JP2014011707A - Projector, and control method therefor - Google Patents

Abstract

A projector capable of realizing uniform brightness without changing the configuration of a circuit that corrects trapezoidal distortion by filtering and a control method therefor are provided.
A filter coefficient calculation unit detects a maximum value and a minimum value for a deformation rate for each pixel representing a degree of deformation due to trapezoidal distortion, and a plurality of values are determined according to a range (minimum value to maximum value) of the deformation rate. The filter coefficient corresponding to the deformation rate of is calculated. Then, the filter coefficient is corrected by multiplying the calculated filter coefficient by a luminance correction coefficient for correcting the luminance deviation caused by the trapezoidal distortion, and stored in the filter coefficient storage unit 42. The deformation rate calculation unit 43 calculates the deformation rate of the pixel to be processed by the filter calculation unit 45, and the filter calculation unit 45 stores the filter coefficient corresponding to the deformation rate calculated by the deformation rate calculation unit 43 as a filter coefficient. The data is read from the unit 42 and subjected to filter processing.
[Selection] Figure 4

Description

  The present invention relates to a projector that projects an image and a control method thereof.

  If a projector that projects an image is installed with an inclination with respect to the projection surface, a trapezoidal distortion that causes the displayed image to be deformed into a trapezoidal shape occurs. In addition, when the projector is tilted, the distance to the projector varies greatly depending on the position in the image, resulting in uneven brightness. For this reason, there has been proposed a projector (liquid crystal projector device) capable of adjusting the luminance when correcting the trapezoidal distortion (see, for example, Patent Document 1).

JP 2004-289503 A

  However, as in the projector described in Patent Document 1, in addition to the circuit for correcting the trapezoidal distortion, the circuit for adjusting the brightness complicates the circuit configuration of the projector and increases the cost. It has the problem of being invited.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A projector according to this application example is a projector that projects an image based on image information, and includes a parameter generation unit that generates a filter coefficient for filter processing for correcting trapezoidal distortion of the image, A correction processing unit that performs the filtering process on the image information using the filter coefficient generated by the parameter generation unit, and an image projection that projects the image based on the image information corrected by the correction processing unit A parameter generation unit that generates the filter coefficient so that the trapezoidal distortion is corrected; and the filter coefficient that corrects a bias in luminance associated with the trapezoidal distortion. And a coefficient adjustment unit for adjustment.

  According to this projector, since the bias of the brightness is corrected by adjusting the filter coefficient for correcting the trapezoidal distortion, the configuration of the circuit that corrects the trapezoidal distortion by the filter processing is used to correct the luminance. Uniformity can also be realized. That is, it is not necessary to newly add a circuit for making the luminance uniform.

  Application Example 2 In the projector according to the application example, the coefficient generation unit generates the filter coefficient in association with a deformation rate that represents a degree of deformation of the image due to the trapezoidal distortion, and the coefficient adjustment unit includes: You may make it adjust the said filter coefficient produced | generated by the said coefficient production | generation part according to the deformation rate corresponding to the said filter coefficient.

  Application Example 3 In the projector according to the application example described above, the coefficient adjustment unit multiplies the filter coefficient generated by the coefficient generation unit by a luminance correction coefficient corresponding to a deformation rate corresponding to the filter coefficient. May be.

  Application Example 4 In the projector according to the application example, the correction processing unit includes a deformation rate calculation unit that calculates the deformation rate for each position of the image, and the filter coefficient generated by the parameter generation unit. A filter operation unit that performs the filtering process using a filter coefficient corresponding to the deformation rate calculated by the deformation rate calculation unit.

  Application Example 5 A projector control method according to this application example is a projector control method for projecting an image based on image information, and generates a filter coefficient for filter processing for correcting trapezoidal distortion of the image. Based on the parameter generation step, the correction processing step of applying the filter processing to the image information using the filter coefficient generated in the parameter generation step, and the image information corrected in the correction processing step, An image projecting step for projecting an image, wherein the parameter generating step is a coefficient generating step for generating the filter coefficient so that the trapezoidal distortion is corrected, and a luminance deviation due to the trapezoidal distortion is corrected. A coefficient adjustment step for adjusting the filter coefficient as described above. And butterflies.

  According to this projector control method, since the luminance deviation is corrected by adjusting the filter coefficient for correcting the trapezoidal distortion, the configuration of the circuit that corrects the trapezoidal distortion by the filter processing is used. Further, it is possible to achieve uniform luminance. That is, it is not necessary to newly add a circuit for making the luminance uniform.

  Application Example 6 In the projector control method according to the application example described above, in the coefficient generation step, the filter coefficient is generated in association with a deformation rate indicating a degree of deformation of the image due to the trapezoidal distortion, and the coefficient adjustment is performed. In the step, the filter coefficient generated in the coefficient generation step may be adjusted according to a deformation rate corresponding to the filter coefficient.

  Application Example 7 In the projector control method according to the application example described above, in the coefficient adjustment step, a luminance correction coefficient corresponding to a deformation rate corresponding to the filter coefficient is added to the filter coefficient generated in the coefficient generation step. You may make it multiply.

  Application Example 8 In the projector control method according to the application example, the correction processing step includes a deformation rate calculation step for calculating the deformation rate for each position of the image, and the filter generated in the parameter generation step. A filter calculation step for performing the filtering process using a filter coefficient corresponding to the deformation rate calculated in the deformation rate calculation step among the coefficients may be provided.

  Further, when the projector and the control method thereof are constructed using a computer, the form and the application example are recorded as a program for realizing the function, or the program can be read by the computer. It is also possible to configure in the form of a recording medium or the like. Recording media include flexible disks, hard disks, optical disks such as CDs and DVDs, magneto-optical disks, memory cards and USB memories equipped with nonvolatile semiconductor memory, projector internal storage devices (semiconductor memories such as RAM and ROM), etc. Various media readable by the computer can be used.

1 is a block diagram showing a schematic configuration of a projector. It is explanatory drawing for demonstrating trapezoid distortion correction, (a) is a figure which shows the image (before correction | amendment) drawn on the pixel area | region of a liquid crystal light valve based on the image information before correction | amendment, (b), The figure which shows a mode that the image before correction | amendment is projected, (c) is a figure which shows the image (after correction | amendment) drawn on the pixel area based on the image information after correction | amendment, (d) projects the image after correction | amendment. The figure which shows a mode. It is explanatory drawing for demonstrating a deformation rate, (a) is a figure which shows the image before correction | amendment drawn by the pixel area, (b) is a figure which shows the image after correction | amendment drawn by the pixel area. The block diagram which shows the structure of an image correction part. The graph for demonstrating a brightness | luminance correction coefficient. The flowchart for demonstrating operation | movement of a filter coefficient calculation part.

Hereinafter, the projector of this embodiment will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating a schematic configuration of the projector 1.
As shown in FIG. 1, the projector 1 includes an image projection unit 10, a control unit 20, a storage unit 21, an operation panel 22, an image information input unit 23, an image processing unit 24, an image correction unit 25, and the like.

  The image projection unit 10 includes a light source device 11 as a light source, a liquid crystal light valve 12 as a light modulation device, a projection lens 13 as a projection optical system, a liquid crystal drive unit 14 and the like. The image projection unit 10 corresponds to a display unit, and the light emitted from the light source device 11 is modulated into image light by the liquid crystal light valve 12, and this image light is projected from the projection lens 13 to project the projection surface S. Display an image.

  The light source device 11 includes a discharge-type light source lamp 11a made of an ultra-high pressure mercury lamp, a metal halide lamp, or the like, and a reflector 11b that reflects light emitted from the light source lamp 11a toward the liquid crystal light bulb 12 side. The light emitted from the light source device 11 is converted into light having a substantially uniform luminance distribution by an integrator optical system (not shown) and enters the liquid crystal light valve 12.

  The liquid crystal light valve 12 is configured by a transmissive liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates. The liquid crystal light valve 12 includes a rectangular pixel region 12a in which a plurality of pixels (not shown) are arranged in a matrix, and a driving voltage can be applied to the liquid crystal for each pixel. When the liquid crystal driving unit 14 applies a driving voltage corresponding to the input image information to each pixel, each pixel is set to a light transmittance corresponding to the image information. For this reason, the light emitted from the light source device 11 is modulated by passing through the pixel region 12 a of the liquid crystal light valve 12 to become image light corresponding to the image information, and is enlarged and projected by the projection lens 13. In this specification, setting the light transmittance of each pixel of the liquid crystal light valve 12 (pixel region 12a) based on image information is also referred to as “drawing an image”.

  The control unit 20 includes a CPU (Central Processing Unit), a RAM (Random Access Memory) used for temporary storage of various data, and the like, and the projector is operated by the CPU operating according to a control program stored in the storage unit 21. 1 operation is controlled. That is, the control unit 20 functions as a computer together with the storage unit 21.

  The storage unit 21 is configured by a nonvolatile memory such as a flash memory or a mask ROM (Read Only Memory). The storage unit 21 stores a control program for controlling the operation of the projector 1, various setting data for defining operation conditions of the projector 1, and the like.

  The operation panel 22 corresponds to an input operation unit that receives a user's input operation, and includes a plurality of operation keys (not shown) for the user to give various instructions to the projector 1. When the user operates various operation keys on the operation panel 22, the operation panel 22 receives this operation and outputs a control signal corresponding to the operated operation key to the control unit 20. When a control signal is input from the operation panel 22, the control unit 20 performs processing based on the input control signal and controls the operation of the projector 1. Instead of the operation panel 22 or together with the operation panel 22, a remote control (not shown) capable of remote operation may be used as the input operation unit. In this case, the remote control transmits an infrared operation signal corresponding to the user's operation content, and a remote control signal receiving unit (not shown) receives this and transmits it to the control unit 20.

  The image information input unit 23 includes a plurality of input terminals, and various types of image information are input to these input terminals from an external image supply device (not shown) such as a video reproduction device or a personal computer. The image information input unit 23 performs signal conversion processing or the like on the input image information as necessary, and outputs it to the image processing unit 24.

  The image processing unit 24 converts the image information input from the image information input unit 23 into image information indicating the gradation of each pixel of the liquid crystal light valve 12, that is, image information for defining a driving voltage applied to each pixel. Convert. Here, the converted image information includes a plurality of pixel values corresponding to each pixel of the liquid crystal light valve 12. The pixel value determines the light transmittance of the corresponding pixel, and the luminance of light emitted from each pixel is defined by the pixel value. Further, the image processing unit 24 adjusts the image quality such as brightness, contrast, and sharpness for the converted image information based on an instruction from the control unit 20, and OSD (on-screen display) such as a menu image. A process of superimposing and displaying the image is performed as necessary, and the processed image information is output to the image correction unit 25.

  The image correction unit 25 performs a process for correcting trapezoidal distortion that occurs when an image is projected from an oblique direction with respect to the projection surface S. Specifically, the image correction unit 25 performs filter processing for distorting the image in a shape that can cancel the trapezoidal distortion on the image information (pre-correction image information) input from the image processing unit 24, and after the processing Is supplied to the liquid crystal drive unit 14 as corrected image information. When the liquid crystal driving unit 14 drives the liquid crystal light valve 12 in accordance with the corrected image information input from the image correcting unit 25, an image is projected on the projection surface S with the trapezoidal distortion corrected.

  FIG. 2 is an explanatory diagram for explaining trapezoidal distortion correction. FIG. 2A shows an image (pre-correction image) drawn in the pixel area 12a of the liquid crystal light valve 12 based on the pre-correction image information. (B) is a figure which shows a mode that the image before correction | amendment is projected, (c) is a figure which shows the image (after correction | amendment) drawn on the pixel area 12a based on the image information after correction | amendment, (d) is a figure. It is a figure which shows a mode that the image after correction | amendment is projected.

As shown in FIG. 2A, an image (input image Pi) based on the image information input from the image processing unit 24 is drawn as the pre-correction image P0 over the entire pixel area 12a, and is obliquely projected on the projection plane S. When projected, the input image Pi is distorted and displayed due to trapezoidal distortion, as shown in FIG. On the other hand, as shown in FIG. 2 (c), the pre-correction image P0 (input image Pi) is distorted in the reverse direction of the trapezoidal distortion, and the outside of the input image Pi has a black pixel value, that is, the light transmittance is minimized. When the corrected image P1 set to such a pixel value is projected onto the projection surface S, the trapezoidal distortion is canceled as shown in FIG. 2D, and the input image Pi is displayed in a rectangular shape. As shown in the figure, the coordinates (pixel coordinates) of four vertices of the upper left, upper right, lower right, and lower left of the pre-correction image P0 are respectively (x ₀ , y ₀ ), (x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ ), and the coordinates of the points corresponding to these four vertices in the corrected image P1 are (X ₀ , Y ₀ ), (X ₁ , Y ₁ ), ( X ₂ , Y ₂ ) and (X ₃ , Y ₃ ). Here, the degree of deformation (deformation rate) of the post-correction image P1 with respect to the pre-correction image P0 differs depending on the position (coordinates) of the image. For example, in the example shown in FIG. 2, the vertex (X ₃ , Y ₃ The degree of reduction is larger in the vicinity of the vertex (X ₁ , Y ₁ ) than in the vicinity of).

  FIGS. 3A and 3B are explanatory diagrams for explaining the deformation rate. FIG. 3A is a diagram showing an uncorrected image P0 drawn in the pixel region 12a, and FIG. 3B is a post-correction image drawn in the pixel region 12a. It is a figure which shows the image P1. Note that, this figure explains the deformation rate of these pixels by paying attention to two pixels at the upper right and lower left vertices as representatives, and in order to facilitate the explanation, the pixel of interest and its surroundings For these pixels, the size of the pixels and the spacing between the pixels are shown enlarged.

As shown in FIG. 3B, in the corrected image P1, the distance between the pixel pl1 adjacent to the left of the pixel of interest and the pixel pr1 adjacent to the right of the pixel of interest is a1, and the top of the pixel of interest Let b1 be the distance between the pixel pu1 adjacent to and the pixel pd1 adjacent below the pixel of interest. Also, as shown in FIG. 3A, in the pre-correction image P0, the distance between the pixel pl0 corresponding to the pixel pl1 and the pixel pr0 corresponding to the pixel pr1 is a0, the pixel pu0 corresponding to the pixel pu1, and the pixel The distance from the pixel pd0 corresponding to pd1 is b0. In the present embodiment, the a1 / a0, defined as the deformation ratio epsilon _x in the lateral direction (X direction) in the pixel, the b1 / b0, as a modification ratio epsilon _y in the vertical direction (Y direction) of the pixel Define. When the deformation rates ε _x and ε _y are defined in this way, the deformation rates ε _x and ε _y are closer to the vertex (X ₁ , Y ₁ ) than to the vicinity of the vertex (X ₃ , Y ₃ ). Small value. The definition of the deformation ratios ε _x and ε _y is not limited to the above. For example, the ratio of the inter-pixel distance a1 to the x-direction component of the inter-pixel distance a0 and the inter-pixel distance of the inter-pixel distance b0 to the y-direction component. The ratio of b1 may be defined as deformation rates ε _x and ε _y , respectively.

FIG. 4 is a block diagram illustrating a configuration of the image correction unit 25.
As shown in FIG. 4, the image correction unit 25 includes a parameter generation unit 30 and a correction processing unit 40.

  The parameter generation unit 30 includes a projection conversion coefficient calculation unit 31, a filter coefficient calculation unit 32, and a luminance correction coefficient storage unit 33, and parameters (projection conversion coefficient and filter coefficient) for correcting trapezoidal distortion. And generated according to the inclination of the projector 1.

  Inclination information corresponding to the inclination of the projector 1 is input from the control unit 20 to the projection conversion coefficient calculation unit 31. For example, the control unit 20 images the projection surface S by an imaging unit (not shown) in a state where the pre-correction image P0 is projected, and derives inclination information representing the inclination of the projection surface S with respect to the projector 1 based on the imaging result. The inclination information is output to the projective transformation coefficient calculation unit 31. Note that the method for deriving the tilt information is not limited to the above, and the tilt information may be derived by detecting the tilt of the projector 1 using an acceleration sensor or the like (not shown), or the user may operate the operation panel 22 or the remote control. The tilt information may be designated or input.

The projective transformation coefficient calculation unit 31 is based on the tilt information input from the control unit 20, and coordinates (X ₀ , Y ₀ ), (X ₁ , Y ₁ ), (X ₂ ) of the four vertices of the corrected image P1. , Y ₂ ), (X ₃ , Y ₃ ). Further, the projective conversion coefficient calculation unit 31 calculates a projective conversion coefficient that defines the conversion from the pre-correction image P0 to the post-correction image P1 using the calculated coordinates of the vertex of the post-correction image P1. Here, as described above, the coordinates of the four vertices of the upper left, upper right, lower right, and lower left of the pre-correction image P0 are respectively (x ₀ , y ₀ ), (x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ ), and the coordinates of these four vertices in the corrected image P1 are (X ₀ , Y ₀ ), (X ₁ , Y ₁ ), (X ₂ , Y ₂ ), ( X ₃ , Y ₃ ), a projection transformation determinant as shown in Equation (1) is established using eight projection transformation coefficients A to H. For this reason, the projective conversion coefficient calculation unit 31 calculates the projective conversion coefficients A to H from the equation (1), and outputs the calculation results to the filter coefficient calculation unit 32 and the correction processing unit 40.

  If the pre-correction image P0 is converted to the post-correction image P1 by this projective conversion, the coordinates (x, Y) in the pre-correction image P0 corresponding to arbitrary coordinates (X, Y) in the post-correction image P1. y) can be derived from the following equations (2) and (3).

The filter coefficient calculation unit 32 refers to the projection conversion coefficient calculated by the projection conversion coefficient calculation unit 31 and the luminance correction coefficient stored in the luminance correction coefficient storage unit 33, and performs filter processing by the correction processing unit 40. The filter coefficient for determining the pixel value of each pixel in the corrected image P1 is calculated. Here, since the pixel value in the corrected image P1 changes according to the values of the deformation rates ε _x and ε _y , the filter coefficient calculation unit 32 calculates the filter coefficient for each value of the deformation rates ε _x and ε _y. Calculate and output to the correction processing unit 40. The filter coefficient calculated by the filter coefficient calculation unit 32 is a coefficient of a vertical / horizontal separation type one-dimensional filter, and the filter coefficient calculation unit 32 calculates the horizontal filter coefficient according to the value of the horizontal deformation rate ε _x. And the filter coefficient in the vertical direction corresponding to the value of the deformation rate ε _y in the vertical direction are calculated individually.

The brightness correction coefficient storage unit 33 stores in advance a brightness correction coefficient table in which brightness correction coefficients are associated with a plurality of values of the vertical and horizontal deformation rates ε _x and ε _y . The luminance correction coefficient is a coefficient for correcting the luminance deviation due to the trapezoidal distortion, and the filter coefficient calculation unit 32 uniformly corrects the luminance by multiplying the calculated filter coefficient by the luminance correction coefficient.

FIG. 5 is a graph for explaining the luminance correction coefficient, and shows the relationship between the deformation rate and the luminance correction coefficient.
As shown in FIG. 5, the luminance correction coefficient takes a value of 1 when the deformation ratios ε _x and ε _y are 1.0 (same size), and increases as the deformation ratios ε _x and ε _y decrease. It is set to take. This is because a portion where the deformation ratios ε _x and ε _y are small (that is, a portion where the value of a1 / a0 is small) is greatly enlarged on the projection surface S to lower the luminance, and this luminance reduction is compensated. For this reason, a luminance correction coefficient is associated with which the luminance increases as the values of the deformation ratios ε _x and ε _y become smaller.

FIG. 6 is a flowchart for explaining the operation of the filter coefficient calculation unit 32.
When the projector 1 is installed and tilt information is input from the control unit 20, the filter coefficient calculation unit 32 operates according to the flow shown in FIG. It is assumed that the filter coefficient calculation unit 32 first calculates a horizontal filter coefficient among the vertical and horizontal filter coefficients.

As shown in FIG. 6, in step S101, the filter coefficient calculation unit 32 detects the maximum value and the minimum value for the lateral deformation rate ε _x . Here, the position where the deformation rate ε _x is maximized or minimized is a position where the distance to the projection plane S is maximized or minimized, and is one of the four vertices of the image. Therefore, the filter coefficient calculation unit 32 calculates the deformation rate ε _x of the four vertices based on the projective transformation coefficient, and extracts the maximum value and the minimum value from these. The distribution of the deformation rate ε _x changes depending on the inclination of the projector 1 with respect to the projection plane S. That is, the larger the inclination of the projector 1, the smaller the deformation rate ε _x (for example, 0.5 to 0.8), and the smaller the inclination of the projector 1, the more the deformation rate ε _x. It becomes large (for example, 0.8 to 1.0).

In step S102, the filter coefficient calculation unit 32 according to the range of deformation rates epsilon _x (minimum to maximum value), to calculate the transverse filter coefficients corresponding to a plurality of deformation ratios epsilon _x. The filter coefficient calculation unit 32 according to the present embodiment divides a range including the minimum value and the maximum value of the deformation rate ε _x in increments of 0.1, and derives filter coefficients corresponding to the respective ranges. For example, when the minimum value of the deformation rate ε _x is 0.75 and the maximum value is 1.0, four deformation rates ε _x of 0.7, 0.8, 0.9, and 1.0 are respectively set. Four corresponding filter coefficients are calculated. In order to prevent the occurrence of moire in the corrected image P1, for example, it is desirable to determine the filter coefficient so as to function as a low-pass filter having a cut-off frequency of ½ of the deformation rate. Further, the filter coefficient calculation unit 32 normalizes the sum of the filter coefficients to 1.

In step S <b> 103, the filter coefficient calculation unit 32 corrects the horizontal filter coefficient based on the luminance correction coefficient table stored in the luminance correction coefficient storage unit 33. Filter coefficient calculating unit 32, to the filter coefficient for each deformation ratio epsilon _x generated in step S102, it corrects the filter coefficients by multiplying the luminance correction coefficient corresponding to each deformation ratio epsilon _x. That is, for a certain value of the horizontal deformation rate ε _x , the filter coefficient before correction calculated in step S102 is h _ε [i] (i is the number of symbols), and the luminance correction coefficient corresponding to the deformation rate ε _x is Assuming k _ε , the corrected filter coefficient h _ε [i] ′ is as shown in Equation (4).

Next, the filter coefficient calculation unit 32 calculates the filter coefficient in the vertical direction according to the flow shown in FIG. 6 as in the horizontal direction. That is, in step S101, the filter coefficient calculation unit 32 detects the maximum value and the minimum value for the vertical deformation rate ε _y , and in step S102, the filter coefficient calculation unit 32 corresponds to the range of the deformation rate ε _y (minimum value to maximum value). The vertical filter coefficient corresponding to a plurality of deformation ratios ε _y is calculated. In step S103, the generated vertical filter coefficient is corrected with reference to the luminance correction coefficient table.

  Returning to FIG. 4, the correction processing unit 40 includes a projective transformation coefficient storage unit 41, a filter coefficient storage unit 42, a deformation rate calculation unit 43, a frame memory 44, and a filter calculation unit 45. Yes. The correction processing unit 40 performs filter processing for correcting trapezoidal distortion for the image information sequentially input from the image processing unit 24 based on the projective transformation coefficient generated by the parameter generation unit 30 and the filter coefficient for each deformation rate. The processed image information is output to the liquid crystal driving unit 14.

The projection transformation coefficient storage unit 41 stores the projection transformation coefficient calculated by the projection transformation coefficient calculation unit 31. The filter coefficient storage unit 42 stores the filter coefficient calculated by the filter coefficient calculation unit 32 for each value of the deformation ratios ε _x and ε _y .

The deformation rate calculation unit 43 calculates the deformation rates ε _x and ε _y of the pixels of the corrected image P1 that are processed by the filter calculation unit 45, and outputs them to the filter calculation unit 45. Specifically, the deformation rate calculation unit 43 uses the projective transformation coefficient to calculate the position before correction, that is, the corresponding position in the pre-correction image P0 for the pixel to be processed in the corrected image P1 and the surrounding pixels. Lead. Then, the deformation rate calculation unit 43 calculates the deformation rates ε _x and ε _y in accordance with the definitions of the deformation rates ε _x and ε _y described above.

  Image information (pixel values) before correction input from the image processing unit 24 is sequentially input to the frame memory 44. Then, the filter calculation unit 45 performs filter processing on the image information in units of frames stored in the frame memory 44, and sequentially determines the pixel value of each pixel of the corrected image P1. Specifically, the filter calculation unit 45 sets one of the pixels constituting the post-correction image P1 as a processing target, and includes the image information of the pre-correction image P0 stored in the frame memory 44 based on the projective transformation coefficient. The pixel value of the pixel to be referred to (reference pixel) is specified and extracted from the filter coefficient, and the filter coefficient corresponding to the deformation rate calculated by the deformation rate calculation unit 43 is read from the filter coefficient storage unit 42, and is used as the pixel value of the reference pixel. On the other hand, a new pixel value is determined by performing filter processing using the read filter coefficient. If the filter coefficient corresponding to the deformation rate calculated by the deformation rate calculating unit 43 is not stored in the filter coefficient storage unit 42, the filter coefficient corresponding to the closest deformation rate may be used. A corresponding filter coefficient may be derived by interpolating the deformation rate in the vicinity.

  The filter calculation unit 45 sequentially performs a horizontal filter process and a vertical filter process, and performs this for all pixels. The filter calculation unit 45 then outputs the processed image information to the liquid crystal drive unit 14. As a result, the input image Pi is projected onto the projection surface S in a state where the keystone distortion is corrected and the luminance deviation is also corrected.

  Note that the projection conversion coefficient calculation unit 31 and the filter coefficient calculation unit 32 of the parameter generation unit 30 may calculate new parameters when the inclination of the projector 1 with respect to the projection plane S changes, and processing at high speed is essential. Therefore, it is desirable to be able to realize with software. On the other hand, since the correction processing unit 40 needs to process sequentially input image information at high speed, it is desirable that the correction processing unit 40 be realized by hardware.

  As described above, according to the projector 1 of the present embodiment, the following effects can be obtained.

  (1) According to the projector 1 of the present embodiment, since the deviation in luminance is corrected by adjusting the filter coefficient for correcting the trapezoidal distortion, a circuit that corrects the trapezoidal distortion by the filter processing (correction) Using the configuration of the processing unit 40), it is possible to achieve uniform luminance. That is, it is not necessary to newly add a circuit for making the luminance uniform.

(2) According to the projector 1 of the present embodiment, the minimum value and the maximum value of the deformation ratios ε _x and ε _y are obtained in step S101, and the filter coefficient is calculated in step S102 from the minimum value to the maximum value. Since only the filter coefficient corresponding to the range is calculated, the time required for calculating the filter coefficient can be shortened. In addition, the storage capacity of the filter coefficient storage unit 42 that stores the calculated filter coefficients can be saved.

  In the present embodiment, the filter coefficient calculation unit 32 when calculating the filter coefficient in step S102 corresponds to the coefficient generation unit, and the filter coefficient calculation unit 32 when correcting the filter coefficient in step S103 is the coefficient adjustment unit. Equivalent to.

(Modification)
Moreover, you may change the said embodiment as follows.

In the above embodiment, the brightness correction coefficient storage unit 33 stores a brightness correction coefficient table in which brightness correction coefficients are associated with a plurality of values of the deformation rates ε _x and ε _y. You may make it memorize | store the numerical formula represented as a function of deformation rate (epsilon) _x , (epsilon) _y .

In the above embodiment, the deformation rate calculation unit 43 calculates the deformation rates ε _x and ε _y for each pixel, but is not limited to this mode. For example, the deformation ratios ε _x and ε _y may be calculated for each region including a plurality of pixels.

  In the above-described embodiment, the projector 1 may be a three-plate projector that modulates color image light using three liquid crystal light valves 12 that respectively transmit red light, green light, and blue light. The liquid crystal light valve 12 may include a sub-pixel that can transmit red light, green light, and blue light.

  In the above-described embodiment, the transmissive liquid crystal light valve 12 is used as the light modulator, but a reflective light modulator such as a reflective liquid crystal light valve may be used. In addition, it is possible to use a micromirror array device that modulates light emitted from a light source by controlling the emission direction of incident light for each micromirror as a pixel.

  In the above embodiment, the light source device 11 is constituted by the discharge-type light source lamp 11a. However, the light source device 11 may be applied to a solid light source such as an LED (Light Emitting Diode) light source or a laser light source, or other light sources. it can.

  DESCRIPTION OF SYMBOLS 1 ... Projector, 10 ... Image projection part, 11 ... Light source device, 11a ... Light source lamp, 11b ... Reflector, 12 ... Liquid crystal light valve, 12a ... Pixel area, 13 ... Projection lens, 14 ... Liquid crystal drive part, 20 ... Control part DESCRIPTION OF SYMBOLS 21 ... Memory | storage part 22 ... Operation panel 23 ... Image information input part 24 ... Image processing part 25 ... Image correction part 30 ... Parameter generation part 31 ... Projection conversion coefficient calculation part 32 ... Filter coefficient calculation part 33... Luminance correction coefficient storage unit 40... Correction processing unit 41. Projection conversion coefficient storage unit 42. Filter coefficient storage unit 43. Deformation rate calculation unit 44 44 Frame memory 45 45 Filter operation unit P 0. Pre-correction image, P1 ... post-correction image, Pi ... input image, S ... projection plane.

Claims (8)

A projector that projects an image based on image information,
A parameter generator for generating a filter coefficient for filter processing for correcting the trapezoidal distortion of the image;
A correction processing unit that performs the filter processing on the image information using the filter coefficient generated by the parameter generation unit;
An image projection unit that projects the image based on the image information corrected by the correction processing unit;
With
The parameter generation unit includes a coefficient generation unit that generates the filter coefficient so that the trapezoidal distortion is corrected, and a coefficient adjustment unit that adjusts the filter coefficient so as to correct a luminance deviation associated with the trapezoidal distortion. A projector comprising: The projector according to claim 1,
The coefficient generation unit generates the filter coefficient in association with a deformation rate representing a degree of deformation of the image due to the trapezoidal distortion,
The projector is characterized in that the coefficient adjustment unit adjusts the filter coefficient generated by the coefficient generation unit in accordance with a deformation rate corresponding to the filter coefficient. The projector according to claim 2,
The projector according to claim 1, wherein the coefficient adjustment unit multiplies the filter coefficient generated by the coefficient generation unit by a luminance correction coefficient corresponding to a deformation rate corresponding to the filter coefficient. The projector according to claim 2, wherein
The correction processing unit includes: a deformation rate calculating unit that calculates the deformation rate for each position of the image; and the deformation rate calculated by the deformation rate calculating unit among the filter coefficients generated by the parameter generating unit. A filter operation unit that performs the filtering process using a filter coefficient corresponding to
A projector characterized by comprising: A method of controlling a projector that projects an image based on image information,
A parameter generating step for generating a filter coefficient for filtering to correct the trapezoidal distortion of the image;
Using the filter coefficient generated in the parameter generation step, a correction processing step for performing the filter processing on the image information;
An image projection step of projecting the image based on the image information corrected in the correction processing step;
With
The parameter generating step includes a coefficient generating step for generating the filter coefficient so that the trapezoidal distortion is corrected, and a coefficient adjusting step for adjusting the filter coefficient so as to correct a luminance deviation associated with the trapezoidal distortion. And a projector control method. A projector control method according to claim 5, comprising:
In the coefficient generation step, the filter coefficient is generated in association with a deformation rate representing a degree of deformation of the image due to the trapezoidal distortion,
In the coefficient adjustment step, the filter coefficient generated in the coefficient generation step is adjusted in accordance with a deformation rate corresponding to the filter coefficient. The projector control method according to claim 6, comprising:
In the coefficient adjustment step, the projector control method is characterized in that the filter coefficient generated in the coefficient generation step is multiplied by a luminance correction coefficient corresponding to a deformation rate corresponding to the filter coefficient. A projector control method according to claim 6 or 7,
The correction processing step includes: a deformation rate calculation step for calculating the deformation rate for each position of the image; and the deformation rate calculated in the deformation rate calculation step among the filter coefficients generated in the parameter generation step. A filter operation step for performing the filtering process using a filter coefficient corresponding to
A projector control method comprising:

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