JP2004233813A - Apparatus, method, and program for color unevenness correcting image processing, and projection type image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type image display device that deters color unevenness by correcting the visual field angle dependence of a liquid crystal panel through gradation control over a plurality of pixels without requiring special measurements, a correcting circuit, etc. <P>SOLUTION: A color unevenness correcting image processing apparatus which is mounted on the projection type image display device having a display control part is equipped with: an input means of receiving source image data consisting of the image data of respective colors R, G, and B; a gradation value allocating means of allocating two different kinds of allocated gradation values to individual pixels constituting the image data according to the gradation values of the pixels; a pixel converting means of converting the individual pixels into combined pixels obtained by adjacently arranging a plurality of pixels having the two different kinds of allocated gradation values; and an output means of outputting the display image data of the individual colors R, G, and B consisting of the combined pixels to the display control part. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to color unevenness correction in a projection type image display device such as a liquid crystal projector.
[0002]
[Background Art]
2. Related Art A liquid crystal projector including a light valve having a liquid crystal panel and projecting source image data onto a screen or the like is known. The light valve of the liquid crystal projector is provided with a liquid crystal panel of three colors RGB. The light valve supplies the source image data separated into the three color components of RGB to the liquid crystal panels of the respective colors, combines the light passing through the liquid crystal panels of the respective colors, and projects an image on a screen.
[0003]
[Problems to be solved by the invention]
As a problem in the image display of the liquid crystal projector, there is occurrence of color unevenness. The color unevenness means that when a source image having a gray surface is displayed, coloring is partially generated on a display image on a screen. The main cause of the color unevenness is that the viewing angle dependency of the RGB three-color liquid crystal panel used as the light valve of the liquid crystal projector differs for each color panel and also depends on the position on the same color panel. Different things, and so on.
[0004]
In a conventional liquid crystal projector, gray level image data is actually displayed on a screen through the liquid crystal projector to measure the coloring of each part of the displayed image, and a correction circuit is provided, and color unevenness is generated based on the measurement result. The displayed image was corrected so as not to be performed. However, such an operation of actually displaying image data to measure color unevenness and setting a correction circuit requires labor, resulting in an increase in cost and hindering a reduction in the price of a liquid crystal projector.
[0005]
Recently, there has been a tendency to reduce the size of light valves in order to reduce the cost of liquid crystal projectors. As the size of the light valve is reduced, it is necessary to condense the light to be incident on the liquid crystal panel of each color. Be more susceptible. In addition, in a liquid crystal projector in which such a light valve is miniaturized, there is a type in which a multi-lens array is provided in the light valve in order to sufficiently condense the light incident on the light valve. Since the design is such that a large incident angle is generated, color unevenness is more likely to occur.
[0006]
The present invention has been made in view of the above points, and does not require a special measurement or correction circuit, and corrects the viewing angle dependency of a liquid crystal panel by controlling the gradation of a plurality of pixels to be displayed. It is an object to provide a projection-type image display device capable of suppressing the occurrence of unevenness.
[0007]
[Means for Solving the Problems]
According to one aspect of the present invention, a color shading correction image processing apparatus mounted on a projection type image display apparatus including a display control unit includes: an input unit that receives source image data including image data of each of RGB; For image data of each color, gradation value allocating means for allocating two types of different allocated gradation values to each pixel constituting the image data according to the gradation value of the pixel; A pixel conversion unit that converts a plurality of pixels having different types of assigned gradation values into a combination pixel arranged adjacent to each other, and an output unit that outputs display image data of each color of RGB including the combination pixel to the display control unit. , Is provided.
[0008]
The projection type image display device includes, for example, a light valve having a liquid crystal panel for each of RGB colors, and projects and displays a source image on a screen or the like. The color shading correction image processing device mounted on the projection type image display device receives the source image data from an external image source or the like, and, for each pixel in the image data of each of RGB, based on the gradation value of the pixel. Different types of assigned gradation values are determined. For example, if the gradation value of a specific pixel of image data of a certain color is 127 out of 256 gradations (gradation value range of 0 to 255), for example, a gradation value 0 and a gradation A tone value of two gray levels with a tone value 255 is assigned. Then, a plurality of pixels having the two assigned gradation values are arranged adjacent to each other to form a combination pixel, and the pixel is displayed instead of the original one pixel. This makes it possible to improve the viewing angle dependence of the liquid crystal panel used in the projection type image display device by displaying different gray levels adjacently to the combined pixels to be displayed, and as a result, color unevenness occurs. Can be suppressed.
[0009]
In one aspect of the color unevenness correction image processing apparatus, the gradation value allocating unit includes, for each pixel, a first allocation gradation value larger than the gradation value of the pixel, and a gradation value of the pixel. A small second assigned gradation value is assigned. As a result, two different gray levels are assigned according to the gray level of the original pixel, and the viewing angle dependence of a liquid crystal panel or the like can be improved.
[0010]
As a preferred example, it is preferable that the gradation value is assigned so that 1/2 of the sum of the first assigned gradation value and the second assigned gradation value is equal to the gradation value of the pixel. it can. In this example, the assigned gradation value can be obtained by a simple calculation based on the gradation value of the original pixel.
[0011]
In another preferred example, the gradation value allocating unit can determine the allocated gradation value based on display characteristics of an electro-optical panel used in the display control unit. In this example, by considering display characteristics of a liquid crystal panel or the like used in the projection type image display device, for example, γ characteristics, it is possible to correct color unevenness suitable for the characteristics of the device.
[0012]
In another aspect of the color unevenness correction image processing apparatus, the pixel conversion unit includes two pixels having the first assigned gradation value and two pixels having the second assigned gradation value. Are generated in a diagonal direction to generate a combined pixel composed of a total of four pixels. As described above, by configuring a combination pixel including four pixels in which four allocated pixel values are arranged diagonally, it is possible to improve the viewing angle dependency in both the vertical and horizontal directions and suppress color unevenness. It becomes possible.
[0013]
According to another aspect of the present invention, a projection-type image display device includes the above-described color non-uniformity correction image processing device, and light that has passed through an electro-optical panel for each of RGB colors driven in accordance with the display image data of each of the RGB colors. A display control unit for combining and projecting onto the screen, wherein, among the electro-optical panels for each of the RGB colors, the electro-optical panel for a specific one color is perpendicular to the electro-optical panel for the other two colors. It is arranged at a position shifted by half a pixel relatively in the direction and / or the horizontal direction.
[0014]
According to the above-described projection type image display device, by disposing one of the electro-optical panels of each color of RGB used for the display control unit at a position shifted by half a pixel relative to the other two, The visual resolution in the shifted direction can be increased. Therefore, it is possible to compensate for the reduced resolution by forming the combination pixels, and as a result, it is possible to correct the color unevenness without lowering the resolution.
[0015]
In a preferred example, the one specific color can be green. Generally, it is said that the sensitivity in human visual perception is high in the three colors of RGB, so that it is considered that the resolution can be effectively improved by displacing the green electro-optical panels. .
[0016]
According to another aspect of the present invention, a projection-type image display device includes the above-described color non-uniformity correction image processing device, and light that has passed through an electro-optical panel for each of RGB colors driven in accordance with the display image data of each of the RGB colors. A display control unit that synthesizes and projects the image on a screen, wherein the display control unit includes a driving unit that drives the electro-optical panel with a driving signal corresponding to the display image data, and the driving unit includes the display image. Among the pixels included in each combination pixel in the data, a level correction for increasing the level at the time of rising of the drive signal corresponding to the pixel having the assigned gradation value having the larger difference from the gradation value of the pixel before conversion. I do.
[0017]
According to the above-described projection type image display device, the display control unit has the electro-optical panel driven by the drive signal corresponding to the display image data. An electro-optical panel such as a liquid crystal panel has a delay in response to an input drive signal, which is more remarkable when a change in the gradation value of a display pixel is large. Of the two assigned gradation values included in the combination pixel in the display image data, the pixel having a larger difference from the gradation level of the original pixel is more susceptible to such a delay in response. For, by applying level correction for increasing the level of the drive signal, the response can be improved and the display quality can be improved.
[0018]
According to another aspect of the present invention, a color shading correction image processing method executed in a projection type image display device including a display control unit includes: an input step of receiving source image data composed of image data of each of RGB; A gradation assignment step of assigning two different assignment gradation values to each pixel constituting the image data in accordance with the gradation value of the pixel, for each color image data; A pixel conversion step of converting a plurality of pixels having different assigned gradation values into a combination pixel arranged adjacent to each other, and an output step of outputting display image data of each color of RGB composed of the combination pixel to the display control unit, Is provided. By this color non-uniformity correction image processing, the combined pixels to be displayed are displayed with different gray levels adjacent to each other, so that the viewing angle dependency of a liquid crystal panel or the like used in the projection type image display device can be improved, As a result, the occurrence of color unevenness can be suppressed.
[0019]
According to another aspect of the present invention, a color non-uniformity correction image processing program executed by a computer mounted on a projection-type image display device including a display control unit includes an input device that receives source image data composed of image data of RGB colors. Means, for each of the RGB image data, gradation value allocating means for allocating two different types of allocated gradation values to each pixel constituting the image data in accordance with the gradation value of the pixel; A pixel conversion means for converting a plurality of pixels having the two different assigned gradation values into a combination pixel arranged adjacent to each other, and an output for outputting display image data of each color of RGB composed of the combination pixel to the display control unit. The computer functions as means. By executing the color non-uniformity correction image processing program on the computer, the above-described color non-uniformity correction image processing apparatus can be easily realized.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0021]
[First Embodiment]
First, a liquid crystal projector according to a first embodiment of the image display device of the present invention will be described. FIG. 1 shows a schematic configuration of a liquid crystal projector 10 according to the first embodiment. The liquid crystal projector 10 receives color image data from an image source 7 such as a personal computer or a VTR, and displays a color image on a screen (not shown). As illustrated, the liquid crystal projector 10 includes a control unit 12 and a light valve 15. The control unit 12 includes a CPU 13 and a program ROM 14. The program ROM 14 stores processing programs corresponding to various processes executed by the liquid crystal projector 10, and the CPU 13 controls the operation of the liquid crystal projector 10 by executing the various processing programs stored in the program ROM 14. The color unevenness correction image processing for the color unevenness correction according to the present invention is also realized by the CPU 12 executing the color unevenness correction image processing program stored in the program ROM 14 in advance.
[0022]
FIG. 2 shows a configuration example of the light valve 15. In FIG. 2, 5431 is a light source, 5442 and 5444 are dichroic mirrors, 5443, 5448 and 5449 are reflection mirrors, 5445 is an incident lens, 5446 is a relay lens, 5447 is an emission lens, and 100R, 100G, and 100B are liquid crystal panels of RGB colors. 5451 is a cross dichroic prism, and 5437 is a projection lens. The light source 5431 includes a lamp 5440 such as a metal halide and a reflector 5441 that reflects light from the lamp. The dichroic mirror 5442 that reflects blue light and green light transmits red light of the light flux from the light source 5431 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 5443, and is incident on the red light liquid crystal panel 100R. On the other hand, among the color lights reflected by the dichroic mirror 5442, the green light is reflected by the green light reflecting dichroic mirror 5444, and is incident on the green light liquid crystal panel 100G.
[0023]
On the other hand, the blue light also passes through the second dichroic mirror 5444. For blue light, in order to prevent light loss due to a long optical path, a light guiding means including a relay lens system including an incident lens 5445, a relay lens 5446, and an output lens 5447 is provided, and the blue light is converted into blue light through this. Incident on the liquid crystal panel 100B. The three color lights modulated by the respective liquid crystal panels enter the cross dichroic prism 5451. This prism has four right-angle prisms bonded together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface. The three color lights are combined by these dielectric multilayer films to form light representing a color image. The combined light is projected on a screen 5452 by a projection lens 5437, which is a projection optical system, and an image is enlarged and displayed.
[0024]
Next, the principle of color unevenness correction according to the present invention will be described with reference to FIG. In the present invention, the viewing angle dependency of the liquid crystal panel 100 is improved by displaying two types of gray levels in one pixel of the source image to be displayed by the liquid crystal projector 10, and the occurrence of color unevenness is suppressed. It is known that a liquid crystal panel, particularly a TN (Twisted Nematic) liquid crystal, has a narrow viewing angle, but can improve the viewing angle by displaying pixels having different gradations in the vertical and horizontal directions (IBM literature).
[0025]
By applying this idea, instead of displaying each pixel included in the source image data as it is at the original gradation value, as shown in FIG. Display as a set of As described above, one pixel having a certain gradation value is a set of four pixels having two different gray levels (hereinafter, the gradation values of these pixels are referred to as “assigned gradation values”) (“combination pixel”). ), The viewing angle dependency of the liquid crystal panel 100 can be improved, and the occurrence of color unevenness can be suppressed.
[0026]
For example, as shown in FIG. 3B, assuming that the gradation value of a pixel to be displayed is 127 in the range of 0 to 255, this one pixel has a gradation value of “0”. It is displayed as a combination pixel composed of one pixel and two pixels having a gradation value of “255” (this process is also referred to as “pixel conversion”). In general, when the gradation value of a pixel to be displayed is X, the pixel is composed of two pixels whose gradation value is “0” and two pixels whose gradation value is “2X”. Is displayed as a combination pixel. Thereby, the viewing angle dependency can be improved for each pixel.
[0027]
Next, the flow of color unevenness correction image processing according to the present embodiment will be described with reference to FIG. FIG. 4 is a schematic flowchart of the color unevenness correction image processing according to the first embodiment. This process is performed by the CPU 13 executing the color non-uniformity correction program.
[0028]
First, the liquid crystal projector 10 receives source image data to be displayed from the external image source 7 (Step S2). The received source image data is sent to the control unit 12. The CPU 13 calculates an assigned gradation value for each pixel of the source image data according to the color shading correction image processing program (step S4). In the example of FIG. 3B, the CPU 13 calculates the assigned gradation values “0” and “255” for one pixel whose gradation value is 127 in the source image data. Then, the CPU 13 outputs to the light valve 15 a combination pixel composed of two pixels (total four pixels) having each assigned gradation value. In the example of FIG. 3B, the CPU 13 outputs to the light valve 15 data of four pixels composed of a combination of the assigned gradation values “0” and “255”. Then, the light valve 15 displays the input pixel data on the screen using the liquid crystal panels 100R, 100G, and 100B.
[0029]
As described above, according to the present embodiment, one pixel of the source image data to be displayed is constituted by a combination of pixels having two gray levels and is displayed, so that the field of view of the liquid crystal panel 100 in the light valve 15 is displayed. It is possible to improve the angle dependency and thereby suppress the occurrence of color unevenness.
[0030]
[Second embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, as in the first embodiment, one pixel of the source image data is displayed as a combination of pixels having two different gray levels. However, the relative positions (alignment) of the three color liquid crystal panels 100R, 100G, and 100B in the light valve 15 are adjusted in order to prevent a reduction in resolution.
[0031]
In the first embodiment, as shown in FIG. 3, one pixel in the source image data is displayed as two pixels having two different gray levels, that is, as a combined pixel including a total of four pixels. Therefore, as a display image itself, one pixel of the source image data is represented by four display pixels, and the resolution of the display image is substantially の of the source image in both the vertical and horizontal directions. . Therefore, in the present embodiment, the image data to be displayed is generated in the same manner as in the first embodiment, but the position of one of the three RGB liquid crystal panels 100 in the light valve 15 is changed to the other two colors. It is shifted by 1/2 pixel relative to the liquid crystal panel. As a result, it is possible to increase the resolution reduced to に よ り by the color unevenness correction image processing of the source image data, and return to the original resolution of the source image. Hereinafter, this method will be described in detail with reference to FIG.
[0032]
Normally, one pixel of a display image output (projected to a screen) by the liquid crystal projector 10 is configured as a combination of pixels of three colors RGB. When the alignment of the pixels of each color of RGB matches, the pixel is displayed as a white pixel as shown in FIG. For convenience of explanation, this state is shown with the RGB pixels aligned in the horizontal direction as shown in FIG. That is, when the vertical alignments of the pixels of the respective colors RGB match (there is no shift), the pixels of the respective colors of RGB are shown aligned in the horizontal direction in FIG. If the alignment of the pixels of each color of RGB matches, the actual display pixel is displayed as a superposition of them, and becomes white.
[0033]
On the other hand, as shown in FIG. 5B, for example, when the G (green) pixel among the three RGB colors is shifted by half a pixel in the vertical direction with respect to the other two colors, the human eye Are recognized as three pixels as shown on the left side of FIG. That is, the resolution can be improved by shifting the position of the pixel for any one color relative to the pixels for the other two colors by a half pixel.
[0034]
As shown in FIG. 5 (c), pixels to be displayed by the same color unevenness correction image processing as in the first embodiment are represented by two gray levels (a hatched pixel is a dark pixel, and a non-hatched pixel is a bright pixel. ), And only the G (green) pixel of the three RGB colors is shifted vertically by half a pixel with respect to the other two pixels based on the above-described concept. Four levels 1 to 4 are obtained (1 is the brightest), and the resolution in the vertical direction increases. In FIG. 5C, the gray level arrangement of the pixels of each color exemplifies a portion in which three bright, dark, and bright pixels are vertically arranged. However, as shown in FIG. 5D, the resolution similarly increases even in a portion where three pixels of dark, bright, and dark are arranged in the vertical direction.
[0035]
The resolution in the vertical direction is increased by shifting the alignment of the liquid crystal panel by a half pixel in this manner. The pixels displayed on the liquid crystal panel of each color are as shown in the example of FIG. 3 of the first embodiment. In addition, since two types of gray levels, dark, bright, and dark, are also repeated in the horizontal direction, two different gray levels, dark and bright in the horizontal direction, are actually used as shown in FIG. Are arranged, and the effect of improving the viewing angle dependency in the horizontal direction is maintained. When the alignment of the liquid crystal panel for one color (for example, G (green)) in the light valve 15 is shifted only by half a pixel in the vertical direction as in the example of FIG. However, if the same color liquid crystal panel is simultaneously shifted by half a pixel in the horizontal direction, the resolution in both the vertical direction and the vertical direction can be increased.
[0036]
As described above, in the present embodiment, as in the first embodiment, one pixel is expressed as a combination of two pixels of two gray levels by color shading correction image processing, and in addition, three colors in the light valve 15 are added. Of the liquid crystal panel of one color is shifted by half a pixel with respect to the other two colors, thereby improving the viewing angle dependency and suppressing the color unevenness, while lowering the resolution. (Strictly speaking, the resolution is reduced by the color non-uniformity correction image processing, but the decrease is compensated for by shifting the alignment of the liquid crystal panel by half a pixel.)
[0037]
Specifically, the three color liquid crystal panels 100R, 100G, and 100B in the light valve 15 are subjected to color unevenness correction image processing using two gray level pixels, as shown in FIG. It includes the repetition of pixels. Therefore, as schematically shown in FIG. 7A or FIG. 7B, for example, the G (green) liquid crystal panel 100G is vertically shifted with respect to the other two color liquid crystal panels 100R and 100B. In this case, the light valve 15 may be shifted by half a pixel. FIGS. 7A and 7B are diagrams schematically showing a state in which the liquid crystal panel 100G is viewed on the same plane as the paper of FIG. 2 from the direction of the screen 5452 in FIG.
[0038]
In the second embodiment, as described above, of the three color liquid crystal panels in the light valve 15, a specific one color liquid crystal panel is shifted by a half pixel relative to the other two colors, that is, Only the structure inside the light valve 15 is different from that of the first embodiment, and the color unevenness correction image processing performed by the control unit 12 in the liquid crystal projector 10 is the same as that of the first embodiment. Regarding the color of the liquid crystal panel shifted by half a pixel, considering that the human visual sensitivity is the highest for the green among the three RGB colors, the green (G) liquid crystal panel 100G is shifted to the other two colors. If the shift is made with respect to the liquid crystal panel, the degree of improvement in the resolution perceived by human vision is expected to be higher.
[0039]
As described above, according to the second embodiment, the resolution is improved by adjusting the alignment of the liquid crystal panels of each color in the light valve while suppressing the occurrence of color unevenness by the color unevenness correction image processing in the first embodiment. Can also be suppressed.
[0040]
[Third embodiment]
Next, a third embodiment of the present invention will be described. The third embodiment is a liquid crystal panel used in the light valve 15 when determining an assigned gradation value having two types of gray levels in the color unevenness correction image processing performed in the first and second embodiments. , Specifically, γ characteristics (tone characteristics).
[0041]
FIG. 8A shows an example of a γ characteristic (tone characteristic) of a TN mode liquid crystal panel. The horizontal axis represents the input gradation value of 256 gradations (0 to 255), and the vertical axis represents the output gradation value of 256 gradations (0 to 255). A characteristic 70 in the figure is a characteristic for determining an assigned gradation value for a pixel close to black, and a characteristic 72 is a characteristic for determining an assigned gradation value for a pixel close to white. For example, as shown in FIG. 8B, assuming that the tone value of a specific pixel in the source image is X (X <127, that is, gray close to white), this is assigned to the assigned tone value Xw (white ) And Xb (from black). Further, as shown in FIG. 8C, if the gradation value of a specific pixel in the source image is Y (Y> 127, that is, gray close to black), this is assigned to the assigned gradation value Yw (white ) And Yb (from black). As a result, it is possible to determine an assigned gradation value suitable for the display characteristics of the liquid crystal panel provided in the light valve 15.
[0042]
[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, in the first and second embodiments, of the assigned gradation values determined for a specific pixel to be displayed, the difference between the assigned gradation value and the gradation value of the pixel in the source image is larger. For the pixel of, level correction is applied to an image signal when the pixel is displayed.
[0043]
A liquid crystal panel as an image display device has a drawback that response is slow due to the property of displaying light and dark of an image by a change in the orientation of liquid crystal molecules. For example, even when a pixel of a liquid crystal panel is driven by an input signal Si having a steep level change as shown in FIG. 9A, the alignment of liquid crystal molecules changes gradually with time, and therefore the pixel of the pixel indicated by the signal So A change in the gradation level causes a delay in response. Therefore, there is known a method of improving the response by performing level correction on an input signal waveform supplied to a drive circuit of a liquid crystal panel. That is, as shown in FIG. 9B, a signal Sc whose level is increased for a predetermined period (for example, one frame of image data) is generated with respect to the input signal Si, and the liquid crystal panel is driven by the signal Sc. Thereby, the response of the liquid crystal panel can be improved. Such a technique is described, for example, in Japanese Patent No. 3305240.
[0044]
In the present embodiment, the above-described method is used to apply the above-described level correction to the drive signal of the pixel having a larger change from the tone value of the original image data. FIG. 10 shows a configuration of a liquid crystal projector 10a according to the fourth embodiment. The liquid crystal projector 10a of the present embodiment is configured by adding a frame memory 16 and a corrected display image signal calculating unit 17 to the liquid crystal projector 10 of the first embodiment. The frame memory 16 delays the source image signal from the image source 7 by one frame and supplies the delayed display image signal to the corrected display image signal calculation means 17. Further, the source image signal without delay is also supplied from the image source 7 to the corrected display image signal calculating means 17. The correction display image signal calculating means 17 can be a look-up table (LUT) storing a correction level amount set according to, for example, the source image signal and the source image signal delayed by one frame. 7 and the correction level amount is supplied to the light valve 15 in accordance with the input from the frame memory 16. As a result, the light valve 15 drives the liquid crystal panel with the drive signal after the level correction (see the output So in FIG. 9B), so that the response is improved.
[0045]
The response delay of the liquid crystal panel cannot be ignored as the change in the gradation level of the pixel to be displayed is large. In the present embodiment, the level correction has an assigned gradation value that has a large difference from the gradation value of the pixel of the source image among the two types of assigned gradation values generated by the color unevenness correction image processing. Apply to the other pixel. For example, in the case shown in FIG. 8B, the tone value of a specific pixel of the source image is X, and the assigned tone values of the two types of pixels generated by the color shading correction image processing are Xw and Xb, respectively. is there. Since the tone value X of the pixel of the source image is close to white, level correction is performed on the image signal (drive signal for driving the liquid crystal panel) corresponding to the assigned tone value Xb closer to black. Improve response. On the other hand, the level correction is not performed on the image signal corresponding to the assigned gradation value Xw having a small difference between the gradation values. Similarly, in the example of FIG. 8C, the drive signal corresponding to the assigned gradation value Yw is subjected to level correction to improve the response, and the image signal corresponding to the assigned gradation value Yb is improved. No level correction is performed. As a result, it is possible to improve the response and the display quality by applying the level correction to the assigned gradation value having a larger change from the gradation value of the pixel of the source image.
[0046]
FIG. 11 shows a flowchart of the color unevenness correction image processing according to the present embodiment. In FIG. 11, first, the liquid crystal projector 10a receives source image data from the image source 7 (step S12), and calculates an assigned gradation value for each pixel (step S14). In this case, the calculation of the assigned gradation value may be twice the gradation value of the target pixel as in the first embodiment, or may be performed in consideration of the γ characteristic of the liquid crystal panel as in the third embodiment. May be determined.
[0047]
Next, the corrected display image signal calculation means 17 in the liquid crystal projector 10a determines the level correction amount and generates a corrected display image signal (Step S16). Then, the corrected display image signal generated for the pixel for which the level correction is to be performed is supplied from the corrected display image signal calculating means 17 to the light valve 15, and the pixel for which the level correction is not to be performed is displayed from the control unit 12. The image signal is supplied to the light valve 15 (Step S18). The light valve 15 drives the liquid crystal panel 100 based on the input image signal to display an image.
[Brief description of the drawings]
FIG. 1 shows a schematic configuration of a liquid crystal projector according to a first embodiment.
FIG. 2 shows a schematic configuration of a light valve.
FIG. 3 is an explanatory diagram of color unevenness correction image processing according to the first embodiment.
FIG. 4 is a flowchart of color unevenness correction image processing according to the first embodiment.
FIG. 5 is an explanatory diagram of an example of color unevenness correction image processing according to a second embodiment.
FIG. 6 shows an example of a pixel arrangement of a liquid crystal panel according to a second embodiment.
FIG. 7 schematically shows a relative arrangement example of a liquid crystal panel according to a second embodiment.
FIG. 8 is an explanatory diagram of color unevenness correction image processing according to a third embodiment.
FIG. 9 is a diagram illustrating an outline of level correction according to a fourth embodiment.
FIG. 10 shows a schematic configuration of a liquid crystal projector according to a fourth embodiment.
FIG. 11 is a flowchart of color unevenness correction image processing according to a fourth embodiment.
[Explanation of symbols]
7 image source, 10 liquid crystal projector, 12 control unit,
13 CPU, 14 program ROM, 15 light valve,
16 frame memory, 17 correction display image signal calculation means

Claims (10)

In a color shading correction image processing device mounted on a projection type image display device including a display control unit,
Input means for receiving source image data composed of image data of each color of RGB;
A gradation value allocating unit for allocating two different types of allocated gradation values to the pixels constituting the image data for each of the RGB image data, in accordance with the gradation values of the pixels;
A pixel conversion unit configured to convert each of the pixels into a combination pixel in which a plurality of pixels having the two different assigned gradation values are arranged adjacent to each other;
An output unit that outputs display image data of each of the RGB colors composed of the combination pixels to the display control unit. The tone value assigning means assigns, for each pixel, a first assigned tone value larger than the tone value of the pixel and a second assigned tone value smaller than the tone value of the pixel. The color non-uniformity correction image processing apparatus according to claim 1. 3. The color unevenness correction image processing apparatus according to claim 2, wherein a half of a sum of the first assigned tone value and the second assigned tone value is equal to a tone value of the pixel. . The color unevenness correction image processing apparatus according to claim 2, wherein the gradation value allocating unit determines the allocated gradation value based on a display characteristic of an electro-optical panel used in the display control unit. . The pixel conversion means includes a combination pixel including a total of four pixels in which two pixels having the first assigned gradation value and two pixels having the second assigned gradation value are arranged diagonally. The color unevenness correction image processing apparatus according to claim 2, wherein the image is generated. An uneven color correction image processing apparatus according to any one of claims 1 to 5,
A display control unit that combines light that has passed through the electro-optical panel for each color of RGB that is driven according to the display image data of each color of RGB and projects the light on a screen,
Among the electro-optical panels for each of the RGB colors, the electro-optical panel for one specific color is shifted by half a pixel in the vertical direction and / or the horizontal direction relative to the electro-optical panel for the other two colors. A projection-type image display device, wherein the projection-type image display device is arranged at a position where the image is displayed. 7. The projection type image display device according to claim 6, wherein the specific one color is green. An uneven color correction image processing apparatus according to any one of claims 2 to 5,
A display control unit that combines light that has passed through the electro-optical panel for each color of RGB that is driven according to the display image data of each color of RGB and projects the light on a screen,
The display control unit includes a driving unit that drives the electro-optical panel with a driving signal according to the display image data,
The driving unit is configured to control a rising edge of a driving signal corresponding to a pixel having an assigned gradation value having a larger difference from a gradation value of a pixel before conversion among pixels included in each combination pixel in the display image data. A projection-type image display device, which performs a level correction for increasing a time level. In the color unevenness correction image processing method executed in the projection type image display device including the display control unit,
An input step of receiving source image data composed of image data of RGB colors;
A gradation value allocating step of allocating two different types of allocated gradation values to the respective pixels constituting the image data for the image data of each of the RGB colors, according to the gradation values of the pixels;
A pixel conversion step of converting each of the pixels into a combination pixel in which a plurality of pixels having the two different assigned gradation values are arranged adjacent to each other;
An output step of outputting display image data of each of the RGB colors composed of the combination pixels to the display control unit. A color non-uniformity correction image processing program executed by a computer mounted on a projection-type image display device including a display control unit,
Input means for receiving source image data composed of image data of each of RGB colors;
A gradation value allocating unit for allocating two different types of allocated gradation values to the respective pixels constituting the image data for the RGB image data,
A pixel conversion unit configured to convert each of the pixels into a combination pixel in which a plurality of pixels having the two different assigned gradation values are arranged adjacent to each other;
A color non-uniformity correction image processing program that causes the computer to function as output means for outputting display image data of each of the RGB colors composed of the combination pixels to the display control unit.

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