JP2011176629A - Controller and projection type video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detection accuracy of a test pattern projected on a screen. <P>SOLUTION: A side ratio calculation part 42 measures length of each of two sides opposite to each other of the screen 300 reflected in an image picked up by an imaging part 30, and calculates a ratio of length of the two sides. A light quantity ratio calculation part 43 calculates a ratio between light quantity projected on one of the two sides and light quantity projected on the other side of the installed screen 300. A correction value generation part 44 generates a correction value according to the ratio calculated by the light quantity ratio calculation part 43. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for driving and controlling a projection display apparatus and a projection display apparatus equipped with the control apparatus.

  2. Description of the Related Art In recent years, a projection video display device (hereinafter referred to as a projector as appropriate) equipped with a camera has been put into practical use. Some projectors equipped with a camera can capture a test pattern projected on a screen with the camera and perform keystone correction or autofocus adjustment based on the captured image.

  In trapezoidal distortion correction using a captured image, a method for identifying the shape of the projected test pattern by detecting an edge in the captured image and correcting the video signal so that the distortion of the shape is canceled out Is often used.

  Also, in autofocus adjustment using captured images, a method for adjusting the focus by calculating the contrast of images captured at multiple lens positions and detecting the lens position that maximizes the contrast (contrast detection method) Is often used.

JP 2005-159426 A JP 2005-159427 A

  When the screen is not directly facing the projector, that is, when the screen is inclined, the distance between each position in the screen surface and the projector is non-uniform. Since the projected light quantity at each position in the screen plane is inversely proportional to the square of the distance from the light source, the reflected light quantity becomes smaller as the position is farther from the projector.

  In any of the above-described trapezoidal distortion correction and autofocus adjustment, it is necessary to detect a high frequency component in the captured image. Therefore, when the screen is inclined, the detection accuracy of the high frequency component is lowered. For example, in the trapezoidal distortion correction, when the threshold for edge detection is set to the long distance side, an edge other than the target edge is often erroneously detected as the target edge on the short distance side.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a technique capable of improving the detection accuracy of a test pattern projected on a screen.

  A control device according to an aspect of the present invention is a control device to be mounted on a projection display apparatus including a projection unit that projects an image on a screen and an imaging unit that images the screen. Measure the lengths of the two opposite sides of the screen captured in the image captured by, and calculate the ratio of the lengths of the two sides, and the ratio calculated by the side ratio calculation unit A light amount ratio calculating unit that calculates a ratio between a light amount projected on one of the two sides of the installed screen and a light amount projected on the other side, and a light amount ratio calculating unit A correction value generation unit that generates a correction value according to the ratio calculated by the above.

  Another aspect of the present invention is a projection display apparatus. This apparatus includes a projection unit that projects an image on a screen, an imaging unit for imaging the screen, and the control device described above.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, and the like are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the detection accuracy of the test pattern projected on the screen can be improved.

It is a figure which shows the positional relationship of the projection type video display apparatus concerning embodiment of this invention, and a screen. It is a figure which shows an example of the captured image imaged by the imaging part in the positional relationship shown in FIG. It is a figure which shows the structure of the projection type video display apparatus concerning embodiment of this invention. It is a figure which shows an example of the captured image in which the image of the screen was reflected. It is a figure which shows the correction | amendment gain in the screen position shown in FIG. It is a figure which shows the structure of the trapezoid distortion correction part which concerns on embodiment. It is a figure for demonstrating trapezoid distortion correction. FIG. 7A shows vertical trapezoidal distortion correction, and FIG. 7B shows horizontal trapezoidal distortion correction. It is a figure which shows the structure of the auto-focus adjustment part which concerns on embodiment. It is a figure for demonstrating the determination process of the focus position of a focus lens. It is a figure which shows the structure of the projection type video display apparatus concerning the modification 1 of this Embodiment. It is a figure which shows the structure of the trapezoid distortion correction part which concerns on the modification 1 of this Embodiment. It is a figure which shows the structure of the auto-focus adjustment part which concerns on the modification 1 of this Embodiment. It is a figure which shows the structure of the projection type video display apparatus concerning the modification 2 of this Embodiment. It is a figure for demonstrating the distance ratio to the point on an inclination screen and a front screen. It is a figure which shows another example of the correction gain in a screen position.

  FIG. 1 is a diagram showing a positional relationship between a projection display apparatus 200 and a screen 300 according to an embodiment of the present invention. The projection display apparatus 200 according to the embodiment includes an imaging unit 30 for photographing the direction of the screen 300. The imaging unit 30 is installed so that the optical axis center thereof is parallel to the optical axis center of the projection light projected from the projection display apparatus 200. In FIG. 1, the screen 300 does not face the projection display apparatus 200, and the right side is inclined to the heel.

  FIG. 2 illustrates an example of a captured image PuI captured by the imaging unit 30 in the positional relationship illustrated in FIG. In the captured image PuI, a projection image PrI projected from the projection display apparatus 200 and depicting a mountain and the sun is shown. Further, the image SI of the screen 300 is also captured in the captured image PuI. Since the amount of light projected at each position in the screen 300 is inversely proportional to the square of the distance from the light source, the luminance level gradually decreases from the left side to the right side of the image SI on the screen 300. That is, the image becomes darker as it goes to the right. In the projection display apparatus 200 according to the embodiment, the luminance level of the image SI on the screen 300 is flattened or made uniform.

  FIG. 3 is a diagram showing a configuration of the projection display apparatus 200 according to the embodiment of the present invention. The projection display apparatus 200 includes a projection unit 10, a lens driving unit 20, an imaging unit 30, and a control device 100. The control device 100 includes an image analysis unit 40, a captured image signal correction unit 50, a trapezoidal distortion correction unit 60, an autofocus adjustment unit 70, an image memory 82, a video signal setting unit 84, and a drive signal setting unit 86.

  The configuration of the control device 100 can be realized in terms of hardware by a CPU, memory, or other LSI of an arbitrary computer, and is realized by a program loaded in the memory in terms of software. Depicts functional blocks realized by. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  The projection unit 10 projects an image on the screen 300. The projection unit 10 includes a light source 11, a light modulation unit 12, and a focus lens 13. As the light source 11, a halogen lamp having a filament-type electrode structure, a metal halide lamp having an electrode structure for generating arc discharge, a xenon short arc lamp, a high-pressure mercury lamp, an LED lamp, or the like can be employed.

  The light modulation unit 12 modulates the light incident from the light source 11 in accordance with the video signal set by the video signal setting unit 84. For example, a DMD (Digital Micromirror Device) can be employed for the light modulator 12. The DMD includes a plurality of micromirrors corresponding to the number of pixels, and generates desired video light by controlling the direction of each micromirror according to each pixel signal.

  The focus lens 13 adjusts the focal position of the light incident from the light modulation unit 12. The lens position of the focus lens 13 is moved on the optical axis by the lens driving unit 20. The image light generated by the light modulation unit 12 is projected onto the screen 300 via the focus lens 13.

  The lens driving unit 20 moves the position of the focus lens 13 according to the driving signal set from the driving signal setting unit 86. For the lens driving unit 20, a stepping motor, a voice coil motor (VCM), a piezoelectric element, or the like can be employed.

  The imaging unit 30 captures the screen 300 and the projected image projected on the screen 300 as a main subject. The imaging unit 30 includes a solid-state imaging device 31 and a signal processing circuit 32. As the solid-state imaging device 31, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, a CCD (Charge Coupled Devices) image sensor, or the like can be adopted. The signal processing circuit 32 performs various signal processing such as A / D conversion and conversion from the RGB format to the YUV format on the signal output from the solid-state imaging device 31 and outputs the signal to the control device 100. In the present embodiment, the data is output to the image analysis unit 40 and the captured image signal correction unit 50.

  The image analysis unit 40 analyzes the captured image signal output from the imaging unit 30. The image analysis unit 40 includes a screen position detection unit 41, a side ratio calculation unit 42, a light amount ratio calculation unit 43, and a correction value generation unit 44.

  The screen position detection unit 41 detects the positions of the four sides (upper side, lower side, left side, and right side) of the screen 300 captured in the captured image by extracting edges in the captured image.

  The side ratio calculation unit 42 measures the lengths of two opposite sides (for example, the left side and the right side) of the screen 300 shown in the captured image, and calculates the ratio of the lengths of the two sides. The ratio of the distance from the projection unit 10 to one of the two sides and the distance from the projection unit 10 to the other side is the reciprocal of the ratio of the lengths of the two sides. That is, the shorter the side length, the longer the distance from the projection unit 10 to the side.

  Based on the ratio calculated by the side ratio calculation unit 42, the light quantity ratio calculation unit 43 projects the light amount projected on one of the two sides of the installed screen 300 and the other side. The ratio with the amount of light is calculated. The amount of light projected on each side is inversely proportional to the square of the distance from the projection unit 10 to each side. That is, the longer the distance from the projection unit 10 to each side, the smaller the amount of light projected on each side. The ratio of the distance from the projection unit 10 to one side and the distance from the projection unit 10 to the pixel located between the one side and the other side can be calculated from the coordinate position of the pixel. Therefore, it is possible to calculate a ratio between the light amount projected on one side and the light amount projected on the pixel.

  The correction value generation unit 44 generates a correction value for each pixel according to the ratio calculated by the light amount ratio calculation unit 43. In the present embodiment, a correction gain to be multiplied with each pixel signal is generated. The reflected light amount of each pixel between the two sides (note that external light other than projection light is ignored) changes in gradation from one side to the other side. The correction value generation unit 44 generates a correction gain for each pixel so as to cancel or suppress this gradation change.

  A correction gain for completely matching the luminance level of each pixel may be generated, or a correction gain for reducing the change rate of the luminance level of each pixel may be generated. In the former case, the brightness level of the other pixels may be matched with the pixel having the highest brightness level, or the brightness levels of all the pixels may be matched with the average brightness level. Functions for calculating these correction gains can be easily generated by those skilled in the art.

  Through the above processing, a correction gain for compensating the horizontal or vertical tilt of the screen 300 in the signal processing can be generated. Of course, it is also possible to generate a correction gain for compensating for both the horizontal and vertical tilts of the screen 300 at a time.

  That is, the side ratio calculation unit 42 measures the lengths of the upper side, the lower side, the left side, and the right side of the screen 300 shown in the captured image, and calculates the ratio of the lengths of the upper side and the lower side and the lengths of the left side and the right side. Each ratio is calculated. The light quantity ratio calculation unit 43 calculates the ratio between the light quantity projected on the upper side of the screen and the light quantity projected on the lower side based on the ratio of the length of the upper side and the lower side described above, and the length of the left side and the right side described above. Based on the ratio, the ratio between the amount of light projected on the left side of the screen and the amount of light projected on the right side is calculated.

  The correction value generation unit 44 generates a correction value for each pixel according to the two ratios calculated by the light amount ratio calculation unit 43. The reflected light amount of each pixel between the upper side and the lower side described above changes in gradation from the upper side to the lower side. The same applies to the left side and the right side. The correction value generation unit 44 generates a correction gain for each pixel so as to simultaneously cancel or suppress both the horizontal and vertical gradation changes.

  Hereinafter, a specific example of correction gain generation will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram illustrating an example of a captured image in which an image of the screen 300 is captured.

  FIG. 4 illustrates an example in which the imaging unit 30 captures an image with a VGA (640 × 480) size. The screen position detection unit 41 detects the vertex coordinates of the four corners of the screen 300 captured in the captured image, and the side ratio calculation unit 42 measures the lengths of the upper side, the lower side, the left side, and the right side of the screen 300. To do. Here, the upper side is 270 pixels, the lower side is 300 pixels, the left side is 230 pixels, and the right side is 184 pixels.

  Since the lower side is longer than the upper side and the left side is longer than the right side, it can be seen that the lower left corner of the screen 300 is closest to the projection unit 10 and the upper right corner is farthest. The ratio of the upper side to the lower side is 270/300 = 9/10. Further, the ratio of the distance from the projection unit 10 to the upper side to the distance from the projection unit 10 to the lower side is 10/9, which is the reciprocal thereof. Since the projected light amount decreases in inverse proportion to the square of the distance, the ratio of the projected light amount on the upper side to the projected light amount on the lower side is 1 / (10/9) ^ 2 = 0.81.

  The ratio of the right side to the left side is 184/230 = 8/10. The ratio of the distance from the projection unit 10 to the right side to the distance from the projection unit 10 to the left side is 10/8 of the reciprocal thereof. Since the projected light quantity decreases in inverse proportion to the square of the distance, the ratio of the projected light quantity on the right side to the projected light quantity on the left side is 1 / (10/8) ^ 2 = 0.64.

  FIG. 5 is a diagram showing the correction gain at the screen position shown in FIG. In FIG. 5, the luminance levels of the pixels other than the lower left corner of the screen 300 are matched with the luminance levels of the lower left corner pixels. Since it is not necessary to correct the luminance level of the pixel in the lower left corner, the correction gain is 1. On the other hand, the correction gain for the luminance level of the pixel in the upper right corner is (1 / 0.81) × (1 / 0.64) ≈1.93 using the above ratio. Based on these results, the correction value generation unit 44 generates a correction gain at each screen position as shown in FIG.

  Returning to FIG. The captured image signal correction unit 50 generates the pixel signal output from the imaging unit 30 by the correction value generation unit 44 so that the luminance level of the screen image captured in the captured image is flattened or made uniform. Correction is performed using the correction value. For example, each pixel signal is multiplied by the correction gain of each corresponding pixel. The image signal whose luminance level is flattened or uniformed by the captured image signal correction unit 50 is output to the trapezoidal distortion correction unit 60 and the autofocus adjustment unit 70.

  The trapezoidal distortion correction unit 60 corrects the trapezoidal distortion of the image projected on the screen 300. The trapezoidal distortion occurs when the screen 300 and the projection display apparatus 200 are not facing each other. For example, when the optical axis of the projection light is shifted upward, a trapezoidal distortion in which the upper portion of the screen 300 swells occurs.

  When the projection display apparatus 200 is started up or when a keystone adjustment is instructed by a user operation, the video signal setting unit 84 reads a trapezoidal distortion adjustment test pattern from the image memory 82 and projects it onto the projection unit 10. Let The test pattern is formed of, for example, a quadrangle (square, rectangle, parallelogram, rhombus, etc.). The imaging unit 30 images the test pattern projected on the screen 300. The trapezoidal distortion correcting unit 60 detects the trapezoidal distortion based on the shape of the test pattern reflected in the captured image, and corrects the video signal to be set in the video signal setting unit 84 so that the trapezoidal distortion is canceled. .

  FIG. 6 is a diagram illustrating a configuration of the trapezoidal distortion correction unit 60 according to the embodiment. The trapezoidal distortion correction unit 60 includes an edge extraction unit 61, a distortion detection unit 62, and a video signal correction unit 63. The edge extraction unit 61 detects an edge from the captured image in which the test pattern is captured. At that time, the edge extraction unit 61 extracts an edge within the range of the screen area set by the screen position detection unit 41. The edge is extracted at a location where a luminance level change exceeding a predetermined threshold has occurred.

  The distortion detection unit 62 specifies how much it swells in the vertical and horizontal directions from the vertex coordinates of the test pattern specified by the edge extraction. The video signal correcting unit 63 corrects the video signal to be set in the video signal setting unit 84 so that the swelling of the test pattern projected on the screen 300 is canceled.

  FIG. 7 is a diagram for explaining trapezoidal distortion correction. FIG. 7A shows vertical trapezoidal distortion correction, and FIG. 7B shows horizontal trapezoidal distortion correction. In FIG. 7A, the upper part of the projection image PrI is swollen. The video signal correction unit 63 gradually scales down the horizontal width of the video from the upper end to the lower end of the video to be projected so that a quadrangle whose aspect ratio is maintained is projected onto the screen 300. In FIG. 7B, the left part of the projection image PrI is swollen. The video signal correction unit 63 gradually scales down the vertical width of the video from the left end to the right end of the video to be projected so that a quadrangle whose aspect ratio is maintained is projected onto the screen 300.

  The autofocus adjustment unit 70 adjusts the focus by using a contrast detection method. When the projection display apparatus 200 is activated or when autofocus adjustment is instructed by a user operation, the video signal setting unit 84 reads out a test pattern for autofocus adjustment from the image memory 82 and causes the projection unit 10 to project it. . The test pattern is formed of, for example, a stripe pattern or a checker flag pattern. The imaging unit 30 images the test pattern projected on the screen 300. The autofocus adjustment unit 70 determines the position of the focus lens 13 based on the sharpness of the test pattern imaged by the imaging unit 30 at a plurality of lens positions.

  FIG. 8 is a diagram illustrating a configuration of the autofocus adjustment unit 70 according to the embodiment. The autofocus adjustment unit 70 includes a detection area setting unit 71, a high-pass filter 72, an integration unit 73, and a lens position determination unit 74. The detection area setting unit 71 sets a detection area from which high-frequency components are extracted by the high-pass filter 72 in the captured image. For example, the detection area setting unit 71 may set the screen area set by the screen position detection unit 41 as the detection area. Moreover, you may set the one part area | region (for example, center area | region) in a screen area | region as the said detection area.

  The high pass filter 72 extracts a high frequency component exceeding a predetermined threshold value of the image signal in the detection region, and supplies the extracted high frequency component to the integrating unit 73. The high pass filter 72 may extract high frequency components in the horizontal direction, or may extract high frequency components in both the horizontal direction and the vertical direction.

  The integrating unit 73 integrates the high frequency components extracted by the high pass filter 72 at each lens position, and supplies the integrated high frequency component to the lens position determining unit 74. When high frequency components are extracted in both the horizontal direction and the vertical direction by the high-pass filter 72, the integrating unit 73 adds both high frequency components. The lens position determination unit 74 determines the position of the focus lens 13 from which the maximum integration value is detected among the plurality of integration values supplied from the integration unit 73 as the in-focus position.

  FIG. 9 is a diagram for explaining the determination process of the focus position of the focus lens 13. When the autofocus function is enabled, the autofocus adjustment unit 70 instructs the video signal setting unit 84 to project a test pattern, and moves the focus lens 13 from the near side to the far side or from the far side to the near side. A control signal for sequentially moving in a predetermined step width is set in the drive signal setting unit 86. The video signal setting unit 84 sets the video signal of the test pattern in the light modulation unit 12, and the drive signal setting unit 86 sets the drive signal corresponding to the control signal in the lens driving unit 20.

  The autofocus adjustment unit 70 calculates the sharpness (the integrated value can be used) included in the test pattern imaged at each lens position of the focus lens 13. This sharpness increases as the focus lens 13 approaches the in-focus position. When the rise peaks and falls, the autofocus adjustment unit 70 determines the previous lens position as the focus position.

  Returning to FIG. The image memory 82 holds image data to be projected on the screen 300. The image data is supplied from a PC or the like via an external interface (not shown). In the present embodiment, a test pattern projected during trapezoidal distortion correction or autofocus adjustment is also held. The video signal setting unit 84 sets a video signal based on the image data held in the image memory 82 in the light modulation unit 12. The video signal setting unit 84 sets the video signal after the trapezoidal distortion correction supplied from the trapezoidal distortion correcting unit 60 to the optical modulation unit 12 during a period in which the trapezoidal distortion correcting function by the trapezoidal distortion correcting unit 60 is valid. The drive signal setting unit 86 sets a drive signal for moving the focus lens 13 to the lens position designated by the autofocus adjustment unit 70 in the lens drive unit 20.

  As described above, according to the present embodiment, the non-uniformity in the amount of reflected light due to the tilt of the screen 300 can be compensated for in signal processing by correcting the captured image signal. Therefore, by extracting a test pattern for trapezoidal distortion detection or autofocus adjustment from the corrected captured image signal, the detection accuracy of the test pattern can be improved. Therefore, the keystone distortion correction accuracy or the autofocus adjustment accuracy can be improved.

  FIG. 10 is a diagram showing a configuration of a projection display apparatus 200 according to the first modification of the present embodiment. FIG. 11 is a diagram illustrating a configuration of the trapezoidal distortion correction unit 60 according to the first modification of the present embodiment. FIG. 12 is a diagram illustrating a configuration of an autofocus adjustment unit 70 according to the first modification of the present embodiment.

  The configuration of the projection display apparatus 200 shown in FIG. 10 is a configuration in which the captured image signal correction unit 50 is removed as compared with the projection display apparatus 200 shown in FIG. Instead, a threshold correction unit 64 is added to the trapezoidal distortion correction unit 60, and a threshold correction unit 75 is added to the autofocus adjustment unit 70.

  In the first modification, the correction value generated by the correction value generation unit 44 is not the captured image signal correction unit 50 but the threshold correction unit 64 in the trapezoidal distortion correction unit 60 and the threshold correction unit 75 in the autofocus adjustment unit 70. Set to As the correction value of the first modification, a correction value representing the gradation change itself is used instead of the correction value for canceling the gradation change of the luminance level in the captured screen image as in the above-described correction value. .

  The threshold correction unit 64 added to the trapezoidal distortion correction unit 60 detects an edge from the image signal output from the imaging unit 30 so that the luminance level of the screen image captured in the captured image is assumed to be flat. The threshold for correction is corrected using the correction value generated by the correction value generation unit 44 and set in the edge extraction unit 61. When the edge extraction unit 61 is configured with a high-pass filter, the filter strength of each pixel is corrected. Normally, the threshold for detecting the edge is the same for all pixels, but in Modification 1, the edge of the area corresponding to the screen image is detected in accordance with the gradation change of the luminance level in the screen image. The threshold value for gradation is changed.

  The threshold correction unit 75 added to the autofocus adjustment unit 700 converts the high-frequency component of the image signal output from the imaging unit 30 so that the luminance level of the screen image captured in the captured image is assumed to be flat. The threshold value for detection is corrected using the correction value generated by the correction value generation unit 44 and set in the high-pass filter 72. That is, the filter strength for each pixel is corrected. Normally, the threshold for detecting the high-frequency component is the same for all pixels, but in Modification 1, the high-frequency component in the region corresponding to the screen image is set in accordance with the gradation change of the luminance level in the screen image. The threshold value for detection is changed in gradation.

  As described above, according to the first modification, the threshold value for detecting an edge or a high-frequency component from the image signal output from the imaging unit 30 is changed in gradation in accordance with the gradation change in the luminance level in the screen image. Thus, it can be assumed that the luminance level of the screen image is flat. Therefore, the same effects as those obtained by correcting the captured image signal described in the above-described embodiment can be obtained.

  FIG. 13 is a diagram showing a configuration of a projection display apparatus 200 according to the second modification of the present embodiment. The configuration of the projection display apparatus 200 shown in FIG. 13 is a configuration in which the captured image signal correction unit 50 is removed and a video signal correction unit 83 is added, compared to the projection display apparatus 200 shown in FIG. is there. In the second modification, the correction value generated by the correction value generation unit 44 is set not in the captured image signal correction unit 50 but in the video signal correction unit 83. As the correction value of Modification 2, a correction value for canceling the gradation change in the luminance level in the image of the captured screen is used as in the above-described correction value.

  The video signal correction unit 83 corrects the video signal to be projected on the screen using the correction value generated by the correction value generation unit 44 so that the amount of light projected on the screen surface is flattened. The video signal to be projected onto the screen mainly corresponds to a test pattern for trapezoidal distortion detection or autofocus adjustment. The video signal correcting unit 83 changes the gradation of the test pattern using the correction value. Thereby, the light quantity of each pixel of the test pattern projected on the screen surface is flattened. Therefore, the same effects as those obtained by correcting the captured image signal described in the above-described embodiment can be obtained.

  Further, the video signal correcting unit 83 may correct the video signal based on actual data instead of the test pattern using the correction value. Note that the non-uniformity in the amount of light often causes the user to feel that correction is not as necessary as the shape distortion. Accordingly, the video signal correction may be limited to the test pattern.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  For example, the screen position detection unit 41 may perform simple correction of the projection light amount before detecting the screen position from within the captured image. For example, the screen position detection unit 41 should monitor the luminance level of the image captured by the imaging unit 30 in the horizontal direction and the vertical direction, and set the video signal setting unit 84 so that the luminance levels are flattened. Correct the video signal. The correction here is not as strict as the correction described above, but may be rough. For example, when the difference in luminance level between the upper part and the lower part in the captured image is larger than a predetermined set value, the video signal in the region with the smaller luminance level is increased. The same applies between the left part and the right part. Thereby, the detection accuracy of the screen image in a captured image can be improved. If the screen image is accurately detected, the inclination of the screen can be accurately detected by the correction processing according to the above-described embodiment.

  In the example of the correction gain at the tilted screen position described with reference to FIG. 5, the correction gain is calculated on the assumption that the distance ratio from the projection unit to the pixel changes linearly from one side of the screen to the opposite side. Alternatively, the correction gain at the tilted screen position may be calculated in consideration of the positional relationship between the screen and the tilted screen facing each other. This calculation method will be described with reference to FIG.

  FIG. 14 is a diagram illustrating a state in which the positional relationship among the projection display apparatus 200, the facing screen 400, and the inclined screen 410 is observed from the upper surface. The amount of light projected from the projection port M of the projection display apparatus 200 is adjusted so as to have the same luminance at the points A, Bv, Cv, Dv, and Ev on the facing screen 400 without gain correction. ing. Even if the screen 400 faces the projection port M, the distance from the projection port to the screen center point Cv is different from the distances from the screen end points A and Ev. Is set in advance. Such correction can be performed by general shading correction.

  In this state, when the inclined screen 410 is arranged instead of the facing screen 400, the points Bv, Cv, Dv, Ev on the facing screen are projected as points Br, Cr, Dr, Er on the inclined screen, respectively. As is apparent from the figure, the distance from the projection port M to the points Br to Er on the inclined screen is different from the initially set distance from the points Bv to Ev on the facing screen. Therefore, the correction value generation unit 44 obtains a distance ratio between the distance Lv from the projection port M to each point on the facing screen 400 and the distance Lr from the projection port M to each point on the inclined screen 410. The correction gain can be calculated.

  This distance ratio is obtained by the following procedure. In FIG. 14, xy orthogonal coordinates with the projection port M as the origin are considered. It is assumed that the straight screen is represented by a straight line y = b and the inclined screen is represented by a straight line y = ax + c (a to c are real numbers). Since the projection on the facing screen is equally spaced, the distance Lv from the projection port M to the point on the facing screen (point Dv in the figure) can be obtained from the three-square theorem. The distance Lr to the point Dr on the inclined screen corresponding to the point Dv can be obtained from the intersection of the straight line connecting the projection port M and the point Dv and the straight line y = ax + b representing the inclined screen. In this way, the correction gain = Lr / Lv for each point on the facing screen can be calculated. FIG. 15 shows an example of the distribution on the xy plane of the correction gain at the tilted screen position, and the lower left point in the figure corresponds to the left end of the screen. As can be seen from the figure, the correction gain increases in a quadratic function from the left end to the right end of the screen.

  DESCRIPTION OF SYMBOLS 10 Projection part, 11 Light source, 12 Light modulation part, 13 Focus lens, 20 Lens drive part, 30 Imaging part, 31 Solid-state image sensor, 32 Signal processing circuit, 40 Image analysis part, 41 Screen position detection part, 42 Side ratio calculation Unit, 43 light quantity ratio calculation unit, 44 correction value generation unit, 50 captured image signal correction unit, 60 trapezoidal distortion correction unit, 61 edge extraction unit, 62 distortion detection unit, 63 video signal correction unit, 64 threshold correction unit, 70 auto Focus adjustment unit, 71 detection area setting unit, 72 high-pass filter, 73 integration unit, 74 lens position determination unit, 75 threshold correction unit, 82 image memory, 83 video signal correction unit, 84 video signal setting unit, 86 drive signal setting unit , 100 control device, 200 projection type image display device, 300 s Lean.

Claims (6)

A control device to be mounted on a projection display apparatus comprising: a projection unit that projects an image on a screen; and an imaging unit for imaging the screen,
A side ratio calculation unit that measures the lengths of two opposite sides of the screen captured in the image captured by the imaging unit, and calculates a ratio of the lengths of the two sides;
Based on the ratio calculated by the side ratio calculation unit, the ratio of the light amount projected on one of the two sides of the installed screen and the light amount projected on the other side is calculated. A light quantity ratio calculation unit to perform,
A correction value generation unit that generates a correction value according to the ratio calculated by the light amount ratio calculation unit;
A control device comprising:   A captured image signal correction unit that corrects a pixel signal output from the imaging unit using the correction value so that a luminance level of a screen image captured in the image captured by the imaging unit is flattened; The control device according to claim 1, further comprising:   A threshold for detecting an edge or a high-frequency component from the image signal output from the imaging unit, so that the luminance level of the screen image captured in the image captured by the imaging unit is assumed to be flat, The control device according to claim 1, further comprising a threshold correction unit that corrects the correction value using the correction value.   2. The video signal correction unit according to claim 1, further comprising: a video signal correction unit that corrects a video signal to be projected on the screen using the correction value so that the amount of light projected on the screen surface is flattened. The control device described. The side ratio calculation unit measures the lengths of the upper side, the lower side, the left side, and the right side of the screen captured in the image captured by the imaging unit, the ratio of the lengths of the upper side and the lower side, and the left side and the right side Calculate length ratios respectively,
The light amount ratio calculation unit calculates a ratio between the light amount projected on the upper side of the screen and the light amount projected on the lower side based on the ratio of the length of the upper side and the lower side, and the length of the left side and the right side Based on the ratio, the ratio of the amount of light projected on the left side of the screen and the amount of light projected on the right side is calculated,
5. The control device according to claim 1, wherein the correction value generation unit generates a correction value according to the two ratios calculated by the light amount ratio calculation unit. A projection unit that projects an image on a screen;
An imaging unit for imaging the screen;
A control device according to any one of claims 1 to 5;
A projection-type image display device comprising: