JP2009253331A - Correction value table generating method, correction value table generating apparatus and image processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a correction value table generating method for highly precisely correcting the deterioration in display quality resulting from crosstalk of an optical modulation element, and to provide a correction value table generating apparatus and an image processing apparatus. <P>SOLUTION: The correction value table generating method for generating a correction value table for correcting an image signal corresponding to a display image using the optical modulation element includes: a crosstalk characteristic curve calculating step of calculating a crosstalk characteristic curve of the display image based on the characteristic information for a plurality of scanning lines of the display image; an approximate value calculating step of calculating an approximate value in a given scanning direction of the display image from the crosstalk characteristic curve calculated in the crosstalk characteristic curve calculating step; and a correction value calculating step of calculating a correction value of the image signal based on the approximate value calculated in the approximate value calculating step. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a correction value table generation method, a correction value table generation device, and an image processing apparatus including a correction value table.

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, for example, a viewing field in a movie theater or a museum, an advertising field, a CAD (Computer Aided Desig).
It is also adopted in business fields such as n) displays, and it is often required to display larger and higher-definition images as compared with the consumer display devices described above.

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 if the technique disclosed in Patent Document 1 is used, there is a problem that there is a case where deterioration of display quality cannot be prevented.

The present invention has been made in view of the technical problems as described above, and one of its purposes is as follows.
An object of the present invention is to provide a correction value table generation method, a correction value table generation device, and an image processing device for accurately correcting deterioration of display quality caused by crosstalk of light modulation elements.

In order to solve the above-described problems, the present invention provides a correction value table generation method for generating a correction value table for correcting an image signal corresponding to a display image using a light modulation element, wherein a plurality of scans of the display image are performed. A crosstalk characteristic curve calculating step for calculating a crosstalk characteristic curve of the display image based on characteristic information for a line, and the crosstalk characteristic curve calculated in the crosstalk characteristic curve calculating step, A correction including an approximate value calculation step of calculating an approximate value in a given scanning direction, and a correction value calculation step of calculating a correction value of the image signal based on the approximate value calculated in the approximate value calculation step Related to value table generation method.

According to the present invention, the crosstalk characteristic curve of the display image is calculated based on the characteristic information for a plurality of scanning lines of the display image, and the correction value of the image signal is calculated based on the approximate value of the crosstalk characteristic curve. As a result, display quality degradation caused by crosstalk of the light modulation element can be accurately corrected from a display image using the light modulation element.

In the correction value table generating method according to the present invention, the crosstalk characteristic curve calculating step includes an extraction step of extracting a crosstalk occurrence portion from the characteristic information of each scanning line, and an interpolation of the removal portion removed in the extraction step. An interpolation step for obtaining interpolation characteristic information for each scanning line, and an averaging step for averaging the interpolation characteristic information for the plurality of scanning lines obtained in the interpolation step to calculate the crosstalk characteristic curve. Can do.

According to the present invention, as a result of extracting the crosstalk occurrence portion from the characteristic information, the crosstalk characteristic curve is calculated based on the interpolation characteristic information obtained by interpolating the removed removal portion. A well-reflected crosstalk characteristic curve can be obtained, and display quality degradation caused by crosstalk can be corrected with higher accuracy.

In the correction value table generation method according to the present invention, the characteristic information includes image information acquired for each given number of pixels of each scanning line, and the interpolation step is performed by extracting the extraction step. The interpolation characteristic information can be obtained using corrected image information obtained by averaging a plurality of pieces of image information including image information at the endmost part of the crosstalk occurrence portion.

According to the present invention, it is possible to avoid a situation in which when the image information at the endmost part is used, the change in the image information becomes too large and the correction value error becomes large.

In the correction value table method according to the present invention, when the gradation value of the pixel is G, the image information of the characteristic information corresponding to the position of the pixel is L, and the approximate value is P, the correction value calculating step The correction value calculated in step (G) may be (G−G × L / P).

  According to the present invention, a correction value can be generated with a simple process.

  In the correction value table method according to the present invention, the characteristic information may be luminance.

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

In the correction value table method according to the present invention, 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 repeatedly acquiring image information of a plurality of pixels at the measurement pixel positions in each measurement image constituting a plurality of measurement images displayed using the light modulation element; A characteristic information calculation step for calculating crosstalk characteristic information of the display image based on the image information acquired in the first image information acquisition step and the plurality of image information acquired in the second image information acquisition step; And each of the measurement images constituting the plurality of measurement images is arranged at a given interval in the scanning direction with the halftone image as a background image. Includes first and second patterns having gradations different gradation tone images, the plurality of measurement images, said first and second patterns of each measurement image,
They may be shifted from each other in the scanning direction.

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 repeatedly acquired. Each measurement image has a halftone image as a background image, a first pattern and a second pattern which are arranged at a given interval in a given scanning direction and have gradations different from the gradation of the halftone image. In the plurality of measurement images, the first and second patterns are shifted in a given scanning direction. 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, and the change information can be acquired along the scanning direction. Therefore, in the characteristic information calculation step, since the crosstalk characteristic information of the light modulation element is calculated based on the image information, the influence of the crosstalk of the light modulation element, which could not be measured conventionally, is highly accurate. It becomes possible to measure and to quantify as crosstalk characteristic information. As a result, it is possible to contribute to generation of a correction value that can reduce the influence of crosstalk with high accuracy.

In the correction value table method according to the present invention, the scanning direction may be a horizontal scanning direction of the display image.

According to the present invention, the image information is acquired using the measurement image in which the first and second patterns are arranged at a given interval in the horizontal scanning direction of the display image. It becomes possible to generate a measurement value that accurately reflects the influence of crosstalk in the horizontal scanning direction, which causes display quality degradation more than in the scanning direction.

In the correction value table method 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, it is possible to generate a measurement value that reflects the influence of the crosstalk with higher accuracy. It becomes like this.

In the correction value table 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 the sensory experiment by a plurality of viewers, the first patterns P1, P when the interval d is equal to or greater than h
The effect of crosstalk becomes conspicuous in the region between 2, and when the interval d is about 2 × h, the effect of crosstalk is most noticeable in the region, and when the interval d becomes 3 × h, The result was that the effect was less noticeable. Therefore, according to the present invention, by considering the manufacturing variation of the light modulation element, searching for the interval d in the range of h ≦ d <3 × h,
It becomes possible to increase the measurement accuracy of the influence of the crosstalk and generate a measurement value that can reduce the influence of the crosstalk with higher accuracy.

In the correction value table method according to the present invention, the operation mode of the light modulation element may be normally white, 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. It becomes possible to generate a correction value that reflects the influence of the crosstalk of the modulation element more accurately than when the first and second patterns have other gradations.

In the correction value table method according to the present invention, the operation mode of the light modulation element may be normally black, 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 becomes possible to generate a correction value that reflects the influence of the crosstalk of the modulation element more accurately than when the first and second patterns have other gradations.

The present invention is also a correction value table generation device for generating a correction value table for correcting an image signal corresponding to a display image using a light modulation element, and includes characteristic information for a plurality of scanning lines of the display image. Based on the crosstalk characteristic curve calculation unit that calculates the crosstalk characteristic curve of the display image based on the crosstalk characteristic curve calculated by the crosstalk characteristic curve calculation unit, the display image in a given scanning direction Related to a correction value table generation device including an approximate value calculation unit that calculates an approximate value and a correction value calculation unit that calculates a correction value of the image signal based on the approximate value calculated by the approximate value calculation unit To do.

According to the present invention, the crosstalk characteristic curve of the display image is calculated based on the characteristic information for a plurality of scanning lines of the display image, and the correction value of the image signal is calculated based on the approximate value of the crosstalk characteristic curve. As a result, display quality degradation caused by crosstalk of the light modulation element can be accurately corrected from a display image using the light modulation element.

In the correction value table generation device according to the present invention, the crosstalk characteristic curve calculation unit includes:
The crosstalk occurrence portion can be extracted from the characteristic information of each scanning line to obtain the interpolation characteristic information of each scanning line, and the crosstalk characteristic curve can be calculated by averaging the interpolation characteristic information for the plurality of scanning lines.

According to the present invention, as a result of extracting the crosstalk occurrence portion from the characteristic information, the crosstalk characteristic curve is calculated based on the interpolation characteristic information obtained by interpolating the removed removal portion. A well-reflected crosstalk characteristic curve can be obtained, and display quality degradation caused by crosstalk can be corrected with higher accuracy.

In the correction value table apparatus according to the present invention, when the gradation value of the pixel is G, the image information of the characteristic information corresponding to the position of the pixel is L, and the approximate value is P, the correction value is (G
-G × L / P).

According to the present invention, it is possible to provide a correction value table generation device capable of generating correction values with simple processing.

The present invention also provides an image processing apparatus for correcting an image signal corresponding to a display image using a light modulation element, and storing a correction value generated by any one of the correction value table generation methods described above. The present invention relates to an image processing apparatus including a table and an image signal correction unit that corrects the image signal based on a correction value of the correction value table.

According to the present invention, it is possible to provide an image processing apparatus that accurately corrects display quality degradation caused by crosstalk of light modulation elements.

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.

In the following embodiments, a correction value for correcting an image signal corresponding to a display image using the light modulation element is calculated in order to reduce the influence of crosstalk of the light modulation element, and the calculated correction value Is stored in the correction value table. When an image signal corresponding to the display image is input, the image signal is corrected based on the correction value stored in the correction value table, and an image using the light modulation element is displayed based on the corrected image signal. Thus, the influence of the crosstalk of the display image is reduced.

Hereinafter, an image display system having such a correction value table and reducing the influence of crosstalk will be described.

FIG. 1 is a block diagram showing a configuration example of an image display system according to an embodiment of the present invention.

The image display system 500 in this embodiment includes a projector (image display device) PJ,
An image processing apparatus 600 is included. The projector PJ functions as an image display device equipped with a liquid crystal panel as a light modulation element, and displays an image on the screen SCR by controlling the transmittance of the liquid crystal panel irradiated with light from the light source based on the image signal. be able to. The image processing apparatus 600 has a correction value table, corrects an input image signal from an image signal generation apparatus (not shown) based on the correction value stored in the correction value table, and converts the corrected image signal into the projector PJ. To supply. By doing so, it is possible to display an image with reduced influence of crosstalk of the liquid crystal panel of the projector PJ on the screen SCR.

The image display system 500 may include a correction value table generation device 700 that generates a correction value table included in the image processing device 600. The correction value table generation device 700 generates a correction value based on the measurement result of the display image on the screen SCR by the projector PJ, and generates a correction value table in which the generated correction value is tabulated.

In FIG. 1, the projector PJ, the image processing apparatus 600, and the correction value table generation apparatus 700 have been described as being provided separately. However, the projector PJ includes the image processing apparatus 600 and the correction value table generation apparatus 700. It may have at least one function, or the image processing apparatus 600 may have the function of the correction value table generation apparatus 700.

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 1
40, a 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. This polarization conversion element 11
6 is applied to the superimposing lens 118.

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 dichroic mirror for G 120G is transmitted to the relay optical system 14
The light incident on 0 and 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. Relay lens 14
2 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 includes an R liquid crystal panel 130R and a G liquid crystal panel 1.
It has a function of outputting combined light obtained by combining incident light from the 30G and B liquid crystal panels 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 is a block diagram showing a configuration example of the image processing apparatus 600 shown in FIG. In FIG. 3, FIG.
The same parts are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  The image processing apparatus 600 includes a correction value table 610 and an image signal correction unit 620.

The correction value table 610 functions as an LUT (Look-up Table) using the input image signal or a value corresponding to the image signal as an index, and the correction value generated by the correction value table generation device 700, or Data for correcting the correction values into a table (correction value table data) is stored. In the correction value table 610, correction values are stored in association with input image signals or pixel values corresponding to the input image signals. The correction value table 610 may store a correction value in association with each of the pixel values corresponding to the input image signal, or the pixel values sampled discretely among all the pixel values corresponding to the input image signal. A correction value may be stored in association with each other.

The image signal correction unit 620 corrects the input image signal based on the correction value stored in the correction value table 610, and outputs the corrected image signal to the projector PJ. Image signal correction unit 62
0 may read a correction value corresponding to the input image signal from the correction value table 610 and correct the input image signal using the correction value as it is, or may correct a plurality of correction values corresponding to the input image signal as correction values. The input image signal may be corrected by using the correction value after interpolation read out from the table 610 and interpolating the plurality of correction values according to the input image signal.

A correction value table 61 used for correcting an image signal by such an image processing apparatus 600.
The correction value stored in 0 is generated by the correction value table generation device 700.

FIG. 4 shows a block diagram of a configuration example of the correction value table generation apparatus 700 of FIG. In FIG. 4, the same parts as those in FIG.

The correction value table generation device 700 includes a characteristic information storage unit 710, a crosstalk characteristic curve calculation unit 720, an approximate value calculation unit 730, and a correction value calculation unit 740.

The characteristic information storage unit 710 stores the characteristic information of the display image of the projector PJ, and the characteristic information obtained based on the measurement result of the measurement system (not shown) is stored in the characteristic information prior to the generation of the correction value table. Stored in the unit 710. Such characteristic information storage unit 710
Stores characteristic information for a plurality of scanning lines of the display image of the projector PJ. As the characteristic information, for example, luminance can be adopted, but information other than luminance may be used.

The crosstalk characteristic curve calculation unit 720 calculates the crosstalk characteristic curve of the display image based on the characteristic information for a plurality of scanning lines of the display image of the projector PJ stored in the characteristic information storage unit 710. The crosstalk characteristic curve is information relating to a change in image information in a given scanning direction of the display image of the projector PJ due to the crosstalk of the liquid crystal panel as the light modulation element. The scanning direction may be the horizontal scanning direction of the display image or the vertical scanning direction of the display image. Hereinafter, the horizontal scanning direction will be described as an example.

The approximate value calculation unit 730 calculates an approximate value in a given scanning direction of the display image of the projector PJ from the crosstalk characteristic curve calculated by the crosstalk characteristic curve calculation unit 720. Here, the scanning direction is preferably the horizontal scanning direction of the liquid crystal panel,
When the scanning direction of the liquid crystal panel coincides with the scanning direction of the display image, it is the horizontal scanning direction of the display image. This is because the influence of crosstalk is greater in the horizontal scanning direction than in the vertical scanning direction. In the following, it is assumed that the horizontal scanning direction of the liquid crystal panel and the horizontal scanning direction of the display image match.

The correction value calculation unit 740 calculates a correction value for the image signal based on the approximate value calculated by the approximate value calculation unit 730. The correction value calculated by the correction value calculation unit 740 is output as correction value table data of the correction value table 610 of the image processing apparatus 600 of FIG.

Next, the operation of the correction value table generation apparatus 700 in this embodiment will be described. The function of the correction value table generating apparatus 700 may be realized by hardware or may be realized by software. In the following, it is assumed that the function of the correction value table generation device 700 is realized by software processing.

FIG. 5 shows a block diagram of a hardware configuration example of the correction value table generation apparatus 700 of FIG.

The correction value table generation device 700 includes a CPU 800, an I / F circuit 810, a read only memory (ROM) 820, and a random access memory (Random Access Me).
mory: RAM) 830 and bus 840, and through the bus 840, the CPU 800 and I / F
The circuit 810, the ROM 820, and the RAM 830 are electrically connected.

For example, the ROM 820 or the RAM 830 stores a program that realizes the function of the correction value table generation device 700. The CPU 800 reads out a program stored in the ROM 820 or the RAM 830 and executes a process corresponding to the program, whereby the function of the correction value table generating apparatus 700 can be realized by software processing. Note that the RAM 830
Used as a work area for processing by the CPU 800, an I / F circuit 810, and a ROM 8
It is used as 20 buffer areas. The I / F circuit 810 performs input interface processing of image information that is a measurement result of a display image of a projector PJ (not shown).

FIG. 6 shows a flowchart of a processing example of the correction value table generation device 700 of FIG. For example, FIG.
A program for realizing the processing shown in FIG. 6 is stored in the ROM 820 or the RAM 830, and the CPU 800 reads out the program stored in the ROM 820 or the RAM 830 and executes processing corresponding to the program. 6 can be realized by software processing.
7A, FIG. 7B, FIG. 7C, FIG. 7D, FIG. 7E, FIG.
Explanatory drawing of step S100 is shown.

First, the correction value table generating apparatus 700 acquires, as characteristic information, a group of information on luminance unevenness in the horizontal scanning direction for a plurality of scanning lines of a display image (hereinafter referred to as luminance unevenness) (step S100). The acquired luminance unevenness information is stored in the characteristic information storage unit 710. Such luminance unevenness information is preferably calculated based on a measurement result obtained by a crosstalk measurement method described later.

This crosstalk measurement method uses a halftone image and a measurement image having the first and second patterns with the halftone image as a background image, to obtain a halftone image at a measurement pixel position in the horizontal scanning direction. This is a method for obtaining luminance unevenness information by measuring a luminance difference as a reference. 7A shows a halftone image, and FIGS. 7B to 7F vertically scan the first and second patterns P1 and P2 using the halftone image of FIG. 7A as a background image. It represents images shifted from each other in the horizontal scanning direction while maintaining the position in the direction. The first and second patterns P1 and P2 are rectangular patterns whose shapes are different from each other as long as the gradation is different from the gradation of the halftone image. 7B to FIG.
In (F), it is assumed that the gradation of the rectangular patterns P1 and P2 is black.
That is, in step S100, as the first image information acquisition step, image information of a plurality of pixels at a given measurement pixel position in the halftone image of FIG. 7A displayed using the light modulation element is acquired. In addition, as the second image information acquisition step, image information at the measurement pixel position in each measurement image is repeatedly acquired for each of FIGS. 7B to 7F.
And the crosstalk characteristic information of the display image calculated based on the image information acquired in the first image information acquisition step and the plurality of image information acquired in the second image information acquisition step is the luminance unevenness information. To be acquired. Here, each measurement image constituting a plurality of measurement images has a gradation different from the gradation of the halftone image, with the halftone image as a background image, arranged at a given interval in the horizontal scanning direction. In the plurality of measurement images including the first and second patterns, the first and second patterns of each measurement image are shifted from each other in the horizontal scanning direction.

Subsequent to step S100, the correction value table generation device 700 performs the crosstalk of the display image based on the characteristic information for a plurality of scanning lines of the display image stored in the characteristic information storage unit 710 as a crosstalk characteristic curve calculation step. A characteristic curve is calculated (step S102).
.

Next, the correction value table generation device 700 performs step S10 as an approximate value calculation step.
An approximate value in the horizontal scanning direction of the display image is calculated from the crosstalk characteristic curve calculated in step 2 (step S104).

And the correction value table production | generation apparatus 700 is step S1 as a correction value calculation step.
Based on the approximate value calculated in 04, the correction value of the image signal is calculated (step S1).
06). Thereafter, the correction value table generating apparatus 700 performs a process of storing the correction value calculated in step S106 in the correction value table 610 (step S108), and ends a series of processes (end). Here, the process of step S108 is a process of storing the calculated correction value and the image signal (or its pixel value) corresponding to the correction value in the correction value table 610 in association with each other.

Next, specific processing contents in steps S102 to S106 in FIG. 6 will be described.

FIG. 8 shows a flowchart of the processing content of step S102 of FIG. For example, ROM 8 in FIG.
20 or RAM 830 stores a program for realizing the processing shown in FIG. 8, and the CPU 800 reads out the program stored in the ROM 820 or RAM 830 and executes the processing corresponding to the program. The processing shown in FIG. 6 can be realized by software processing.
FIG. 9A and FIG. 9B are explanatory diagrams of the processing of FIG. FIG. 9A and FIG.
The vertical axis represents the luminance difference with reference to the halftone image, and the horizontal axis represents the change in luminance difference when the horizontal pixel position is represented as luminance unevenness.

FIG. 10A, FIG. 10B, and FIG. 10C are explanatory diagrams of the processing of FIG. FIG.
A) and FIG. 10C schematically show changes in the luminance difference when the vertical axis represents the luminance difference with reference to the halftone image and the horizontal axis represents the pixel position in the horizontal direction as luminance unevenness. It is.

When calculating the crosstalk characteristic curve, the correction value table generation apparatus 700 uses the crosstalk characteristic curve calculation unit 720 as an extraction step to perform luminance unevenness that is characteristic information of each scanning line as shown in FIG. The measurement result (luminance unevenness information) is read from the characteristic information storage unit 710, and the process of removing the measurement result of the luminance at the pattern positions of the rectangular patterns P1 and P2 is performed from the measurement result (step S150). As a result, as shown in FIG. 9B, the crosstalk characteristic curve calculation unit 720 acquires luminance unevenness information in which the crosstalk occurrence portion is extracted from the characteristic information of each scanning line.

When the luminance unevenness information shown in FIG. 9B is acquired, as an interpolation step, the crosstalk characteristic curve calculation unit 720 linearly interpolates the removed portion by the removal processing in step S150 for each luminance unevenness information of each scanning line. A luminance unevenness curve (interpolation characteristic information) is obtained (step S152).
).

More specifically, in step S152, the crosstalk characteristic curve calculation unit 720 includes a plurality of pieces of image information including image information of the endmost part generated by the removal process of step S150 among the extracted crosstalk occurrence portions. A luminance unevenness curve is obtained using the corrected image information obtained by averaging (one or more pieces of image information adjacent to the extreme end). For example, when the crosstalk characteristic curve calculation unit 720 interpolates the removed portion between the extreme ends Q1 and Q10 in FIG. 10A in step S152, as shown in FIG. A luminance unevenness curve is obtained by using the average value Q1 ′ of the part Q1 and the measurement point Q2 of the crosstalk occurrence part adjacent to the endmost part Q1. Note that an average value is obtained for the other end points of the luminance unevenness in FIG. 10A as in FIG. 10B, and a luminance unevenness curve is obtained using the average value.

By doing so, it is possible to avoid a situation in which the luminance change becomes too large when the luminance unevenness curve is used using the measurement point of the extreme end Q1, and the error of the correction value becomes large.

When the brightness unevenness curve is calculated for each scanning line in step S152, as an averaging step, the crosstalk characteristic curve calculating unit 720 averages the brightness unevenness curves for a plurality of scanning lines obtained in step S150, and A crosstalk characteristic curve as shown in FIG. 10C is calculated (step S154), and a series of processing ends (end).

When the crosstalk characteristic curve is calculated as described above in step S102 of FIG. 6, the correction value table generation device 700 samples points on the crosstalk characteristic curve in the approximate value calculation unit 730, An approximate value of luminance unevenness is obtained by a known approximation method (for example, a sixth-order least square method).

Then, the correction value calculation unit 730 uses G as the gradation value corresponding to the image signal of the pixel, L as the measurement result (image information of the characteristic information) corresponding to the position of the pixel acquired in step S100.
When the approximate value obtained in step S102 is P, a correction value obtained by the equation (GG × L / P) is calculated. Using the correction value thus obtained, the horizontal coordinate of the screen is x,
A two-dimensional correction value table with the calculated correction value as y is generated.

Next, image signal correction processing using the correction values calculated as described above will be described. The function of the image processing apparatus 600 that performs the correction processing of the image signal using the correction value calculated as described in the present embodiment may be realized by hardware or may be realized by software. In the following, it is assumed that the functions of the image processing apparatus 600 are realized by software processing.

The image processing apparatus 600 has a configuration as shown in FIG. 5 similarly to the correction value table generation apparatus 700, and the above processing is performed by a CPU that has read a program for realizing image signal correction processing from the memory. It can be realized.

FIG. 11 shows a flowchart of a processing example of the image processing apparatus 600 of FIG. For example, a program for realizing the processing shown in FIG. 11 is stored in the ROM or RAM of the image processing apparatus 600 (not shown), and the CPU (not shown) reads the program stored in the ROM or RAM and corresponds to the program. By executing the above processing, the image signal correction processing shown in FIG. 11 can be realized by software processing.

In the present embodiment, prior to the processing described below, the correction value table 6 of the image processing apparatus 600 is used.
10, the correction value is stored. In addition, in order to further improve the accuracy of the crosstalk correction, a reference correction intensity is prepared, and the image is corrected using the correction intensity corrected according to the gradation corresponding to the image signal to be corrected and the size in the horizontal direction. The signal shall be corrected. The reason why the correction intensity is corrected according to the gradation and the horizontal size with respect to the reference correction intensity is that the characteristic information referred to by the correction value table generation device 700 changes according to the gradation and the horizontal size, This is because changing the correction value obtained by the correction value calculation unit 740 can further reduce the influence of crosstalk.

First, the image processing apparatus 600 inputs an image signal of the pixel (Step S200).
The subsequent processing is performed on a pixel basis. Subsequent to step S200, a variable i that defines the number of pixels of one horizontal scanning line is initialized (step S202). Step S2
In 02, it is assumed that the variable i is set to “1”. In the following, it is assumed that the number of pixels in one horizontal scanning line is L (L is a natural number).

Next, the variables i and L are compared (step S204), and when the value of the variable i is determined to be L or less (step S204: Y), the image processing apparatus 600 sets the gradation value of the pixel to the variable Ai. (Step S206).

Next, the image processing apparatus 600 reads the correction value Ti stored in the correction value table 610 corresponding to the image signal of the pixel, multiplies the correction intensity FN, and calculates the adjustment correction value Ri of the pixel ( Step S208).

Here, the correction strength FN is a correction strength corrected based on the reference correction value FN0. For example, using the ratio (ΔG / ΔG0) of the luminance difference ΔG between the luminance of the pixel and the luminance of the halftone image used for measuring the characteristic information with respect to the luminance difference ΔG0 when the reference correction value FN0 is calculated,
A correction intensity FN obtained by correcting the reference correction value FN0 is obtained. Alternatively, the reference correction is performed by using the ratio (S1 / S0) of the horizontal size S1 of the continuous pixel group including the pixel to the horizontal size S0 of the rectangular pattern when the reference correction value FN0 is calculated. A corrected intensity FN obtained by correcting the value FN0 is obtained.

When the adjustment correction value Ri is obtained in step S208, the image processing apparatus 600 obtains the corrected image signal Bi by (Ai + Ri) (step S210). That is, the corrected image signal is obtained by adding the adjustment correction value Ri to the gradation value of the pixel.

Subsequently, the variable i is incremented (step S212), and the process returns to step S204.

In step S204, when the value of the variable i is larger than L (step S204), a series of processing is ended (end).

FIG. 12 shows an example of the result of the processing in FIG. 11 performed by the image processing apparatus 600. In FIG. 12, the vertical axis represents the luminance difference based on the halftone image, and the horizontal axis represents the luminance difference when the horizontal pixel position is represented. The luminance unevenness before the processing in FIG. It represents the luminance unevenness.

In a sensory experiment by a plurality of viewers, it was confirmed that the influence of crosstalk that appeared in the display image before correction no longer appeared in the display image after correction, and as shown in the measurement result of FIG. The luminance difference in the area between P2 can be made zero.

In such a crosstalk occurrence portion, for example, 0.
The luminance difference can be corrected to be less than 3 [cd / m ² ]. The value of the color difference ΔE = 0.8 to 1.6 is the limit that can be discriminated by human eyes when adjacent images with different brightness (“New Color Science Handbook” [2nd edition] The University of Tokyo Press 1988, first edition), and a luminance difference of less than 0.3 corresponds to “color difference ΔE <0.8”. Therefore, it can be seen from the correction result that the influence of the crosstalk can be almost eliminated.

As described above, in the present embodiment, since the crosstalk characteristic does not change so much in the vertical scanning direction of the image, the crosstalk characteristic information in the horizontal scanning direction is obtained, and the correction value is obtained based on the crosstalk characteristic information. As a result, it is possible to accurately correct deterioration in display quality caused by crosstalk of the light modulation element. In addition, since the capacity of the correction value can be reduced, highly accurate crosstalk correction can be realized at low cost.

Prior to the correction value table generation process in the above-described embodiment, the luminance unevenness information acquisition process stored in the characteristic information storage unit 710 in FIG. 4 and acquired in step S100 in FIG. 6 is performed as follows. Is desirable.

FIG. 13 shows a flowchart of another processing method of the correction value table generation processing in this embodiment.

That is, first, in the crosstalk measurement system described later, luminance unevenness information is measured from the display image of the projector PJ (step S300). The luminance unevenness information is, as crosstalk characteristic information, measured luminance (image information) at a measurement pixel position in a halftone image, and a measurement image having two rectangular patterns using the halftone image as a background image. The luminance at the measurement pixel position is repeatedly measured while shifting the rectangular pattern in the horizontal scanning direction, and is calculated using the luminance difference between the two.

More specifically, the luminance unevenness information includes 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 a light modulation element; A second image information acquisition step of repeatedly acquiring image information of a plurality of pixels at the measurement pixel positions in each measurement image constituting the plurality of measurement images displayed using the light modulation element; A characteristic information calculation step for calculating luminance unevenness information (crosstalk characteristic information) of the display image based on the image information acquired in the image information acquisition step and the plurality of pieces of image information acquired in the second image information acquisition step; Is generated by Here, each of the measurement images constituting the plurality of measurement images has a gradation different from the gradation of the halftone image, with the halftone image as a background image, arranged at a given interval in the scanning direction. In the plurality of measurement images including the first and second patterns, the first and second patterns of each measurement image are shifted from each other in the scanning direction.

Subsequent to step S300, the correction value table generation device 700 generates the correction value table described in the above embodiment (step S302), and the series of processing ends (step S302).
End). The processing content of step S302 is the same as that in FIG.

Hereinafter, the principle of a method for measuring luminance unevenness information as crosstalk characteristic information in the present embodiment will be described. The luminance unevenness information in the present embodiment is calculated based on the measurement result measured by the next crosstalk measurement system.

FIG. 14 shows a configuration example of the crosstalk measurement system in the present embodiment. 14, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

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 PJ, an image information measurement unit IM, and a characteristic information generation device 200. In the crosstalk measurement system 10, an image is projected onto the screen SCR by a projector PJ equipped with a liquid crystal panel as a light modulation element, and the crosstalk characteristic of the liquid crystal panel is measured from the 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. . The function of such an image information measuring unit IM is, for example, a CCD (Ch
arge 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 characteristic information generating apparatus 200 acquires image information measured by the image information measuring unit IM,
Based on this image information, the crosstalk characteristic of the liquid crystal panel as the light modulation element of the projector PJ is calculated.

In FIG. 1, a projector PJ, an image information measuring unit IM, and a characteristic information generating device 2
00 is described as being provided separately, but the projector PJ may have at least one function of the image information measurement unit IM and the characteristic information generation device 200, or the image information measurement unit IM may The function of the characteristic information generation apparatus 200 may be included.

The projector PJ in FIG. 14 is the same as the projector PJ in FIG.

  FIG. 15 shows a block diagram of a configuration example of the characteristic information generating apparatus 200 of FIG.

The characteristic information generation apparatus 200 includes an image information acquisition unit 210 and a characteristic information calculation unit 220, and the measurement result of the image information measurement unit IM that measures the display image affected by the crosstalk of the liquid crystal panel of the projector PJ. Based on the above, the crosstalk characteristic information of the liquid crystal panel is calculated.

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 is arranged at a given interval in the horizontal scanning direction (given scanning direction) of the image, and has a gradation different from the gradation of the halftone image. Includes first and second patterns. The reason why the first and second patterns are arranged in the horizontal scanning direction of the image is as follows.
Among the influence of the crosstalk of the liquid crystal panel appearing in the horizontal scanning direction and the vertical scanning direction of the image,
The deterioration of display quality is caused by the influence of crosstalk in the horizontal scanning direction, and the influence of crosstalk in the vertical scanning direction is negligible.

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.

When the operation mode of the projector PJ's liquid crystal panel is 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 can be taken by the display image, and the first and second patterns of the measurement image are black. A pattern is desirable. 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 corresponding to the intermediate value between the maximum value and the minimum value of the gradation values that can be taken by the display image (
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 characteristic information generation device 200 is based on the image information of the halftone image acquired by the image information acquisition unit 210 and the image information of the measurement image, and the crosstalk characteristic information of the liquid crystal panel of the projector PJ. Is calculated. 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 characteristic information generating apparatus 200 in this embodiment will be described. The function of the characteristic information generating apparatus 200 may be realized by hardware or software. In the following, it is assumed that the function of the characteristic information generation device 200 is realized by software processing.

The characteristic information generating apparatus 200 has a configuration as shown in FIG. 5 like the correction value table generating apparatus 700, and the above processing is performed by a CPU that reads a program for realizing image signal correction processing from a memory. Can be realized.

FIG. 16 shows a flowchart of a processing example of the characteristic information generating apparatus 200 of FIG. For example, a program for realizing the processing shown in FIG. 16 is stored in the ROM or RAM included in the characteristic information generation apparatus 200, and the CPU included in the characteristic information generation apparatus 200 is the ROM or RAM.
The crosstalk measurement processing shown in FIG. 16 can be realized by software processing by reading out the program stored in and executing processing corresponding to the program.

FIGS. 17A and 17B are explanatory diagrams of the processing of FIG. FIG. 17 (A) is the same as FIG.
FIG. 17B illustrates an explanatory diagram of a measurement image in the process of FIG. 16.

  FIG. 18 is an explanatory diagram of a rectangular pattern of the measurement image in the process of FIG.

As shown in FIG. 16, first, the characteristic information generating 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 characteristic information generating apparatus 200 receives, 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. The projector PJ changes the modulation factor of the liquid crystal panel based on the image signal, and the screen SC
Project to R.

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. The characteristic information generating apparatus 200 acquires the image information measured by the image information measuring unit IM in the image information acquiring unit 210 as the first image information acquiring step (step S).
12).

Next, the characteristic information generating apparatus 200 displays the measurement image on the screen SC on the projector PJ.
R is displayed (step S14). For example, as shown in FIG. 17B, the characteristic information generating apparatus 200 uses the halftone image in step S10 as a background image as shown in FIG. 17B, and two black images spaced by a distance d in the horizontal scanning direction. An image signal of an image having a rectangular pattern (first and second patterns) is supplied to the projector PJ, and the projector PJ changes the modulation factor of the liquid crystal panel based on the image signal and projects it onto 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. 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.

As shown in FIG. 18, the edge interval d between the two black rectangular patterns P1 and P2 is h ≦ d <3 × h with respect to the width h in the horizontal scanning direction of the rectangular pattern P1 (or rectangular pattern P2).
It is desirable to satisfy This is due to the edge interval d in the sensory experiment by a plurality of viewers.
When h is greater than or equal to h, the influence of crosstalk becomes conspicuous in the area between the rectangular patterns P1 and P2, and when the edge interval d is about 2 × h, the influence of crosstalk is most noticeable in the area. This is based on the result that the influence of 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. The characteristic information generation device 200 acquires the image information measured by the image information measurement unit IM in the image information acquisition unit 210 as the second image information acquisition step (step S16). More specifically, the image information acquisition unit 2
10 acquires image information of a plurality of pixels at the measurement pixel positions in the measurement image having two rectangular patterns having a halftone image as a background image and displayed using a liquid crystal panel.

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 are rectangular patterns P1, P
2 pixel positions and halftone image pixel positions. 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. As a result, the image information acquisition unit 210 can capture a luminance unevenness information group 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 characteristic information generation device 200 uses the image information acquired in step S12 (first image information acquisition step) and step S16 (second image information acquisition) 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) (Step S18), and a series of processing is ended (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. Step S12 and step S
16, since the luminance of the same horizontal scanning line is acquired, the characteristic information calculation unit 220 uses the halftone image as a reference and the crosstalk characteristic that is change information of the luminance difference for one or a plurality of horizontal scanning lines. Information can be calculated.

FIG. 19 is an explanatory diagram of crosstalk measured in the process of FIG. FIG. 19 schematically shows changes in luminance difference when the vertical axis represents the luminance difference based on the halftone image and the horizontal axis represents the pixel position in the horizontal direction.

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, the characteristic information calculation unit 22
In the crosstalk characteristic information calculated by 0, the influence of the crosstalk can be quantified as a luminance difference of the crosstalk portion. 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. 20 shows an example of the measurement result of the measurement image measured by the crosstalk measurement method in the present embodiment. FIG. 20 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. 20 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. 20 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.
The region between 1 and P2 has the largest luminance difference from the halftone image, which is considered to be the influence of crosstalk. On the other hand, when attention is paid to the luminance unevenness in the vertical direction (vertical scanning direction) in FIG. 20, 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, even by performing crosstalk correction on the image signal corresponding to the pixels in the horizontal scanning direction,
It can be seen that display quality degradation can be greatly reduced.

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. 21 shows an example of crosstalk characteristic information obtained from the measurement result of the crosstalk measurement method in the present embodiment. In FIG. 21, 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. 21 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. Thereby, the luminance difference ΔL with the halftone image between the rectangular patterns P1 and P2
Therefore, the influence of crosstalk in the horizontal scanning direction can be quantified.

Therefore, by ignoring the crosstalk in the vertical scanning direction as described above, FIG.
When the crosstalk characteristic in the horizontal scanning direction as shown in FIG. 1 is quantified, the influence of the crosstalk of the image corresponding to the display image is corrected based on the above-described crosstalk characteristic information to reduce the influence of the crosstalk. It is possible to contribute to the display of the selected image.

In this case, for example, as shown in FIGS. 7A to 7E, 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.
By repeatedly obtaining image information using each measurement image and obtaining each luminance difference, FIG.
1 crosstalk characteristic information is calculated. That is, by repeating the second image information acquisition step to acquire luminance unevenness in the horizontal scanning direction, the influence of crosstalk in the horizontal scanning direction of the liquid crystal panel for displaying the measurement image can be quantitatively determined, and the display image Correction of the image signal of the pixel corresponding to 1 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.

22A, 22B, and 22C are explanatory diagrams of the display position of the rectangular pattern. FIG. 22A 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. 22B shows a second example in which the rectangular patterns P1 and P2 are located at the center of the image.
The explanatory view of the image for measurement is shown. FIG. 22C 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.

22A to 22C, 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. 22A to 22C
The measurement results of the crosstalk measurement method of the present embodiment using the respective measurement images are as follows.

FIG. 23 shows an example of the measurement result of the crosstalk measurement method of the present embodiment using the measurement images of FIGS. 22 (A) to 22 (C). In FIG. 23, the vertical axis represents the luminance difference from the halftone image, the horizontal axis represents the pixel position in the horizontal direction, and the halftone using the respective measurement images in FIGS. 22 (A) to 22 (C). This represents the change in luminance difference from the image. The crosstalk characteristic information shown in FIG. 23 is also averaged for each pixel position or sampled pixel position, as in FIG. 21, the change information of the luminance difference in the scanning line where the rectangular pattern exists in the horizontal scanning direction. Information.

23, the measurement result C1 by the crosstalk measurement method of the present embodiment when the measurement image of FIG. 22A is used, and the present embodiment of the present embodiment when the measurement image of FIG. 22B is used. 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. 22C 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 represented 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. 24A, FIG. 24B, and FIG. 24C are explanatory diagrams of gradations of a rectangular pattern.
FIG. 24A 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. 24B 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. 24C shows an explanatory diagram of a rectangular pattern in which the gradation values of the rectangular patterns P1 and P2 are the maximum value (white) of all possible gradation values.

24A to 24C, the display positions of the rectangular patterns P1 and P2, the edge interval,
The shape and size are all the same, and only the position in the image is different. 24 (A) to 24 (
The measurement result of the crosstalk measurement method of this embodiment using each measurement image of C) is as follows.

FIG. 25 shows an example of the measurement result of the crosstalk measurement method of the present embodiment using measurement images having rectangular patterns of a plurality of types of gradations including those shown in FIGS. 24 (A) to 24 (C). FIG.
5 is a halftone image using a plurality of measurement images each having a rectangular pattern of a plurality of types of gradations, with the vertical axis representing the luminance difference from the halftone image and the horizontal axis representing the pixel position in the horizontal direction. Represents the change in the difference in brightness. The crosstalk characteristic information shown in FIG. 25 is also averaged for each pixel position or each sampled pixel position, as in FIG. 21, the change information of the luminance difference in the scanning line where the rectangular pattern exists in the horizontal scanning direction. Information.

In FIG. 25, as the gradation value of the rectangular pattern is smaller, the luminance difference with the halftone image in the region between the rectangular patterns P1 and P2 changes in the positive direction. However, focusing on the absolute value of the luminance difference, the gradation value is the maximum value (white) than when the gradation value of the rectangular pattern is the minimum value (black).
In this case, the luminance difference from the halftone image becomes larger. 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 normally black mode,
By using the rectangular patterns P1 and P2 with white gradation, the influence of crosstalk can be measured with higher accuracy.

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.

In the present embodiment, luminance unevenness information is acquired by using the crosstalk measurement method as described above, thereby contributing to generation of a correction value that reduces the influence of crosstalk that could not be reflected so far with high accuracy. It becomes like this.

As described above, the correction value table generation method, the correction value table generation device, and the image processing device according to the present invention have been described based on the above embodiment, but the present invention is not limited to the above embodiment, and the gist thereof is described. The present invention can be implemented in various forms without departing from the scope of the invention, and 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 transmission type liquid crystal panel as the light modulation element has been described as an example. However, a light valve using a four-plate or more transmission type liquid crystal panel is used. It may be adopted.

(4) In the above-described embodiment, it has been described that the influence of crosstalk is reduced by correcting the image signal based on the correction value generated by the method of the present embodiment in the previous stage of the projector PJ. The invention is not limited to this. For example, after the projector PJ, the influence of crosstalk may be reduced based on the correction value generated by the method of the present embodiment. In this case, the image signal may be corrected based on the correction value generated by the method of the present embodiment in the drive circuit (light modulation element control circuit) that drives the source line of the liquid crystal panel of the projector PJ.

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

1 is a block diagram of a configuration example of an image display system in an embodiment according to the present invention. The block diagram of the structural example of the projector of FIG. FIG. 2 is a block diagram of a configuration example of the image processing apparatus in FIG. 1. The block diagram of the structural example of the correction value table production | generation apparatus of FIG. The block diagram of the hardware structural example of the correction value table production | generation apparatus of FIG. The flowchart of the example of a process of the correction value table production | generation apparatus of FIG. 7A, FIG. 7B, FIG. 7C, FIG. 7D, FIG. 7E, and FIG. 7F are explanatory diagrams of step S100 in FIG. FIG. 7 is a flowchart of processing contents in step S102 in FIG. 6. 9A and 9B are explanatory diagrams of the processing of FIG. FIG. 10A, FIG. 10B, and FIG. 10C are explanatory diagrams of the processing of FIG. FIG. 2 is a flowchart of a processing example of the image processing apparatus in FIG. 1. The figure which shows an example of the result of the process of FIG. 11 of an image processing apparatus. The flowchart of the other processing method of the production | generation process of the correction value table in this embodiment. 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 characteristic information generation apparatus of FIG. The flowchart of the example of a process of the characteristic information generation apparatus of FIG. 17A and 17B 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. 22A, 22B, and 22C are explanatory diagrams of the display position of the 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 of Drawing 22 (A)-Drawing 22 (C). 24A, 24B, and 24C 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 ... Characteristic information generation device, 210 ... Image information acquisition unit,
220 ... Characteristic information calculation unit, 500 ... Image display system, 600 ... Image processing device,
610 ... correction value table, 620 ... image signal correction unit,
700 ... correction value table generation device, 710 ... characteristic information storage unit,
720 ... a crosstalk characteristic curve calculation unit, 730 ... an approximate value calculation unit,
740 ... Correction value calculation unit, 800 ... CPU, 810 ... I / F circuit, 820 ... ROM,
830 ... RAM, 840 ... bus, IM ... image information measuring unit, PJ ... projector,
SCR ... Screen

Claims (15)

A correction value table generation method for generating a correction value table for correcting an image signal corresponding to a display image using a light modulation element,
A crosstalk characteristic curve calculating step for calculating a crosstalk characteristic curve of the display image based on characteristic information for a plurality of scanning lines of the display image;
An approximate value calculating step of calculating an approximate value in a given scanning direction of the display image from the crosstalk characteristic curve calculated in the crosstalk characteristic curve calculating step;
A correction value table generation method comprising: a correction value calculation step of calculating a correction value of the image signal based on the approximate value calculated in the approximate value calculation step. In claim 1,
The crosstalk characteristic curve calculating step includes:
An extraction step of extracting a crosstalk occurrence portion from the characteristic information of each scanning line;
An interpolation step of interpolating the removed portion removed in the extraction step to obtain interpolation characteristic information of each scanning line;
A correction value table generation method comprising: an averaging step of calculating the crosstalk characteristic curve by averaging the interpolation characteristic information for the plurality of scanning lines obtained in the interpolation step. In claim 2,
The characteristic information comprises image information acquired for a given number of pixels of each scan line;
The interpolation step includes
A correction value characterized in that the interpolation characteristic information is obtained by using corrected image information obtained by averaging a plurality of pieces of image information including image information of the endmost portion of the crosstalk occurrence portion extracted in the extraction step. Table method. In any one of Claims 1 thru | or 3,
When the gradation value of the pixel is G, the image information of the characteristic information corresponding to the position of the pixel is L, and the approximate value is P,
The correction value calculated in the correction value calculation step is:
A correction value table generation method, wherein (G−G × L / P). In any one of Claims 1 thru | or 4,
A correction value table generation method, wherein the characteristic information is luminance. In any one of Claims 1 thru | or 5,
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 repeatedly acquiring image information of a plurality of pixels at the measurement pixel positions in each measurement image constituting a plurality of measurement images displayed using the light modulation element;
A characteristic information calculation step of calculating crosstalk characteristic information of the display image based on the image information acquired in the first image information acquisition step and the plurality of image information acquired in the second image information acquisition step. Including
Each of the measurement images constituting the plurality of measurement images is
A first image and a second pattern having a gradation different from a gradation of the halftone image, the halftone image being a background image, arranged at a given interval in the scanning direction,
The plurality of measurement images are:
A correction value table generation method, wherein the first and second patterns of each measurement image are shifted from each other in the scanning direction. In claim 6,
The scanning direction is:
A correction value table generation method, wherein the display image is in a horizontal scanning direction. In claim 6 or 7,
The first and second patterns are:
A correction value table generation method, wherein the correction value table is a pattern having a rectangular shape. In any of claims 6 to 8,
When the width of the first pattern in the scanning direction is h,
The interval is
A method for generating a correction value table, wherein h is less than 3 × h. In any one of Claims 6 thru | or 9.
The operation mode of the light modulation element is normally white,
The correction value table generation method, wherein the first and second patterns are black patterns. In any one of Claims 6 thru | or 9.
The operation mode of the light modulation element is normally black,
The correction value table generation method, wherein the first and second patterns are white patterns. A correction value table generation device that generates a correction value table for correcting an image signal corresponding to a display image using a light modulation element,
A crosstalk characteristic curve calculating unit that calculates a crosstalk characteristic curve of the display image based on characteristic information for a plurality of scanning lines of the display image;
From the crosstalk characteristic curve calculated by the crosstalk characteristic curve calculation unit,
An approximate value calculation unit for calculating an approximate value in a given scanning direction of the display image;
A correction value table generation device, comprising: a correction value calculation unit that calculates a correction value of the image signal based on the approximation value calculated by the approximation value calculation unit. In claim 13,
The crosstalk characteristic curve calculation unit
Extracting a crosstalk occurrence portion from characteristic information of each scanning line to obtain interpolation characteristic information of each scanning line, and averaging the interpolation characteristic information for the plurality of scanning lines to calculate the crosstalk characteristic curve. Correction value table generation device to perform. In claim 12 or 13,
When the gradation value of the pixel is G, the image information of the characteristic information corresponding to the position of the pixel is L, and the approximate value is P,
The correction value is
A correction value table generation device characterized by being (G−G × L / P). An image processing apparatus for correcting an image signal corresponding to a display image using a light modulation element,
A correction value table for storing correction values generated by the correction value table generation method according to any one of claims 1 to 11,
An image processing apparatus comprising: an image signal correction unit that corrects the image signal based on a correction value of the correction value table.