JP2011135445A - Image projection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform color correction processing of a projection image using reflection light from a surface to be projected, appropriately in accordance with change in projection area or projection position caused by an input image format or a projection display mode. <P>SOLUTION: An image projection apparatus 100 drives an optical modulation element 4 in response to an image signal and projects, on a projection surface 200, a projection image formed by light from the optical modulation element. The apparatus has: a color detecting unit 9 which receives reflection light reflected on the projection surface and detects a color of the projection surface; a color correcting unit 5 for performing color correction processing on the image signal; a data extracting unit 15 for extracting, from color detection data obtained by the color detecting unit, a data region corresponding to at least one of a format of the image signal, a format of the projection image, a projection position of the projection image and a distortion correction amount of the projection image; and a correction value calculating unit 13 for calculating a correction value to be used in the color correcting unit based on data in the extracted data region. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an image projection apparatus such as a projector having a function of performing color correction (so-called wall color correction) of a projected image using reflected light from a projection surface.

The projection surface on which an image is projected by the projector includes not only a dedicated white screen but also a non-white projection surface such as a wall or a partition. In addition, projectors are often used not only in dark rooms but also in illuminated rooms.
A wall that automatically detects the color of the projected image (white balance) by detecting the influence of the color of the projected surface and the color tone (color balance) of the projected image using a detector such as an optical sensor or a CCD camera. A projector having a color correction function is disclosed in Patent Document 1. In this projector, red (R), green (G), and blue (B) components at the time of projecting a white image are detected, and the gains of the R, G, and B components are adjusted so that the necessary white balance can be obtained. .
Patent Document 2 discloses a projector that divides a projection surface into a plurality of areas, measures a color level for each divided area with a color light sensor, and determines a color correction level for each divided area. ing.
Further, some image signals input to the projector have various resolutions and aspect ratios (hereinafter referred to as an input image format), and the projector is provided with projection display modes corresponding to various input image formats. . Thus, when projecting a document in a presentation, projecting a movie having an aspect ratio of 16: 9, projecting a television broadcast image, and the like, a good image is projected by a projection display mode appropriate for the application. be able to.

JP 2003-333611 A JP 2006-349792 A

However, the wall color correction function in the projectors disclosed in Patent Documents 1 and 2 is not taken into consideration when the projection area or projection position of the image changes. For this reason, when the projection area and the projection position change due to the change of the input image format and the projection display mode, it is necessary to measure the influence of the color of the projection surface and the color tone of the projection image again. In other words, good wall color correction cannot be performed unless such measurement is performed again.
The present invention provides an image projection apparatus capable of appropriately performing color correction processing of a projected image using reflected light from a projection surface in response to changes in a projection area and a projection position depending on an input image format and a projection display mode. I will provide a.

An image projection apparatus according to one aspect of the present invention drives a light modulation element according to an image signal, and projects a projection image formed by light from the light modulation element onto a projection surface. The image projection apparatus is obtained by a color detection unit that receives reflected light reflected by a projection surface and detects a color of the projection surface, a color correction unit that performs color correction processing on an image signal, and a color detection unit. Data extraction means for extracting a data area corresponding to at least one of the format of the image signal, the format of the projection image, the projection position of the projection image, and the distortion correction amount of the projection image from the color detection data; And correction value calculation means for calculating a correction value used by the color correction means based on the data.

  According to the present invention, the correction value for the color correction process is calculated using the data of the data area corresponding to the format of the image signal, the projection position of the projection image, and the distortion correction amount of the projection image among the color detection data. Therefore, it is possible to perform an appropriate color correction process according to these projection conditions.

1 is a block diagram illustrating a configuration of a liquid crystal projector that is Embodiment 1 of the present invention. FIG. 6 is a flowchart illustrating an automatic color tone adjustment process in the projector according to the first embodiment. FIG. 3 is a diagram illustrating a relationship between an input image and a projection image (SXGA image) in the first embodiment. FIG. 3 is a diagram illustrating a relationship between an input image and a projection image (XGA image) in the first embodiment. FIG. 3 is a diagram illustrating a relationship between a projected image and an imaging region in the first embodiment. FIG. 5 is a block diagram illustrating a configuration of a liquid crystal projector that is Embodiment 2 of the present invention. The figure which shows the lens shift function (upper side) of a projector. The figure which shows the lens shift function (lower side) of a projector. 9 is a flowchart showing automatic color tone adjustment processing in the projector of Embodiment 2.

  Embodiments of the present invention will be described below 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 a video signal (input image signal) 21 output from an image supply device such as a personal computer or video equipment to generate a digital video signal in a predetermined format. If the video signal 21 is an analog signal, A / D conversion is performed to generate a digital video signal in a predetermined format.
The generated digital video signal is output to the digital signal processing circuit 2. The digital signal processing circuit 2 performs, for the digital video signal, resolution conversion processing and frame rate conversion processing suitable for driving the liquid crystal panel 4 as an image forming element. The digital signal processing circuit 2 generates a video signal for displaying a test pattern as a reference image.
The R, G, B video signals (projected image signals) output from the digital signal processing circuit 2 are input to the display drive circuit 3. The display drive circuit 3 is provided with a gain / offset processing unit (correction means) 5 and a γ correction unit 6, which enables gain / offset processing and independent processing for R, G, and B video signals. Signal processing related to luminance and color such as γ correction processing is performed. The display drive circuit 3 generates drive signals for the liquid crystal panels 4 (R panel 4R, G panel 4G, and B panel 4B) as three light modulation elements based on the processed R, G, and B video signals. To do. The display driving circuit 3 generates a timing pulse for causing the liquid crystal panel 4 to form an original image corresponding to the driving signal.
The projection lens (projection optical system) 7 irradiates the image light, which is obtained by combining R, G, B light from the R panel 4R, G panel 4G, and B panel 4B illuminated by the light source lamp 16, onto the projection surface 200. Project.
The liquid crystal projector 100 includes an imaging sensor (color detection unit) 9 that captures an image projected on the projection surface 200 through the projection lens 7.
The imaging sensor 9 is an area-type CCD sensor that photoelectrically converts an optical image that is reflected light reflected by the projection surface 200 and collected by the imaging lens, and an analog image signal output from the CCD sensor as a digital image. An A / D conversion unit for A / D converting the signal is provided. The imaging sensor 9 generates rectangular imaging data (R, G, B signals) having M pixels in the horizontal direction and N pixels in the vertical direction. Further, since it is desirable that the imaging sensor 9 captures all the projection images of the liquid crystal projector 100, the imaging sensor 9 can capture the same area as the projection image, or somewhat wider. However, it is not always necessary to capture all of the projectable area.
Imaging data (color detection data) 25 obtained by the imaging sensor 9 is stored in the imaging data storage unit 14.
The controller 8 is composed of a microcomputer or the like, and controls the test pattern display for the digital signal processing circuit 2 and controls various processes such as gain / offset processing and gamma processing for the display driving circuit 3. . The control content includes setting of a gain value that is a parameter for performing gain processing, for example.
Furthermore, the controller 8 controls the entire system in an integrated manner, such as decoding commands from an operation panel (not shown) and communicating with the nonvolatile memory 10.
The liquid crystal projector of this embodiment has a function of performing automatic color tone adjustment processing (color correction processing), which is also referred to as automatic wall color correction processing. In the color tone adjustment process, the projection area calculation unit (data extraction unit) 15 included in the controller 8 extracts only imaging data in a necessary data area from the imaging data 22 stored in the imaging data storage unit 14. Then, the sensor value 24 is calculated for each RGB color using the imaging data of the data area, and the sensor value 24 is output to the video correction amount calculation unit (correction value calculation means) 13 provided for each RGB color. To do.
The image correction amount calculation unit 13 obtains a predetermined white balance in the projection image using the sensor value 24 obtained by the projection area calculation unit 15 and the sensor reference value 23 stored in the nonvolatile memory 10 in advance. The gain value for the R, G, B video signals (image signals) is calculated. Then, the calculated gain value is output to the display drive circuit 3.
Next, the automatic color tone adjustment process performed by the projector 100 of the present embodiment will be described with reference to the flowchart of FIG. This process is executed by the controller 8 according to the computer program.
(Step S01)
The controller 8 causes the digital signal processing circuit 2 to generate a white test pattern (white image) and project it onto the projection surface 200. Then, the projection surface 200 in a state where the white test pattern is projected is captured by the imaging sensor 9, the imaging data 25 including the color information of the projection surface 200 is acquired, and stored in the imaging data storage unit 14.
(Step S02)
The controller 8 causes the projection area calculation unit 15 to select a data area corresponding to the format (input image format) of the video signal 21 and the projection display mode set by the projector from the imaging data 22 stored in the imaging data storage unit 14. Image data is extracted. Extraction of imaging data is performed for each RGB color.
The format of the video signal 21 includes the resolution and aspect ratio of the video signal 21. Further, the resolution and aspect ratio of the projected image are determined by the projection display mode. For this reason, “according to the projection display mode” is synonymous with “according to the format of the projected image”. The format of the video signal 21 and the projection display mode are each one of the projection conditions.
Here, the projection display mode includes a full screen display mode for displaying at a projection resolution of the projector regardless of the input image format, a real display mode for displaying in the format of the input image format as it is, and the like.
The relationship between the input image format, the projection image, the imaging area, and the imaging data extraction area will be described with reference to FIGS. Here, the projection resolution of the projector is SXGA size (1280 × 1024), and the projection display mode is the real display mode.
First, as shown in FIG. 3, when the input video is SXGA size, the projected image is projected with the resolution of the projector as it is. As shown in FIG. 4, when the input video is XGA size (1024 × 768), since the projection resolution of the projector is SXGA size, the projected image is inward of the case where the video signal of SXGA size is input. Projected, and its periphery becomes a non-display area (black projection area).

The relationship between the imaging area of the imaging sensor 9 and the projected image at this time is shown in FIG. The imaging area of the imaging sensor 9 is an area slightly wider than the projection resolution of the projector (in this case, the SXGA size). For this reason, when a video signal of SXGA size is input, from the imaging data obtained in the imaging region shown in FIG. 5A (imaging data stored in the imaging data storage unit 14) to an SXGA size projection image. Image data of the corresponding data area is extracted. Similarly, when an XGA-size video signal is input, as shown in FIG. 5B, only the image data in the data area corresponding to the XGA-size projection image is extracted from the image-capture data in the image-capture area. The imaging data in the display area is excluded from the calculation.
As described above, by extracting and using the imaging data of the data area corresponding to the input image format, it is possible to perform a more accurate color tone adjustment process without performing an operation using extra data.
(Step S03)
The controller 8 causes the projection area calculation unit 15 to calculate the sensor value 24 for each RGB color using the extracted imaging data, and causes the image correction amount calculation unit 13 to output the sensor value 24.
As a calculation method of the sensor value 24, for example, there are (1) a method using an average value as a sensor value, and (2) a method of obtaining a frequency distribution and using data having the highest frequency as a sensor value, and using other calculation methods. You can also.

  The image correction amount calculation unit 13 uses the sensor reference value 23 stored in the nonvolatile memory 10 and the sensor value 24 calculated by the projection area calculation unit 15 to correct the correction amount (gain for each RGB color). Value). Here, the sensor reference value 23 is a value calculated for each RGB color from the imaging data obtained by the imaging sensor 9 when predetermined reference white light is projected onto the reference (standard) screen. The sensor reference value 23 is measured in a factory adjustment process or the like and stored in the nonvolatile memory 10.

The video correction amount calculation unit 13 calculates a gain value as a correction amount so that the RGB ratio of the sensor reference value 23 is the same as the corrected RGB ratio.
(Step S04)
The controller 8 outputs the calculated correction amount (gain value) to the display drive circuit 3. Thereby, the projection image whose color tone has been adjusted is displayed on the projection surface 200. For example, even when an image is projected on the projection surface 200 having a chromatic color, it is possible to project an image having a hue close to that when projected onto the reference screen.
(Step S05)
When the projection area is changed on the projection surface 200, such as when the input video signal is switched during image projection, the controller 8 detects this, and performs the processing from step S02 to step S04 again. Since the color information of the projection surface 200 is stored in the imaging data storage unit 14, even when the projection area or the projection position changes due to the change of the input image format or the projection display mode, the test pattern is not projected again. Color tone adjustment processing according to new projection conditions becomes possible.
For this reason, it is possible not only to perform a good color tone adjustment process taking into consideration the input image format and the projection display mode, but also to reduce the user's burden and discomfort.
The parameters for extracting the imaging data of the data area corresponding to the projection area include a keystone distortion correction amount and a digital shift amount in addition to the input image format and the projection display mode. The trapezoidal distortion correction is performed by converting a trapezoidal shape distorted in a direction opposite to the distortion on the projection surface into an original image displayed on the liquid crystal panel 4 in order to correct a projection image distorted into a trapezoidal shape during so-called oblique projection into a rectangular image. It is a function to do. The trapezoidal distortion correction amount is a correction amount in the trapezoidal distortion correction. Digital shift is a function that adjusts the projection position of the projected image on the projection surface by shifting the display position of the original picture on the liquid crystal panel 4, and the digital shift amount is a shift from the reference original picture position. Amount. These trapezoidal distortion correction amount and digital shift amount are also one of the projection conditions.
A data area corresponding to at least one of the input image format, the projection display mode (projection image format), the projection position of the projection image by digital shift, and the trapezoidal distortion correction amount of the projection image is extracted from the imaging data 25. What should I do?

FIG. 6 shows the configuration of a projector 100 ′ that is Embodiment 2 of the present invention. In FIG. 6, the same components as those shown in the first embodiment (FIG. 1) are denoted by the same reference numerals as those in the first embodiment, and the description is omitted.
The projection lens 7B having a lens shift function includes a lens shift mechanism (not shown) and a position sensor that detects a lens shift position (projection direction). The position sensor outputs the lens shift position 40 to the controller 8. The imaging sensor 9B can change the imaging direction (light receiving direction), and the imaging direction is changed by an imaging sensor driving unit (direction changing unit) 30 included in the controller 8.
The lens shift function described above is to shift the projection position of the projected image on the projection surface 200 without moving the entire projector 100 ′ by shifting the projection lens 7B in the direction orthogonal to the optical axis. It is a function that can.
FIG. 7 shows a state in which the projection lens 7B is shifted upward and an image is projected onto the projection surface 200. In order to perform the color tone adjustment process in this state, the color information of the projection image must be acquired, and thus the imaging direction of the imaging sensor 9B needs to be directed upward. FIG. 8 shows a state in which the projection lens 7B is shifted downward and an image is projected on the projection surface 200. In order to perform the color tone adjustment processing in this state, the imaging direction of the imaging sensor 9B needs to be directed downward. Although not shown, the same applies to the case where the projection lens 7B is shifted left and right, and the imaging direction of the imaging sensor 9 needs to be matched with the direction in which the projection image is shifted.
The flowchart in FIG. 9 shows an automatic color tone adjustment process performed by the projector 100 ′ of this embodiment. The flowchart in FIG. 9 corresponds to a flowchart in which conditions and processing relating to lens shift are added to the flowchart shown in the first embodiment (FIG. 2).
(Step S10)
The controller 8 acquires the lens shift position 40 from a position sensor provided in the projection lens 7B.
(Step S11)
The controller 8 controls the imaging sensor driving unit 30 according to the acquired lens shift position 40, and changes the imaging direction of the imaging sensor 9B to the same direction as the projection direction of the projection image (direction of the projection position of the projection image). .
(Step S01 to Step S04)
The controller 8 performs the processing from step S01 to step S04 shown in the first embodiment (FIG. 2), and is based on the imaging data of the data area extracted according to the projection condition from the imaging data obtained by the imaging sensor 9B. Adjust the color tone of the projected image.

(Step S05)
The controller 8 determines whether or not the projection condition has been changed, and determines whether or not the lens shift position has been changed. When the lens shift position is changed, it is necessary to acquire the color information of the projection surface 200 again, and the process returns to step S10.

According to the present embodiment, in a use such as a home theater or a conference presentation in which the lens shift function is often used, a good color tone adjustment can be automatically performed according to the lens shift.
Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.
In the above embodiment, a projector using a liquid crystal panel as a light modulation element has been described. However, the present invention can also be applied to a projector using another light modulation element such as a micromirror device (DMD).

It is possible to provide an image projection apparatus capable of performing a good color correction process.

4 Liquid crystal panel 5 Gain / offset processing unit 8 Controller 9, 9B Image sensor 13 Image correction amount calculation unit 15 Projection area calculation unit 100, 100 ′ Liquid crystal projector

Claims (2)

An image projection device that drives a light modulation element according to an image signal and projects a projection image formed by light from the light modulation element onto a projection surface,
Color detection means for detecting the color of the projection surface by receiving the reflected light reflected by the projection surface;
Color correction means for performing color correction processing on the image signal;
From the color detection data obtained by the color detection means, a data area corresponding to at least one of the format of the image signal, the format of the projection image, the projection position of the projection image, and the distortion correction amount of the projection image. Data extraction means for extracting;
An image projection apparatus comprising: a correction value calculation unit that calculates a correction value used by the color correction unit based on data in the data area. A function of shifting a projection optical system that projects light from the light modulation element onto the projection surface in a direction orthogonal to the optical axis of the projection optical system;
The image projection apparatus according to claim 1, further comprising a direction changing unit that changes a light receiving direction of the color detection unit according to a shift position of the projection optical system.