection display apparatus capable of performing the method. .

  In recent years, projection display devices such as liquid crystal projectors are widely used for business purposes such as presentations and conferences, and home uses such as home theaters, and accordingly, miniaturization and weight reduction are progressing. For this reason, there are various places where the projector is projected, and it may not always be possible to place the projector in front of the screen due to place restrictions.

  In general, the projector is often inclined from a projector placed on a desk toward the upper screen. However, due to the relative inclination between the projector body and the screen, geometric distortion called trapezoidal distortion occurs on the screen. As a means for solving this problem, many projectors have a trapezoidal correction function for correcting this trapezoidal distortion by signal processing.

  Patent Document 1 describes in detail a method for calculating trapezoidal correction based on the relative tilt angle between the projector body and the screen.

  Patent Document 2 describes a distortion correction method for correcting the positions of the four corners of an image displayed on a projection surface based on a user operation. When a correction point is selected and the direction key is pressed, the correction point is moved by a predetermined distance, and a distortion correction parameter is calculated.

JP 2005-123669 A JP 2003-304552 A

  The method of moving each correction point with the direction key in the four corner designation type distortion correction has the following problems. That is, if the movement distance in one action is small, the number of operations to obtain a desired shape increases when the distortion is large, which takes time. On the other hand, if the moving distance in one action is large, the desired shape cannot be precisely obtained.

  It is an object of the present invention to provide a projection image distortion correction method and a projection display device that can solve such problems and can quickly and accurately correct a projection image to a desired shape.

  A distortion correction method for a projection image according to the present invention is a distortion correction method for a projection image that corrects distortion of the projection image based on the inclination of the projection optical axis with respect to the screen, and the amount of movement of the projection image in response to a single movement instruction. A step of setting an initial movement amount, a selection step of selecting a correction point on the projection image, and a movement of moving the correction point selected in the selection step in the direction designated by the user based on the movement amount A step of reducing the amount of movement, a step of calculating a deformation parameter according to the correction point moved in the movement step, and a step of deforming the projection image based on the deformation parameter. The initial movement amount when the correction point is not the initial position is smaller than the initial movement amount when the correction point is the initial position.

  A projection display device according to the present invention is a projection display device that projects an image on a screen, and includes an image processing unit that performs geometric deformation on an image to be projected, and an image processed by the image processing unit. A projection optical system for projecting onto the screen, means for designating a correction point for the geometric deformation on the projection image displayed on the screen, and moving the correction point by a movement amount in response to one movement instruction. A movement control means, wherein an initial movement amount is initially set as the movement amount, a movement control means for reducing the movement amount according to the movement instruction, and a correction point after movement by the movement control means, Control means for determining a deformation parameter of geometric deformation of the image processing means and controlling the image processing means so as to perform the geometric deformation according to the deformation parameter.

  According to the present invention, since the amount of movement is initially large, even if the distortion is large, it can be brought close to the desired shape with a small number of operations, and the amount of movement gradually decreases, so it is easy to precisely match the desired shape. Become. As a result, the distortion of the projected image can be corrected quickly and accurately.

It is a schematic block diagram of one Example of this invention. It is a flowchart which shows the basic control operation | movement of a present Example. It is a schematic block diagram of an image processing unit. It is a flowchart of the deformation | transformation process for distortion correction of a present Example. It is a flowchart of the deformation | transformation process for distortion correction of a present Example. It is explanatory drawing of a deformation | transformation process which contrasts the image area on a liquid crystal element, and the image area of the projection image on a screen. It is explanatory drawing which shows the mode of a deformation | transformation of the image area by distortion correction operation. It is explanatory drawing which shows the mode of a deformation | transformation of the image area by distortion correction operation. It is explanatory drawing which shows the mode of a deformation | transformation of the image area by distortion correction operation. It is explanatory drawing which shows the mode of a deformation | transformation of the image area by distortion correction operation. It is explanatory drawing which shows the mode of a deformation | transformation of the image area by distortion correction operation. It is a flowchart of the deformation | transformation process for distortion correction of another Example. It is a flowchart of the deformation | transformation process for distortion correction of another Example. It is an example of a correspondence table between the correction point selection count and the movement amount. It is a flowchart of the deformation | transformation process which changed FIG. 4A. It is explanatory drawing of the deformation | transformation process in the process shown in FIG. It is a flowchart of a distortion correction operation in the case of having two distortion correction modes. It is explanatory drawing of projective transformation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic block diagram of an embodiment of a projection display device according to the present invention applied to a projector using a transmissive liquid crystal panel. The liquid crystal projector 100 of this embodiment controls the light transmittance of the liquid crystal element according to the image to be displayed, and projects the light transmitted through the liquid crystal element onto the screen, thereby displaying the image on the screen.

  With reference to FIG. 1, the overall configuration of this embodiment will be described. The liquid crystal projector 100 includes a CPU 110, a ROM 111, a RAM 112, an operation unit 113, an image input unit 130, and an image processing unit 140. The liquid crystal projector 100 further includes a liquid crystal control unit 150, liquid crystal elements 151R, 151G, and 151B, a light source control unit 160, a light source 161, a color separation unit 162, a color composition unit 163, an optical system control unit 170, and a projection optical system 171. The liquid crystal projector 100 further includes a recording / playback unit 191, a recording medium 192, a communication unit 193, an imaging unit 194, a display control unit 195, and a display unit 196.

  CPU 110 controls each operation block of liquid crystal projector 100. The ROM 111 stores a control program that describes the processing procedure of the CPU 110. The RAM 112 temporarily stores a control program and data as a work memory of the CPU 110. The CPU 110 can temporarily store still image data and moving image data reproduced from the recording medium 192 by the recording / reproducing unit 191 in the RAM 112, and can reproduce each image and video using the program of the ROM 111. The CPU 110 can also temporarily store still image data and moving image data received by the communication unit 193 in the RAM 112 and reproduce each image and video using the program in the ROM 111. The CPU 110 can also temporarily store the image data and video data obtained by the imaging unit 194 in the RAM 112, convert them into still image data and moving image data using the program of the ROM 111, and record them on the recording medium 192. .

  The operation unit 113 receives a user instruction and transmits an instruction signal corresponding to the operation content to the CPU 110. The operation unit 113 includes, for example, a switch, a dial, and a touch panel provided on the display unit 196. The operation unit 113 also includes a signal receiving unit (such as an infrared receiving unit) that receives a radio signal from the remote controller and transmits a predetermined instruction signal to the CPU 110 based on the received signal. CPU 110 controls each operation block of liquid crystal projector 100 in accordance with a control signal input from operation unit 113 or communication unit 193.

  The image input unit 130 is a means for inputting a video signal from an external device. For example, the image input unit 130 is a composite terminal, S video terminal, D terminal, component terminal, analog RGB terminal, DVI-I terminal, DVI-D terminal, or HDMI (registered trademark). ) Including terminals. The image input unit 130 includes an analog / digital converter that converts an analog video signal into a digital video signal. The image input unit 130 supplies the received video signal to the image processing unit 140. The external device that supplies a video signal to the image input unit may be any device that can output a video signal, such as a personal computer, a camera, a mobile phone, a smartphone, a hard disk recorder, and a game machine.

  The image processing unit 140 subjects the video signal input from the image input unit 130 to change processing such as the number of frames, the number of pixels, and the image shape, and supplies the video signal to the liquid crystal control unit 150. The image processing unit 140 has functions of frame decimation processing, frame interpolation processing, resolution conversion processing, and distortion correction processing (keystone correction processing). In addition to the video signal from the image input unit 130, the image processing unit 140 can also perform the above-described change processing on the image and video reproduced by the CPU 110.

  The image processing unit 140 includes an image processing microprocessor having the above-described functions, or is realized by the CPU 110 executing a program stored in the ROM 111.

  The liquid crystal control unit 150 controls the transmittance of the liquid crystal elements (liquid crystal display panels) 151R, 151G, and 151B in units of pixels in accordance with the video signal from the image processing unit 140. That is, the liquid crystal control unit 150 drives the liquid crystal element (liquid crystal display panel) 151R according to the R (red) signal of the video signal processed by the image processing unit 140, and drives the liquid crystal element 151G according to the G (green) signal. The liquid crystal element 151B is driven in accordance with the B (blue) signal. Thereby, the liquid crystal element 151R displays a red image of the RGB image to be displayed, the liquid crystal element 151G displays a green component image, and the liquid crystal element 151B displays a blue image. The liquid crystal control unit 150 includes a dedicated microprocessor, or is realized by the CPU 110 executing a program stored in the ROM 111.

  The light source control unit 160 includes a microprocessor that controls on / off of the light source 161 and the amount of light when the light source is on. Of course, the function of the light source control unit 160 may be replaced by the CPU 110 in accordance with a program stored in the ROM 111. The light source 161 generates illumination light for the liquid crystal elements 151R, 151G, and 151B. The light source 161 includes, for example, a halogen lamp, a xenon lamp, a high pressure mercury lamp, or the like. The output light of the light source 161 is divided into red, green, and blue light by the color separation unit 162, and each divided light enters the liquid crystal elements 151R, 151G, and 151B. The color separation unit 162 includes an element that separates the output light of the light source 161 into red (R), green (G), and blue (B), such as a dichroic mirror or a prism. In addition, when using LED etc. which output the light corresponding to each color as the light source 161, the color separation part 162 is unnecessary.

  The liquid crystal elements 151R, 151G, and 151B each modulate the illumination light separated by the color separation unit 162 to generate an optical image of each color. Specifically, the liquid crystal control unit 150 controls the transmittance of each pixel of the liquid crystal element 151R in accordance with the red component of the image to be displayed, and the liquid crystal element 151R is made incident with light of a certain intensity, so that the electric signal Is converted into a red component optical image (red image). Similarly, the liquid crystal element 151G generates an optical image with a green component (green image), and the liquid crystal element 151B generates an optical image with a blue component (blue image).

  The color synthesizing unit 163 synthesizes the light transmitted through the liquid crystal elements 151R, 151G, and 151B so that the pixels do not deviate from each other. Thereby, an optical image expressing the original color is generated. The color synthesizing unit 163 includes elements that spatially synthesize optical images of red (R), green (G), and blue (B) transmitted through the liquid crystal elements 151R, 151G, and 151B, such as dichroic mirrors and prisms. . The optical image synthesized by the color synthesizing unit 163 is a full-color image and is projected onto a screen (not shown) by the projection optical system 171. The projection optical system 171 includes a plurality of lenses and lens driving actuators, and the projection images can be enlarged, reduced, and focused by driving the lenses with the actuators. The optical system control unit 170 includes a control microprocessor that controls the projection optical system 171. The function of the optical system control unit 170 may be replaced by the CPU 110 executing a program stored in the ROM 111.

  In the case of a single plate type, an RGB image is displayed with one liquid crystal element, and the liquid crystal element is illuminated with light from a high-intensity light source, so that the color separation unit 162 and the color composition unit 163 are not necessary.

  The recording / playback unit 191 plays back still image data and moving image data from the recording medium 192, receives still image data and moving image data of images and videos obtained by the imaging unit 194 from the CPU 110, and records them on the recording medium 192. The recording / playback unit 191 also records still image data and moving image data received by the communication unit 193 on the recording medium 192. The recording / playback unit 191 includes, for example, an interface electrically connected to the recording medium 192 and a microprocessor for communicating with the recording medium 192. The CPU 110 may replace some functions of the recording / playback unit 191 with a program stored in the ROM 111.

  The recording medium 192 records still image data, moving image data, and other data. As the recording medium 192, any recording medium such as a magnetic disk, an optical disk, or a semiconductor memory can be used. The recording medium 192 may be detachable from the projector 100 or may be a built-in type.

  The communication unit 193 communicates with an external device and receives control signals, still image data, moving image data, and the like from the external device. For example, the communication unit 193 can use a wireless LAN, a wired LAN, USB, or Bluetooth (registered trademark), and the communication method is not limited to a specific one. When the terminal of the image input unit 130 is, for example, an HDMI (registered trademark) terminal, the communication unit 193 may perform CEC communication via the terminal. The external device is, for example, a personal computer, a camera, a mobile phone, a smartphone, a hard disk recorder, a game machine, or a remote control.

  The imaging unit 194 is arranged so as to capture an image projected by the projection optical system 171 (capture the screen direction). The imaging unit 194 transmits the captured image data to the CPU 110. The CPU 110 temporarily stores the image data from the imaging unit 194 in the RAM 112 and converts the image data into still image data or moving image data based on a program stored in the ROM 111. The imaging unit 194 includes an imaging element that converts an optical image into an image signal, a lens that enters an optical image of a subject into the imaging element, an actuator that drives the lens, a microprocessor that controls the actuator, and an output image signal from the imaging element as a digital signal. An AD conversion unit for converting into You may provide the imaging part which image | photographs directions other than a screen direction, for example, the viewer side opposite to a screen.

  The display control unit 195 causes the display unit 196 to display an image such as an operation screen for operating the liquid crystal projector 100 and a switch icon. The display control unit 195 includes a display control microprocessor or the like, but the function may be replaced by the CPU 110 with a program stored in the ROM 111.

  The display unit 196 displays an operation screen and a switch icon for operating the liquid crystal projector 100 as described above. The display unit 196 includes a device that displays an image, such as a liquid crystal display, a CRT display, an organic EL display, or an LED display. The display unit 196 may be configured to emit an LED or the like corresponding to each button in order to post a specific button so that the user can recognize it.

  The functions of the image processing unit 140, the liquid crystal control unit 150, the light source control unit 160, the optical system control unit 170, the recording / playback unit 191 and the display control unit 195 may be realized by one or a plurality of microprocessors.

  FIG. 2 shows a flowchart of the basic operation of this embodiment. The basic operation of the present embodiment will be described with reference to FIG. The operation shown in the flow shown in FIG. 2 is basically executed by the CPU 110 controlling each functional block based on a program stored in the ROM 111. The flow shown in FIG. 2 starts when the user gives an instruction to turn on the liquid crystal projector 100 using the operation unit 113 or a remote controller (not shown).

  When the user instructs the liquid crystal projector 100 to be turned on using the operation unit 113 or a remote controller (not shown), the CPU 110 supplies power from a power supply circuit (not shown) to each part of the projector 100 from a power supply unit (not shown).

  Next, the CPU 110 determines the display mode selected by the operation of the operation unit 113 or the remote controller by the user (S210). The display modes of the liquid crystal projector 100 include an input image display mode, a file playback display mode, and a file reception display mode. The input image display mode is a display mode for displaying video input from the image input unit 130. The file playback display mode is a display mode for displaying still image data and moving image data and video read from the recording medium 192. The file reception display mode is a display mode for displaying still image data and moving image data and video received from the communication unit 193.

  The display mode when the power is turned on may be the display mode at the end of the previous time, or any display mode may be the default display mode. In these cases, the process of step S210 can be omitted.

  Assume that the input image display mode is selected in step S210. When the input image display mode is selected, the CPU 110 determines whether or not a video signal is input from the image input unit 130 (S220). The CPU 110 waits until the input is detected if no input is made (No in S220), and executes the projection process (S230) if the input is made (Yes in S220).

  As a projection process, the CPU 110 transmits a video signal from the image input unit 130 to the image processing unit 140, causes the image processing unit 140 to perform deformation of the number of pixels, the frame rate, and the shape, and performs processing for one screen. The image is transmitted to the liquid crystal control unit 150. The CPU 110 causes the liquid crystal control unit 150 to display the liquid crystal elements 151R, 151G, and the liquid crystal elements 151R, 151G, so that the transmittance corresponds to the gradation level of each color component of red (R), green (G), and blue (B) of the image for one screen. The transmittance of 151B is controlled.

  The CPU 110 causes the light source control unit 160 to output illumination light from the light source 161. The color separation unit 162 separates the output light of the light source 161 into red (R), green (G), and blue (B), and supplies each light to the liquid crystal elements 151R, 151G, and 151B. The light of each color supplied to the liquid crystal elements 151R, 151G, 151B is spatially modulated by limiting the amount of light transmitted through each pixel of each liquid crystal element, and an optical image of each color is generated. The red (R), green (G), and blue (B) color images transmitted through the liquid crystal elements 151R, 151G, and 151B are combined by the color combining unit 163. The RGB optical image synthesized by the color synthesis unit 163 is projected on a screen (not shown) by the projection optical system 171.

  This projection processing is sequentially executed for each image of one frame while the image is projected. During this time, when the user inputs an instruction to operate the projection optical system 171 from the operation unit 113, the CPU 110 instructs the optical system control unit 170 to control the projection optical system 171 according to the instruction content. For example, the focus of the projected image is changed or the magnification of the optical system is changed.

  While executing the display process, the CPU 110 determines whether or not an instruction to switch the display mode is input from the operation unit 113 by the user (S240). When the user inputs an instruction to switch the display mode from the operation unit 113 (Yes in S240), the CPU 110 returns to S210 again and determines the display mode. At this time, the CPU 110 transmits a menu screen for causing the image processing unit 140 to select a display mode as an OSD image, and controls the image processing unit 140 to superimpose the OSD screen on the image being projected. The user selects a display mode while viewing the projected OSD screen.

  When the user does not input an instruction to switch the display mode from the operation unit 113 during the display process (No in S240), the CPU 110 determines whether or not an instruction to end projection is input from the operation unit 113 by the user (No). S250). When the user inputs an instruction to end projection from the operation unit 113 (Yes in S250), the CPU 110 stops power supply to each block of the projector 100 and ends image projection. On the other hand, when the user inputs an instruction to end projection from the operation unit 113 (No in S250), the CPU 110 returns to S220, and thereafter, until the user inputs an instruction to end projection from the operation unit 113, step S220. Repeat the process of S250.

  With the operation as described above, the liquid crystal projector 100 projects an image on the screen.

  In the file playback display mode, the CPU 110 causes the recording / playback unit 191 to read out the file list of still image data and moving image data and the thumbnail data of each file from the recording medium 192 and temporarily store them in the RAM 112. Then, the CPU 110 generates a character image based on the file list temporarily stored in the RAM 112 and an image based on the thumbnail data of each file according to the program of the ROM 111, and transmits the image to the image processing unit 140. Then, the CPU 110 controls the image processing unit 140, the liquid crystal control unit 150, and the light source control unit 160 in the same manner as the normal projection processing (S230).

  The user inputs an instruction to select characters and images respectively corresponding to still image data and moving image data recorded on the recording medium 192 on the projection screen using the operation unit 113. In accordance with this instruction, the CPU 110 controls the recording / reproducing unit 191 so as to read out selected still image data and moving image data from the recording medium 192. The CPU 110 temporarily stores the read still image data or moving image data in the RAM 112, and reproduces the image or video of the still image data or moving image data according to the program of the ROM 111.

  For example, the CPU 110 sequentially transmits the reproduced moving image data to the image processing unit 140, and controls the image processing unit 140, the liquid crystal control unit 150, and the light source control unit 160 in the same manner as the normal projection processing (S230). When reproducing still image data, the CPU 110 transmits the reproduced image data to the image processing unit 140, and controls the image processing unit 140, the liquid crystal control unit 150, and the light source control unit 160 in the same manner as the normal projection processing (S230). To do.

  In the file reception display mode, the CPU 110 temporarily stores still image data and moving image data received from the communication unit 193 in the RAM 112, and reproduces an image or video of the still image data or moving image data according to the program of the ROM 111. For example, the CPU 110 sequentially transmits the reproduced moving image data to the image processing unit 140, and controls the image processing unit 140, the liquid crystal control unit 150, and the light source control unit 160 in the same manner as the normal projection processing (S230). When the still image data is reproduced, the CPU 110 transmits the reproduced image to the image processing unit 140, and controls the image processing unit 140, the liquid crystal control unit 150, and the light source control unit 160 in the same manner as the normal projection processing (S230). To do.

  The image projected on the screen by the liquid crystal projector 100 causes a trapezoidal distortion based on the inclination of the projection optical axis with respect to the screen. This trapezoidal distortion can be eliminated by preliminarily projecting the projection image so as to cancel the distortion, and the image processing unit 140 performs the deformation. FIG. 3 shows a schematic block diagram of the image processing unit 140. The image processing unit 140 includes various image processing units 310, an OSD superimposing unit 320, and a deformation processing unit 330.

  The original image signal S301 is an image signal before being processed by the image processing unit 140, which is input from the image input unit 130, the recording / playback unit 191 or the communication unit 193 according to the display mode. The timing signal S302 is a timing signal such as a vertical synchronization signal, a horizontal synchronization signal, or a clock synchronized with the original image signal S301, and is supplied from the supply source of the original image signal S301. Each block in the image processing unit 140 operates based on the timing signal S302. However, the timing signal may be regenerated and used inside the image processing unit 140.

  Various image processing units 310 cooperate with the CPU 110 to acquire statistical information including the histogram and APL of the original image signal S301, and generate an image signal S303 subjected to various image processing. Various image processing includes IP conversion, frame rate conversion, resolution conversion, γ conversion, color gamut conversion, color correction, and edge enhancement, and since these details are well known, detailed description thereof is omitted. The various image processing units 310 output the generated image signal S303 to the OSD superimposing unit 320.

  The OSD superimposing unit 320 superimposes a user menu and guide information for operation as an OSD image on the image signal S303 in accordance with an instruction from the CPU 110, and outputs the generated OSD superimposed image signal S304 to the deformation processing unit 330.

の関係にある。ここで、Ｍは元画像から変形後画像への３×３の射影変換行列であり、ＣＰＵ１１０から入力される。（ｘｓｏ，ｙｓｏ）は、図１２に実線で示す元画像の１つの頂点の座標である。（ｘｄｏ，ｙｄｏ）は、図１２に一点鎖線で示す変形後画像の、元画像の頂点（ｘｓｏ、ｙｓｏ）に対応する頂点の座標値である。 The deformation processing unit 330 performs geometric deformation based on the deformation formula or deformation parameter set by the CPU 110 on the OSD superimposed image signal S304 from the OSD superimposing unit 320 to generate a post-deformation image signal S305. The keystone correction can be realized by projective transformation, and the CPU 110 sets parameters for the projective transformation in the deformation processing unit 330 in advance. If the coordinates of the original image are (xs, ys) and the coordinates of the transformed image are (xd, yd),

Are in a relationship. Here, M is a 3 × 3 projective transformation matrix from the original image to the transformed image, and is input from the CPU 110. (Xso, yso) is the coordinates of one vertex of the original image indicated by the solid line in FIG. (Xdo, ydo) is the coordinate value of the vertex corresponding to the vertex (xso, yso) of the original image of the transformed image indicated by the alternate long and short dash line in FIG.

式２で求められた元画像の座標（ｘｓ、ｙｓ）が整数値になる場合、元画像の座標（ｘｓ、ｙｓ）上の画素値をそのまま変形後画像の座標（ｘｄ，ｙｄ）の画素値としてもよい。 From the CPU 110, an inverse matrix M ⁻¹ of the matrix M of Expression (1) and offsets (xso, yso), (xdo, ydo) are input to the deformation processing unit 330. The deformation processing unit 330 obtains the coordinates (xs, ys) of the original image corresponding to the coordinates (xd, yd) after deformation according to the equation (2). That is,

When the coordinates (xs, ys) of the original image obtained by Expression 2 have an integer value, the pixel values on the coordinates (xs, ys) of the original image are directly used as the pixel values of the coordinates (xd, yd) of the transformed image. It is good.

  However, in general, the coordinates of the original image obtained by Expression (2) are not always integer values. For this reason, generally, the pixel value of the coordinates (xd, yd) of the image after deformation is obtained by interpolation using the values of the surrounding pixels. As an interpolation method, bilinear, bicubic, or any other interpolation method may be used. When the coordinates of the original image obtained based on Expression (2) are outside the range of the original image area 620, the transformation processing unit 330 sets the pixel value to black or a background color set by the user.

  In this way, the deformation processing unit 330 creates a post-deformation image by obtaining pixel values for all coordinates (or all pixels) of the post-conversion image.

The CPU 110 inputs the matrix M and its inverse matrix M ⁻¹ to the deformation processing unit 330. However, the CPU 110 inputs the inverse matrix M ⁻¹ to the deformation processing unit 330, and the deformation processing unit 330 generates the matrix M inside. May be. Alternatively, the CPU 110 may input the matrix M to the deformation processing unit 330, and the deformation processing unit 330 may generate the inverse matrix M ⁻¹ therein.

  As described above, the post-deformation image signal S305 output from the deformation processing unit 340 is supplied to the liquid crystal control unit 150 and displayed on the liquid crystal elements 151R, 151G, and 151B.

  Next, with reference to FIG. 4A and FIG. 4B and FIG. 5 and FIG. 6A to FIG. 4A and 4B are flowcharts executed by the CPU 110. The operations shown in FIGS. 4A and 4B are activated when the user starts four-corner designation type distortion correction using the operation unit 113 or a remote controller (not shown). FIG. 5 is a schematic diagram comparing the image areas of the liquid crystal elements 151R, 151G, and 151B with the image areas projected on the screen 540. FIG. 5A shows image areas of the liquid crystal elements 151R, 151G, and 151B, and FIG. 5B shows a projected image on the screen. Only one liquid crystal element 151R, 151G, 151B is shown as a representative.

  It is assumed that the entire surface of the liquid crystal element is an image area 510 and is projected on the screen. When the liquid crystal projector 100 and the screen are inclined relatively vertically and horizontally with an inclination angle, the projected image on the screen becomes a distorted square 520, although the shape differs depending on the inclination angle and optical conditions. Points P1 to P4 indicate the four corners of the image area on the liquid crystal element when distortion correction is not performed. Points P1 to P4 are correction points of the pre-projection image, and are points that are moved or adjusted for trapezoidal distortion correction. Points PS1 to PS4 are points indicating four corners on the projection image corresponding to the correction points P1 to P4. A rectangle 530 indicated by a broken line is the shape of the projected image targeted by the user.

  CPU110 determines whether the position of the correction points P1-P4 is an initial position (S401). The initial position is a position in a state where no distortion correction deformation is performed, and correction points P1 to P4 shown in FIG. 5A are initial positions.

  When determining that all of the correction points P1 to P4 are the initial positions, the CPU 110 sets a predetermined initial movement amount d1 as the movement amount d in one action (S402). If it is determined that even one of the four correction points P1 to P4 is not the initial position, the CPU 110 sets a predetermined movement amount d2 smaller than the initial movement amount d1 as the movement amount d for one movement instruction by the user ( S403). The movement amount d is a variable, and the value is used as a movement amount when the correction point is moved in the subsequent steps.

  After steps S402 and S403, in S404, CPU 110 displays one of correction points P1 to P4 as a candidate for selection of a movement target point. For example, as indicated by reference numeral 540 in FIG. 5B, the color near the point PS1 is changed to a conspicuous color or blinked. Alternatively, a method for displaying the fact on the OSD may be used. Further, the OSD superimposing unit 320 may be instructed to display a user operation guide at the same time.

  The CPU 110 waits for an operation of a remote control key or a body switch by the user (S405).

  When receiving the user operation, the CPU 110 determines whether the operated key is any one of the direction keys (up, down, left, and right) (S406). If it is a direction key, the CPU 110 understands that it is a movement instruction, changes the movement target point candidate according to the pressed direction key (S407), and returns to S406. For example, in a state where the point PS1 is a candidate, if the right key is pressed, the point to be moved is changed to PS2 for the point, and if the down key is pressed, the point candidate to be moved is changed to PS3. To change. When the up key or the left key is pressed while the point PS1 is a candidate, the CPU 110 does not change the movement target point candidate.

  If the operated key is not a direction key, the CPU 110 determines whether it is a determination key (S408). If it is the enter key, the CPU 110 determines the correction point of the pre-projection image corresponding to the current movement target candidate point as the movement target point (S409). For example, when the point PS1 is a movement target point candidate, the point P1 of the pre-projection image becomes the movement target point. At this time, the CPU 110 may instruct the OSD superimposing unit 320 to display an operation guide for movement.

  The CPU 110 waits for a user operation for moving the determined movement target point (S410). When receiving the user operation, the CPU 110 determines whether the operated key is any of the direction keys (up, down, left, and right) (S411). If it is a direction key, the CPU 110 moves the movement target point by the movement amount d set in step S402 or S403 in accordance with the pressed direction key (S412). For example, the CPU 110 moves to the right when the right key is pressed while the point P1 shown in FIG. 5A is the movement target point, and moves downward by the movement amount d when the down key is pressed. However, since it cannot be moved outside the panel size of the liquid crystal element, when the point P1 is at the panel apex, the point P1 is not moved even when the up key or the left key is pressed. The post-deformation image area when the right key is pressed once from the initial position and the point P1 moves to the point P1 'is indicated by reference numeral 550 in FIG.

  As described above, the CPU 110 causes the deformation processing unit 330 to execute the geometric deformation process using the quadrangle having the four correction points including the movement target point as vertices as the post-deformation image area (S413), and returns to step S410. For the deformation process in S413, the CPU 110 calculates a deformation parameter, specifically, a projective transformation matrix M and an offset so that the square 510 as the image area before correction becomes the post-deformation image area 550, and the deformation processing unit Set to 330.

  If the operated key is not a direction key (S411), the CPU 110 determines whether or not the enter key has been operated (S414). If it is not the enter key, the CPU 110 is an invalid key operation, so the process returns to step S410 and waits for the next user operation. If it is the enter key (S414), the CPU 110 ends the movement process for this movement target point, and decreases the movement amount d by the predetermined movement reduction amount Δd for the next movement target point (S415). When the movement amount d becomes zero or less by this subtraction, the CPU 110 sets the movement amount d to the movement minimum value dmin. By such movement amount reduction processing and movement control, the movement amount d gradually decreases with each operation. That is, precise position adjustment becomes possible as the movement instruction operation is repeated.

  After S415, the CPU 110 returns to step S404 and performs processing for selecting the next movement target point.

  If the operated key is not the enter key (S408), the CPU 110 determines whether the operated key is the end key (S416). If it is an end key, the CPU 110 ends the four corner correction. If it is not the end key, the CPU 110 determines whether or not the operated key is a reset key (S417). In the case of the reset key, the CPU 110 returns the correction points P1 to P4 to the initial position (S418), performs the deformation process (S419), returns to step S402, and sets the movement amount d as the initial movement amount d1. The deformation process in step S416 is the same as that in step S413. Returning the movement amount to the initial movement amount d1 means performing a new deformation next. This is because it is assumed that the amount of deformation up to the target shape is large.

  With reference to FIGS. 6A to 6E, the correspondence between the user operation and the change in the movement amount will be described. Assume that the four corner designation type distortion correction is started from the state where the four correction points are at the initial positions. The screen projection image at this stage has a shape indicated by reference numeral 520 in FIG. 6A. FIG. 6A is the same as FIG.

  In step S402 of FIG. 4A, the initial movement amount d1 is set as the movement amount d. For example, d1 is 9 pixels. In step S404, the point PS1 is displayed as a movement target point candidate, but the user presses the right key once and then presses the decision key in order to adjust the point PS2 having the largest distortion. Then, the point P2 is determined as a correction point. Next, the user presses the down key to bring the point PS2 closer to the vertex of the target shape 530. Then, the point P2 moves down 9 pixels on the panel to become the position of the point PS2 'shown in FIG. 6B. Since the deformation process is performed, an image having a shape indicated by reference numeral 610 in FIG. 6B is projected on the screen. Here, the reason why the point PS2 moves diagonally without moving vertically on the screen is that it moves 9 pixels downward on the panel, and it moves diagonally on the screen projected at an inclination. become.

  When the user further presses the down key twice and the left key once, the vertex moves to the position of the point PS2 ″ in FIG. 6C, and the projected image on the screen has a shape indicated by reference numeral 620 in FIG. 6C. At the time, the point PS2 ″ does not coincide with the vertex of the target shape 530, but fine adjustment is performed later, so the position of the point P2 is determined by pressing the enter key. Here, although not clearly shown to the user, the movement amount is decreased by a movement decrease amount Δd in step S415. If the movement decrease amount Δd is 2 pixels, the movement amount d is 9−2 = 7 pixels, and this movement amount d is applied to the movement of the next correction point. When returning to the movement target point selection, the point PS2 is displayed as a movement target point candidate.

  Next, in order to adjust the point PS1 having a large distortion, the user presses the left key once and then presses the enter key to set the point P1 as a movement target point. If the right key is pressed twice and the down key is pressed once in the same procedure, the point P1 moves 14 pixels to the right and 7 pixels downward, and an image having the shape indicated by reference numeral 630 in FIG. 6D is projected on the screen. The Here, the user presses the enter key to determine the position of the point P1.

  Thereafter, the next correction point PS3 is adjusted in units of 5 pixels, and the point PS4 is adjusted in units of 3 pixels. At this point, the four corners are approximately in the vicinity of the desired position, and an image having the shape indicated by reference numeral 640 in FIG. 6E is projected.

  The points PS1 to PS4 are sequentially selected again, and the correction points are moved by P1 to P4 by pressing the direction key. This time, since the amount of movement is in units of one pixel, it can be precisely aligned with a desired position, and finally the shape of the projected image on the screen matches the target shape 530.

  As described above, according to the present embodiment, in the distortion correction of the method in which the four corners are gradually moved, even when the distortion is large, the initial movement is large, so that the desired shape can be approximated with a small number of operations. Since the amount of movement is gradually reduced, the operation to match the desired shape is facilitated, and the desired shape can be precisely matched.

  In the example described above, the movement amount d is the same in the left-right direction and the up-down direction, but the left-right direction movement amount dx and the up-down direction movement amount dy may be different values.

  Although an example of a projector using a transmissive liquid crystal panel as a display device has been described, the present invention can also be applied to a projector using a display device such as a DLP or LCOS (reflection liquid crystal) panel. The display panel may be a single plate type or a three plate type.

  The processing content for reducing the movement amount of the correction point may be changed as follows. That is, when setting the initial movement amount d1 or d2 as the movement amount d in steps S402 and S403, a variable is prepared for each correction point as the movement amount d, and these are set as dp1 to dp4, respectively. In step S402, the initial movement amount d1 is set to dp1 to dp4, and in step S403, the initial movement amount d2 is set to dp1 to dp4. In step S415, when one of the correction points is moved and determined, the movement amount dpi (i = 1 to 4) corresponding to the moved correction point is decreased by a predetermined movement reduction amount Δd. .

  Other processes are the same as those in the first embodiment. As in the description of the first embodiment, if the initial movement amount d1 is 9 pixels and the movement decrease amount Δd is 2 pixels, the same correction point needs to be selected five times in order to set the movement amounts dp1 to dp4 to 1 pixel. Yes, the number of operations increases. It is desirable to determine the initial movement amount d1 and the movement decrease amount Δd so that the movement amounts dp1 to dp4 become one pixel when the same correction point is selected twice or three times.

  If the change is made in this way, the movement amount decreases according to the number of selections for each correction point, so the order of selecting the four correction points is irrelevant to the movement amount. In the first embodiment, it is most efficient to move the point PS2 having a large distortion first and apply the initial movement amount d1. On the other hand, in this embodiment, no matter what correction point is selected, since the initial movement amount d1 is applied at the time of the first selection, there is no difference in the number of operations depending on the correction point selection order of the user. Therefore, even if the distortion is large, the movement is large at the beginning, so that the desired shape can be obtained with a small number of operations. In addition, since the moving amount gradually becomes smaller, it can be precisely adjusted to a desired shape finally.

  The point that the amount of movement decreases according to the number of selections for each correction point is the same as in the second embodiment. However, a variable indicating the number of selections is provided for each correction point, and the selection is performed by counting the number of selections for each correction point. The amount of movement according to the number of times is applied.

  7A and 7B show a flowchart executed by the CPU 110 to realize such an operation. A different part from FIG. 4A and FIG. 4B is demonstrated in detail.

  If it is determined in step S401 that all four correction points are the initial positions, the CPU 110 sets the selection frequency information of each correction point to zero (S701). If it is determined that even one of the four correction points is not the initial position, the CPU 110 sets the selection number information of each correction point to a predetermined selection number n (S702). Here, n is a convenient number for setting the movement amount small. Although details will be described later, n is 1 or 2 here.

  When the movement target point is determined in step S409, the CPU 110 increments the correction point selection count of the selected correction point (S703). Next, the CPU 110 sets the movement amount based on the table shown in FIG. When the number of correction point selections is 1, the movement amount = 9 pixels. When the correction point is selected, the movement amount = 5 pixels. When the correction point is selected, the movement amount = 1 pixel. As a result, the amount of movement decreases each time a correction point is selected.

  The selection count n set in step S702 has a close relationship with the table shown in FIG. If n = 1, the number of selections is incremented in step S703, so that the movement amount d is 5 pixels at the first selection and 1 pixel at the second and subsequent selections. If n = 2, the moving amount d is 1 pixel from the first selection.

  In the first embodiment, when it is determined that the key operated in step S414 in FIG. 4B is the enter key, in step S415, the movement amount d is decreased by a predetermined movement reduction amount Δd for the next correction point. . On the other hand, in this embodiment, the movement amount d is set according to the number of selections in step S704, so this processing is not necessary. Therefore, the process returns to step S404 without processing.

  In the present embodiment, as in the second embodiment, since the movement amount decreases according to the number of selections for each correction point, the order in which the four correction points are selected is independent of the movement amount and the number of operations. Even when the distortion is large, it moves greatly at the beginning, so that it can be brought close to the desired shape with a few operations. In addition, since the moving amount gradually becomes smaller, it can be precisely adjusted to a desired shape finally.

  In this embodiment, the adjustment start position of the correction point is set inside the four corners of the image area on the panel. Thereby, the frequency | count of operation can be reduced. FIG. 9 is a flowchart executed by the CPU 110 to realize such an operation, and shows a part changed from FIG. 4A. A different part from FIG. 4A is demonstrated in detail.

  If the CPU 110 determines in step S401 in FIG. 9 that all four correction points are the initial positions (four corners of the image area of the panel), the correction points P1 to P4 are moved to the adjustment start position in addition to the movement amount setting. (S901). The adjustment start positions are the four corners of a quadrangle indicated by reference numeral 1010 in FIG. 10A, and these points are preset inside the four corners of the panel.

  The CPU 110 performs deformation processing using the quadrangle 1010 formed at the four adjustment start positions as the post-deformation image area (S902). Then, a square image indicated by reference numeral 1020 in FIG. 10B is projected.

  Thereafter, as in the first embodiment, the CPU 110 moves the correction points P1 to P4 to match the target shape 530.

  If it is determined in step S417 that the reset key has been pressed, the process returns to step S402. The processes in steps S418 and S419 are unnecessary because equivalent processes are performed in steps S901 and S902.

  In this example, compared to the first embodiment, the distance for moving and adjusting the correction points P1 and P2 to match the target shape 530 is shorter. The correction point P3 is substantially the same, and the correction point P4 is slightly longer, but the total of the four points is shorter, and as a result, the number of user operations can be reduced.

  Although it depends on the tilt angle and distance between the screen and the optical axis, compared to the case where all correction points are moved inward, setting the initial position as described above will shorten the overall movement adjustment distance. There are many.

  Since the correction point can be moved outward, the degree of freedom of user adjustment is increased.

  In this embodiment, the angle-designated distortion correction based on the relative tilt angle between the projector main body and the screen is linked to the four-corner designated distortion correction which is the correction point selection distortion correction. FIG. 11 shows a flowchart executed by the CPU 110 to realize such a cooperative operation. The flow shown in FIG. 11 is activated when the user instructs the start of distortion correction using the operation unit 113 or a remote controller (not shown).

  First, the CPU 110 determines a distortion correction mode that is separately set from a menu or the like (S1101). If it is in the angle-designated distortion correction mode, the process proceeds to step S1102, and the CPU 110 executes a conventional angle-designated distortion correction process.

  If it is the four-corner designated distortion correction mode that is the correction point selection distortion correction mode, the process advances to step S1103, and the CPU 110 executes any one of the processes in FIGS. 4A and 4B, FIG. 7A, FIG. 7B, and FIG.

  When executing the four-corner designated distortion correction in step S1103 after the completion of step S1102, the CPU 110 holds the correction points P1 to P4 as a result of executing the angle-designated distortion correction, and shifts to the four-corner designated distortion correction. This is used when correcting to a shape close to a desired shape by specifying an angle and performing fine adjustment by specifying four corners. Since the deformation process has already been performed with the angle designation and the correction points P1 to P4 are not the initial positions, it is determined in step S401 that they are not the initial positions, and the initial movement amount d2 is set as the movement amount d. The initial movement amount d1 is not suitable for fine adjustment because it is large as the movement amount in one action, but the initial movement amount d2 is suitable for fine adjustment because the movement amount in one action is small.

  With this control, in this embodiment, the four corner designated distortion correction is started in a state where the adjustment result in the angle designated distortion correction is held, and the movement amount is set to be small. Thereby, quick fine adjustment can be realized.

  The above-described embodiments are illustrative embodiments for facilitating understanding of the present invention, and the present invention is not limited to the above-described embodiments. That is, the said Example does not limit the invention which concerns on a claim, and all the combinations of the characteristics demonstrated by the Example are not necessarily essential for this invention.

  Each functional block of the above-described embodiment is not necessarily realized by individual hardware. That is, for example, the functions of several functional blocks may be realized by a single piece of hardware. In addition, the function of one or a plurality of functional blocks may be realized by a coordinated operation of some hardware.

  The object of the present invention can also be achieved by supplying a storage medium storing software program codes for realizing the functions of the above-described embodiments to the apparatus. At this time, the computer (or CPU or MPU) including the control unit of the supplied apparatus reads and executes the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code itself and the storage medium storing the program code constitute the present invention.

  As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

  In some cases, an OS (basic system or operating system) running on the apparatus performs part or all of the processing based on the above-described program code instruction, and the functions of the above-described embodiments are realized by the processing. included.

  The program code read from the storage medium is written in a memory provided in a function expansion board inserted into the apparatus or a function expansion unit connected to a computer, and the case where the functions of the above-described embodiments are realized is also included. . At this time, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

Claims (8)

A projection image distortion correction method for correcting distortion of a projection image based on an inclination of a projection optical axis with respect to a screen,
Setting an initial movement amount as a movement amount of the projection image in response to one movement instruction;
A selection step of selecting a correction point on the projection image;
A movement step of moving the correction point selected in the selection step in the direction indicated by the user based on the movement amount;
A decreasing step for reducing the amount of movement;
Calculating a deformation parameter corresponding to the correction point moved in the moving step;
Deforming the projection image based on the deformation parameter,
A projected image distortion correction method, wherein the initial movement amount when the correction point is not the initial position is smaller than the initial movement amount when the correction point is the initial position.   The projection image distortion correction method according to claim 1, wherein the reduction step is performed in accordance with the execution of the selection step.   The projection image distortion correction method according to claim 1, wherein the reduction step reduces the movement amount according to the number of times the correction point is selected.   4. The distortion correction of a projected image according to claim 1, further comprising a step of returning the movement amount to an initial movement amount in response to resetting the correction point to the initial position. 5. Method.   The distortion of the projected image according to claim 1, wherein when the correction point is the initial position, the correction point is moved to an adjustment start position inside the initial position. Correction method.   The projection image distortion correction method according to claim 5, further comprising: moving the correction point to an adjustment start position inside the initial position when the correction point is reset to the initial position. . Further, an angle-designated distortion correction mode for correcting distortion of the projection image according to the tilt angle of the projection optical axis with respect to the screen, and correction of distortion of the projection image by selecting and moving the correction point of the projection image And a step of selecting a correction point selection distortion correction mode to be performed,
7. The correction point adjusted in the angle-designated distortion correction mode is held when the angle-designated distortion correction mode is shifted to the correction point selection distortion correction mode. The distortion correction method of the projection image as described in 2. A projection display device that projects an image on a screen,
Image processing means for performing geometric deformation on the image to be projected;
A projection optical system that projects an image processed by the image processing means onto a screen;
Means for designating correction points for the geometric deformation on the projected image displayed on the screen;
Movement control means for moving the correction point by a movement amount in response to a single movement instruction, wherein an initial movement amount is initially set as the movement amount, and movement control is performed to reduce the movement amount in accordance with the movement instruction. Means,
Control means for determining a deformation parameter for geometric deformation of the image processing means in accordance with the correction point after movement by the movement control means, and for controlling the image processing means to perform the geometric deformation in accordance with the deformation parameter; A projection display device comprising:

Images