JP2011239216A - Control apparatus and projection type image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection type image display device capable of excellently reproducing the color inherent in an image even when a color image is projected on a colored screen or a wall surface.SOLUTION: The project type image display device 200 is provided with a projection part 10 for projecting an image onto a screen through a lens, and an imaging part 30 for imaging the screen. A screen frame detecting part 40 detects a screen frame from an image imaged by the imaging part 30. A screen color determination part 60 determines a color of the screen in connection with the inside of the detected screen frame. A color correction part 70 performs a color correction on the image so that color tones defined in the image on the assumption of a white screen can be reproduced on a colored screen.

Description

  The present invention relates to a color correction technique in a projection display apparatus that projects an image on a screen.

  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 have a so-called easy setting function in which a projected test pattern is captured by the camera, and autofocus adjustment is performed based on the captured image.

  In Patent Document 1, a camera that captures a focus pattern projected on a screen, a focus area setting unit that sets a focus area on a captured image of the camera, and a focus area portion of the captured image, A projection apparatus including an autofocus control unit that automatically performs focus adjustment is disclosed. According to this, regardless of the zoom adjustment position of the projection lens of the projector, autofocus control is performed only in the area where the focus pattern is projected. Therefore, even if there is strong disturbance light around the screen, highly accurate automatic focus adjustment is possible.

JP 2004-205684 A

  In general, a projection display apparatus is configured to display an image having a correct color tone when a color image signal composed of input signals of the three primary colors R, G, and B is projected on a white screen. . Therefore, when a color image is projected on a screen other than white or on a colored wall surface, the image is reproduced with a color different from the original color tone.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a projection-type image that can reproduce the original color of the image satisfactorily even when the color image is projected onto a colored screen or wall surface. It is to provide a color correction technique for a display device.

  In order to solve the above problems, a control device according to an aspect of the present invention is a projection-type image display device including a projection unit that projects an image on a screen via a lens and an imaging unit that images the screen. A control device to be mounted, which includes a screen frame detection unit that detects a screen frame from an image captured by the imaging unit, a screen color determination unit that determines a screen color within the detected screen frame, and white And a color correction unit that performs color correction on the video so that the color tone defined for the video is reproduced on the colored screen.

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

  According to the present invention, even when a color image is projected onto a colored screen in the projection display apparatus, the original color of the image can be reproduced well.

It is a figure which shows the positional relationship of the projection type video display apparatus concerning one Embodiment of this invention, and a screen. It is a figure which shows the structure of the projection type video display apparatus concerning one Embodiment of this invention. It is a figure which shows an example of the color determination method of the screen frame in a prior art. It is a figure which shows an example of the color determination method of the screen frame in a prior art. It is a figure which shows the color determination method of the screen frame by one Embodiment of this invention. 5 is a flowchart of color correction processing according to an embodiment of the present invention.

  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 such that the optical axis center thereof and the optical axis center of the projection light projected from the projection display apparatus 200 have a parallel relationship, for example. 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 is a diagram illustrating a configuration of the projection display apparatus 200. The projection display apparatus 200 includes a projection unit 10, a lens driving unit 20, an imaging unit 30, and a control unit 100. The control unit 100 includes a screen frame detection unit 40, a screen color determination unit 60, a color correction unit 70, an image memory 82, a video signal setting unit 84, a drive signal setting unit 86, and an autofocus adjustment unit 90.

  The configuration of the control unit 100 can be realized in terms of hardware by a CPU, memory, or other LSI of an arbitrary computer, and can be realized in terms of software by a program loaded in the memory. Depicts functional blocks realized by. Accordingly, 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 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 specific pattern for screen frame detection and a test pattern projected during autofocus adjustment are 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 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 90 in the lens drive unit 20.

  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 a 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 unit 100.

  In this embodiment, it is necessary to detect a screen frame on which an image is projected before color correction of the image is executed. Therefore, when the projection display apparatus 200 is activated or in response to an instruction such as a button operation by the user, the projection unit 10 projects and displays a specific pattern for screen frame detection, for example, a white image on the entire screen. . The imaging unit 30 images the screen 300 and the specific pattern projected on the screen 300 and outputs the image to the screen frame detection unit 40.

  The screen frame detection unit 40 detects a screen frame that appears in the image captured by the imaging unit 30. More specifically, the screen frame detection unit 40 detects the positions of the four sides (upper side, lower side, left side, and right side) of the screen shown in the captured image by extracting the edges in the captured image. The detected screen frame is specified by, for example, vertex coordinates of four corners.

  The screen color determination unit 60 determines the color of the screen using only the screen frame detected by the screen frame detection unit 40 as an evaluation target. The color determination may use a known color sensor or any other method.

  When the color of the projection surface of the screen determined by the screen color determination unit 60 is not a white color but a specific color, the color correction unit 70 obtains the original color tone defined in the video signal on the premise of the white screen. Execute color correction (for example, change of RGB gain setting) according to the detected color tone on the video signal supplied from the image memory 82 to the video signal setting unit 84 so that close hues can be reproduced on the screen. To do. The video signal setting unit 84 outputs the color-corrected video signal to the light modulation unit 12.

  In many cases, the screen color determined by the screen color determination unit 60 is not uniform due to the tilt of the screen 300 or the influence of external light. Therefore, it is preferable to adjust the color correction weighting for the video signal in accordance with the color difference of each part on the screen.

  Since the color correction itself for the three primary color video signals as described above is a well-known technique, further detailed description is omitted in this specification.

  Although not described in detail in this specification, the video signal supplied to the video signal setting unit 84 is subjected to scaling processing for enlarging and reducing the image in accordance with the size of the screen frame and the shape of the detected projected image. Thus, other corrections such as a trapezoidal correction process for correcting the shape of the image are also performed.

  The autofocus adjustment unit 90 adjusts the focus using a known method such as 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 by, 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 90 is configured to determine the position of the lens based on the sharpness of the detection area set by the screen frame detection unit 40 in a plurality of images respectively captured by the imaging unit 30 at a plurality of lens positions. To decide. Hereinafter, the configuration of the autofocus adjustment unit 90 will be described more specifically.

  The autofocus adjustment unit 90 includes a high-pass filter, an integration unit, and a lens position determination unit (not shown). The high-pass filter 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. The high pass filter may extract a high frequency component in the horizontal direction, or may extract a high frequency component in both the horizontal direction and the vertical direction.

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

  When the autofocus function is enabled, the autofocus adjustment unit 90 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 90 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 90 determines the previous lens position as the focus position.

  FIG. 3 is a diagram showing an example of a screen frame color determination method in the prior art. In the figure, the imaging range of the imaging unit 30 is denoted by F, and the screen frame is denoted by W. In this conventional projection display apparatus having a screen color correction function, for example, the color of the center point (or area having a predetermined area) A of the image projection range is measured by a color sensor (not shown) or the like. There is one that performs color correction of video based on the above.

  FIG. 4 is a diagram illustrating another example of a screen frame color determination method in the prior art. In the projection display apparatus having the conventional screen color correction function, the screen color is determined based on the entire captured image, and the color correction of the video is performed based on this color.

  However, in the method shown in FIG. 3, when the screen is tilted or when there is ambient light, the difference in darkness of the screen, which is different between the side closer to the imaging unit and the side far from the imaging unit, can be reflected in the color correction. Can not. Further, in the method as shown in FIG. 4, since the color outside the screen frame W is also reflected, there is a problem that the optimum color correction for the video signal cannot be performed.

  FIG. 5 is a diagram illustrating a screen frame color determination method according to an exemplary embodiment of the present invention. In this method, when a captured image is acquired from the imaging unit 30, first the detection of the screen frame W is executed. Then, the screen color is determined using the detected screen frame as an evaluation target. By doing this, it is possible to perform color correction on the video signal in consideration of only the inside of the screen frame, not the partial area or the entire captured image.

  FIG. 6 is a flowchart of color correction processing according to an embodiment of the present invention. First, the projection unit 10 projects and displays a specific pattern for detecting a screen frame, for example, an entire white image on the screen 300 (S10). The imaging unit 30 images the screen 300 and the specific pattern projected on the screen 300, and outputs the image to the screen frame detection unit 40 (S12). The screen frame detection unit 40 detects a screen frame from the captured image (S14). The screen color determination unit 60 evaluates the color in the detected screen frame and determines the screen color (S16). The color correction unit 70 corrects the determined screen color deviation and corrects the gain of the RGB signal in the video signal setting unit 84 so that the original color tone of the video signal is reproduced (S18).

  In S14, if the frame of the screen 300 cannot be detected, the screen color determination unit cannot determine the color, so the video signal setting unit 84 may supply the video with the default RGB tone.

  Or, since the projection range is projected larger than the screen 300, the screen frame may not be detected correctly. Therefore, if the screen frame cannot be detected in S14, it may be attempted to detect the screen frame based on the image captured by the imaging unit again after reducing the specific pattern and projecting it.

  As described above, according to the present embodiment, the color of the screen that is the projection destination of the video signal is accurately recognized, and color correction processing is executed on the video signal according to the color condition. Can do.

  In the prior art, the color of the video signal is corrected by determining the color of the screen with a partial area or the whole of the captured image as an evaluation target. On the other hand, in the present embodiment, the screen frame is first detected by projecting a specific pattern, and only the color within the frame is set as the evaluation target. Thus, it is possible to realize video signal color correction with improved color reproducibility without being influenced by the color outside the screen or the color at a specific point.

  The case where the projection display apparatus projects an image on the dedicated screen 300 has been described above. However, an image is often projected onto a simple wall without using a screen. At this time, the screen frame detection unit 40 may not detect the screen frame, or may erroneously detect the outer periphery of the image projected on the wall surface as the screen frame. If the screen frame cannot be detected, the image may be projected with default settings, or the screen color determining unit 60 determines the color of the portion immediately outside the range of the projected image as the wall color. The color correction unit 70 may perform color correction of the video based on this color.

  If the outer periphery of the projected image is mistakenly detected as a screen frame, the color of the wall cannot be determined. As a countermeasure, a step of reducing the projection pattern and performing projection display and detecting the screen frame based on the captured image again may be added. If the size of the screen frame specified by the second screen frame detection is different from the size of the screen frame specified by the first screen frame detection, it is considered that the outer periphery of the projected image is erroneously detected as a screen frame. It is done. Therefore, the screen color determination unit 60 may determine the color of the portion immediately outside the range of the projected image as the color of the wall surface, and the color correction unit 70 may perform color correction of the image based on this color.

  On the other hand, if the size of the screen frame specified by the second screen frame detection and the size of the screen frame specified by the first screen frame detection substantially match, the outer frame of the screen 300 can be detected correctly. It is thought that. Accordingly, in this case, as usual, the color in the screen 300 is determined, and the color correction unit 70 performs color correction of the video signal based on this color.

  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.

  DESCRIPTION OF SYMBOLS 10 Projection part, 30 Imaging part, 40 Screen frame detection part, 60 Screen color determination part, 70 Color correction part, 82 Image memory, 84 Image signal setting part, 86 Drive signal setting part, 90 Auto-focus adjustment part, 100 Control part , 200 projection display device, 300 screen.

Claims (3)

A control device mounted on a projection display apparatus comprising: a projection unit that projects an image on a screen through a lens; and an imaging unit for imaging the screen,
A screen frame detection unit for detecting a screen frame from an image captured by the imaging unit;
A screen color determining unit that determines the color of the screen within the detected screen frame;
A color correction unit that performs color correction on the image so that the color tone defined in the image is reproduced on a colored screen on the premise of a white screen;
A control device comprising:   The color correction unit adjusts the weight of color correction for the video according to the difference in color of each part on the screen when the screen color determined by the screen color determination unit is non-uniform. The control device according to claim 1. A projection unit that projects an image onto a screen via a lens;
An imaging unit for imaging the screen;
The control device according to claim 1 or 2,
A projection-type image display device comprising:

Images