JP2010130481A - Image projection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately perform color tone correction with respect to a projection image even when a size or position of a projection area of the projection image is changed. <P>SOLUTION: An image projection apparatus includes: a color information acquiring means 9 for acquiring color information of a predetermined range including a projected plane 200; a color tone adjusting means 13 for performing color tone adjustment processing for adjusting a color tone of an image; a distance detecting means 12 for detecting a distance from the image projection apparatus to the projected plane; a zoom state detecting means 11 for detecting a zoom state of a projection optical system; and a projection area calculating means 15 for calculating a projection area of the image on the basis of detection result of the distance detecting means and the zoom state detecting means. The color tone adjusting means extracts color information of the projection area calculated by the projection area calculating means from color information of the predetermined range acquired by the color information acquiring means, and performs color tone adjustment processing based on the extracted color information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image projection apparatus (hereinafter referred to as a projector) that performs a color tone adjustment process that changes the color tone of a projected image in accordance with the color of a projection surface or ambient light.

  Projected surfaces on which an image is projected by a projector are not necessarily white, such as a wall surface and a partition, as well as a dedicated white screen. In addition, projectors are often used not only in dark rooms but also in rooms illuminated by illumination light. The color tone (color balance) of the projected image changes due to the influence of the color of the projection surface and the color of the illumination light (environment light). For this reason, some conventional projectors have a so-called wall color correction function that corrects the color tone of a projected image in accordance with the color of a projection surface or the color of ambient light.

  In Patent Document 1, color information on a projection surface including a projection image is detected using a color sensor or a CCD sensor (camera), and the color balance of the projection image is automatically corrected based on the detection result. A projector is disclosed. In this projector, red (R), green (G), and blue (B) color information in a state in which a white image is projected is detected, and the input image signal R, Adjust the gain for the G and B components.

In Patent Document 2, the projection surface is divided into a plurality of areas, and the R, G, and B levels (color information) are measured for each of the areas by a color light sensor, and the areas are based on the measurement results. A projector for correcting the color tone for each is disclosed.
JP 2003-333611 A JP 2006-349792 A

  However, in the projector wall color correction function disclosed in Patent Document 1 and Patent Document 2, the size and position of the projection area of the projected image with respect to the projection surface changes depending on the installation status of the projector and the state of the projection lens. Not taken into account. That is, when the size or position of the projection area on the projection surface changes, the color information detected by the sensor may include color information of an area of the projection surface where no image is projected. In this case, it is not possible to accurately correct the color tone of the projected image.

  The present invention provides an image projection apparatus capable of accurately performing color tone correction on a projection image even when the size or position of the projection area of the projection image changes.

  The image projection apparatus of the present invention is an image projection apparatus that projects an image onto a projection surface through a projection optical system. The image projection apparatus includes a color information acquisition unit that acquires color information in a predetermined range including a projection surface, a color tone adjustment unit that performs a color tone adjustment process for adjusting the color tone of the image, and a projection surface from the image projection device. Based on the distance detection means for detecting the distance up to, the zoom state detection means for detecting the zoom state of the projection optical system, the detection result of the distance detection means and the detection result of the zoom state detection means, the projection area of the image is determined. Projection area calculating means for calculating. The color tone adjusting unit extracts the color information of the projection area calculated by the projection area calculating unit from the color information in the predetermined range acquired by the color information acquiring unit, and adjusts the color tone based on the extracted color information. It is characterized by performing processing.

  According to the present invention, since the color information in the projection area of the actual image is extracted from the color information obtained in the predetermined range and the color tone adjustment processing is performed, the projection can be performed even when the size or position of the projection area changes. It is possible to accurately adjust the color tone of the image.

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

  FIG. 1 shows a configuration of a liquid crystal projector 100 as an image projection apparatus that is Embodiment 1 of the present invention.

  In FIG. 1, reference numeral 1 denotes a video input circuit, which converts R, G, B input video signals 21 input from an image supply device such as a personal computer or video equipment into a digital video signal of a predetermined format. The digital video signal generated by the video input circuit 1 is output to the image processing circuit 2.

  The image processing circuit 2 performs resolution conversion processing, frame rate conversion processing, and the like suitable for driving the liquid crystal panel 4 as an image forming element on the digital video signal. Further, the image processing circuit 2 generates a video signal for displaying a test pattern as a reference image. The R, G, and B video signals output from the image processing circuit 2 are input to the display driving circuit 3.

  The display drive circuit 3 is provided with a gain / offset processing unit 5 and a gamma (γ) correction unit 6, and thereby, gain / offset processing and γ correction are performed for each of the R, G, and B video signals. Signal processing relating to luminance and color such as processing is performed. The display drive circuit 3 generates drive signals for the three liquid crystal panels 4 (R panel 4R, G panel 4G, and B panel 4B) based on the R, G, and B video signals subjected to these processes.

  The display driving circuit 3 generates timing pulses for causing the liquid crystal panel 4 to form an image (original image) corresponding to the driving signal.

  White light from the light source lamp 16 is decomposed into R light, G light, and B light by a color separation optical system (not shown). The R light, G light, and B light illuminate the R panel 4R, G panel 4G, and B panel 4B, respectively. The R light, G light, and B light image-modulated by the R panel 4R, G panel 4G, and B panel 4B are combined by a color combining optical system (not shown) and guided to the projection lens 7.

  The projection lens (projection optical system) 7 includes a plurality of lens units, and zooming is possible by moving some lens units in the optical axis direction.

  The projection lens 7 projects the color image light synthesized by the color synthesis optical system onto the projection surface 200. Thereby, a projection image as a color image is displayed on the projection surface 200.

  In this embodiment, the case where a lens is used as the projection optical system will be described. However, an optical system other than the lens may be used.

  The imaging unit 9 as the color information acquisition unit images a predetermined range including the projection surface 200. Although not shown in detail, the imaging unit 9 includes an imaging lens that forms an optical image on light from a predetermined range (hereinafter referred to as an imaging range) including the projection surface 200, that is, reflected light from the imaging range, and the optical image. And an area type CCD sensor for photoelectric conversion. Furthermore, the imaging unit 9 includes an A / D conversion unit that converts an analog imaging signal from the CCD sensor into a digital imaging signal.

  Then, the imaging unit 9 generates rectangular imaging data composed of M pixel groups in the horizontal direction and N pixels in the vertical direction from the digital imaging signal output from the A / D conversion unit. The imaging data includes R, G, and B color information. That is, the imaging unit 9 acquires color information of a predetermined imaging range. The imaging data obtained by the imaging unit 9 is stored in the imaging data storage unit 14 included in the controller 8.

  It is preferable that the area of the imaging range by the imaging unit 9 is the same as or slightly wider than the maximum image projection area that can be projected by the liquid crystal projector 100. In the present embodiment, the imaging unit 9 will be described as having an imaging range with an area covering at least the entire projection surface 200.

The zoom position detection unit 11 as a zoom state detection unit detects a zoom position indicating the zoom state of the projection lens 7, and uses the information on the zoom position as a projection region calculation unit 15 included in the controller 8. Send to.
The distance sensor 12 as a distance detection unit detects the distance (projection distance) from the liquid crystal projector 100 (projection lens 7) to the projection surface 200 using light such as infrared rays, and sends it to the projection area detection unit 15.

  The controller 8 serving as a control unit is configured by a microcomputer, and serves as a color tone adjusting unit that performs the color tone adjustment processing for adjusting the color tone of the projected image with the imaging data storage unit 14 and the projection area detection unit 15 described above. A video correction amount calculation unit 13.

  The controller 8 performs display control of the test pattern through the image processing circuit 2 and obtains information on digital shift and trapezoidal distortion correction described later, which is performed in the image processing circuit 2. The controller 8 controls various processes such as a gain / offset process and a gamma process performed in the display drive circuit 3. For example, a gain value that is a parameter for performing gain processing is set. Further, the controller 8 controls the entire operation of the liquid crystal projector 100 by decoding a command input through an operation unit (not shown) or communicating with the nonvolatile memory 10.

  The liquid crystal projector 100 according to the present embodiment has an automatic color tone adjustment (color tone correction) function also called a wall color correction function. In this automatic tone adjustment function, the controller 8 mainly performs tone correction processing according to the flowchart (computer program) shown in FIG.

  First, in step S01, the controller 8 causes the image processing circuit 2 to generate a white test pattern original and display it on the liquid crystal panel 4. Then, the controller 8 causes the imaging unit 9 to acquire color information of a predetermined imaging range including the projection surface 200 in a state where the white test pattern image is projected onto the projection surface 200 (white projection state). Imaging data including the color information is stored in the imaging data storage unit 14.

  Next, in step S02, the projection area detection unit 15 in the controller 8 actually projects a projected image in the imaging range of the imaging unit 9 based on information indicating detection results by the zoom position detection unit 11 and the distance detection unit 12. The projection area 24 is calculated as the area on which is projected. At this time, when the digital shift function or the trapezoidal distortion correction function is used, the projection area 24 is calculated based on the information on the digital shift amount and the trapezoidal distortion correction amount.

  Here, “calculating the projection area” means calculating parameters necessary for specifying the actual projection area, such as the position (coordinates), size, and shape of the projection area.

  An example of the relationship between the imaging range of the imaging unit 9 and the projection area of the actual projection image is shown in FIG. The imaging range indicated by 31 in FIG. 3 is a range larger than the maximum projection area in which the liquid crystal projector 100 can project an image with the projection lens 7 at the wide end. That is, the imaging unit 9 always acquires color information (imaging data) in an area range larger than the actual projection area 32 by the liquid crystal projector 100.

  As described above, the projection area detection unit 15 calculates the actual projection area 32 based on at least detection results from the zoom position detection unit 11 and the distance detection unit 12.

  The digital shift function is a function that electrically shifts the position of the original image on the liquid crystal panel 4 (on the image forming element) to change the image projection position on the projection surface 200, that is, the position of the projection area. is there. With the digital shift function, the image projection position can be changed without moving the projector 100 itself. Even if the detection results by the zoom position detection unit 11 and the distance detection unit 12 are the same, the image projection position changes due to the shift amount from the reference position of the original image on the liquid crystal panel 4 or the shift position of the original image being different. For this reason, these digital shift amounts or digital shift positions are set as one of the calculation parameters of the projection area.

  Furthermore, the trapezoidal distortion correction function is a function that corrects the shape of a projected image from a trapezoid to a rectangle when an image is projected from an oblique direction onto the projection surface 200, and the shape of the original image on the liquid crystal panel 4 is a rectangle. It is done by correcting to a trapezoid. Even if the detection results by the zoom position detection unit 11 and the distance detection unit 12 are the same, the shape of the projection area changes due to the difference in the shape of the original image on the liquid crystal panel 4, and thus the correction amount of the trapezoidal distortion is set as the projection area. Is one of the calculation parameters.

  Next, in step S03, the image correction amount calculation unit 13 in the controller 8 includes the imaging data (R, G, and B color information on the projection surface) 22 stored in the imaging data storage unit 14. The color information of the projection area calculated by the projection area detection unit 15 is extracted. That is, color information obtained by overlapping the color of the actual projection image and the color of the projection surface 200 is extracted from the color information of the imaging range acquired by the imaging unit 9.

  In step S04, the video correction amount calculation unit 13 performs a color tone adjustment process. Specifically, based on the extracted color information and the correction reference value 23 stored in advance in the memory 10, the gain / offset processing unit 5 so that a predetermined white balance is obtained in the projected image on the projection surface 200. The gain values for the R, G, and B video signals input to are calculated. The gain value calculated here is hereinafter referred to as a correction gain value. Then, the correction gain value calculated for each of R, G, and B is transmitted to the display drive circuit 3.

  The correction reference value 23 is each of R, G, and B color component values calculated from imaging data obtained by the imaging unit 9 when reference white light is projected onto a reference (standard) screen. The correction reference value 23 is measured in an adjustment process at the manufacturing factory of the liquid crystal projector 100 and stored in the nonvolatile memory 10.

  The image correction amount calculation unit 13 makes the ratio of the R, G, B color component values after gain correction the same as the ratio of the R, G, B color component values of the correction reference value 23. The correction gain value is calculated.

  Next, in step S05, the controller 8 corrects the correction gain value transmitted from the video correction amount calculation unit 13 to the display drive circuit 3 for the R, G, B video signals input from the image processing circuit 2. The gain / offset process corresponding to is performed. Then, the processed R, G, and B video signals are output to the R panel 4R, the G panel 4G, and the B panel 4B, respectively. Such a process is also referred to as a gain correction process based on the extracted color information.

  By the above processing, when the color image projected on the projection surface 200 is projected on the reference screen regardless of the color of the projection surface 200 (or illumination light as ambient light that illuminates the projection surface 200). It has a good color tone (color balance) close to.

  Next, in step S06, the controller 8 waits until a new color tone adjustment processing command is input from an operation panel (not shown).

  As described above, according to the present embodiment, since the color information in the projection area of the actual image is extracted from the color information obtained by the imaging unit 9 in the predetermined imaging range, the color adjustment processing is performed. Even when the size or position of the projection area changes, the color tone can be adjusted accurately. In addition, since only the color information in the projection area of the actual image is used for the calculation of the color tone adjustment process, the calculation using the unnecessary color information is not performed, and the color tone adjustment process can be performed at high speed.

  FIG. 4 shows the configuration of a liquid crystal projector that is Embodiment 2 of the present invention. The basic configuration of the projector 100 ′ according to the present embodiment is the same as that of the projector 100 according to the first embodiment, and components having the same or similar functions as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment. However, the projector 100 ′ of the present embodiment has a lens shift function.

  The lens shift function is a function that shifts a lens unit that constitutes at least a part of the projection lens 7 in a direction orthogonal to the optical axis to change the position (image projection position) of the projection area of the projection image on the projection surface. is there. Thus, the image projection position can be changed without moving the projector 100 ′ itself.

  In FIG. 4, reference numeral 40 denotes a lens shift unit including a lens unit that constitutes a part of the projection lens 7, and 41 denotes a lens shift position detection unit that detects the shift position of the lens shift unit 40. The lens shift position detector 41 outputs shift position information to the controller 8.

  Reference numeral 9B denotes an imaging unit configured in the same manner as the imaging unit 9 of the first embodiment. As shown in FIGS. 5 and 6, the imaging unit 9 </ b> B is an image that is shifted on the projection surface 200 by the lens shift unit 40 shifting the maximum amount left and right or up and down with the projection lens 7 at the wide end. It has an imaging range (indicated by a black dotted line) capable of imaging the whole (indicated by a dotted dotted line).

  Similar to the digital shift function described in the first embodiment, by using the lens shift function, the image projection position changes even if the detection results by the zoom position detection unit 11 and the distance detection unit 12 are the same. For this reason, the shift position (or the shift amount from the reference position) of the lens shift unit 40 is set as one of the calculation parameters of the projection area.

  In the present embodiment, the tone correction processing performed by the controller 8 is basically the same as the processing shown in FIG. However, in step S03 of FIG. 2, the projection region detection unit 15 is based on the detection results by the zoom position detection unit 11 and the distance detection unit 12 and the shift position (or shift amount) of the lens shift unit 40. Of the nine imaging ranges, the projection area 24 of the actual projection image is calculated. Of course, when the digital shift function and the trapezoidal distortion correction function are used, the digital shift amount and the trapezoidal distortion correction amount are also used for calculating the projection area 24.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment when the present invention is implemented.

  For example, in each of the above-described embodiments, the image projection apparatus using the liquid crystal panel as the image forming element has been described. It can also be applied to devices.

1 is a block diagram illustrating a configuration of a projector that is Embodiment 1 of the present invention. FIG. 3 is a flowchart illustrating a flow of color tone adjustment processing according to the first exemplary embodiment. FIG. 3 is a diagram illustrating a relationship between an imaging range and a projection area in the projector according to the first embodiment. FIG. 5 is a block diagram illustrating a configuration of a projector that is Embodiment 2 of the present invention. FIG. 10 is a diagram illustrating a relationship between a lens shift function and an imaging range in the projector of Embodiment 2. FIG. 10 is a diagram illustrating a relationship between a lens shift function and an imaging range in the projector of Embodiment 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Video input circuit 2 Image processing circuit 3 Display drive circuit 4 Liquid crystal panel 5 Gain / offset processing part 6 Gamma correction part 7 Projection lens 8 Controller 9, 9B Image pick-up part 11 Zoom position detection part 12 Distance detection part 13 Video correction amount calculation part DESCRIPTION OF SYMBOLS 14 Imaging data memory | storage part 15 Projection area detection part 16 Light source lamp 31 Imaging range 32 Projection area 40 Lens shift part 41 Lens shift position detection part 100,100 'Liquid crystal projector 200 Projection surface

Claims (4)

An image projection apparatus that projects an image onto a projection surface through a projection optical system,
Color information acquisition means for acquiring a predetermined range of color information including the projection surface;
Color tone adjusting means for performing color tone adjustment processing for adjusting the color tone of the image;
Distance detecting means for detecting a distance from the image projection device to the projection surface;
Zoom state detecting means for detecting the zoom state of the projection optical system;
A projection area calculation means for calculating a projection area of the image based on the detection result of the distance detection means and the detection result of the zoom state detection means;
The color tone adjusting unit extracts color information of the projection area calculated by the projection area calculating unit from the color information in the predetermined range acquired by the color information acquiring unit, and based on the extracted color information And performing the color tone adjustment process. Having a function of correcting the trapezoidal distortion of the image,
The image projection apparatus according to claim 1, wherein the projection area calculation unit calculates the projection area based on a correction amount of the trapezoidal distortion. The image projection device projects light from an original image formed on an image forming element onto the projection surface through the projection optical system,
The image projection apparatus has a function of changing the position of the projection area on the projection surface by shifting the position of the original image in the image forming element,
The image projection apparatus according to claim 1, wherein the projection area calculation unit calculates the projection area based on a shift amount or a shift position of the original image. The image projection apparatus has a function of changing a position of the projection area on the projection surface by shifting a lens unit constituting at least a part of the projection optical system in a direction orthogonal to the optical axis,
The image projection apparatus according to claim 1, wherein the projection area calculation unit calculates the projection area based on a shift amount or a shift position of the lens unit.