JPH06269014A - Picture correction device - Google Patents

Abstract

(57) [Abstract] [Purpose] Concerning color television receivers that are compatible with various scanning frequencies, it automatically corrects for convergence, geometric distortion, brightness, etc., resulting in highly accurate correction and significant adjustment time. An object is to provide an image correction device that can be shortened. A signal whose scanning frequency has been converted by the scanning frequency conversion unit 11 so as to be synchronized with the vertical detection cycle of the image pickup unit 2 is supplied to a test signal generation unit 5, which is then converted into a test signal corresponding to the input scanning frequency and an image is obtained. It is supplied to the display device 1.
The photoelectric conversion signal from the image pickup unit 2 is supplied to the position / level detection unit 3, the position and level of the test signal are detected, and the error calculation unit 4 calculates an error value for each color. The calculation signal from the error calculation unit 4 is supplied to the correction signal creation unit 6 to create various correction signals, and is supplied to the convergence geometric distortion correction unit 8 and the brightness correction unit 7 for automatic adjustment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for correcting a color television receiver capable of supporting various scanning frequencies, and more particularly to an image correcting apparatus for automatically making various corrections such as convergence, geometric distortion and brightness. It is a thing.

[0002]

2. Description of the Related Art Generally, in a video projector for magnifying and projecting in a screen by using three projection tubes that emit three primary colors, an incident angle (hereinafter referred to as a "concentration angle") of the projection tube with respect to the screen is different from each projection. Since the tubes are different, color shift, focus shift, deflection distortion, and brightness change occur on the screen. Each of these corrections uses a method in which an analog correction waveform is created in synchronism with the horizontal and vertical scanning periods, and the size and shape of this waveform are changed to make adjustments, but there is a problem in terms of correction accuracy. is there.

Further, there is a problem that it takes a long time to adjust because various corrections are manually corrected by visually observing the shift on the screen. Therefore, as a method with high convergence accuracy, the digital convergence apparatus of Japanese Patent Publication No. 59-8114 and a method of automatically correcting the deflection distortion are disclosed in Japanese Patent Publication No. 3-38797 and Japanese Patent Publication No.
-48553 discloses an automatic convergence correction device,
Japanese Patent Application Laid-Open No. 64-54993 discloses a convergence error correction method as a method for detecting and correcting the convergence error.

FIG. 22 shows a block diagram of a conventional automatic convergence correction device capable of automatic correction. As shown in FIG. 22, in order to adjust the convergence of the color image display device, a region obtained by dividing the entire display screen of the image display device into positive integers N and M in the horizontal and vertical directions, respectively,
The signal generator 102 generates a low-frequency signal in which the display signal waveform of each color in each area of the matrix is a line-symmetrical waveform in the horizontal and vertical directions. The generated low frequency signal is passed through the signal switch 103 to the image display device 10.
1 is supplied to the image processing device 105 while the signal from the imaging device 104 that captures the display screen of the image display device 101 is supplied to the image processing device 105. Here, in calculating the horizontal and vertical barycentric positions of the signal for each of the regions, the signal converted into the digital signal introduced into the image processing apparatus 105 is subjected to interpolation processing and thresholds are applied to lower the signal. The center-of-gravity position for each area is obtained by approximating the frequency signal waveform by a quadratic equation, and then the center-of-gravity error value between each color is calculated, and based on this center-of-gravity error value, the image display device 1
01 Convergence is automatically adjusted.

[0005]

However, in the correction device having the conventional structure as described above, since the center of gravity position is calculated by the quadratic approximation of the low frequency signal waveform, complicated processing is required in the image processing section. Therefore, there is a problem that the circuit scale becomes very large. In addition, since image processing is performed using a low-frequency signal that is a line-symmetrical mountain-shaped waveform,
The position detection sensitivity and accuracy at each level change due to the image receiving gamma characteristic of the image display device, and the correction accuracy decreases. Further, since the driving condition of the display device changes depending on the scanning frequency of the input signal, there is a problem that the convergence, the geometrical distortion, and the brightness must be adjusted again.

In view of the above, the present invention automatically corrects various corrections such as convergence, geometric distortion, and brightness when a display screen of an image display device having different scanning frequencies is imaged by an image pickup device having a predetermined scanning frequency. In addition, it is an object of the present invention to provide an image correction device capable of highly accurate correction and greatly shortening the adjustment time.

[0007]

SUMMARY OF THE INVENTION A first invention is a test signal generating means for generating an adjustment test signal for displaying on a display screen of a color image display device capable of coping with input signals having different scanning frequencies. Image pickup means for picking up the display screen of the image display device at a predetermined scanning frequency, detection means for detecting the position and level of the photoelectric conversion signal from the image pickup means, and an error value for each color from the output signal of the detection means And a correction signal generating means for generating a correction signal for correcting convergence, geometric distortion and luminance from an output signal of the error calculating means, and the test signal generating means includes the image capturing means. The test signal of the vertical scanning frequency synchronized with the vertical frequency of is generated.

According to a second aspect of the present invention, image pickup means for picking up a display screen of an image display device capable of handling input signals having different scanning frequencies at a predetermined scanning frequency, and an average value of photoelectric conversion signals from the image pickup means. Extracting means, detecting means for detecting the position and level from the signal from the extracting means, error calculating means for calculating an error value for each color from the detection signal, convergence and geometric distortion from the error calculating signal, and And a creating means for creating a correction signal for correcting the brightness.

[0009]

According to the present invention, it is possible to create a test signal in which the vertical scanning frequency of the test signal is synchronized with the detection frequency of the image pickup device for picking up an image, and to detect the position and level by extracting the average value of the photoelectric conversion signal. As a result, it is possible to realize automatic adjustment of convergence, geometric distortion, and brightness correction in a multi-scan image display device capable of handling input signals having different scanning frequencies.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an image correction apparatus according to the first embodiment of the present invention.

In FIG. 1, reference numeral 1 is a brightness correction unit 7, a convergence geometric distortion correction unit 8, a deflection yoke (including a convergence yoke) 9, a cathode ray tube (hereinafter abbreviated as CRT) 1
0 is a multi-scan image display device capable of coping with input signals having different scanning frequencies, 2 is an image capturing unit for capturing a test signal display image from the image display device 1 at a predetermined scanning frequency, and 3 is an image capturing unit. A position / level detecting unit for detecting the position and level of the imaged test signal, 4 is an error calculating unit for calculating an error value for each color from the signal detected by the position / level detecting unit 5, Is a test signal generating section for generating a test signal for convergence adjustment, 6 is a correction signal generating section for generating various correction signals based on the error calculation signal from the error calculating section 4, and 7 is a CRT 1
A brightness correction unit that corrects the brightness of 0, 8 is a convergence geometric distortion correction unit that corrects convergence and geometric distortion,
Reference numeral 11 denotes a scanning frequency conversion unit that synchronizes the vertical frequency of the test signal from the test signal generation unit 5 with the vertical scanning frequency of the imaging unit 2.

The operation of the image correcting apparatus of the present embodiment having the above-described structure will be described below with reference to FIG.

The input signals shown in FIGS. 2 (c) and 2 (e) are supplied to the multi-scan image display device 1 and the scanning frequency converter 11, and an image is displayed on the display screen of the multi-scan image display device 1. Also, the test signal shown in FIGS. 2B and 2D synchronized with the input synchronizing signal shown in FIGS. 2C and 2E is output from the test signal generator 5. A display screen of this test signal is shown in FIG. As shown in FIG. 2A, a mountain-shaped signal is projected as a convergence or geometric distortion adjustment test signal. The display screen on which the test signal shown in FIG. 2A is displayed is imaged by the imaging unit 2, and the display image light is converted into an electric signal. The image pickup unit 2 is composed of, for example, a CCD camera having a current method of about 250,000 pixels, and therefore, as shown in FIGS.
As shown in, the photoelectric conversion signal corresponding to the scanning frequency of the current method is output.

However, the vertical scanning cycle of the image display device 1 shown in FIG. 2E and the vertical detection cycle of the image pickup unit 2 shown in FIG. 2I are different. FIG. 3 shows a display screen when the photoelectric conversion signal from the image pickup unit 2 is displayed on the monitor. Figure 3
(a), (b), and (c) show display screens for each elapsed time. Figure 3 (a)
As shown in (b) and (c), the asynchronous vertical blanking period shifts upward with time. This factor is generated because the vertical cycle is asynchronous and the phase changes for each field.

Therefore, in the present embodiment, the scanning frequency converter 11
Scan frequency conversion is performed so as to be synchronized with the vertical detection cycle of the image pickup unit 2, and this signal is supplied to the test signal generation unit 5.
A test signal corresponding to the input scanning frequency (FIG. 2 (e)) shown in FIG. 2 (d) is converted into the input scanning frequency (FIG. 2 (h)).
It is converted into a test signal corresponding to (i)) and supplied to the image display device 1. The photoelectric conversion signal from the imaging unit 2 is
The level and the level of the test signal supplied to the level detector 3 are detected. The position detection signal from the position / level detector 3 is supplied to the error calculator 4 to calculate an error value for each color. The calculation signal from the error calculation unit 4 is supplied to the correction signal creation unit 6 to create various kinds of correction signals, and is supplied to the convergence geometric distortion correction unit 8 and the brightness correction unit 7 in the image display device 1 to automatically Convergence Geometric distortion adjustment and white balance adjustment are performed.

The block diagram of FIG. 4 will be used to describe the operation of the automatic convergence geometric distortion correction of the image correction apparatus of the present embodiment having the above-described structure in detail. A synchronizing signal is input to the input terminal 26, a deflection circuit 14 creates a correction current for raster scanning the screen, and the correction current is supplied to the deflection yoke 9 to control scanning. Further, the video signal from the input terminal 25 is input to the video circuit 13, and various kinds of signal processing and amplification for driving the cathode electrode of the CRT 10 are performed. The synchronizing signal from the input terminal 26 is supplied to the address generating circuit 22 and the vertical scanning frequency detecting circuit 21.

The address generation circuit 22 creates horizontal / vertical address signals for generating a test signal, and the vertical scanning frequency detection circuit 21 detects the input vertical scanning frequency to synchronize with the image pickup cycle of the CCD camera 16. The address generation circuit 22 is controlled so that an address signal for generating a test signal of the vertical cycle shown in FIG. 2D is created. The address signal from the address generation circuit 22 is supplied to the test signal generation ROM 23, and
A conical test signal synchronized with the vertical imaging period shown in (a) is generated. The rectangular part (□ in the center of the screen of FIG.
FIG. 5B shows a signal waveform obtained by enlarging the (part). The test signal from the test signal generation ROM 22 is supplied to the D / A converter 24 and converted into an analog signal.

Generally, the relationship between the input signal voltage (E) and the light emission output (L) of a CRT can be approximated by the following equation L = kE ^r , and the input signal voltage (E) and the light emission output (L)
When both are shown on a logarithmic scale, gamma (γ) has its slope, which is the gamma (γ) characteristic of the CRT. Generally, the gamma characteristic of a CRT is γ = 2.2. See also FIG.
(a) A solid line shows a characteristic diagram of an actual input signal voltage (E) versus light emission output (L) of the 7-type projection tube.

From the above, the test signal generation ROM 23
In this case, the ROM for generating the test signal and the conversion data of the gamma characteristic 2.2 of the input / output characteristic shown in the solid line in FIG. 6B are written. Therefore, from the test signal generating ROM 23, the sin shown in FIG. Converted to a ^two- wave, mountain-shaped test signal. The digital signal from the test signal generation ROM 23 is supplied to the D / A converter 24 and converted into an analog signal. The test signal converted into an analog signal by the D / A converter 24 is supplied to the switching circuit 12 in the image display device 1, switched to the video signal from the input terminal 25, and supplied to the video circuit 13 to be supplied to the CRT 10. The test signal is displayed on the screen. The display image of the test signal displayed on the screen of the CRT 10 is picked up by the CCD camera 16 and the image shown in FIG.
A conical photoelectric conversion signal whose rising / falling changes almost linearly as shown in (c) is obtained.

First, the operation waveform diagram of FIG. 7 is used to describe the position detecting method. The conical photoelectric conversion signal shown in FIG. 5C from the CCD camera 16 is supplied to the analog / digital (A / D) converter 17, and the information on the test signal display screen shown in FIG. Converted to a signal. The digital signal converted by the A / D converter 17 is supplied to the frame memory 18 to store display information.
The data from the frame memory 18 is read out by extracting the data corresponding to each adjustment area, and is supplied to the CPU 19 to detect the position of the center of gravity and calculate the error value.

In the CPU 19, a high-accuracy position can be obtained even in the current system of a black and white CCD camera of about 380,000 pixels and a system with a low detection accuracy in which the sample frequency of the A / D converter 17 is about 14.32 MHz. Detection will be required. FIG. 7A shows a sample frequency fsap = 14.32 MHz (sampling period 70 in the A / D converter 17).
ns) indicates the photoelectric conversion signal converted, and the center of gravity position which is the apex of the photoelectric conversion signal at this time exists at the sample point S7. FIG. 7B shows a case where the position of the center of gravity, which is the apex of the photoelectric conversion signal, exists between the sampling points S6 and S7. In this case, since the sample points are coarse, highly accurate position detection cannot be performed.

Therefore, in this embodiment, the position of the center of gravity is calculated by linear approximation based on the voltage of the sample point near the position of the center of gravity, and the position can be detected with high accuracy. As shown in FIG. 7C, the rising sampling points S4 to S6 of the photoelectric conversion signal
By calculating the intersection of the linear approximation data of the data D4 to D6 and the linear approximation data of the data D9 to D7 of the falling sample points S9 to S7 of the photoelectric conversion signal, high accuracy is achieved even in a system with rough detection accuracy. The position of the center of gravity can be calculated.

Next, the operation waveform diagram of FIG. 8 is used to explain the method of calculating the error value. In the case of calculating the convergence error, as shown in the waveform diagram of FIG. 8A, the G signal is treated as a reference signal, the R signal has an error value t1 in the leftward direction, and the B signal has an error value in the rightward direction t2. . When calculating the geometric distortion error, as shown in the waveform diagram of FIG. 8B, a specific sample point S20 is treated as a reference signal, the R signal is t3 to the left, the G signal is t4 to the left, B signal is t to the left
An error value of 5 is calculated. The calculation of the barycentric position and the error value is managed by the information corresponding to the address of the sample point.

As described above, the data in which the position of the center of gravity and the error value are calculated by the CPU 19 are supplied to the correction signal creating circuit 20 to create the correction signal for correcting the convergence and the geometric distortion, and the image display device. It is supplied to the convergence correction circuit 15 and the deflection circuit 14 in the No. 1 unit.

The convergence correction circuit 15 can be performed by the digital convergence method as described in the conventional example, and its basic block diagram is shown in FIG. The basic configuration is an address generation circuit 27 for creating various address signals from synchronization signals, an operation circuit 32 for calculating correction data based on a control signal from the correction signal creation circuit 20, and data of each correction point. For storing data, an interpolation circuit 29 for interpolating data between correction points, a D / A converter 30 for converting the interpolated data into an analog amount, and a smoothing analog amount. LPF (low-pass filter) 31 of.

Further, FIG. 10 shows a relational diagram of the movement on the screen of the correction change by the correction waveform of the analog system. As shown in FIG. 10, convergence correction can be automatically performed by calculating the barycentric positions of the screen center and the peripheral portion. That is, the number of the plurality of mountain-shaped test signals displayed on the screen is determined by the method of the convergence correction circuit. Further, the correction of the geometrical distortion of the screen amplitude and the deflection distortion in the deflection circuit 14 is the same as that of the conventional method, and therefore its explanation is omitted.

As described above, the convergence, the deflection distortion, the screen amplitude, etc. are automatically corrected from the data in which the position of the center of gravity is detected.

Next, the block diagram of FIG. 11, the display screen diagram of FIG. 12 and the operation characteristic diagram of FIG. 13 will be used to describe in detail the method of creating the test signal corresponding to the imaging scanning frequency. The horizontal synchronizing signal is supplied to a phase synchronizing circuit (PLL) 33 to generate a reference clock signal synchronized with the horizontal synchronizing signal, and this reference clock is supplied to a horizontal counter 34 to create a horizontal address signal. The horizontal address signal and the vertical synchronizing signal from the horizontal counter 34 are supplied to the vertical counter 37 to create an address signal in the vertical direction. The input vertical synchronizing signal is supplied to the scanning line number detection circuit 41 and the scanning frequency detection circuit 42 which are configured by a counter or the like, and the number of scanning lines and the vertical scanning frequency are detected. The detection signals from the scanning line number detection circuit 41 and the scanning frequency detection circuit 42 are supplied to the discrimination circuit 43, which creates a control signal for synchronizing with the imaging scanning cycle, and this discrimination signal is supplied to the vertical counter 37 for imaging. A vertical address signal for synchronizing with the scanning cycle is created.

Address signals from the horizontal counter 34 and the vertical counter 37 are supplied to the test signal ROM (1) 35 and the test signal ROM (2) 38. R for test signal
In the OM (1) 35, the data of the mountain shape test signal for convergence adjustment shown in FIG. 12 (a) is written. Further, in the test signal ROM (2) 38, the data of the window test signal for white balance adjustment shown in FIG. 12B is written.

An enlarged view of FIG. 12 (a) is shown in FIG. 12 (c), and an enlarged view of FIG. 11 (b) is shown in FIG. 11 (d). As shown in FIG. 12 (c), a cone-shaped test signal is used during convergence adjustment, and as shown in FIG. 11 (d), white / white balance adjustment is performed according to the highlight / gamma / low light adjustment items. A window-like test signal with varying tonal levels is generated.

Each test signal from the test signal ROM (1) 35 and the test signal ROM (2) 38 is supplied to the switching circuit 36, and a signal selected for each adjustment mode is output. The signal from the switching circuit 36 is supplied to the γ (gamma) correction ROM 39 having the input / output characteristic shown by the solid line in FIG. 6B, and gamma correction corresponding to the image reception gamma of the image display device is performed. That is, the γ (gamma) correction ROM 39 is shown in FIG.
Data for converting the input data of the broken line into the solid line of FIG. 6B is written. Since the operation dynamic range of the CCD camera 16 and the A / D converter 17 shown in FIG. 3 is limited, the detection sensitivity and accuracy of the characteristic shown by the solid line in FIG.

Therefore, in this embodiment, as shown by the broken line in FIG. 6 (a), correction is made so that the relationship between the drive voltage and the screen brightness changes in proportion to make the detection sensitivity and accuracy at all gradations constant. And highly accurate position detection and level detection.
Data for converting the input data indicated by the broken line in FIG. 12B into the solid line shown in FIG. 12B is written in the γ (gamma) correction ROM 39, and the gamma correction is performed. γ (gamma)
The digital signal from the correction ROM 39 is the A / D converter 4
It is supplied to 0 and converted into an analog signal.

The CCD camera 16 shown in FIG. 3 has the specifications of the horizontal scanning frequency fH = 15.75 kHz, the vertical scanning frequency fV = 60 Hz, and the number of scanning lines of 525 in the current system, and the effective pixels are 768 × 493 = 380,000. It is a pixel. Therefore,
The image displayed on the screen of the multi-scan compatible image display device 1 is detected by the CCD camera 16 of the current system and scan-converted into a photoelectric conversion signal of the signal specifications of the current system. When the input signal of the horizontal scanning frequency fH = 31.5 kHz of FIG. 13 (a) and the vertical scanning frequency fV = 120 Hz of FIG. 13 (e) is supplied to the image display device 1, it is created in synchronization with the input synchronizing signal. The generated test signal is shown in Fig. 13 (a).
It is shown in (c).

The test signals shown in FIGS. 13 (a) and 13 (c) are displayed on the screen, and the signals detected by the CCD camera 16 of the current system are shown in FIGS. 13 (b) and 13 (d). As shown in FIGS. 13B and 13D, scan conversion is performed into a signal corresponding to the scanning frequency of the current system.

As described above, when the multi-scan image display screen is detected by the image pickup device having a specific scanning cycle, the asynchronous vertical blanking period shifts upward with time as described with reference to FIG. This factor occurs because the phase of each field changes due to the asynchronous vertical cycle. Therefore, in this embodiment, the test signal generating method as shown in (Table 1) is used.

[0036]

[Table 1]

The horizontal scanning frequency is synchronized with the input horizontal synchronizing signal supplied to the multi-scan image display device 1, and the vertical scanning frequency is synchronized with the imaging scanning cycle of the CCD camera 16 or is set to be higher than the imaging scanning frequency. There is. That is, when the scanning frequency of the input vertical synchronizing signal is 60 Hz or more, it is synchronized with the input vertical synchronizing signal supplied to the multi-scan image display device 1, and when it is 60 Hz or less, the test signal is generated in synchronization with the imaging scanning frequency. Further, the discrimination circuit 43 controls the vertical counter 37 based on the number of scanning lines and the scanning frequency information.

Thus, by creating a test signal in which the vertical scanning frequency of the test signal is synchronized with the detection frequency of the image pickup element for picking up an image, stable and highly accurate detection can be realized, and the image receiving gamma correction of the test signal can be realized. With this, the detection sensitivity and accuracy in all gradations are made constant, and highly accurate position detection and level detection are realized.

Next, in order to explain the case of adjusting the brightness of the second adjustment item (white balance adjustment), the block diagram of FIG. 4 and the operation waveform diagram of FIG. 12 are used. The input signal is supplied to the image display device 1, and an image is displayed on the display screen. In addition, a brightness adjustment test signal from the test signal generation ROM 23 shown in FIG. 12D (partially enlarged view) is supplied to the image display device 1 and used at the time of brightness correction. Figure 1
2 (b) shows the display screen. The display screen on which the test signal shown in FIG. 12B is projected is imaged by the CCD camera 16 and the display image light is converted into an electric signal.

The level of each area is detected from the photoelectric conversion signal from the CCD camera 16 image pickup unit 2 and the error value of each color is calculated. The calculated signal is supplied to the correction signal generating circuit 20 and various A correction signal is created and supplied to the video circuit 13 in the image display device 1 to automatically perform brightness correction such as white balance (highlight / gamma / lowlight) and uniformity.

The block diagram of FIG. 14 is used to describe the operation of the automatic brightness correction of the image correction apparatus of the present embodiment having the above-described structure in detail. FIG. 14 shows a block diagram of the video circuit 13 shown in FIG. The video signal from the input terminal and the test signal from the test signal generator are supplied to the switching circuit 12 to switch signals. The signal from the switching circuit 12 is supplied to the gain control circuit 45, performs gain control for drive adjustment of contrast and highlight, and is supplied to the clamp circuit 46. Clamp circuit 4
In 6, DC reproduction is performed and the uniformity correction circuit 47 is performed.
Is supplied to. The uniformity correction circuit 47 performs a correction for equalizing the brightness of the central portion and the peripheral portion of the screen, and supplies it to the gamma correction circuit 48. The gamma correction circuit 48 corrects the change in the RGB emission characteristics of the 7-inch projection tube shown in FIG. Video output circuit 4
In 9, the CRT is amplified to a state where it can be driven and then applied to the CRT.

Before explaining the present embodiment, gamma correction in the case where saturation of the phosphor occurs will be described with reference to FIG. FIG. 15 is an emission characteristic diagram of R, G, B of a video projector for displaying a large screen using red, green, blue (hereinafter abbreviated as R, G, B) type 7 projection tubes. As can be seen from FIG. 15, in contrast to the linear characteristic of G, the emission characteristic of B has a non-linear region from a certain level of the beam current. The cause of the non-linear region is the saturation of the B phosphor in the large current region. Therefore, as can be seen from this figure, the non-linear characteristic due to this saturation is canceled to give a linear characteristic as shown by the dotted line in FIG. 15, and the chromaticity is made constant in all regions from the low luminance region to the high luminance region. In order to keep it, it is necessary to gamma-correct the video signal as shown in FIG.

Now, the operation of the embodiment of the brightness correction constructed as shown in FIG. 14 will be described below. To explain this operation, the adjustment order table of (Table 2) and the display screen diagram of FIG. 17 are used together.

[0044]

[Table 2]

[Table 2] is a table showing the adjustment order of the brightness adjustment. In the adjustment order, the low brightness is detected first and the low light is adjusted, and the high brightness is detected second and the high order is adjusted. Adjust the light, the third is to detect the medium to high brightness due to phosphor saturation and adjust the gamma, and the fourth is to detect the high brightness again to correct the change in highlight during gamma adjustment. The highlight is adjusted, and the middle to high brightness of the final entire screen (center and peripheral parts of the screen) is detected to perform uniformity adjustment for uniforming the screen.

As can be seen from Table 2, the low light, gamma and highlight adjustments can be made only by detecting the brightness in the center of the screen, but the uniformity adjustment requires the brightness detection in the center and the peripheral part of the screen. Therefore, as shown in the display screen of the test signal in FIG. 17, when performing low light, gamma, and highlight adjustment, a window signal for each gradation is generated in the center of the screen as shown in FIG. When the uniformity adjustment is performed, the screen brightness is detected by generating the test signal of the window signal at the center and the peripheral portion of the screen as shown in FIG. 17 (b).

FIG. 18 shows an input / output characteristic diagram for showing the test signal level in each adjustment item. As shown in FIG. 18, a test signal having a level corresponding to each adjustment mode is output from the D / A converter 24 in FIG. For example, a test signal with an input voltage of 10 to 20 V during low light adjustment, an input voltage of 50 to 100 V during gamma adjustment, 100 V during highlight adjustment, and 50 to 60 V during uniformity adjustment is displayed on the display screen.

First, the case of adjusting the white balance will be described. What is white balance adjustment? C
The color balance for each gradation due to the emission characteristics of the RT10 is adjusted. The test signal of each gradation shown in FIG. 18 is displayed on the screen of the CRT10, and the level amount of each gradation is C.
It is detected by the CD camera 16. The signal photoelectrically converted by the CCD camera 16 is supplied to the A / D converter 17, and the signal shown in FIG.
Information on the test signal display screen shown in 7 (a) is converted into a digital signal. The digital signal from the A / D converter 17 is supplied to the frame memory 18 and the display information is stored therein. The data from the frame memory 18 is extracted and read out from the data corresponding to each adjustment region, supplied to the CPU 19, and the level is detected and the error value is calculated. CPU1
The error value signal from 9 is supplied to the correction signal generation circuit 20.

In the correction signal generating circuit 20, as shown in FIG. 18, a low light control signal is supplied as a black level signal (10 to 20%) and an intermediate to white level signal (50 to 100%).
The gamma control signal is generated by and the highlight control signal is generated by the white level signal (100%). The low light control signal is supplied to the clamp circuit 46 and controls the cutoff of the RGB signals that drive the CRT 10. Further, the gamma control signal is supplied to a gamma correction circuit 48 configured by a broken line approximation of several points to correct the saturation characteristic of the B phosphor. Further, the highlight control signal is supplied to the gain control circuit 45 to control the amplitude of the RGB signals that drive the CRT 10, so that the white balance can be automatically adjusted.

Second, the case of adjusting the uniformity will be described. Uniformity adjustment is a CRT
The brightness balance in each part of the screen due to the optical system (lens or screen) is corrected, and the test signal of each gradation shown in FIG. 18 is displayed on the screen of the CRT 10, and the level amount of each gradation is CCD. It is detected by the camera 16. CC
The signal photoelectrically converted by the D camera 16 is an A / D converter 17
Is supplied to the digital camera, and the information on the test signal display screen shown in FIG. 17A is converted into a digital signal. The digital signal from the A / D converter 17 is supplied to the frame memory 18 and the display information is stored therein. The data from the frame memory 18 is read by extracting the data corresponding to each adjustment area,
It is supplied to the CPU 19 to detect the level and calculate the error value.

The error value signal from the CPU 19 is supplied to the correction signal generating circuit 20. In the correction signal generation circuit 20,
As shown in FIG. 18, an intermediate level signal (50-60
%) Creates a uniformity control signal. The uniformity correction signal is supplied to a uniformity correction circuit 47 composed of an analog modulator that multiplies the video signal and the correction signal to create a modulated video signal, and controls the amplitude of each part of the RGB signal that drives the CRT 10. , It is possible to automatically adjust the uniformity for displaying a uniform screen.

As described above, from the data whose level has been detected, the brightness correction such as white balance and uniformity is automatically corrected.

As described above, according to the present embodiment, the position and the level can be detected easily from the photoelectric conversion signal of the test signal in which the vertical scanning frequency of the test signal is synchronized with the detection frequency of the image pickup device for picking up an image. With the configuration, various corrections compatible with multi-scan can be realized, and highly accurate position detection and level detection can be performed regardless of the image receiving gamma of the image display device, so that highly accurate correction can be realized.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 19 is a block diagram of the image correction apparatus according to the second embodiment of the present invention.

In FIG. 19, reference numeral 50 designates an average value extraction unit for extracting the average value of the photoelectric conversion signals from the image pickup unit 5, 5
Reference numeral 1 is a position level detection unit for detecting the position and level from the extracted signal. The same elements as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The operation of the image correcting apparatus of the second embodiment constructed as above will be described below with reference to the operation waveform chart of FIG. The test signal from the test signal generator 5 shown in FIG. 20A is supplied to the image display device 1, and the test signal is displayed on the display screen. The photoelectric conversion signal obtained by picking up the image of the test signal displayed on the display screen of the CRT 10 by the image pickup unit 2 becomes a signal on which an unnecessary signal such as indoor lighting is superimposed as shown in FIG. The photoelectric conversion signal of FIG. 20B from the image pickup unit 2 is supplied to the average value extraction unit 50. The average value extraction unit 50 detects the correlation between frames and
The unnecessary signal, which is a signal having no correlation shown in (c), is extracted, and the unnecessary signal is removed from the photoelectric conversion signal to obtain a photoelectric conversion signal in which the unnecessary signal is deleted as shown in FIG. To be extracted.

In this way, the average value of the photoelectric conversion signals from the image pickup means, that is, the correlation between the frames is detected, and unnecessary signals having no correlation are removed, and then the position detection in the horizontal and vertical directions for each area is performed. By performing the level detection, stable and highly accurate automatic correction can be realized.

When considering the multi-scan compatible image display device 1, it can be roughly classified into a direct view type and a projection type, but considering the cause of generation of an unnecessary signal, the possibility of the projection type being higher because of the two-body configuration. Become. (Table 3) shows the causes of generation of unnecessary signals.

[0059]

[Table 3]

Unwanted signals can be roughly classified into those having a correlation and those having no correlation, and according to this embodiment, all unnecessary signals can be removed.

The block diagram of FIG. 21 will be used in order to explain the operation of the average value extraction unit 50 of the image correction apparatus of the present embodiment having the above-described structure in detail. A /
An analog photoelectric conversion signal from the image pickup unit 2 is input to the D converter 52, and the analog signal is converted into a digital signal. The digital signal from the A / D converter 52 has a coefficient (1-
K) 53, adder 54, coefficient (K), and frame memory 5
6 is supplied to the noise reducer. The noise reducer performs averaging processing between frames to obtain a noise-reduced signal, which is supplied to the CPU 57. The synchronization signal is supplied to the scanning line number / scanning frequency detection circuit 58,
The error between the imaging cycle of the imaging unit 2 and the driving cycle of the image display device 1 is predicted in advance, and this prediction signal is supplied to the CPU 57.

In the CPU 57, unnecessary signals are removed by the noise reducer processing and the prediction signal from the scanning line number / scanning frequency detection circuit 58. After the unnecessary signal removal processing is completed by the CPU 57, the position and level are detected and the error value is calculated. A correction signal is created by the correction signal creation unit 5 based on the calculation result from the CPU 57. Unwanted signals due to the asynchronous processing of the display system and the detection system are removed by the scanning frequency discrimination processing, and unnecessary signals having no correlation such as indoor illumination light are removed by the noise reducer processing. Therefore, it is possible to remove the signals of all the items of the cause of generation of the unnecessary signal shown in (Table 3), so that it is possible to detect with high accuracy.

As described above, according to the present embodiment, the average value of the photoelectric conversion signals from the image pickup means is extracted to remove unnecessary uncorrelated signals, and the position and level are detected from the signals, thereby stabilizing the stability. Since high-accuracy detection can be performed, high-accuracy correction can be realized.

In this embodiment, the image display device using the CRT has been described for easy understanding, but it goes without saying that other display devices are also effective.

In the present embodiment, the image receiving gamma of the image display device has been described as being corrected on the test signal generation side. However, gamma correction is performed in the loop of test signal generation-image display-imaging-centroid position detection. Needless to say, the existence of.

Further, although the case where the position of the test signal displayed on the image display device is detected as a conical shape has been described in the present embodiment, another shape such as a quadrangular pyramid may be used.

In the present embodiment, the case has been described in which 25 test signals are displayed on the screen to digitally perform convergence correction, but if the method is one in which convergence adjustment is effectively performed, another number or You may perform by a method.

Further, in the present embodiment, when the horizontal and vertical barycentric positions of respective regions are calculated by linear approximation from the conical photoelectric conversion signal whose rising and falling are substantially linearly changed from the image pickup means. However, the calculation may be performed by non-linear approximation as long as simple approximation can be performed.

In this embodiment, the test signal A
Although the case where the PL is changed to detect the level information has been described, the signals having different APLs may be simultaneously displayed for detection.

In the present embodiment, the case where the image display device and the detection system have a two-piece construction has been described. However, in the case of an integral construction such as a rear projection type video projector, the display screen from the rear side is detected. Good.

In this embodiment, the case where one screen is displayed as the image display device has been described, but it goes without saying that it is also effective in a multi-screen display device composed of a plurality of display screens.

[0072]

As described above, according to the first aspect of the present invention, the position and level are detected from the photoelectric conversion signal of the test signal synchronized with the detection frequency of the image pickup device for picking up the vertical scanning frequency of the test signal. Thus, various corrections compatible with multi-scan can be realized with a simple configuration, and highly accurate position detection and level detection can be performed regardless of the image reception gamma of the image display device, so that highly accurate correction can be realized.

According to the second aspect of the invention, the average value of the photoelectric conversion signals from the image pickup means is extracted to remove unnecessary uncorrelated signals, and the position and level are detected from the signals, whereby the display system is obtained. It is possible to perform stable and highly accurate detection even in a two-body system in which the detection system is separated and a display device that is compatible with multi-scan, so that highly accurate correction can be realized and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of an image correction apparatus according to an embodiment of the present invention.

FIG. 2 is a relationship diagram showing a display screen and operation waveforms for explaining the operation of the embodiment.

FIG. 3 is a display screen diagram for explaining the operation of the embodiment.

FIG. 4 is a block diagram for explaining the operation of the embodiment.

FIG. 5 is a relationship diagram showing a display screen and operation waveforms for explaining the operation of the embodiment.

FIG. 6 is a characteristic diagram for explaining the operation of the embodiment.

FIG. 7 is an operation waveform diagram for explaining the operation of the embodiment.

FIG. 8 is an operation waveform diagram for explaining the operation of the embodiment.

FIG. 9 is a block diagram of a convergence correction unit of the same embodiment.

FIG. 10 is a diagram showing a relationship between a correction wave and a correction change for explaining the operation of the embodiment.

FIG. 11 is a block diagram of a test signal generator of the same embodiment.

FIG. 12 is a relationship diagram showing a display screen and operation waveforms for explaining the operation of the embodiment.

FIG. 13 is an operation waveform chart for explaining the operation of the embodiment.

FIG. 14 is a block diagram of a video circuit of the same embodiment.

FIG. 15 is a characteristic diagram for explaining a gamma correction operation of the same embodiment.

FIG. 16 is a characteristic diagram for explaining the gamma correction operation of the same embodiment.

FIG. 17 is a display screen diagram for explaining the operation of the embodiment.

FIG. 18 is a characteristic diagram for explaining the operation of the embodiment.

FIG. 19 is a block diagram of an image correction apparatus according to a second embodiment of the present invention.

FIG. 20 is an operation waveform diagram for explaining the operation of the embodiment.

FIG. 21 is a block diagram of an average value extraction unit of the same embodiment.

FIG. 22 is a block diagram of a conventional automatic convergence correction device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image display device 2 Imaging unit 3, 51 Position / level detection unit 4 Error calculation unit 5 Test signal generation unit 6 Correction signal creation unit 7 Luminance correction unit 8 Convergence geometric distortion correction unit 11 Scanning frequency conversion unit 15 Convergence correction circuit 16 CCD camera 17 A / D converter 18 Frame memory 19 CPU 20 Correction signal generation circuit 21 Vertical frequency detection circuit 22 Address generation circuit 23 Test signal generation ROM 24 D / A converter 50 Average value extraction unit

Claims (4)

[Claims] 1. A test signal creating means for creating an adjustment test signal for displaying on a display screen of a color image display device capable of responding to input signals having different scanning frequencies, and a predetermined display screen for the display screen of the image display device. Image pickup means for picking up an image at a scanning frequency, detection means for detecting the position and level of a photoelectric conversion signal from the image pickup means, error calculation means for calculating an error value for each color from the output signal of the detection means, and the error And a correction signal creating means for creating a correction signal for correcting convergence, geometric distortion and brightness from the output signal of the calculating means, wherein the test signal creating means has a vertical scanning frequency synchronized with the vertical frequency of the imaging means. An image correction device characterized in that a test signal is created. 2. A test signal having a frequency higher than the vertical frequency of the image pickup means is created.
The image correction device described. 3. A test signal creating means for creating an adjustment test signal for displaying on a display screen of a color image display device capable of responding to input signals having different scanning frequencies, and a predetermined display screen for the display screen of the image display device. Imaging means for imaging at a scanning frequency, extraction means for extracting an average value of photoelectric conversion signals from the imaging means, detection means for detecting a position and a level from the signal from the extraction means, and an output signal of the detection means. An error calculating means for calculating an error value for each color from, and a correction signal generating means for generating a correction signal for correcting convergence, geometric distortion and luminance from an output signal of the error calculating means. Image correction device. 4. The image correction apparatus according to claim 3, wherein the extraction means detects a correlation between frames of the photoelectric conversion signal from the image pickup means and extracts an average value.