JPH09281921A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to inexpensively correct luminance unevenness, color unevenness on a screen in high luminance over the whole area of luminance levels of input video signals by correcting the amplitudes and the DC levels of the video signals related to the video signals of R, G, B. SOLUTION: A first D/A conversion means 7 converts the DC level correcting digital data read out from a memory device 6 storing the digital data of the amplitude and the DC level for correcting the luminance unevenness of a projection image on the screen related to at least one color among red color, green color, blue color into an analog signal. Further, an A/C conversion means 10 converts the video signal to a digital signal. Then, a multiplier circuit 11 corrects the output signal of the A/D conversion means 10 by the amplitude correcting digital data read out from the memory device 6. Further, a second D/A conversion means 12 converts the output signal of the multiplier circuit 11 to the analog signal. Then, an addition circuit 13 corrects the output signal of the second D/A conversion means 12 by the output signal of the first D/A conversion means 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device, and more particularly to a projection type image display device having a circuit device for correcting uneven brightness on a projection screen.

[0002]

2. Description of the Related Art In recent years, with the increase in size of projection screens for color projection image display devices, there has been a variation in the light sources and image display elements (LIGHT VULVE) that make up the device, and on the screen caused by peripheral dimming of projection lenses. It has become necessary to incorporate into the projection-type image display device a circuit for correcting the uneven brightness of each color of red, green, and blue depending on the position of, and the uneven color due to the superposition thereof. As disclosed in Japanese Patent No. 243495, the following methods have been conventionally considered.

The structure of a conventional example is shown in FIG. First, a video signal of a constant luminance level is input to the projection type image display device, and this video is projected on a screen. Next, the brightness level is measured by the image pickup camera for each area obtained by appropriately dividing the projection area of the screen, and the DC difference data from the target brightness level is recorded in the memory 5 as brightness correction data. The memory 5 in which the correction data is recorded is incorporated in the brightness correction circuit of the projection type image display device. This correction data is read by calculating the address of the memory corresponding to the screen area divided during the luminance measurement from the horizontal and vertical synchronization signals of the input video signal, and this correction data is read by the D / A conversion circuit 7. Driving an image display element (LIGHT VULVE) such as a liquid crystal display element of the projection type image display device with a video signal which is converted into an analog value and the analog correction value is added to the input video signal by using the adder circuit 13. The brightness unevenness and color unevenness on the screen are corrected by.

[0004]

However, since the luminance measurement which is the basis of the correction data is performed at a certain luminance level, a low luminance (near black level) video input signal is changed to a high luminance (near white level). It is not always possible to say that the luminance and color unevenness are corrected over the entire area of the video input signal of (1).

Further, the projection type image display device is required to support switching of the projection direction corresponding to the front direction and the back direction, and switching of the installation state of the device such as floor mounting or ceiling mounting. Therefore, the position of the unevenness on the screen also varies depending on these projection directions and installation conditions.
A correction corresponding to this is also required at the same time.

[0006]

In order to solve the above problems, the projection type image display device of the first invention of the present invention is at least red, green and blue (hereinafter abbreviated as R, G and B). A memory device storing digital data of amplitude and DC level for correcting luminance unevenness of a projected image on a screen for a video signal of one color, and first DC converting digital data for DC level read from the memory device into an analog signal D / A conversion means, A / D conversion means for converting the video signal into a digital signal, and the amplitude correction digital data read from the memory device to the A / D conversion means.
A multiplication circuit for correcting the output signal of the D conversion means, and a second D / A for converting the output signal of the multiplication circuit into an analog signal.
Conversion means and an adder circuit for correcting the output signal of the second D / A conversion means with the output signal of the first D / A conversion means, and for at least one color of the R, G, B video signals, It is configured to correct both the amplitude and the DC level of the video signal.

Further, the projection type image display apparatus of the second aspect of the present invention for solving the above problems corrects the uneven brightness of the projected image on the screen for the video signal of at least one color of R, G and B. A memory device that stores digital data of amplitude and DC level, and that can specify a read start position and a read direction corresponding to switching of the sweep direction of the projection image display device, and a DC level correction read from the memory device A first D / A conversion means for converting digital data into an analog signal, an A / D conversion means for converting the video signal into a digital signal, and the A / D conversion means with the digital data for amplitude correction read from the memory device.
A multiplication circuit for correcting the output signal of the D conversion means, and a second D / A for converting the output signal of the multiplication circuit into an analog signal.
Conversion means and an adder circuit for correcting the output signal of the second D / A conversion means with the output signal of the first D / A conversion means, and for at least one color of the R, G, B video signals, It is configured to correct both the amplitude and the DC level of the video signal.

The present invention has been made in view of the above background, and its first object is to correct luminance unevenness and color unevenness on a screen with high accuracy over the entire luminance level of the input video signal. A second object is to provide a projection-type image display device capable of performing brightness correction corresponding to the projection direction and installation state of the projection-type image display device.

According to the present invention, the amplitude and DC level of the input video signal are modulated by the brightness correction data according to the above-mentioned configuration. Therefore, in the entire screen projection area, from the low brightness signal level area to the high brightness signal level area. It is possible to correct luminance unevenness and color unevenness corresponding to a wide range of input video signal luminance levels.

Further, even if the position of unevenness of the projected image changes depending on the projection direction and installation condition of the projection type image display device, the memory device is designed to specify the read position and the read direction of the address of the memory device for storing the brightness correction data. By reading the correction data of the device, it becomes possible to correct the unevenness in brightness and the unevenness in color corresponding to the change in the position of the unevenness. Other features and effects of the present invention will be described in the following embodiments.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a digital of amplitude and direct current level for correcting unevenness of brightness of a projected image on a screen for a video signal of at least one color of R, G and B. A memory device that stores data and a first D / A that converts the DC level correction digital data read from the memory device into an analog signal
Converting means and A for converting the video signal into a digital signal
According to the present invention, since both the amplitude and the DC level of the input video signal are modulated by the brightness correction data, the low brightness signal level is read in the entire screen projection area. It is possible to correct luminance unevenness and color unevenness corresponding to a wide range of input video signal luminance levels from a region to a high luminance signal level region. The digital data for amplitude correction that has been output is used for the A / D
A multiplication circuit for correcting the output signal of the conversion means, a second D / A conversion means for converting the output signal of the multiplication circuit into an analog signal, and the second signal with the output signal of the first D / A conversion means. A projection image including an adder circuit for correcting the output signal of the D / A converting means, and correcting both the amplitude and the DC level of the R, G and B video signals for at least one color. The present invention is a display device, and according to the above-described configuration, since both the amplitude and the DC level of an input video signal are modulated by the brightness correction data, the entire screen projection area is changed from the low brightness signal level area to the high brightness signal level. This has an effect that it is possible to correct uneven brightness and uneven color corresponding to a wide range of input image signal brightness levels up to a region.

According to a third aspect of the present invention, digital data of an amplitude and a DC level for correcting luminance unevenness of a projected image on a screen for a video signal of at least one color of R, G and B is stored, and A memory device capable of designating a read start position and a read direction, a first D / A converting means for converting the DC level correction digital data read from the memory device into an analog signal, and the video signal into a digital signal. A / D conversion means, a multiplication circuit for correcting the output signal of the A / D conversion means with digital data for amplitude correction read from the memory device, and a second conversion circuit for converting the output signal of the multiplication circuit into an analog signal. And an adder circuit for correcting the output signal of the second D / A converting means with the output signal of the first D / A converting means. A projection type image display device characterized by correcting both the amplitude and the DC level of the image signal for at least one color of red, green and blue image signals, and the projection direction and installation state of the projection type image display device. Even if the position of the unevenness of the projected image changes due to the change in the position of the unevenness by reading the correction data of the memory device by specifying the reading position and the reading direction of the address of the memory device that stores the brightness correction data. Accordingly, it is possible to correct uneven brightness and uneven color.

(Embodiment 1) An embodiment of a projection type image display device of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of brightness correction of the projection type image display apparatus of the first invention.
In the present embodiment, a memory device 6 storing digital data of amplitude and DC level for correcting luminance unevenness of a projected image on a screen for a video signal of at least one color of red, green and blue, and the memory device 6 First D / A conversion means 7 for converting the DC level correction digital data read from the digital signal into an analog signal, and A / D conversion means 10 for converting the video signal into a digital signal,
A multiplication circuit 11 that corrects the output signal of the A / D conversion means 10 with digital data for amplitude correction read from the memory device 6, and a second D / A that converts the output signal of the multiplication circuit 11 into an analog signal. The conversion means 12 and the adder circuit 13 for correcting the output signal of the second D / A conversion means 12 with the output signal of the first D / A conversion means 7 are provided, and red, green, and blue images are provided. Both the amplitude and the DC level of the video signal are corrected for at least one color of the signal.

In FIG. 1, the video signal input from the video input terminal 1 is converted by the signal processing circuit 9 into R, G, B primary color video signals. On the other hand, the input video signal is input to the sync separation circuit 2, where it is separated into a horizontal sync signal and a vertical sync signal and output. The horizontal synchronizing signal is further input to the phase synchronizing circuit 3, and generates a horizontal synchronizing clock phase-synchronized with the horizontal synchronizing of the input video signal. By inputting the horizontal synchronizing clock and the vertical synchronizing signal into the address counter 4, an address corresponding to the position where the projection screen (hereinafter referred to as screen) is divided into a grid pattern is generated. The memory device 6 is composed of an address counter 4 and a memory 5. In the memory 5, R, G, B corresponding to respective regions obtained by dividing the screen by a method described later with reference to FIG. DC level and amplitude correction data of are stored in advance. Therefore, by inputting the address corresponding to the divided area into the memory 5, the R, G, and B DC level and amplitude correction data corresponding to the respective divided areas are read. The DC level correction data of the read data is the D / A converter 7 respectively.
Then, the amplitude correction data is input to the latch circuit 15, and the DC level and amplitude correction data are latched for each R, G, and B by the clock of the three-phase clock generation circuit 8, and the DC level correction value and the amplitude correction value are D / A converter 7
Is output from the latch circuit 15.

FIGS. 3 and 4 are blocks for explaining a read operation from a memory of correction data corresponding to each of R, G, and B primary color video signals using a three-phase clock signal, and a latch operation of the data. It is a figure and a timing diagram. In FIG. 4A, R1, G1, and B1 are correction data corresponding to R, G, and B in the first area obtained by dividing the projection screen,
2, G2, B2 represent correction data corresponding to R, G, B of the second area located next to the first area on the screen, and R1. G1
The correction data are stored in the order of B1, R2, G2, B2 .... This data is sequentially output to the memory 5 with the original cycle clock of FIG. 4B. To latch the data R, G, and B components separately, the data of FIG. 4C, FIG.
As shown in (e), a three-phase clock pulse created by dividing the original period clock by 3 and phase-shifting each by one period of the original period clock is used as a latch timing pulse for each of R, G, and B. Can be supplied as.

FIG. 3 is a block diagram for realizing the operation of FIG. In FIG. 3, a horizontal synchronizing clock and a vertical synchronizing signal, which are phase-synchronized with the input video signal, are input to the address counter 4, and an address corresponding to the area on the screen determined by the horizontal synchronizing clock and the vertical synchronizing signal is input. Since the address of the memory 5 is set by generating an address further divided by 3 by the original cycle clock, from the memory 5 to the R, G, and B areas corresponding to each area as shown in FIG. The data is output in order.

On the other hand, the original period clock output from the address counter 4 is input to a three-phase clock generation circuit 8,
FIG. 4C in which a clock obtained by dividing the original period clock by 3 is sequentially delayed by one period of the original period clock,
A three-phase clock as shown in (d) and (e) is generated.

At this time, since the DC level data and the amplitude data are output in parallel to the output of the memory device 6, the output of the memory 5 is the D / A converter 7a for DC level data of the R signal. , R signal amplitude data latch circuit 15a, G signal DC level data D / A converter 7b, G signal amplitude data latch circuit 15b, B signal DC level data D / A converter 7c, B It is possible to input in parallel to each input of the signal amplitude data latch circuit 15c. The D / A converter and the latch circuits 7a and 15a are provided with the three-phase clock shown in FIG. 4C, and the 7b and 15b are provided with the three-phase clock shown in FIG. 4D.
Since the three-phase clocks shown in FIG. 4E are input as latch pulses from the three-phase clock generator 8 to c and 15c, the output 1 of each D / A converter and latch circuit is eventually obtained.
6a, 16b, 16c, 16d, 16e, 16f, DC level and amplitude correction data corresponding to the respective R, G, B signals are output in synchronization with the screen upper divided areas.

If the R, G, B correction data is read from the memory device 6 in synchronization with the three-phase clocks in this way, memories are provided independently for the R, G, B correction data. Since there is no need, the memory can be used efficiently and can be constructed at low cost.

R, G, output from the latch circuit of FIG.
The correction signals 16a, 16b, 16c of the amplitude corresponding to B are respectively input to the multiplication circuit 11 of FIG. 1, and R, G, and R of the input video signal digitized by the A / D conversion circuit 10 are input.
The B component is multiplied. Then this multiplied signal is D /
It is input to the A conversion circuit 12 and converted into an analog signal.
The adder circuit 13 adds the DC level correction signals 16d, 16e, and 16f corresponding to R, G, and B output from the D / A conversion circuit of FIG. By this addition and multiplication processing, R, G, and B luminance signals whose DC levels and amplitudes have been corrected for each divided area on the screen are obtained at the output of the addition circuit 13. Therefore, the projection-type image display apparatus uses these signals. If the driving circuit 14 is driven, it is possible to project an image having no brightness unevenness over the entire area of the screen and the entire brightness level of the input video signal.

FIGS. 5 (a) and 5 (b) are diagrams showing the luminance characteristics for understanding the operation concept of the correction data calculation. The horizontal axis shows the input luminance level to the projection type image display device (hereinafter IRE).
The vertical axis represents the brightness level on the screen. In FIG. 5B, for example, the measured luminance at 80 IRE is P
If the luminance measured at 20 IRE is Q point, and the luminance characteristic is gamma-corrected in advance and is almost linear, the luminance characteristic can be linearly approximated like line a. The c line is the target luminance characteristic on the screen and the input signal level is 0.
In the case of, it is a straight line with a certain inclination and the brightness is zero. Considering luminance correction of data measured at a constant input signal level (for example, 80 IRE) as in the prior art (for example, Japanese Patent Laid-Open No. 61-243495), as shown in FIG. The luminance I1 at the 80 IRE (point P) is increased by ΔI to the luminance I2 at the 80 IRE of the target luminance line c (point P '), and the luminance characteristics of the b line obtained by moving the a line in parallel by the ΔI amount. Is corrected to. This correction may be performed by adding a DC level corresponding to ΔI using an adder in hardware. However, at the 0IRE level, since the a line originally has a brightness difference of I with respect to the target brightness line c, the corrected b line has a brightness of (I + ΔI) and an error increases. Therefore, in the present invention, a method is adopted in which the luminance is measured at at least two input levels, and in addition to the correction of the DC component, the inclination of the luminance characteristic, that is, the amplitude is simultaneously corrected.

That is, as shown in FIG. 5A, first, the luminance point P at 80 IRE and the luminance point Q at 20 IRE are measured for only the R signal component, and the straight line a connecting PQ is extended to 0 IRE.
The DC luminance error ΔI at Next, the straight line a is moved in parallel by ΔI so that the brightness becomes 0 when 0IRE is created to create a straight line d, and the ratio β of the inclination between the d line and the c line of the target brightness is obtained. When the ratio β is multiplied by the d line, the target brightness c
You can see that the line is obtained. Therefore, when calculating the correction data, the DC luminance error component ΔI and the inclination ratio β are calculated, and the ΔI and β are simultaneously recorded in the memory 5 of FIG. 1 as the DC level and amplitude correction data, respectively.

Here, in measuring the brightness correction data, the screen is divided into uniform grids, but the address counter 4 of the projection type image display apparatus of FIG. 1 is used.
It is also possible to set non-uniform divided areas by devising the configuration of.

In addition, brightness data acquisition means capable of acquiring brightness data corresponding to two or more different input signal levels in order to create amplitude and DC level correction data for the video signal of at least one color of R, G, and B. It is also possible that correction data is created by the correction data creation unit 17 based on 18 and the data and stored in the memory device 6.

As described above, according to this embodiment of the first aspect of the invention, the brightness of the input video signal is corrected by the brightness correction data of both the amplitude and the DC level, so that the high brightness signal from the low brightness signal level region is corrected. It is possible to widely correct luminance unevenness and color unevenness up to the level region. In addition, by using three-phase clock signals corresponding to R, G, and B video signals, the number of memory devices can be reduced, and cost can be reduced.

(Embodiment 2) FIG. 6 is a block diagram showing a configuration of an embodiment of a projection type image display apparatus of the second invention. The same elements as those in FIG. 1 of the embodiment of the first invention are designated by the same reference numerals and operate in the same manner. The switch 31 is a sweep / count start position control switch, and the sweep start position control terminal 35 of the drive circuit 14 and the count start position control terminal 3 of the address counter 4 for designating the address of the memory 5 in which the correction data is recorded.
Connected to 3. On the other hand, the switch 32 is a sweep / count direction control switch, which is commonly connected to the sweep direction control terminal 36 of the drive circuit 14 and the count direction control terminal 34 of the address counter 4 for designating the address of the memory 5.

The video signal input from the video input terminal 1 is converted by the signal processing circuit 9 into R, G, B primary color video signals. The memory 5 is preliminarily input with the correction data of the R, G, and B DC levels and amplitudes obtained by dividing the screen into a grid pattern and measuring the luminance unevenness corresponding to each area. The address counter 4 has a switch 31.
Since the command from is input to the count start position control terminal 33, the read start address of the memory 5 is specified, and since the command from the switch 32 is input to the count direction control terminal 34, the read start from the memory 5 is started. The position and direction are specified. Also address counter 4
Generates an address signal corresponding to a position where the projection screen is divided from the horizontal sync clock obtained from the sync separation circuit 2 and the phase sync circuit 3, and inputs this address signal to the memory 5 to display the address signal on the screen from the memory 5. R, G, B correction data corresponding to the divided areas are read.

As with the correction data described with reference to FIGS. 1 and 3, the correction data of the DC level and the amplitude are read out by the D / A converters of R, G, and B and the latch circuit, and these values are read out. The brightness of the input video signal is corrected for each of R, G, and B by being input to the multiplication circuit 11 and the addition circuit 13, respectively. The corrected luminance signal is input to the drive circuit 14, but the sweep start position control terminal 35 is designated by the switch 31 and the sweep direction control terminal 36 is designated by the switch 32. The drive circuit is swept in the same direction.

In the memory 5, R on the screen,
The correction data corresponding to the positions of the uneven brightness of G and B is stored. However, when the projection type image display device is switched between the front projection and the rear projection, the horizontal sweep direction of the drive circuit 14 is reversed by the switch 32. It is also necessary to reverse the pattern of uneven brightness in the horizontal direction. In order to deal with this, control is performed with the count direction control terminal 34 of the address counter 4 to reverse the order of the addresses for reading the correction data from the memory 5 in the horizontal direction.

Similarly, when the installation state of the projection type image display apparatus such as floor-standing or ceiling-mounting is switched, the pattern of brightness unevenness is inverted in the vertical direction, so the switches 31, 32 are used to control the sweep start position control terminal 35 and the sweep direction. Terminal 36
By controlling the count start position control terminal 33 and the count direction control terminal 34 of the address counter 4, the order of addresses for reading the correction data from the memory 5 is inverted in the vertical direction. In this way, the correction data of the DC level and the amplitude corresponding to the unevenness of brightness and the unevenness of color of the projection screen, which changes depending on the projection direction and the installation state, are sequentially output from the memory device 6.

The DC level and amplitude correction data output from the memory device 6 are input to the D / A converter 7 and the amplitude correction data to the latch circuit 15, respectively. The DC level and amplitude correction data are latched for each R, G, and B by the clock, and the DC level correction value and the amplitude correction value are output from the D / A converter 7 and the latch circuit 15, respectively, and added by the adder circuit 13 and the multiplier circuit. 11 and a multiplication circuit 1 for each of the R, G and B video signals which are output signals of the signal processing circuit 9.
The value 1 corrects the signal amplitude, and the adder circuit 13 corrects the signal DC level. The brightness-corrected R, G, and B signals are input to the drive circuit 14 to drive the image display element (LIGHT VULVE), so that an image without brightness unevenness and color unevenness should be projected on the screen. become.

As described above, according to the second embodiment of the present invention, by modulating the video signal with both the amplitude and the DC level, a wide range of input from the low luminance signal level region to the high luminance signal level region can be obtained. It is possible to correct uneven brightness and uneven color corresponding to the video signal level, and an address counter that can specify the read start address of the memory and the read direction in synchronization with the sweep direction of the drive circuit of the projection image display device. By using the memory device having the above, it is possible to perform correction corresponding to the switching of the projection direction such as the front direction and the rear direction of the projection type image display device, and the switching of the device installation state such as floor mounting or ceiling mounting.

Further, by using a three-phase clock signal corresponding to each of the R, G and B video signals, the number of memory devices can be reduced and the cost can be reduced.

[0035]

As described above, according to the projection type image display device of the present invention, a memory device for storing data for correcting unevenness in brightness and color of projected images on respective R, G and B screens, A first D / A conversion means for converting the DC level correction digital data read from the memory device into an analog signal, an A / D conversion means for converting the video signal into a digital signal, and read from the memory device. A multiplication circuit for correcting the output signal of the A / D conversion means with amplitude correction digital data, a second D / A conversion means for converting the output signal of the multiplication circuit into an analog signal, and the first D / A conversion means. The output signal of the A conversion means is used as the second D / A.
By including an adder circuit that corrects the output signal of the conversion unit, uneven brightness corresponding to a wide range of input video signal levels from a low brightness signal level region to a high brightness signal level region,
Color unevenness can be corrected.

Further, a memory device in which correction data is repeatedly stored in the order of R, G, B, a three-phase clock generator, R,
By including the G / B D / A conversion circuits and the latch circuits, it is possible to reduce the number of memories and to correct color unevenness and brightness unevenness at low cost.

Further, the projection type image display apparatus is provided with a switching of the projection direction such as a front direction and a rear direction, a floor-standing,
The sweep direction of the drive direction of the projection type image display device is switched according to the switching of the device installation state such as ceiling suspension.
Even if the sweep direction changes, it is possible to easily correct the brightness unevenness and color unevenness on the screen simply by setting the address counter of the memory device in conjunction with this switching.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a projection-type image display device in an embodiment of the first invention.

FIG. 2 is a diagram showing a configuration of a conventional projection display device.

FIG. 3 is a block diagram for explaining a method of reading from a memory device when using a three-phase clock.

FIG. 4 is a timing diagram for explaining a method of reading from a memory device when using a three-phase clock.

FIG. 5 is a block diagram showing a method of correcting a DC level and an amplitude in a luminance characteristic of a video signal.

FIG. 6 is a block diagram showing a configuration of a projection type image display device in an embodiment of the second invention.

[Explanation of symbols]

 1 Video signal input terminal 2 Sync separation circuit 3 Phase synchronization circuit 4 Address counter 5 Memory 6 Memory device 7 D / A conversion circuit 8 Three-phase clock generation circuit 9 Signal processing circuit 10 A / D conversion circuit 11 Multiplication circuit 12 D / A Conversion circuit 13 Adder circuit 14 Drive circuit 15 Latch circuit 31 Sweep / count start position control switch 32 Sweep / count direction control switch 33 Count start position control terminal 34 Count direction control terminal 35 Sweep start position control terminal 36 Sweep direction control terminal

Claims (6)

[Claims] 1. A memory device storing digital data of amplitude and DC level for correcting uneven brightness of a projected image on a screen for a video signal of at least one color of red, green and blue, and read from the memory device. First D / A conversion means for converting DC level correction digital data into an analog signal, A / D conversion means for converting the video signal into a digital signal, and amplitude correction digital data read from the memory device. A multiplication circuit for correcting the output signal of the A / D conversion means, a second D / A conversion means for converting the output signal of the multiplication circuit into an analog signal, and an output signal of the first D / A conversion means. And an adder circuit that corrects the output signal of the second D / A conversion means is provided, and at least one of the red, green, and blue video signals An image display device characterized by correcting both amplitude and DC level. 2. The image display device according to claim 1, wherein a three-phase clock signal corresponding to each of red, green and blue video signals is used for reading the correction data from the memory device. 3. Digital data of amplitude and DC level for correcting unevenness in brightness of a projected image on a screen for at least one of red, green, and blue video signals are stored, and a read start position and a read direction are stored. A memory device that can be designated, a first D / A conversion unit that converts the DC level correction digital data read from the memory device into an analog signal, and an A / D conversion unit that converts the video signal into a digital signal. A multiplying circuit for correcting the output signal of the A / D converting means with digital data for amplitude correction read from the memory device; and a second D / A converting means for converting the output signal of the multiplying circuit into an analog signal. , An addition circuit for correcting the output signal of the second D / A conversion means with the output signal of the first D / A conversion means, and red, green, and blue An image display device, characterized in that both the amplitude and the DC level of the video signal are corrected for at least one color of the color video signal. 4. The image display device according to claim 3, wherein the reading direction is specified in conjunction with the sweep direction switching means of the projection type image display device. 5. The image display device according to claim 3, wherein a three-phase clock signal corresponding to each of red, green and blue video signals is used for reading the correction data from the memory device. 6. A brightness data acquisition unit for measuring brightness data of an image display unit, and an amplitude and a DC level for correcting brightness unevenness of a projected image for a video signal of at least one color of red, green and blue from the brightness data. 6. The image display device according to claim 1, further comprising: a correction data creating unit for creating the digital data, wherein the correction data is output to and stored in a memory device.