JP2001134252A - Data processor, picture display device, and image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data processor, a picture display device and an image pickup device which can suppress deterioration of the picture quality of a projected picture without necessitating much labor and time. SOLUTION: The data processor 200 inputs successively pictures of test patterns having the discontinuous gradation which are projected and displayed on a screen 53 by the picture display device 51, via the image pickup device 52. The data processor 200 samples only the picture data of parts of points e, f, g, and h in the screen 53 and, as a result of the sampling, gradation correction values corresponding to the full gradation in the points e, f, g and h are calculated by arithmetic interpolation. Subsequently, the data processor 200 calculates the gradation correction value of parts other than the points e, f, g and h by the arithmetic interpolation based on the gradation correction value of the points e, f, g, and h.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a data processing device,
For image display devices and imaging devices, more specifically, based on data sampled at relatively coarse sampling intervals, generate correction data corresponding to relatively fine sampling intervals by interpolation, and input data based on the correction data. The present invention relates to a data processing device, an image display device, and an image pickup device for performing correction.

[0002]

2. Description of the Related Art As a projection type image display device capable of correcting luminance unevenness (hereinafter, the projection type image display device is simply referred to as a "display device" in the present specification), Japanese Patent Application Laid-Open No. 8-23525.
There is one disclosed in Japanese Patent Application Publication No. In this display device, an image displayed on a projection screen is captured by an imaging camera. At this time, the screen is divided into a plurality of grid-like areas and photographed, and the luminance on the projection screen is obtained for each area. Subsequently, a brightness correction value corresponding to each area is obtained based on the obtained brightness for each area. The display device is provided with a memory, and a brightness correction value corresponding to each of the divided areas of the projection screen is recorded in the memory.

When the projection display is performed by the display device, an address value corresponding to the divided area of the projection screen is set by an address counter in synchronization with an input video signal input to the display device. The luminance correction value is sequentially read from the memory in accordance with the address value. An analog correction value is obtained by converting the read luminance correction value into an analog value by a D / A conversion circuit, and the analog correction value and an input video signal are arithmetically processed to obtain a luminance on a projection screen. Correct unevenness.

[0004]

In an apparatus using a dichroic mirror, such as a three-tube or three-panel electronic camera or a projection display device, for example, the spectroscopy is performed according to the incident angle of light incident on the dichroic mirror. The characteristics change. Shading occurs due to the phenomenon that the spectral characteristics change due to the difference in the incident angle. This shading causes uneven brightness on the projected screen. If the change in the spectral characteristics caused by the difference in the incident angle is different for each color light, the color balance changes depending on the location on the screen where the image is projected, causing color unevenness. When the color unevenness occurs, for example, the image is colored depending on the location on the screen despite the input of an achromatic image signal. When the color unevenness is corrected in an analog manner as described above, correction may not be performed due to variations in characteristics of components constituting the correction circuit itself and variations in product performance.

On the other hand, it is conceivable to digitally correct the above-described correction of color unevenness and luminance unevenness. In this case, according to the method described above, the projected screen is divided into a plurality of grid-like areas and photographed, the brightness on the projection screen is obtained for each area, and the brightness correction value is set for each area. Can be applied. Then, instead of the analog correction described above, the input video signal is digitally corrected using the correction value read from the memory described above.

However, when the projected screen is divided into a plurality of grid-like areas and the number of divisions when photographing is small, an input video signal corresponding to a certain divided area is corrected using the same correction value. Therefore, the correction is not performed finely. That is, focusing on each of the pixels constituting the projected screen, there is an error that cannot be completely corrected, that is, a residual error. This residual error may change abruptly across the boundary between adjacent divided regions. Then, due to the sudden change in the residual error, the uneven luminance and color unevenness which remain without being corrected suddenly change across the boundary, which is a factor of deteriorating the image quality of the projected image.

In order to suppress such a sudden change in luminance unevenness and color unevenness occurring between the divided areas, correction may be made for each pixel of a displayed image. However, in this case, it takes a lot of trouble and time to obtain the correction value, and the memory space required to store the correction value becomes enormous.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data processing apparatus which does not require much labor and time, requires only a small memory capacity for storing correction values, and can suppress a decrease in image quality of a projected image. , An image display device, and an imaging device.

[0009]

The following invention will be described with reference to FIGS. 1 and 2 showing one embodiment. (1) The data processing apparatus according to the first aspect of the present invention provides a data processing apparatus, comprising: data sampled at a second sampling interval larger than the first sampling interval from data sampled at the first sampling interval. Sample data extracting means 84 for extracting a third sampling interval larger than the first sampling interval and smaller than the second sampling interval by interpolation from the sample data;
Correction data generating means 84 for generating correction data having a sampling interval of: and correction means 77, 78 and 79 for correcting data before correction based on the correction data and generating corrected data. Achieve the goal. (2) In the data processing device according to the second aspect of the invention, the correction data is stored in a look-up table that defines a relationship between a value of the data before correction and a value of the data before correction. (3) The invention described in claim 3 is applied to an image display device that displays an image based on input data. The data processing device according to claim 1 or 2; and a display signal output unit 80 that outputs a display signal for displaying an image based on the corrected data generated by the correction units 77, 78, and 79. Have (4) The invention described in claim 4 is applied to an imaging apparatus having a photoelectric conversion device that photoelectrically converts a subject image formed by a photographing lens and outputs an image signal. The correction means 77, 78, and 79 correct the pre-correction data that is image data generated based on the image signal output from the photoelectric conversion device. To generate corrected data. (5) The image display device according to the invention described in claim 5 is:
Test pattern generating means 82 for generating test pattern data for displaying a plurality of types of predetermined test pattern images; display image for inputting at least a part of a display image based on the test pattern data and outputting image data A monitor 52; and a sample data extractor 84 for extracting sample data from the image data output from the display image monitor 52. (6) The image display device according to the invention described in claim 6,
When the number of display gradations of an image is M, the number of types of test patterns generated by the test pattern generating means 82 is less than M. (7) The image display device according to the invention described in claim 7,
The correction data generation means 84 generates correction data so as to suppress at least one of shading and color unevenness occurring in a displayed image. (8) The image display device according to the invention described in claim 8,
The display image monitor 52 is provided integrally with the image display device 51 or with a screen 53 for displaying images. (9) The image display device according to claim 9 is
From the results obtained with less than M test patterns,
This is obtained by interpolating a correction signal corresponding to a test pattern not generated by the test pattern generating means 82. (10) The imaging device according to the invention described in claim 10,
3. The data processing apparatus according to claim 1, further comprising: a photoelectric conversion unit 52 that captures at least a part of an image based on a plurality of types of test pattern data and outputs image data; , Photoelectric conversion means 5
The sample data is extracted from the image data output from the second sample data. (11) The imaging device according to the invention described in claim 11,
When the number of image display gradations is M, the number of test pattern types is less than M. (12) An imaging device according to the invention described in claim 12 is:
From the results obtained with less than M test patterns,
This is obtained by interpolating a correction signal corresponding to a test pattern that is not imaged. (13) The data processing device according to the thirteenth aspect of the present invention provides a data processing apparatus, comprising: data obtained by sampling an image signal at a first sampling interval at a second sampling interval larger than the first sampling interval. Sample data extracting means 84 for extracting sample data; and, from the sample data, correction data having a third sampling interval larger than the first sampling interval and smaller than the second sampling interval by interpolation processing. Correction data generating means 84 for generating; and correcting means 77, 78 and 79 for correcting an image signal based on the correction data and generating a corrected image signal. (14) In the image display device according to the invention, the image signal is sampled at the second sampling interval larger than the first sampling interval from the data sampled at the first sampling interval. Sample data extraction means 8 for extracting sample data
And correction data generating means 84 for generating correction data having a third sampling interval larger than the first sampling interval and smaller than the second sampling interval from the sample data by interpolation processing; Correction means 7 for correcting the image signal based on the correction data and outputting the corrected image signal
Display means 8 for displaying an image based on the image signal corrected and output by the correction means 84;
0. (15) The image pickup apparatus according to claim 15 includes: a photoelectric conversion unit 52 that photoelectrically converts a subject image to output an image signal; and data obtained by sampling the image signal at a first sampling interval. Sample data extracting means 84 for extracting sample data at a second sampling interval larger than the first sampling interval;
Correction data generating means 84 for generating correction data having a third sampling interval larger than the second sampling interval and smaller than the second sampling interval; and correcting and correcting the image signal based on the correction data. And correction means 77, 78 and 79 for generating the corrected image signal. (16) The imaging device according to the invention of claim 16,
Photoelectric conversion means 52 for capturing at least a part of an image based on a plurality of types of test patterns and outputting an image signal;
Sample data extracting means 84 for extracting sample data at a second sampling interval larger than the first sampling interval from data obtained by sampling the image signal at the first sampling interval;
Correction data generating means 84 for generating, from the sample data, correction data having a third sampling interval larger than the first sampling interval and smaller than the second sampling interval by interpolation processing; And a correcting means for correcting the image signal based on the data and generating a corrected image signal.

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used for easy understanding of the present invention. However, the present invention is not limited to this.

[0011]

FIG. 1 is a diagram showing a schematic configuration of an image display device provided with a data processing device according to an embodiment of the present invention. The image display device 51 includes an imaging device 52 and a data processing device 200. The image display device 51 includes:
For example, it is a projection type liquid crystal projector, a liquid crystal light valve for generating an image based on a video signal input from an external device, a light source for illuminating an image generated by the liquid crystal light valve, and an image illuminated by the light source on a screen 53. And a projection lens for projecting light to the projector. The image display device 51 includes an imaging device 52 for inputting (imaging) an image displayed on the screen 53, and an imaging device 52.
And a data processing device 200 for processing the image signal output from the device. The imaging device 52 and the data processing device 200 are integrated into the image display device 51.

[0012] Imaging device 52 and data processing device 200
Is configured to be supplied with power from the power supply unit of the image display device 51. The image display device 51 is provided with a calibration operation setting switch (not shown). When the operator operates this switch to set the calibration mode, power is supplied to the imaging device 52 and the data processing device 200. On the other hand, in a normal use state, that is, in a state in which an image based on a video signal input from an external device is projected on the screen 53, power is not supplied to the imaging device 52 and the data processing device 200. Therefore, wasteful power consumption is suppressed.
Note that four points e indicated by crosses on the screen 53,
f, g and h will be described later.

FIG. 2 is a block diagram schematically showing the internal configuration of the image display device 51. As shown in FIG. Terminals 71, 72 and 7
3, analog R, G, and B image signals for displaying an image on the screen 53 are input, and are converted into digital image signals by A / D converters 74, 75, and 76, respectively. The timing of A / D conversion by A / D converters 74, 75 and 76 is determined by address supply circuit 87.
Is controlled by a timing signal output from the controller.

The address supply circuit 87 generates the above-mentioned A / D conversion timing signal and address signal from the horizontal synchronizing signal input to the terminal 85 and the vertical synchronizing signal input to the terminal 86. The address signal generated by the address supply circuit 87 is input to lookup tables (hereinafter, the lookup table is referred to as “LUT”) 77, 78, and 79.

Referring to FIG. 3 which schematically shows the internal configuration of the address supply circuit 87, the address supply circuit 87 will be described in more detail. The horizontal synchronization signal input from the terminal 85 is input to the phase comparator 91. Phase comparator 91
The other input is a signal output from a TC terminal of a horizontal counter 93 described later. An analog voltage signal corresponding to the phase difference between the two signals input to the phase comparator 91 is input from the phase comparator 91 to the VCO 92.

The VCO 92 outputs a pulse signal having a frequency corresponding to the input voltage from the phase comparator 91. VCO9
The pulse signal output from the A / D converter 7
4, 75 and 76 and the clock terminal (CK) of the horizontal counter 93. The horizontal counter 93 is an N-ary counter. When N pulses are input from a clock terminal, one pulse is output from a terminal count terminal (TC). The signal output from the terminal count terminal is input to the phase comparator 91, and the phase is compared with the horizontal synchronization signal input from the terminal 85 as described above.

The horizontal counter 93 counts the number of pulse signals output from the VCO 92, and outputs an output terminal (Qn).
The count value is output. This count value is reset when it reaches N. The signal output from the horizontal counter 93 is a parallel signal.
The horizontal address signal is input to T77, 78 and 79. The above N is set according to the horizontal display resolution of the image display device 51.
1, or if the image display device 51 is of a so-called multi-scan type, the setting may be automatically or manually changed according to an input video signal.

The pulse signal output from the terminal count terminal (TC) is also input to the clock terminal (CK) of the vertical counter 94. The vertical synchronization signal input from the terminal 86 is supplied to a reset terminal (RS
T). The vertical counter 94 counts the number of pulse signals input from the horizontal counter 93, and outputs a count value from an output terminal (Qn). This count value is reset when a vertical synchronization signal is input to the reset terminal. The output signal of the vertical counter 94 is also a parallel signal like the output signal of the horizontal counter 93, and the LUT
The vertical address signal is inputted to 77, 78 and 79.

Referring to FIG. 2 again, the internal configuration of the image display device 51 will be described. The outputs of the LUTs 77, 78 and 79 are connected to the terminal A of the switch 81, respectively. The output of the test pattern generation circuit 82 is connected to the terminal B of the switch 81. When the switch 81 is connected to the terminal A, the image data output from the LUTs 77, 78 and 79 is input to the LCD driver 80. L
The CD driver 80 outputs a drive signal to a liquid crystal light valve or the like (not shown) based on the input image data. The details of the test pattern generation circuit 82 will be described later.

The data processing device 200 comprises a CPU 84, a working memory 83 and the like. CPU8
4 issues a test pattern generation command signal to the test pattern generation circuit 82 during the calibration operation described in detail later, and switches the switch 81 to the terminal B. Then, a predetermined test pattern is projected and displayed on the screen 53 (FIG. 1). At this time, the imaging device 52
The image projected on the screen 53 is input, that is, photographed, and an image signal is output to the working memory 83. The CPU 84 processes the image signal stored in the working memory 83 as described later, calculates a correction value for correcting at least one of shading and color unevenness, and performs LUT 77, 78 and 79
Output to LUTs 77, 78 and 79 store these correction values.

In the image display device 51 configured as described above, the calibration operation performed by the data processing device 200 included in the image display device 51 and the image display operation performed by the image display device 51 are sequentially performed. explain. In the following, in order to simplify the description, it is assumed that the display resolution of the image display device 51 is 6 pixels in each of the horizontal direction and the vertical direction. Also, R, G,
The gradation of each color B is 3 bits, that is, 0 (darkest) to 7
It is assumed that there are eight (the brightest) gradations, but the present invention is not limited to these values.

FIG. 4 shows a CPU 8 incorporated in the data processing device 200.
4 is a flowchart for explaining a calibration procedure executed by Step 4. Hereinafter, C will be described with reference to FIGS.
The calibration procedure executed by the PU 84 will be described.

In step S101, the CPU 84
The switch 81 is switched to the terminal B. Note that the switching of the switch 81 may be performed manually by an operator instead of automatically performed by the CPU 84.

In step S102, the CPU 84
A test pattern generation command signal is issued to the test pattern generation circuit. The test pattern generation circuit 82 includes a CPU
In response to the command signal output from 84, a test pattern described below is generated. Then, a predetermined test pattern is displayed on the screen 53.

In this embodiment, the test pattern projected on the screen 53 is a uniform neutral gray pattern in which R, G, and B have the same gradation value.
At this time, the test pattern projected on the screen 53 changes to black, gray, and white according to the change of the gradation value to 0, 4, and 7. However, the image projected on the screen 53 has not been subjected to any correction. For this reason, variations in the γ characteristics (the characteristics of the density of the displayed image with respect to the input signal) of the liquid crystal light valves of the R, G, and B colors,
Affected by shading. As a result, where a uniform pattern having an intermediate color is to be displayed on the screen 53, luminance unevenness or coloring (color unevenness) may occur depending on the location on the screen 53.

An image of the test pattern projected and displayed on the screen 53 is input by the image pickup device 52, and image data is output from the image pickup device 52. CPU84
Changes the type of the test pattern displayed on the screen 53, that is, the gradation of the neutral gray pattern to 0, 4, and 7, and takes the image data output from the imaging device 52 into the work memory 83 a predetermined number of times. (Three times in the present embodiment) is repeated. Hereinafter, in the description of the present embodiment, inputting the image of the test pattern displayed on the screen 53 by the imaging device 52 is referred to as “sampling” or “sample”. The stored image data is referred to as “sample data”.

It is preferable that the input / output characteristics of the image pickup device 52 are strictly adjusted or those whose characteristics are strictly measured. This is because the shading and color unevenness of the image display device 51 are corrected based on the display image on the screen 53 input by the imaging device 52. If the input / output characteristics of the imaging device 52 are not managed, the correction result is
The desired correction result cannot be obtained due to the influence of the input / output characteristics of No. 2.

In step S103, the CPU 84
A correction formula for calculating a gradation correction value is calculated from the sample data stored in the working memory 83. The sample data for calculating the correction formula will be described below with reference to FIG.

FIG. 5A shows an effective display area portion of an image projected and displayed on the screen 53, divided vertically and horizontally into six parts, and numbered for each area. In the present embodiment, the image display device 51 has 6
Pixels, the display resolution is 36 pixels in total.
Each of the 36 numbered regions corresponds to one display pixel. When the CPU 84 calculates the correction formula in step S103, the sample data in the regions 8, 11, 26, and 29 in FIG. This area 8,
11, 26 and 29 are screens 5 shown in FIG.
3 correspond to points e, f, g, and h.

Here, it is assumed that the sample data of the area 8 is as shown in Table 1 below.

[Table 1]

In the sample data of Table 1, R, G, B3
The G data of the color has the same value as the gradation value of the test pattern. That is, the gradation value of the test pattern is set to D
t, where Ds is the gradation value of the sample data, Ds = D
Since it is t, it is not necessary to find the equation for calculating the gradation correction value. On the other hand, as for the R color and the B color, as shown in the graphs of FIG. 6A and FIG.

Referring to FIGS. 6A and 6B, a procedure for obtaining an equation for calculating a gradation correction value for R and B colors from sample data will be described.

According to the graph of FIG. 6A, the projection display characteristics of the R color of the image display device 51 in the area 8 are 0 level for an input value of 0 and 3 levels for an input value of 4.
Then, it can be seen that the projection is displayed at the level of 6 with respect to the input value 7. In other words, it can be understood that the input value should be set to 4 in order to set the brightness level of the projected and displayed image to 3. That is, the correction values for the input values of 0 to 3 may be obtained from the straight line a in FIG. 6A, and the correction values for the input values of 3 to 7 may be obtained from the straight line b in FIG.
At this time, the vertical axis (the gradation value of the sample data) in the graph of FIG.
And the horizontal axis (the gradation value of the test pattern) are output (after correction)
The equation Do = f (Di) may be obtained by substituting the data Do. Then, the equation of the straight line a in FIG. 6A is Do = 4 / 3Di... Equation (1), and the equation of the straight line b is Do = Di + 1.

From the graph of FIG. 6B, in the same manner as described above, the correction value Do for the input value Di of 0 to 4 is obtained from the straight line a of FIG. The correction value Do for Di may be obtained from the straight line b in FIG. Then, the equation of the straight line a in FIG. 6B is Do = 4 / 3Di-4 / 3... Equation (3), and the equation of the straight line b is Do = 3 / 2Di-2. . The CPU 84 performs the process of step S103 according to the algorithm described above. In the above, area 8
In the above description, the processing based on the sample data is used as an example, but the CPU 84 performs the processing based on the sample data in the areas 11, 26, and 29 in the same manner. As described above, C
The PU 84 obtains an equation for calculating a gradation correction value of each of the R, G, and B colors based on the sample data of the regions 8, 11, 26, and 29 in step S103.

In step S104, the CPU 84
A tone correction value is calculated using the equation obtained in step S103. An example of the correction value calculation result by the CPU 84 is shown in Table 2 below.

[Table 2]

Table 2 shows only the gradation correction values of the area 8. In Table 2, when the input value Di (data before correction) of the R color is 7, the correction value Do calculated by Expression (2) is 8
Becomes However, since the gradation value can only exist from 0 to 7, the correction value Do is set to 7 in such a case.

Similarly, when the input value Di of the B color is 0, the correction value Do calculated by the equation (3) is -4/3, but the correction value Do is set to 0 for the same reason as described above. And B
Similarly, the correction value Do when the color input value Di is 7 is 7
And Table 2 shows the results calculated in Equations (1) to (4) rounded to the first decimal place. Note that, here, steps S103 and S10
4, the correction values other than the sample data are calculated by first-order (linear) interpolation, but the present invention is not limited to the above example.

By the processing of steps S101 to S104 by the CPU 84, the gradation correction values of the R, G, and B colors in the regions 8, 11, 26, and 29 are obtained. By the way, the above-described procedure for calculating the tone correction value is performed in the regions 1 to 3.
6, that is, it can be repeated for all the display pixels, but it takes a lot of time to calculate the gradation correction value. In the present embodiment, since the display resolution of the image display device 51 is 36 pixels, it is known that it takes a long time. However, this display resolution is SVGA (80
0 × 600 pixels), XGA (1024 × 768 pixels),
Furthermore, 1280 × 1024 pixels, 1600 × 1200
As the number of pixels increases, the time required for sampling, the memory capacity for storing sample data, and the time required for calculating the correction formula also increase dramatically.

In this embodiment, the gradation correction value of the area 8 is shared as the gradation correction values of the areas 1, 2, 7, and 8.
Similarly, the gradation correction value of the region 11 is set to the regions 5, 6, 11 and 12, and the gradation correction value of the region 26 is set to the regions 25, 26, 3
The tone correction values of 1 and 32 and of the area 29 are assigned to the area 2
9, 30, 35, and 36 are shared as tone correction values. As described above, the gradation correction value of one area is set to 4
By sharing the tone correction values for the two areas, the memory capacity required for storing the tone correction values can be reduced. Hereinafter, as shown in FIG. 5B, an area occupied by the areas 1, 2, 7, and 8 is defined as an area A, and the remaining areas are similarly defined as areas B, C,.
Defined as I. That is, steps S101 to S101
By the processing of 104, the gradation correction values of the areas A, C, G and I have been obtained.

In step S105, the CPU 84
Using the gradation correction values of the R, G, and B colors and gradations of the regions A, C, G, and I, as described below, the regions B,
Tone correction values corresponding to D, E, F and H are obtained by interpolation.

For example, when obtaining the gradation correction value corresponding to the gradation 0 of the R color in the region B, the gradation correction value of the gradation 0 of the R color in each of the regions A and C is added and divided by two. Similarly, the gradation correction values of the regions A and C are averaged for the gradations 1 to 7 of the R color and the gradations 0 to 7 of the G and B colors in the region B. Through the above average value calculation processing, the gradation correction value of each gradation of each of the R, G, and B colors in the area B is calculated.

According to the same procedure as described above, the CPU 8
4 calculates the gradation correction value of the area D by averaging the gradation correction values of the areas A and G for each gradation of each color. The CPU 84 further calculates a gradation correction value for the region F from the gradation correction values for the regions C and I, and a gradation correction value for the region H from the gradation correction values for the regions G and I. The CPU 84 also obtains the gradation correction value of the region E by adding the gradation correction values of the gradations of the respective colors of the regions A, C, G, and I, and dividing by 4. In the above example, a method has been described in which the tone correction values of each tone of each color in the regions B, DF, and H are obtained by averaging the tone correction values of the regions A, C, G, and I. Alternatively, for example, when the number of area divisions is large, it may be obtained by another interpolation method.

In step S106, the CPU 84
The gradation correction value of each gradation of each color of the regions A to I calculated through the processing of steps S103 to S105 is
Transfer to 7, 78 and 79. At this time, the LUT 77
In the RUT 78 for each of the R colors of the areas A to I, and in the LUT 78, the area A
, I, G, and G, and the LUT 79 has areas A to I
Are stored.

Here, the address supply circuit 87 and the LUT 7
The address bus connected to each of 7 to 79 will be described. As described above, LUT77-7
9 stores tone correction values corresponding to the areas A to I in FIG. 5B instead of storing the tone correction values for all the areas 1 to 36 in FIG. I have. That is, the gradation correction values of the area A in FIG. 5B are used for the areas 1, 2, 7, and 8 in FIG. More specifically, LS of the address buses in both the horizontal and vertical directions output from the address supply circuit 87 is used.
B is omitted and the bus width is saved by 2 bits.
By omitting the LSB of the address bus, 000, 001,..., 10 in the horizontal direction of FIG.
The address data described by 0, 101 and the binary number are represented by 00, 01, 10 in the horizontal direction in FIG. 5B. In the present embodiment, the address bus width can be omitted by 2 bits as described above, and the LUTs 77 and 7 can be omitted.
The storage capacities of 8 and 79 can be reduced to 1/4 of those for storing correction values corresponding to all the display pixels. In addition to the fact that the number of measurement points can be reduced at the time of calibration, the time required for calibration can be greatly reduced by performing measurement at only three of the eight gradations as described above.

For example, if the display resolution is 1,024 × 76
8 (10 bits in the horizontal direction × 10 bits in the vertical direction when represented by the bus width), and the display gradation of each of the R, G, and B colors is 256.
In the case of (the number of colors is represented by a bus width of 2 bits × the gradation of 8 bits), an address bus width of as much as 30 bits is required to store the correction values corresponding to all the display pixels. In addition, the time required for the measurement at the time of calibration is enormous. In this regard, according to the present invention, the time required for the measurement at the time of calibration can be significantly reduced, and the hardware scale can be reduced.

In the above-described embodiment, an example has been described in which two pixels in each of the horizontal direction and the vertical direction are stored in the LUTs 77, 78 and 79 as an area corresponding to a total of four pixels. The invention is not limited to the above example. For example, three or more pixels may be grouped together in each of the horizontal and vertical directions. Also, the number of pixels to be grouped in each of the horizontal and vertical directions does not necessarily need to be equal, for example, three pixels in the horizontal direction and two pixels in the vertical direction are grouped together. They may be grouped together. At this time, 2
When the pixels of a multiple of are combined, the address supply circuit 87, the LUTs 77 to 79 and the working memory 8
The address bus connected between the LUT 3 and the LUTs 77 to 79 may be sequentially omitted from the LSB side. When the number of pixels to be grouped is not a multiple of 2, a logic circuit such as an encoder corresponding to the number of pixels to be grouped is provided between the address supply circuit 87 and the LUTs 77 to 79 and between the working memory 83 and the LUTs 77 to 79. With the interposition, the number of address buses connected to the LUTs 77, 78 and 79 can be reduced.

Here, characteristics such as shading and color unevenness will be described. These characteristics change according to the horizontal and vertical positions on the display screen. When the change in the characteristic is captured as a wave, the degree of the change in the characteristic can be represented on the scale of frequency. In this case, since the change in the characteristic occurs in the space of the display screen, the degree of the change in the characteristic can be represented by a scale called spatial frequency. Hereinafter, in the present specification, “characteristics such as shading and color unevenness” are simply referred to as “display unevenness characteristics”.

On the other hand, the displayed image is composed of a plurality of pixels divided into a mesh in both the horizontal and vertical directions. That is, the displayed image is composed of a plurality of pixels arranged on a two-dimensional plane. The color of each pixel is defined by a combination of the gradation values of the three colors R, G, and B. In other words, a two-dimensional display screen is sampled (quantized) at a sampling interval defined by the pixel arrangement pitch.
It can be said that it is.

When the change in the display unevenness characteristic is viewed on the above-mentioned scale of “the sampling interval defined by the pixel arrangement pitch”, the degree of change (spatial frequency) of the display unevenness characteristic is as follows.
It is sufficiently lower than the maximum value of the spatial frequency that can be sampled at the sampling interval. Now, a sampling interval of image data to be displayed is defined as a first sampling interval, and a sampling interval at the time of sampling at the time of calibration is defined as a second sampling interval.
Is defined as the sampling interval of. The sampling interval of the correction value obtained by interpolating the sampling result is defined as a third sampling interval.

If there is no limitation on the time required for the calibration or the capacity of the LUT for storing the correction value, the second sampling interval may be made equal to the first sampling interval. In this case, the interpolation calculation becomes unnecessary. However, in practice, when the number of displayed pixels is around 1 million pixels or exceeds 1 million pixels, it is necessary to set the second sampling interval equal to the first sampling interval. The storage capacity of the LUT is enormous. Therefore, as in the present invention, extracting the sample data at the second sampling interval from the data having the first sampling interval and generating the correction data having the third sampling interval by interpolation is performed by calibration. This is effective in reducing the time required for the operation and in reducing the capacity of the memory for storing the correction data.

It is desirable that the second sampling interval be a sampling frequency (Nyquist frequency) exceeding twice the maximum spatial frequency of display unevenness to be corrected. By determining the second sampling interval in this manner, the display unevenness characteristic itself can be uniquely sampled. Therefore, the display unevenness characteristic sampled at the second sampling interval is interpolated, and the data to be corrected is corrected with the obtained correction data having the third sampling interval, thereby minimizing the residual error. can do.

As for the third sampling interval, the capacity of the LUTs 77, 78, and 79 for storing correction data can be reduced as the interval is increased and approaches the second sampling interval. On the other hand, since data (display area) to be corrected by one correction data increases, a residual error that cannot be completely corrected by the correction data increases. That is, the third sampling interval,
There is a trade-off relationship with the quality of the displayed image. Therefore, the third sampling interval may be set to an arbitrary value larger than the first sampling interval and smaller than the second sampling interval according to the image quality required for the image to be displayed.

Although the sampling interval in the pixel array direction of the image has been described above, the same can be said for the gradation direction. For example, when the display gradation of each of the R, G, and B colors has 256 gradations, the gradation interval defined by the 256 gradations corresponds to the first sampling interval. Then, a sampling interval at which the γ characteristic of the liquid crystal light valve can be sampled is determined as a second sampling interval, and a third sampling interval may be determined according to the image quality required for an image to be displayed.

As is clear from the above description, the "interval" of the sampling interval is not limited to the literal interval in the space where certain data is distributed, but also to any measurable physical quantity such as force or energy. It also includes the sampling interval (corresponding to the resolution at the time of quantization). For example, suppose that there is a certain current signal, and the resolution at the time of A / D conversion of the current signal is 1 mA. The sampling interval in this case is 1
mA. Further, if there is a signal that changes along a certain time axis, the “interval” can also be applied to a direction along the time axis (corresponding to an interval at the time of sampling). That is, in the present embodiment, the data processing device 2
Although 00 processes an image signal, the present invention is also applicable to processing other signals (data).

The above-described procedure for calculating the gradation correction value by the CPU 84 is performed, for example, every time the power of the image display device 51 is turned on. Alternatively, it may be performed at the time of factory shipment or the like. In the case where the operation is performed at the time of factory shipment, the imaging device 52 does not necessarily need to be built in the image display device 51. That is, the image pickup device installed on the assembly line of the image display device 51 may be connected to the image display device 51 in the process of assembling to calculate the gradation correction value. In this case, an imaging device independent of the image display device 51 may be installed so as to substantially face the projection surface of the screen 53. Alternatively, the screen 53 may be made of a polished glass, and the imaging device 52 may be installed on the back side of the screen 53 so that a projection image can be taken from the back side of the screen 53 during calibration. At this time, the relative position between the screen 53 and the imaging device 52 can be fixed by installing the screen 53 and the imaging device 52 integrally.

When the imaging device 52 is provided independently of the image display device 51 as described above, the gradation correction obtained by calibration is performed in a nonvolatile memory (not shown) such as a flash memory. It is desirable to store the value. And LUT77-79 are RA
M, and it is desirable to transfer the tone correction value from the flash memory to each of the LUTs 77 to 79 when the image display device 51 is powered on. When transferring the gradation correction values from the working memory 83 to the LUTs 77 to 79 or from the flash memory (not shown) to the LUTs 77 to 79, the outputs of the A / D converters 74 to 76 are disabled. Similarly, when the image display device 51 projects and displays an image, the working memory 8
3 is disabled and disconnected from the bus connected to the inputs of LUTs 77-79.

-Projection display of image-Each of the LUTs 77 to 79 stores a gradation correction value as described above, and when the image display device 51 performs projection display, The gradation correction is performed as follows.

In the projection display operation of the image display device 51,
To each of the terminals 71 to 73, an analog video signal of each of R, G, and B colors of an image projected and displayed on the screen 53 is input, and to each of the terminals 85, 86, a horizontal synchronizing signal and a vertical synchronizing signal are input. . The switch 81 is switched to the terminal A.

In response to the timing signal being supplied from the address supply circuit 87 to each of the A / D converters 74 to 76, the video signal converted into digital data is supplied to each of the LUTs 77 to 79. At this time,
Each of the LLUTs 77 to 79 from the address supply circuit 87 indicates to which pixel in the display screen the digital video signal (gradation data) output from each of the A / D converters 74 to 76 corresponds. An address signal is provided.

The LUTs 77 to 79 are the A / D converters 7
A video signal (gradation data) corrected in gradation based on the gradation data output from 4 to 76 and the address signal output from the address supply circuit 87 is supplied to the LCD driver 80.
Output to When the LCD driver 80 outputs a drive signal to an image generation device such as a liquid crystal light valve (not shown), an image generated by the image generation device is displayed on the screen 5.
3 is projected and displayed.

In the above, an example has been described in which the gradation correction value of the area 8 in FIG. 5A is used as the gradation correction value of the area A in FIG. 5 corresponding to one pixel, that is, FIG.
In the example of (a), any of the gradation correction values of the regions 1, 2, 7, and 8 may be used as the gradation correction value of the region A. Alternatively, statistical processing is performed on a plurality of tone correction values obtained by measuring an area corresponding to a plurality of pixels included in a specific area, and the statistical processing result is used as the tone correction value of the specific area. Is also good. For example, referring to FIGS. 5A and 5B, the gradation correction value of the area A is obtained by averaging, weighting average, or geometric mean of the gradation correction values of the areas 1 and 8. You may ask. By performing the processing as described above, it is possible to reduce the influence of noise components in the video signal output from the imaging device 52. To further reduce this noise component, the imaging device 5
2 preferably has a function of a noise reducer whose one example is shown in FIG. The noise reducer shown in FIG. 7 is called a recursive type, in which an input video signal is multiplied by a coefficient in frame units, added, and output. This noise reducer may be configured by an electric circuit, or may realize a function equivalent to that shown in FIG. 7 by software processing.

Further, interpolation in the gradation direction (step S in FIG. 4)
The processing in steps S103 to S104) and the interpolation in the arrangement direction of the display pixels (the processing in step S105 in FIG. 4) may be performed not only by linear interpolation but also by nonlinear interpolation using polynomial approximation or the like. .

The flowchart shown in FIG. 4 shows a procedure in which interpolation is first performed in the gradation direction in steps S103 and S104, and then interpolation is performed in the pixel arrangement direction in step S105 to calculate a gradation correction value. ing. On the other hand, interpolation is first performed in the pixel arrangement direction,
Subsequently, it is also possible to calculate a gradation correction value by performing interpolation in the gradation direction.

In the above description of the embodiment, when the image display device 51 performs the projection display, the A / D converters 74, 7
5 and 76 output data from LUTs 77 and 78
The example in which the correction is performed by the steps 79 and 79 has been described. Instead, the LU 84 is provided by the CPU 84 of the information processing device 200 or a separately provided hardware logic or CPU.
The functions of T77, 78 and 79 may be substituted. That is, the display unevenness characteristic sampled at the second sampling interval is interpolated by the CPU 84 or a separate hard logic or CPU to generate data having a third sampling interval for correction. , A / D converters 74, 75 and 76 can be corrected in real time.

In the above description of the embodiment, the imaging device 5
The example of projecting and displaying a neutral gray test pattern on the screen 53 using a so-called color image pickup device as 2 has been described. In the above example, if one test pattern is projected, sample data of three colors of R, G, and B can be obtained almost simultaneously, so that there is an advantage that sampling can be performed at high speed. Instead, although the time required for sampling is slightly increased, the imaging device 5
2 may be a monochrome imaging device. In this case, the test pattern is not a neutral gray test pattern, and the R, G, and B single-color test patterns are switched and displayed in time series, and sampling may be performed each time.

In the above description of the embodiment, an example in which the present invention is applied to a projection type image display device has been described.
The present invention can be applied to other display devices, imaging devices, and the like. For example, a case where the present invention is applied to an imaging device will be described. The imaging device has a photoelectric conversion device that photoelectrically converts a subject image formed by a mounted photographing lens and outputs an image signal. An image processing circuit connected to the subsequent stage of the photoelectric conversion device performs a predetermined process on an image signal output from the photoelectric conversion device, and then performs A / A
D conversion is performed to generate image data.

An image based on the image data output from the image pickup apparatus configured as described above is displayed on a display monitor or the like. Then, the image displayed on the display monitor is sampled using another imaging device, a photoelectric conversion device, or the like, and data for correcting an output signal of the imaging device is generated. At this time, it is preferable that the display characteristics of the display monitor and the imaging device for sampling the image displayed on the display monitor are strictly calibrated or those whose characteristics are known. Further, as the test pattern, a pattern displayed on a display device or the like may be used, or a test chart in which a predetermined test pattern is drawn may be used. Further, at the time of the sampling, the image data output from the imaging device may be directly input to the data processing device and sampled to generate correction data without displaying the image data on the display monitor.

Devices having the above-described imaging device include a digital still camera and a video camera. These digital still cameras and video cameras further include a recording unit for recording image data in a storage device such as a magnetic tape or a flash memory.

In the correspondence between the above-described embodiment and the claims, the CPU 84 functions as sample data extracting means and correction data generating means, the LUTs 77, 78 and 79 function as correcting means, and the LCD driver 80 functions as display signal output means. , The test pattern generation circuit 82 configures a test pattern generation unit, and the imaging device 52 configures a display image monitoring unit.

[0070]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first or thirteenth aspect, sample data is sampled at a second sampling interval larger than the first sampling interval from data sampled at the first sampling interval. The sampled data is extracted to generate correction data having a third sampling interval larger than the first sampling interval and smaller than the second sampling interval by interpolation processing, and based on the corrected data, By correcting the pre-correction data, the time required for extracting the sample data can be reduced, and the memory space required for storing the correction data can be minimized. (2) According to the second aspect of the invention, when the correction data is a look-up table, the correction data can be configured with a memory element having a smaller capacity than the conventional one. (3) According to the third aspect of the present invention, the time required for calibrating the image display device can be reduced, so that the operability is excellent.
Further, since the memory space for storing the correction data can be minimized, the manufacturing cost of the image display device can be reduced. (4) According to the invention described in claim 4, 10, 15 or 16, the time required for calibration of the imaging device can be shortened, so that the operability is excellent. Further, the memory space for storing the correction data can be minimized, so that the manufacturing cost of the imaging device can be reduced. (5) According to the fifth aspect of the present invention, since the calibration can be performed by the image display device alone, it is easy to always maintain the display performance in a high state. (6) According to the invention described in claim 6, by generating test patterns of the number of types less than the number of display gradations and extracting the sample data, the time required for extracting the sample data can be reduced, The time required for calibration can be reduced. (7) According to the invention described in claim 7, at least one of shading and color unevenness occurring in a displayed image can be suppressed, and the image quality of the displayed image can be improved. (8) According to the invention described in claim 8, the portability of the image display device can be improved by providing the display image monitoring means integrally with the image display device or the screen for image display. Further, since the relative position between the display image monitoring means and the image display device or the screen for image display becomes constant, the accuracy of data correction is improved, and a clearer display image can be obtained. (9) According to the ninth aspect of the present invention, a correction signal corresponding to a test pattern not generated by the test pattern generation unit is interpolated from a result obtained by a number of test patterns less than the number of gradations of an image to be displayed. Thus, the capacity of the memory to be mounted and the width of the address bus can be reduced. (10) According to the invention as set forth in claim 14, the time required for calibration of the image display device can be reduced, so that the operability is excellent. Further, since the memory space for storing the correction data can be minimized, the manufacturing cost of the image display device can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an image display device including a data processing device according to an embodiment of the present invention.

FIG. 2 is a block diagram schematically illustrating an internal configuration of an image display device including the data processing device according to the embodiment of the present invention.

FIG. 3 is a block diagram schematically showing an internal configuration of an address supply circuit.

FIG. 4 is a diagram illustrating a CP incorporated in a data processing device;
9 is a flowchart illustrating a calibration procedure performed by U.

FIG. 5 is a diagram illustrating a procedure for calculating a gradation correction value.

FIG. 6 is a diagram illustrating a procedure for obtaining an equation for calculating a gradation correction value.

FIG. 7 is a block diagram conceptually showing a function of a noise reducer incorporated in the imaging apparatus.

[Explanation of symbols]

51 ... image display device 52 ...
Imaging device 53 ... Screens 71, 72, 73 ...
Terminals 74, 75, 76 ... A / D converters 77, 7
8, 79 LUT 80 LCD driver 82 Test pattern generation circuit 84
CPU 85, 86 ... Terminal 87 ... Address supply circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/74 H04N 5/74 D 5C082 9/31 9/31 A F term (reference) 2H093 NC16 NC23 NC24 NC50 ND06 ND09 ND34 ND54 NE06 NG02 5C006 AA01 AA11 AA22 AF13 AF46 AF72 AF81 BB11 BF14 BF15 BF22 EA01 EC02 EC08 EC11 FA22 5C058 BA06 BA07 BA12 BA33 EA02 EA12 5C060 GA01 GD04 JA19 EA05 A05 EB05 A05 EB05 EB05 BA34 BA35 BB42 BB51 CA11 CA81 CB01 DA76 DA86 MM10

Claims (16)

[Claims] 1. sample data extracting means for extracting sample data at a second sampling interval larger than the first sampling interval from data sampled at a first sampling interval; Correction data generating means for generating, from interpolation data, correction data having a third sampling interval larger than the first sampling interval and smaller than the second sampling interval by interpolation processing; And a correction means for correcting the pre-correction data based on the data and generating corrected data. 2. The data processing device according to claim 1, wherein the correction data is stored in a look-up table that defines a relationship between a value of the data before correction and a value of the data before correction. Data processing device. 3. An image display device for displaying an image based on input data, wherein the data processing device according to claim 1 or 2, and an image based on the corrected data generated by the correction unit. And a display signal output means for outputting a display signal for displaying the image. 4. An image pickup device having a photoelectric conversion device for photoelectrically converting a subject image formed by a photographing lens and outputting an image signal, comprising: the data processing device according to claim 1 or 2; An image pickup apparatus, wherein the correction unit corrects the pre-correction data, which is image data generated based on the image signal output from the photoelectric conversion device, to generate the post-correction data. 5. The image display device according to claim 3, wherein test pattern generation means for generating test pattern data for displaying a plurality of predetermined types of test pattern images, and display based on the test pattern data. Display image monitoring means for inputting at least a part of an image and outputting image data, wherein the sample data extracting means extracts the sample data from image data output from the display image monitoring means. An image display device characterized by the above-mentioned. 6. The image display device according to claim 5, wherein when the number of display gradations of the image is M, the number of types of test patterns generated by the test pattern generating means is less than M. An image display device characterized by the above-mentioned. 7. The image display device according to claim 5, wherein said correction data generating means generates said correction data so as to suppress at least one of shading and color unevenness occurring in a displayed image. An image display device for generating. 8. The image display device according to claim 5, wherein said display image monitoring means is provided integrally with said image display device or integrally with a screen for image display. An image display device characterized by the above-mentioned. 9. The image display device according to claim 6, wherein a correction signal corresponding to a test pattern not generated by said test pattern generating means is interpolated from a result obtained by said number of test patterns less than M. An image display device characterized in that it is obtained. 10. The data processing device according to claim 1, further comprising: a photoelectric conversion unit configured to capture at least a part of an image based on a plurality of types of test pattern data and output image data; The image pickup apparatus, wherein the data extracting unit extracts the sample data from the image data output from the photoelectric conversion unit. 11. The imaging device according to claim 10, wherein
When the number of image display gradations is M, the number of types of the test patterns is less than M. 12. The imaging apparatus according to claim 11, wherein a correction signal corresponding to a test pattern that is not imaged is obtained by interpolating from a result obtained by the number of test patterns less than M. apparatus. 13. Sample data extracting means for extracting sample data from data obtained by sampling an image signal at a first sampling interval at a second sampling interval larger than the first sampling interval; Correction data generating means for generating, from the sample data, correction data having a third sampling interval larger than the first sampling interval and smaller than the second sampling interval by interpolation processing; A data processor that corrects the image signal based on the correction data and generates a corrected image signal. 14. A sample data extracting means for extracting sample data at a second sampling interval larger than said first sampling interval from data obtained by sampling an image signal at a first sampling interval; Correction data generating means for generating, from the sample data, correction data having a third sampling interval larger than the first sampling interval and smaller than the second sampling interval by interpolation processing; A correction unit that corrects the image signal based on the correction data and outputs a corrected image signal; and a display unit that displays an image based on the image signal corrected and output by the correction unit. An image display device characterized by the above-mentioned. 15. A photoelectric conversion means for photoelectrically converting a subject image and outputting an image signal, wherein the image signal is selected from data obtained by sampling the image signal at a first sampling interval, the data being larger than the first sampling interval. Sample data extracting means for extracting sample data at a second sampling interval; and a third data sampler which is greater than the first sampling interval and smaller than the second sampling interval by interpolation from the sample data. An imaging apparatus comprising: a correction data generating unit configured to generate correction data having a sampling interval of; and a correction unit configured to correct the image signal based on the correction data and generate a corrected image signal. . 16. A photoelectric conversion unit that captures at least a part of an image based on a plurality of types of test patterns and outputs an image signal; and wherein the image signal is selected from data sampled at a first sampling interval. Sample data extracting means for extracting sample data at a second sampling interval larger than the first sampling interval; and interpolating from the sample data, the sampling data being larger than the first sampling interval, and Correction data generating means for generating correction data having a third sampling interval smaller than the sampling interval, and correcting means for correcting the image signal based on the correction data and generating a corrected image signal. An imaging device comprising: