JP4973563B2 - Crosstalk measurement method, image processing apparatus, and crosstalk measurement system - Google Patents

Description

  The present invention relates to a crosstalk measurement method, an image processing apparatus, and a crosstalk measurement system for measuring the influence of crosstalk of a light modulation element.

  Currently, a liquid crystal panel as a light modulation element is mounted on a consumer display device such as a liquid crystal television, a projector, or a projection television, and an image can be displayed by modulating light from a light source by the liquid crystal panel. Such a display device using a liquid crystal panel is also employed in business fields such as a viewing field in a movie theater or a museum, an advertising field, a display for CAD (Computer Aided Design), and the above-described display device for consumers. In comparison, it is often required to display a larger and higher-definition image.

  Generally, the image quality of a display image using a liquid crystal panel is improved by reducing jaggies, reducing color unevenness, removing noise, reducing crosstalk, and the like, and various improvement techniques have been conventionally known. Among them, a technique for correcting crosstalk that appears as noise such as tailing of a display image is disclosed in Patent Document 1, for example.

  This Patent Document 1 discloses a technique for integrating a difference between a reference signal and an image signal for each horizontal scanning and adding the integration result to a corresponding image signal. Since a voltage for canceling the influence due to potential fluctuation can be applied between the pixel electrode and the counter electrode, a technique for preventing a deterioration in display quality due to so-called lateral crosstalk is disclosed.

JP 2002-116735 A

  However, in Patent Document 1, the crosstalk correction is performed on the assumption that the deterioration in display quality due to crosstalk has no correlation with the position of the black region. For this reason, even when the technique disclosed in Patent Document 1 is used, there are cases in which deterioration of display quality cannot be prevented, and it has been desired that the influence of crosstalk to be corrected can be accurately measured.

  The present invention has been made in view of the technical problems as described above, and one of its purposes is a crosstalk measurement method, an image processing apparatus, and a crosstalk that can accurately measure the crosstalk characteristics of a light modulation element. To provide a measurement system.

In order to solve the above problems, the present invention is a crosstalk measuring method for measuring the influence of crosstalk of a light modulation element from a display image using the light modulation element,
A first image information acquisition step of acquiring image information of a plurality of pixels at a given measurement pixel position in a halftone image displayed using the light modulation element;
A second image information acquisition step of acquiring image information of a plurality of pixels at the measurement pixel position in the measurement image displayed using the light modulation element;
A characteristic information calculation step of calculating crosstalk characteristic information of the light modulation element based on the image information acquired in the first image information acquisition step and the image information acquired in the second image information acquisition step; Including
The measurement image is
The halftone image is a background image, and includes first and second patterns arranged at a given interval in a given scanning direction and having gradations different from the gradation of the halftone image.
See
The crosstalk characteristic information is information obtained by averaging luminance difference change information in the horizontal scanning direction of the light modulation element in which the first and second patterns exist, for each pixel position or sampled pixel position, The present invention relates to a crosstalk measurement method quantified by a luminance difference with a halftone image between a first pattern and a second pattern .

In the present invention, when an image is displayed using a light modulation element, image information of a plurality of pixels at measurement pixel positions in the halftone image is acquired in the first image information acquisition step, and second image information is acquired. In the acquisition step, image information of a plurality of pixels at the measurement pixel positions in the measurement image is acquired. The measurement image includes the first and second patterns having a halftone image as a background image and arranged at a given interval in the horizontal scanning direction and having gradations different from the gradation of the halftone image. The portion where the image information changes due to the influence of the crosstalk of the light modulation element tends to appear around the first and second patterns. Therefore, the characteristic information calculation step, since to calculate the crosstalk characteristic information as a change information of the luminance difference in the horizontal scanning direction of the optical modulator based on the image information of the two images, the horizontal scanning direction light The influence of the crosstalk of the modulation element can be measured not only by the trailing tail of the first pattern, but also by the simple measuring means for the luminance change in the front of the second pattern , and the crosstalk characteristics. It can be quantified as information. In addition, the change in luminance difference caused by crosstalk is not single, and even if the luminance difference changes in the opposite direction to the other pixel positions, the crosstalk in the horizontal scanning direction does not matter whether the luminance difference is positive or negative. The influence can be reduced. As a result, it is possible to provide a crosstalk measurement method that can contribute to correction for reducing the influence of crosstalk, and has an exceptional effect.

  In the crosstalk measurement method according to the present invention, the scanning direction may be a horizontal scanning direction of the light modulation element.

  According to the present invention, image information is acquired using a measurement image in which first and second patterns are arranged at a given interval in a scanning direction in an image corresponding to a horizontal scanning direction of a light modulation element. As a result, the influence of the crosstalk in the horizontal scanning direction, which causes the display quality to deteriorate more than the vertical scanning direction of the light modulation element, can be measured with high accuracy.

  In the crosstalk measurement method according to the present invention, the first and second patterns may be patterns having a rectangular shape.

  According to the present invention, the change in the image information becomes steep, and the influence of the crosstalk can be expressed more significantly in the change in the image information. Therefore, the influence of the crosstalk can be measured with higher accuracy.

  In the crosstalk measurement method according to the present invention, when the width of the first pattern in the scanning direction is h, the interval may be not less than h and less than 3 × h.

  In a sensory experiment by a plurality of viewers, when the interval d is greater than or equal to h, the influence of crosstalk becomes conspicuous in the region between the first and second patterns P1 and P2, and the interval d is about 2 × h. In some cases, the effect of crosstalk was most noticeable in the region, and when the distance d was 3 × h, the effect of crosstalk became less noticeable. Therefore, according to the present invention, it is possible to improve the measurement accuracy of the influence of crosstalk by searching for the interval d in the range of h ≦ d <3 × h in consideration of the manufacturing variation of the light modulation element. become.

  In the crosstalk measurement method according to the present invention, the operation mode of the light modulation element may be a normally white mode, and the first and second patterns may be black patterns.

  According to the present invention, when the operation mode of the light modulation element is the normally white mode, since the measurement image in which the first and second patterns are black patterns is used, the light whose operation mode is normally white mode is used. The influence of the crosstalk of the modulation element can be measured with higher accuracy than when the first and second patterns have other gradations.

  In the crosstalk measurement method according to the present invention, the operation mode of the light modulation element may be a normally black mode, and the first and second patterns may be white patterns.

  According to the present invention, when the operation mode of the light modulation element is the normally black mode, the measurement image in which the first and second patterns are white patterns is used. The influence of the crosstalk of the modulation element can be measured with higher accuracy than when the first and second patterns have other gradations.

  In the crosstalk measurement method according to the present invention, the image information may be luminance.

  According to the present invention, image information can be acquired with high accuracy by a simple measuring means.

Further, the present invention is an image processing apparatus for measuring the influence of crosstalk of a light modulation element from a display image using the light modulation element,
Image information of a plurality of pixels at a given measurement pixel position in a halftone image displayed using the light modulation element, and at the measurement pixel position in a measurement image displayed using the light modulation element An image information acquisition unit that acquires image information of a plurality of pixels;
A characteristic information calculation unit that calculates crosstalk characteristic information of the light modulation element based on the image information of the halftone image acquired by the image information acquisition unit and the image information of the measurement image;
The measurement image is
The halftone image as a background image, viewing including the first and second patterns having gradations different from the tone of the halftone image are spaced a given distance in a given scanning direction,
The crosstalk characteristic information is information obtained by averaging change information of luminance difference in the horizontal scanning direction of the light modulation element in which the first and second patterns exist for each pixel position or sampled pixel position, The present invention relates to an image processing apparatus quantified by a luminance difference with a halftone image between the first and second patterns .

  In the present invention, when an image is displayed using a light modulation element, the image information acquisition unit includes the image information of a plurality of pixels at the measurement pixel position in the halftone image and the measurement pixel in the measurement image. Image information of a plurality of pixels at the position is acquired. The measurement image includes first and second patterns having a gradation different from the gradation of the halftone image that is arranged at a given interval in a given scanning direction with the halftone image as a background image. Therefore, a portion where the image information changes due to the influence of the crosstalk of the light modulation element tends to appear around the first and second patterns. Therefore, since the characteristic information calculation unit calculates the crosstalk characteristic information of the light modulation element based on the image information of the two images, the influence of the crosstalk of the light modulation element, which could not be measured conventionally, is affected. It becomes possible to calculate the crosstalk characteristic information quantified based on the measurement result with high accuracy. As a result, it is possible to provide an image processing apparatus that can contribute to correction that reduces the influence of crosstalk.

  In the image processing apparatus according to the present invention, the scanning direction may be a horizontal scanning direction of the display image.

  According to the present invention, image information is acquired using a measurement image in which first and second patterns are arranged at a given interval in a scanning direction in an image corresponding to a horizontal scanning direction of a light modulation element. As a result, it is possible to calculate crosstalk characteristic information that accurately reflects the influence of crosstalk in the horizontal scanning direction, which causes deterioration in display quality as compared with the vertical scanning direction of the light modulation element.

  In the image processing apparatus according to the present invention, the first and second patterns may be a pattern having a rectangular shape.

  According to the present invention, the change in the image information becomes steep, and the influence of the crosstalk can be expressed more significantly in the change in the image information. Therefore, the crosstalk characteristic information that reflects the influence of the crosstalk more accurately. Can be calculated.

  In the image processing apparatus according to the present invention, when the width of the first pattern in the scanning direction is h, the interval may be h or more and less than 3 × h.

  In a sensory experiment by a plurality of viewers, when the interval d is greater than or equal to h, the influence of crosstalk becomes conspicuous in the region between the first patterns P1 and P2, and when the interval d is about 2 × h The result was that the influence of crosstalk was most noticeable in the region, and the influence of crosstalk became less noticeable when the interval d was 3 × h. Therefore, according to the present invention, the influence of crosstalk is reflected with higher accuracy by searching for the interval d in the range of h ≦ d <3 × h in consideration of the manufacturing variation of the light modulation element. Crosstalk characteristic information can be calculated efficiently.

  In the image processing apparatus according to the present invention, an operation mode of the light modulation element may be a normally white mode, and the first and second patterns may be black patterns.

  According to the present invention, when the operation mode of the light modulation element is the normally white mode, since the measurement image in which the first and second patterns are black patterns is used, the light whose operation mode is normally white mode is used. Compared to the case where the first and second patterns have other gradations, the crosstalk characteristic information that reflects the influence of the crosstalk of the modulation element with higher accuracy can be calculated.

  In the image processing apparatus according to the present invention, the operation mode of the light modulation element may be a normally black mode, and the first and second patterns may be white patterns.

  According to the present invention, when the operation mode of the light modulation element is the normally black mode, the measurement image in which the first and second patterns are white patterns is used. It is possible to calculate crosstalk characteristic information in which the influence of crosstalk of the modulation element is reflected with higher accuracy than when the first and second patterns have other gradations.

  In the image processing apparatus according to the present invention, the image information may be luminance.

  According to the present invention, image information can be acquired by a simple measuring means, which can contribute to cost reduction.

  The present invention also provides a crosstalk measurement system for measuring the influence of crosstalk of a light modulation element from a display image using the light modulation element, wherein the image display unit displays an image using the light modulation element. And an image processing apparatus according to any one of the above, and an image information measurement unit that measures image information at the measurement pixel position in the image displayed by the image display unit.

  According to the present invention, it is possible to provide a crosstalk measurement system that can accurately measure the crosstalk characteristics of a light modulation element.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

  FIG. 1 shows a configuration example of a crosstalk measurement system according to an embodiment of the present invention. FIG. 1 shows a schematic view seen from above.

  The crosstalk measurement system 10 in the present embodiment measures a crosstalk characteristic corresponding to the influence of the crosstalk of the light modulation element from a display image using the light modulation element. Such a crosstalk measurement system 10 can include a projector (image display device) PJ, an image information measurement unit IM, and an image processing device 200. In the crosstalk measurement system 10, an image is projected onto a screen SCR by a projector PJ as an image display device equipped with a liquid crystal panel as a light modulation element, and a crosstalk characteristic of the liquid crystal panel is measured from a display image on the screen SCR.

  The projector PJ is arranged so that the optical axis of the projection optical system is perpendicular to the screen SCR. The optical axis of the projector PJ is preferably arranged so as to penetrate the center position of the screen SCR. In the projector PJ, the passage rate of the liquid crystal panel irradiated with light from the light source is modulated based on the image signal corresponding to the display image, and the modulated light is projected onto the screen SCR.

  The image information measuring unit IM measures image information at a given measurement pixel position in the display image by the projector PJ projected onto the screen SCR. The image information includes luminance, illuminance, pixel values of predetermined color components, and the like, and hereinafter, the image information measuring unit IM measures the luminance. As a result, the image information measuring unit IM can be realized by simple measuring means, and the image information can be acquired with high accuracy.

  The image information measurement unit IM is preferably arranged so that the angle of view covers the entire horizontal direction of the screen SCR, and the measurement center axis of the image information measurement unit IM is arranged so as to penetrate the center position of the screen SCR. . Such a function of the image information measuring unit IM is realized by, for example, a CCD (Charge Coupled Device) image sensor. In the present embodiment, it is assumed that the image information measurement unit IM measures the luminance of all the pixels of the display image on the screen SCR in pixel units.

  The image processing apparatus 200 acquires image information measured by the image information measuring unit IM, and calculates a crosstalk characteristic of a liquid crystal panel as a light modulation element included in the projector PJ based on the image information.

  In FIG. 1, the projector PJ, the image information measurement unit IM, and the image processing device 200 are described as being provided separately. However, the projector PJ includes at least one of the image information measurement unit IM and the image processing device 200. The image information measuring unit IM may have the function of the image processing apparatus 200.

  FIG. 2 shows a configuration diagram of a configuration example of the projector PJ of FIG. In FIG. 2, the projector PJ in the present embodiment is described as being configured by a so-called three-plate type liquid crystal projector, but the projector according to the present invention is limited to that configured by a so-called three-plate type liquid crystal projector. is not.

  The projector PJ includes a light source 110, integrator lenses 112 and 114, a polarization conversion element 116, a superimposing lens 118, an R dichroic mirror 120R, a G dichroic mirror 120G, a reflection mirror 122, an R field lens 124R, and a G field lens 124G. R liquid crystal panel 130R (first light modulation element), G liquid crystal panel 130G (second light modulation element), B liquid crystal panel 130B (third light modulation element), relay optical system 140, cross dichroic prism 160 and a projection lens 170.

  The liquid crystal panels used as the R liquid crystal panel 130R, the G liquid crystal panel 130G, and the B liquid crystal panel 130B are transmissive liquid crystal display devices. The relay optical system 140 includes relay lenses 142, 144, and 146 and reflection mirrors 148 and 150.

  The light source 110 is composed of, for example, an ultra-high pressure mercury lamp, and emits light including at least R component light, G component light, and B component light. The integrator lens 112 has a plurality of small lenses for dividing the light from the light source 110 into a plurality of partial lights. The integrator lens 114 has a plurality of small lenses corresponding to the plurality of small lenses of the integrator lens 112. The superimposing lens 118 superimposes the partial light emitted from the plurality of small lenses of the integrator lens 112.

  The polarization conversion element 116 includes a polarization separation film and a λ / 2 plate, and converts light having a random polarization direction emitted from the light source 110 into linearly polarized light, for example, s-polarized light. The superimposing lens 118 is irradiated with the s-polarized light from the polarization conversion element 116.

  The light that has passed through the superimposing lens 118 is incident on the R dichroic mirror 120R. The R dichroic mirror 120R has a function of reflecting R component light and transmitting G component and B component light. The light transmitted through the R dichroic mirror 120R is applied to the G dichroic mirror 120G, and the light reflected by the R dichroic mirror 120R is reflected by the reflection mirror 122 and guided to the R field lens 124R.

  The dichroic mirror for G 120G has a function of reflecting G component light and transmitting B component light. The light transmitted through the G dichroic mirror 120G enters the relay optical system 140, and the light reflected by the G dichroic mirror 120G is guided to the G field lens 124G.

  In the relay optical system 140, in order to minimize the difference between the optical path length of the B component light transmitted through the G dichroic mirror 120G and the optical path length of the other R component and G component light, the relay lenses 142, 144, 146 is used to correct the difference in optical path length. The light transmitted through the relay lens 142 is guided to the relay lens 144 by the reflection mirror 148. The light transmitted through the relay lens 144 is guided to the relay lens 146 by the reflection mirror 150. The light transmitted through the relay lens 146 is applied to the B liquid crystal panel 130B.

  The light applied to the R field lens 124R is converted into parallel light and is incident on the R liquid crystal panel 130R. The R liquid crystal panel 130R functions as a light modulation element (light modulation unit), and the transmittance (passage rate, modulation rate) changes based on the R image signal. Therefore, the light (first color component light) incident on the R liquid crystal panel 130R is modulated based on the R image signal, and the modulated light is incident on the cross dichroic prism 160.

  The light applied to the G field lens 124G is converted into parallel light and is incident on the G liquid crystal panel 130G. The G liquid crystal panel 130G functions as a light modulation element (light modulation unit), and the transmittance (passage rate, modulation rate) changes based on the G image signal. Therefore, the light (second color component light) incident on the G liquid crystal panel 130G is modulated based on the G image signal, and the modulated light is incident on the cross dichroic prism 160.

  The B liquid crystal panel 130B irradiated with the light converted into parallel light by the relay lenses 142, 144, and 146 functions as a light modulation element (light modulation unit), and has a transmittance (passage rate) based on the B image signal. , Modulation rate) is changed. Therefore, the light (third color component light) incident on the B liquid crystal panel 130B is modulated based on the B image signal, and the modulated light is incident on the cross dichroic prism 160.

  The R liquid crystal panel 130R, the G liquid crystal panel 130G, and the B liquid crystal panel 130B have the same configuration. Each liquid crystal panel is a liquid crystal, which is an electro-optical material, sealed and encapsulated in a pair of transparent glass substrates. For example, a polysilicon thin film transistor is used as a switching element, and the transmittance of each color light is corresponding to the image signal of each pixel. Modulate.

  In this embodiment, a liquid crystal panel as a light modulation element is provided for each color component constituting one pixel, and the transmittance of each liquid crystal panel is controlled by an image signal corresponding to the pixel. That is, the image signal for the R component pixel is used to control the transmittance (passage rate, modulation factor) of the R liquid crystal panel 130R, and the image signal for the G component pixel is transmitted through the G liquid crystal panel 130G. The image signal for the B component pixel is used for controlling the transmittance of the B liquid crystal panel 130B. In the projector PJ in this embodiment, the image signal for each color component is corrected, and the corrected image signal is supplied to each liquid crystal panel provided for each color component, and the transmittance is controlled for each liquid crystal panel.

  The cross dichroic prism 160 has a function of outputting combined light obtained by combining incident light from the R liquid crystal panel 130R, the G liquid crystal panel 130G, and the B liquid crystal panel 130B as outgoing light. The projection lens 170 is a lens that enlarges and forms an output image on the screen SCR, and has a function of enlarging or reducing the image in accordance with the zoom magnification.

  Thus, the projector PJ in this embodiment displays an image using light modulated by the liquid crystal panel as the light modulation element. Therefore, when crosstalk occurs in the liquid crystal panel, the crosstalk affects the display image of the projector PJ.

  FIG. 3 shows a configuration diagram of a configuration example of the image processing apparatus 200 of FIG.

  The image processing apparatus 200 includes an image information acquisition unit 210 and a characteristic information calculation unit 220. The image processing apparatus 200 calculates the crosstalk characteristic information of the liquid crystal panel based on the measurement result of the display image of the projector PJ by the image information measuring unit IM.

  The image information acquisition unit 210 includes image information (luminance) of a plurality of pixels at a given measurement pixel position in a halftone image displayed using the liquid crystal panel (light modulation element) of the projector PJ, and the liquid crystal of the projector PJ. Image information (luminance) of a plurality of pixels at the measurement pixel position in the measurement image displayed using the panel (light modulation element) is acquired.

  Here, the measurement image uses a halftone image as a background image, and includes first and second patterns having gradations different from the gradation of the halftone image. The first and second patterns are arranged at a given interval in the scanning direction of the image corresponding to the horizontal scanning direction (given scanning direction) of the liquid crystal panel as the light modulation element. That is, the scanning direction is preferably the horizontal scanning direction of the liquid crystal panel, and is the horizontal scanning direction of the display image when the scanning direction of the liquid crystal panel matches the scanning direction of the display image. The reason why the first and second patterns are arranged in the horizontal scanning direction of the image is that the influence of the horizontal scanning direction is the influence of the crosstalk of the liquid crystal panel that appears in the horizontal scanning direction and the vertical scanning direction of the image. This is because it is more prominently recognized by human eyes.

  Further, it is desirable that the first and second patterns included in the measurement image have a rectangular shape. By doing so, the luminance change becomes steep, and the influence of crosstalk can be expressed more significantly in the luminance change.

  Further, when the operation mode of the liquid crystal panel of the projector PJ is the normally white mode, the halftone image is an image (gray image) having a gradation between the maximum value and the minimum value of the gradation values that the display image can take. It is desirable that the first and second patterns of the measurement image are black patterns. By doing so, the change in gradation is steep around the first and second patterns, and the influence of crosstalk becomes easier to see. As a result, the influence of the crosstalk of the liquid crystal panel operating in the normally white mode can be measured with higher accuracy.

  Alternatively, when the operation mode of the liquid crystal panel of the projector PJ is the normally black mode, the halftone image is an image (gray image) corresponding to the intermediate value between the maximum value and the minimum value that the display image can take. It is desirable that the first and second patterns of the measurement image are white patterns. By doing so, the change in gradation is steep around the first and second patterns, and the influence of crosstalk becomes easier to see. As a result, the influence of the crosstalk of the liquid crystal panel operating in the normally black mode can be measured with higher accuracy.

  The characteristic information calculation unit 220 of the image processing apparatus 200 obtains the crosstalk characteristic information of the liquid crystal panel of the projector PJ based on the image information of the halftone image and the image information of the measurement image acquired by the image information acquisition unit 210. calculate. The crosstalk characteristic information is calculated as luminance difference change information, color difference change information, or illuminance difference change information based on a halftone image. In the present embodiment, since the luminance from the image information measurement unit IM is acquired by the image information acquisition unit 210, the change information of the luminance difference is calculated as the crosstalk characteristic information.

  Next, the operation of the image processing apparatus 200 in this embodiment will be described. The function of the image processing apparatus 200 may be realized by hardware or software. In the following, it is assumed that the functions of the image processing apparatus 200 are realized by software processing.

  FIG. 4 shows a block diagram of a hardware configuration example of the image processing apparatus 200 of FIG.

  The image processing apparatus 200 includes a CPU 300, an I / F circuit 310, a read only memory (ROM) 320, a random access memory (RAM) 330, and a bus 340. The CPU 300, the I / F circuit 310, the ROM 320, and the RAM 330 are electrically connected.

  For example, the ROM 320 or the RAM 330 stores a program that realizes the function of the image processing apparatus 200. The CPU 300 can realize the functions of the image processing apparatus 200 by software processing by reading a program stored in the ROM 320 or the RAM 330 and executing processing corresponding to the program. Note that the RAM 330 is used as a work area for processing by the CPU 300 or as a buffer area for the I / F circuit 310 or the ROM 320. The I / F circuit 310 performs input interface processing of image information from the image information measuring unit IM.

  FIG. 5 shows a flowchart of a processing example of the image processing apparatus 200 of FIG. For example, a program for realizing the processing shown in FIG. 5 is stored in the ROM 320 or the RAM 330 in FIG. 4, and the CPU 300 reads out the program stored in the ROM 320 or the RAM 330 and executes the processing corresponding to the program. Thus, the crosstalk measurement process shown in FIG. 5 can be realized by software processing.

  FIG. 6A and FIG. 6B are explanatory diagrams of the processing of FIG. FIG. 6A shows an explanatory diagram of a background image in the process of FIG. 5, and FIG. 6B shows an explanatory diagram of a measurement image in the process of FIG.

  FIG. 7 is an explanatory diagram of a rectangular pattern of the measurement image in the process of FIG.

  As shown in FIG. 5, first, the image processing apparatus 200 causes the projector PJ to display a background image that is a halftone image on the screen SCR (step S10). For example, the image processing apparatus 200 supplies, as a halftone image, an image signal of a gray image whose gradation value is an intermediate gradation between the maximum value and the minimum value, as shown in FIG. 6A, to the projector PJ. Then, the projector PJ changes the modulation rate of the liquid crystal panel based on the image signal and projects it on the screen SCR.

  Then, the image information measuring unit IM measures the luminance of a plurality of pixels at a given measurement pixel position in the display image of the projector PJ projected onto the screen SCR in step S10. Here, the image information measuring unit IM measures the luminance of all the pixels of the halftone image that is the display image. As the first image information acquisition step, the image processing apparatus 200 acquires the image information measured by the image information measurement unit IM in the image information acquisition unit 210 (step S12).

  Next, the image processing apparatus 200 causes the projector PJ to display the measurement image on the screen SCR (step S14). For example, as shown in FIG. 6B, the image processing apparatus 200 uses the halftone image in step S10 as a background image and two black rectangles spaced by a distance d in the horizontal scanning direction as shown in FIG. An image signal of an image having a pattern (first and second patterns) is supplied to the projector PJ. The projector PJ changes the modulation rate of the liquid crystal panel based on the image signal and projects it on the screen SCR.

  Here, the two black rectangular patterns P1 and P2 (first and second patterns) have the same shape, and the length h in the horizontal scanning direction of each rectangular pattern is displayed as shown in FIG. 6B. It is set to 1/10 of the horizontal length H of the image. That is, when the sensory experiment by a plurality of viewers is repeated, the effect of crosstalk is more observable when the shape is the same, and the size ratio of the display image to the rectangular pattern is 10 regardless of the size of the display image. This is because the result that it was easy to observe the influence of crosstalk was obtained. At this time, the width h in the horizontal scanning direction of each rectangular pattern is the same as the height v in the vertical scanning direction.

  Further, as shown in FIG. 7, the edge interval d between the two black rectangular patterns P1 and P2 is h ≦ d <3 × h with respect to the horizontal scanning direction width h of the rectangular pattern P1 (or rectangular pattern P2). It is desirable to satisfy This is because, in a sensory experiment by a plurality of viewers, when the edge interval d is greater than or equal to h, the influence of crosstalk becomes conspicuous in the region between the rectangular patterns P1 and P2, and the edge interval d is about 2 × h. This is based on the result that the influence of the crosstalk is most noticeable in the region, and the influence of the crosstalk becomes less noticeable when the edge interval d is 3 × h. Therefore, from this result, the crosstalk measurement accuracy can be improved by searching for the edge interval d in the range of h ≦ d <3 × h in consideration of the manufacturing variation of the liquid crystal panel.

  After displaying the measurement image as described above, the image information measuring unit IM, as in step S12, includes a plurality of images at a given measurement pixel position among the display images of the projector PJ projected on the screen SCR in step S14. The luminance of the pixel is measured. Here, the image information measurement unit IM measures the luminance of all pixels of the measurement image. As the second image information acquisition step, the image processing apparatus 200 acquires the image information measured by the image information measurement unit IM in the image information acquisition unit 210 (step S16). More specifically, the image information acquisition unit 210 has a plurality of pixels at the measurement pixel positions in the measurement image displayed using a liquid crystal panel having two rectangular patterns with a halftone image as a background image. Get image information.

  The measurement pixel position of the image information acquired in step S16 is the same as the measurement pixel position of the image information acquired in step S12. The measurement pixel positions include the positions of the pixels of the rectangular patterns P1 and P2 and the positions of the pixels of the halftone image. In the present embodiment, the measurement pixel position may be all pixel positions in the horizontal scanning direction or pixel positions sampled for each given number of pixels. Accordingly, the image information acquisition unit 210 can capture a luminance unevenness information group (hereinafter referred to as luminance unevenness) for one or a plurality of horizontal scanning lines of the halftone image in step S12. Further, the image information acquisition unit 210 can capture a luminance unevenness information group for one or a plurality of horizontal scanning lines of the measurement image in step S16.

  Subsequently, the image processing apparatus 200 uses the image information acquired in step S12 (first image information acquisition step) and step S16 (second image information acquisition step) as the characteristic information calculation step in the characteristic information calculation unit 220. The crosstalk characteristic information of the liquid crystal panel is calculated based on the image information acquired in () (step S18), and a series of processing ends (end).

  The characteristic information calculation unit 220 uses one or more of the measurement images acquired in step S16 for each pixel position with reference to luminance unevenness of one or more horizontal scanning lines of the halftone image acquired in step S12. A luminance difference for a plurality of horizontal scanning lines is calculated. In step S12 and step S16, since the luminance of the same horizontal scanning line is acquired, the characteristic information calculation unit 220 uses the change information of the luminance difference for one or a plurality of horizontal scanning lines with reference to the halftone image. Certain crosstalk characteristic information can be calculated.

  FIG. 8 is an explanatory diagram of crosstalk measured in the process of FIG. In FIG. 8, the vertical axis represents the luminance difference with reference to the halftone image, and the horizontal axis represents the change in the luminance difference when the horizontal pixel position is represented.

  That is, the characteristic information calculation unit 220 determines the luminance tail portion appearing in the horizontal scanning direction of the rectangular pattern as the crosstalk to be measured, and uses this portion as the crosstalk characteristic information due to the influence of the crosstalk as the background image. The luminance difference is calculated. Therefore, in the crosstalk characteristic information calculated by the characteristic information calculation unit 220, the influence of the crosstalk can be quantified as a luminance difference of the crosstalk part. Therefore, by correcting the image signal so that the luminance difference in the crosstalk portion is reduced, the influence of the crosstalk can be reduced and the display quality can be improved.

  Further, according to the present embodiment, since the luminance unevenness is measured using the halftone image and the measurement image as described above, the measurement is not performed by the conventional crosstalk measurement method as described below. It becomes easy to observe the influence of the crosstalk of the liquid crystal panel that has been possible, the influence of the crosstalk can be measured with higher accuracy, and it can contribute to the crosstalk correction that can further reduce the influence of the crosstalk.

  FIG. 9 shows an example of the measurement result of the measurement image measured by the crosstalk measurement method in the present embodiment. FIG. 9 shows a change in luminance difference from the halftone image averaged for each pixel block divided in the horizontal direction and the vertical direction of the display image. Note that FIG. 9 shows the measurement result of the luminance difference when the edge interval d at which the crosstalk is most easily observed is 2 × h.

  FIG. 9 shows a luminance difference with the halftone image of the entire measurement image, and the luminance difference with the halftone image protrudes in the pixel block corresponding to the rectangular patterns P1 and P2 in the measurement image. In the pixel blocks around the rectangular patterns P1 and P2, the brightness difference from the halftone image is particularly large, and the brightness unevenness is measured.

  When attention is paid to the luminance unevenness in the horizontal direction (horizontal scanning direction) in FIG. 9, the luminance difference from the halftone image is the largest in the region between the rectangular patterns P1 and P2, and this is due to the influence of crosstalk. It is believed that there is. On the other hand, when attention is paid to the luminance unevenness in the vertical direction (vertical scanning direction) in FIG. 9, a luminance difference with a slight amplitude appears in the pixel blocks adjacent to the rectangular patterns P1 and P2. Therefore, according to the method for measuring crosstalk in the present embodiment, it can be seen that the deterioration of display quality is mainly caused by crosstalk in the horizontal scanning direction. As a result, it can be seen that display quality degradation can be greatly reduced and crosstalk in the vertical scanning direction can be ignored by simply correcting the crosstalk for the image signal corresponding to the pixels in the horizontal scanning direction.

  Therefore, the following luminance difference change information is calculated as crosstalk characteristic information from the measurement result obtained by the crosstalk measurement method according to the present embodiment, and the corresponding pixel is handled based on the luminance difference change information. By correcting the image signal, the influence of crosstalk can be reduced.

  FIG. 10 shows an example of crosstalk characteristic information obtained from the measurement result of the crosstalk measurement method in the present embodiment. In FIG. 10, the vertical axis represents the luminance difference from the halftone image, and the horizontal axis represents the pixel position in the horizontal direction.

  The crosstalk characteristic information shown in FIG. 10 is information obtained by averaging luminance difference change information in a scanning line having a rectangular pattern in the horizontal scanning direction for each pixel position or each sampled pixel position. As a result, the luminance difference ΔL with the halftone image between the rectangular patterns P1 and P2 is quantified, so that the influence of crosstalk in the horizontal scanning direction can be quantified.

  Therefore, when the crosstalk characteristic in the horizontal scanning direction as shown in FIG. 10 is quantified in one screen by ignoring the crosstalk in the vertical scanning direction as described above, the crosstalk of the image corresponding to the display image is quantified. Can be corrected based on the above-described crosstalk characteristic information, thereby contributing to display of an image in which the influence of crosstalk is reduced.

  In this case, for example, a plurality of measurement images having rectangular patterns P1 and P2 in which each measurement image is shifted in the horizontal scanning direction in the image are prepared, and the crosstalk characteristic information of FIG. 10 is obtained using each measurement image. calculate. As a result, the influence of the crosstalk in the horizontal scanning direction of the liquid crystal panel on which the measurement image is displayed can be quantitatively determined, and the correction of the image signal of the pixel corresponding to the display image can be performed with high accuracy. Therefore, it is possible to reduce display quality degradation caused by crosstalk, which could not be realized by the conventional crosstalk measurement method.

  In addition, according to the crosstalk measurement method in the present embodiment, the existence of the dependency on the display position of the rectangular pattern, which was not understood by the conventional measurement method, was found from the measurement results.

  FIG. 11A, FIG. 11B, and FIG. 11C are explanatory diagrams of the display position of the rectangular pattern. FIG. 11A shows an explanatory diagram of a first measurement image in which the rectangular patterns P1 and P2 are located on the upper left of the image. FIG. 11B illustrates an explanatory diagram of a second measurement image in which the rectangular patterns P1 and P2 are located at the center of the image. FIG. 11C shows an explanatory diagram of a third measurement image in which the rectangular patterns P1 and P2 are located at the lower right of the image.

  11A to 11C, the gradation values, edge intervals, shapes, and sizes of the rectangular patterns P1 and P2 are all the same, and only the positions in the image are different. The measurement results of the crosstalk measurement method of the present embodiment using the respective measurement images of FIGS. 11A to 11C are as follows.

  FIG. 12 shows an example of measurement results of the crosstalk measurement method of the present embodiment using the measurement images of FIGS. 11 (A) to 11 (C). In FIG. 12, the vertical axis represents the luminance difference from the halftone image, the horizontal axis represents the horizontal pixel position in the image, and the halftones using the respective measurement images of FIGS. 11 (A) to 11 (C). This represents the change in luminance difference from the image. The crosstalk characteristic information shown in FIG. 12 is also averaged for each pixel position or each sampled pixel position, as in FIG. 10, the change information of the luminance difference in the scanning line in the horizontal scanning direction where the rectangular pattern exists. Information.

  In FIG. 12, the measurement result C1 according to the crosstalk measurement method of the present embodiment when using the measurement image of FIG. 11A, and the present embodiment using the measurement image of FIG. 11B. The measurement result C2 by the crosstalk measurement method and the measurement result C3 by the crosstalk measurement method of the present embodiment when using the measurement image of FIG. 11C depend on the display position of the rectangular pattern. It can be seen that the effect of crosstalk is different. In each measurement result, if attention is paid to the change in the luminance difference between the rectangular patterns, the change in the amplitude and the gradient of the luminance difference change, and the influence of the crosstalk is indicated by horizontal scanning as indicated by D1 in FIG. In the direction, it can be seen that there is a tendency for a mountain having the largest luminance difference near the center of the image.

  According to the conventional crosstalk measurement method, the crosstalk has no correlation with the position of the rectangular pattern. Therefore, even if the crosstalk is corrected based on the conventional measurement method, the display quality of the crosstalk is not improved. The part which suppresses deterioration and the part which cannot be suppressed will arise. On the other hand, according to the crosstalk measurement method in the present embodiment, crosstalk means that there is a correlation with the display position of the rectangular pattern, so the influence of crosstalk in the horizontal scanning direction is applied to the pixel position. Therefore, the display quality can be reliably prevented from being deteriorated.

  Further, when paying attention to the measurement result C3, there is a portion where the luminance difference with the halftone image becomes negative due to the influence of the crosstalk, and the change in the luminance difference due to the crosstalk is not in a single direction, but with other pixel positions. It can be seen that there is a portion where the luminance difference changes in the opposite direction.

  According to the conventional crosstalk measurement method, the influence of the crosstalk is limited to a single direction. Therefore, even if the crosstalk is corrected based on the conventional measurement method, the display quality is not deteriorated due to the crosstalk. The part to suppress and the part which cannot be suppressed will arise. On the other hand, the crosstalk measurement method in the present embodiment means that the influence of the crosstalk is not limited to a single direction. Therefore, regardless of whether the luminance difference is positive or negative, The influence of crosstalk can be reduced, and display quality can be reliably prevented from deteriorating.

  Furthermore, in the crosstalk measurement method according to the present embodiment, it is desirable that the relationship between the gradation of the rectangular pattern and the gradation of the halftone image is as follows. In the following description, it is assumed that the operation mode of the liquid crystal panel is the normally black mode. However, the operation mode of the liquid crystal panel can be considered similarly for the normally white mode.

  FIG. 13A, FIG. 13B, and FIG. 13C are explanatory diagrams of gradation of a rectangular pattern. FIG. 13A shows an explanatory diagram of a rectangular pattern in which the gradation values of the rectangular patterns P1 and P2 are the minimum value (black) of all possible gradation values. FIG. 13B illustrates a rectangular pattern in which the gradation values of the rectangular patterns P1 and P2 are different from the gradation value of the halftone image in the vicinity of the intermediate value between the maximum value and the minimum value of all possible gradation values. Represents the figure. FIG. 13C is an explanatory diagram of a rectangular pattern in which the gradation values of the rectangular patterns P1 and P2 are the maximum value (white) among all possible gradation values.

  13A to 13C, the display positions, edge intervals, shapes, and sizes of the rectangular patterns P1 and P2 are all the same, and only the gradation values are different. The measurement results of the crosstalk measurement method of this embodiment using the respective measurement images of FIGS. 13A to 13C are as follows.

  FIG. 14 shows an example of the measurement result of the crosstalk measurement method of the present embodiment using measurement images having a plurality of types of gradation rectangular patterns including those shown in FIGS. 13 (A) to 13 (C). In FIG. 14, the vertical axis represents the luminance difference from the halftone image, the horizontal axis represents the horizontal pixel position in the image, and the halftone using each of a plurality of measurement images having a plurality of types of rectangular patterns. This represents the change in luminance difference from the image. The crosstalk characteristic information shown in FIG. 14 is also averaged for each pixel position or each sampled pixel position, as in FIG. 10, the change information of the luminance difference in the scanning line in the horizontal scanning direction where the rectangular pattern exists. Information.

  In FIG. 14, as the gradation value of the rectangular pattern is smaller, the luminance difference from the halftone image in the region between the rectangular patterns P1 and P2 changes in the positive direction. However, paying attention to the absolute value of the luminance difference, the luminance difference from the halftone image is larger when the gradation value of the rectangular pattern is the maximum value (white) than when the gradation value is the minimum value (black). . That is, when the operation mode of the liquid crystal panel is the normally black mode, the brightness difference between the rectangular pattern P1 and P2 in the region between the rectangular patterns P1 and P2 increases as the gradation of the rectangular patterns P1 and P2 becomes white, It becomes easier to observe the effect of talk. Therefore, when the operation mode of the liquid crystal panel is the normally black mode, the influence of crosstalk can be measured with higher accuracy by using the rectangular patterns P1 and P2 whose gradation is white.

  It should be noted that by adopting an image having an intermediate gradation of the maximum value and the minimum value as the halftone image, a change in gradation due to crosstalk tends to appear as a change in luminance. This is apparent from the known gradation characteristics of the liquid crystal panel as the light modulation element. Therefore, a halftone image having an intermediate gradation is adopted as the background image, and when the operation mode of the liquid crystal panel is a normally black mode, the measurement images of the rectangular patterns P1 and P2 having a white gradation are adopted. Is desirable.

  Similarly, when the operation mode of the liquid crystal panel is the normally white mode, the luminance difference from the halftone image in the region between the rectangular patterns P1 and P2 increases as the gradation of the rectangular patterns P1 and P2 is black. It means to become. Therefore, when the operation mode of the liquid crystal panel is the normally white mode, it is considered that the influence of crosstalk can be measured with higher accuracy by using the rectangular patterns P1 and P2 whose gradation is black.

  Therefore, a halftone image having an intermediate gradation is adopted as the background image, and when the operation mode of the liquid crystal panel is the normally white mode, the measurement images of the rectangular patterns P1 and P2 having the gradation of black are adopted. Is desirable.

  The crosstalk measurement method, the image processing apparatus, and the crosstalk measurement system according to the present invention have been described based on the above embodiments, but the present invention is not limited to the above embodiments and departs from the gist thereof. The present invention can be implemented in various modes as long as it is not, for example, the following modifications are possible.

  (1) Although the liquid crystal panel has been described as an example of the light modulation element in the above embodiment, the present invention is not limited to this.

  (2) In the above embodiment, the light valve is used as the light modulation element. However, the present invention is not limited to this.

  (3) In the above embodiment, a light valve using a so-called three-plate transmissive liquid crystal panel as the light modulation element has been described as an example. However, a light valve using a transmissive liquid crystal panel of four or more plates is used. It may be adopted.

  (4) In the above embodiment, the present invention has been described as a crosstalk measurement method, an image processing apparatus, and a crosstalk measurement system, but the present invention is not limited to this. For example, it may be a program in which a processing procedure of a crosstalk measurement method for realizing the present invention is described, or a recording medium on which the program is recorded.

The figure which shows the structural example of the crosstalk measurement system in embodiment which concerns on this invention. The block diagram of the structural example of the projector of FIG. The block diagram of the structural example of the image processing apparatus of FIG. FIG. 2 is a block diagram of a hardware configuration example of the image processing apparatus in FIG. 1. FIG. 2 is a flowchart of a processing example of the image processing apparatus in FIG. 1. 6A and 6B are explanatory diagrams of the processing of FIG. Explanatory drawing of the rectangular pattern of the image for a measurement in the process of FIG. Explanatory drawing of the crosstalk measured in the process of FIG. The figure which shows an example of the measurement result of the image for a measurement measured by the measuring method of the crosstalk in this embodiment. The figure which shows an example of the crosstalk characteristic information calculated | required from the measurement result of the measuring method of the crosstalk in this embodiment. FIG. 11A, FIG. 11B, and FIG. 11C are explanatory diagrams of display positions of rectangular patterns. FIG. 12 is a diagram illustrating an example of a measurement result of the crosstalk measurement method of the present embodiment using the measurement images of FIGS. 11 (A) to 11 (C). FIGS. 13A, 13B, and 13C are explanatory diagrams of gradations of a rectangular pattern. The figure which shows an example of the measurement result of the measuring method of the crosstalk of this embodiment using the image for a measurement which has a rectangular pattern of multiple types of gradations to include.

Explanation of symbols

10 ... Crosstalk measurement system 110 ... Light source,
112, 114 ... integrator lens, 116 ... polarization conversion element,
118 ... Superimposing lens, 120R ... R dichroic mirror,
120G ... Dichroic mirror for G, 122,148,150 ... Reflective mirror,
124R ... R field lens, 124G ... G field lens,
130R ... R liquid crystal panel, 130G ... G liquid crystal panel,
130B ... Liquid crystal panel for B, 140 ... Relay optical system,
142, 144, 146 ... relay lens, 160 ... cross dichroic prism,
170 ... Projection lens, 200 ... Image processing device, 210 ... Image information acquisition unit,
220 ... characteristic information calculation unit, 300 ... CPU, 310 ... I / F circuit,
320 ... ROM, 330 ... RAM, 340 ... bus, IM ... image information measuring unit,
PJ ... Projector, SCR ... Screen

Claims (11)

A crosstalk measurement method for measuring the influence of crosstalk of a light modulation element from a display image using the light modulation element,
A first image information acquisition step of acquiring image information of a plurality of pixels at a given measurement pixel position in a halftone image displayed using the light modulation element;
A second image information acquisition step of acquiring image information of a plurality of pixels at the measurement pixel position in the measurement image displayed using the light modulation element;
A characteristic information calculation step of calculating crosstalk characteristic information of the light modulation element based on the image information acquired in the first image information acquisition step and the image information acquired in the second image information acquisition step; Including
The measurement image is
The halftone image is a background image, and includes first and second patterns arranged at a given interval in a given scanning direction and having gradations different from the gradation of the halftone image.
See
The crosstalk characteristic information is information obtained by averaging luminance difference change information in the horizontal scanning direction of the light modulation element in which the first and second patterns exist, for each pixel position or sampled pixel position, Quantified by luminance difference between halftone image between first and second pattern
Crosstalk measurement wherein a call. Oite to claim 1,
The first and second patterns are:
A crosstalk measuring method, wherein the pattern has a rectangular shape. In claim 1 or 2 ,
When the width of the first pattern in the scanning direction is h,
The interval is
A crosstalk measuring method, wherein h is less than 3 × h. In any one of Claims 1 thru | or 3 ,
The operation mode of the light modulation element is a normally white mode,
The method for measuring crosstalk, wherein the first and second patterns are black patterns. In any one of Claims 1 thru | or 3 ,
The operation mode of the light modulation element is a normally black mode,
The crosstalk measuring method, wherein the first and second patterns are white patterns. An image processing apparatus for measuring the influence of crosstalk of a light modulation element from a display image using the light modulation element,
Image information of a plurality of pixels at a given measurement pixel position in a halftone image displayed using the light modulation element, and at the measurement pixel position in a measurement image displayed using the light modulation element An image information acquisition unit that acquires image information of a plurality of pixels;
A characteristic information calculation unit that calculates crosstalk characteristic information of the light modulation element based on the image information of the halftone image acquired by the image information acquisition unit and the image information of the measurement image;
The measurement image is
The halftone image as a background image, viewing including the first and second patterns having gradations different from the tone of the halftone image are spaced a given distance in a given scanning direction,
The crosstalk characteristic information is information obtained by averaging change information of luminance difference in the horizontal scanning direction of the light modulation element in which the first and second patterns exist for each pixel position or sampled pixel position, Quantified by the difference in luminance from the halftone image between the first and second patterns
The image processing apparatus according to claim and this. In claim 6 ,
The first and second patterns are:
An image processing apparatus characterized by being a pattern having a rectangular shape. In claim 6 or 7 ,
When the width of the first pattern in the scanning direction is h,
The interval is
An image processing apparatus, wherein h is less than 3 × h. In any of claims 6 to 8 ,
The operation mode of the light modulation element is a normally white mode,
The image processing apparatus according to claim 1, wherein the first and second patterns are black patterns. In any of claims 6 to 8 ,
The operation mode of the light modulation element is a normally black mode,
The image processing apparatus according to claim 1, wherein the first and second patterns are white patterns. A crosstalk measurement system for measuring the influence of crosstalk of a light modulation element from a display image using the light modulation element,
An image display unit for displaying an image using the light modulation element;
An image processing apparatus according to any one of claims 6 to 10 ,
A crosstalk measurement system, comprising: an image information measurement unit that measures image information at the measurement pixel position in the image displayed by the image display unit.