JP2000125225A - Luminance correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminance correction device where a function of higher degree or a nonlinear correction arithmetic operation hard to be realized so far by unitarily applying correction to a luminance signal, realizing and operating a correction function through digital video signal processing. SOLUTION: The luminance correction device is provided with an A/D converter 1 that converts a video luminance signal into a digital signal so as to apply linear correction to the video luminance signal and with a YUV->RGB conversion circuit 6 to the post-stage of the A/D converter 1 so as to reduce the circuit scale in comparison with the signal correction circuit applying an RGB signal, and also with a correction parameter calculation circuit 3 and with a luminance level correction arithmetic circuit 4 so that a detailed correction arithmetic operation with high precision is conducted in the unit of pixels by using a function which takes a distance between a video display pixel position and a reference position in a horizontal direction as an argument.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large screen having a tendency that the luminance at the peripheral portion of the screen is lower than the luminance at the central portion, or a horizontally long screen having an aspect ratio of 9:16, or an LCD. The present invention relates to a luminance correction device for a display device such as a television receiver and a display, in which color unevenness easily occurs on a display image.

[0002]

2. Description of the Related Art In recent years, with the increase in size, wide aspect, and image quality of television receivers, high-contrast images have been demanded, and at the same time, high performance against uneven brightness and uneven color has been demanded. Was.

[0003] A conventional screen peripheral brightness correction device will be described below. FIG. 7 is a block diagram of a conventional screen peripheral luminance correction device. In FIG. 7, reference numeral 101 denotes an RGB image quality adjustment circuit that performs image quality adjustment such as contrast adjustment, gamma correction, and color saturation adjustment for each of the analog RGB signals, and 102 outputs a parabolic waveform using a horizontal synchronization signal as an input. A parabolic waveform generation circuit 103, a modulator for modulating an analog R signal after image quality adjustment, which is an output signal of the RGB image quality adjustment circuit 101, with the parabola waveform generation circuit 102, and an image quality 104 as an output signal of the RGB image quality adjustment circuit 101 A modulator that modulates the adjusted analog G signal with a parabolic waveform generation circuit 102;
Reference numeral 05 denotes a parabolic waveform generation circuit 102 which outputs an analog B signal after image quality adjustment, which is an output signal of the RGB image quality adjustment circuit 101.
A CRT for inputting RGB signals, which are output signals of the modulators 103 to 105, and displaying an image.
It is.

[0004] The operation of the screen peripheral brightness correction device configured as described above will be described below. First,
Analog RGB video signals are input to the RGB image quality adjustment circuit 101, and image quality adjustments such as contrast adjustment, gamma correction, and color saturation adjustment are performed, and then analog RGB video signals are output as in the input. The parabolic waveform generation circuit 102 receives a horizontal synchronizing signal synchronized with the input analog RGB signal and outputs a parabolic waveform synchronized with the horizontal synchronizing signal. A parabolic waveform is generated in an analog manner by a resistor, a capacitor, or the like, and its characteristic is a waveform in which the voltage continuously increases in a direction corresponding to the periphery of the screen on a time axis, and is repeated for each horizontal synchronization signal.

Next, modulators 103 to 105 modulate the output RGB signals of the RGB image quality adjustment circuit 101 with the output parabola waveforms of the parabola waveform generation circuit 102, respectively.
Correction is performed so that the peak amplitude increases toward the periphery of the screen. Analog RG corrected by modulators 103 to 105
The B signal is displayed on the CRT 7 as an image.

[0006]

However, in the configuration of the conventional screen peripheral luminance correction device, since the RGB signals are individually subjected to video modulation processing for each signal,
When the correction is performed on the RGB signals using the same function, the modulators are duplicated, and the circuit scale becomes large. In addition, since the image correction method is analog signal processing, there is a problem that it is difficult to realize a higher-order correction function and it is difficult to perform nonlinear processing.

SUMMARY OF THE INVENTION In view of the above problems, the present invention performs a correction process centrally on a luminance signal. It is another object of the present invention to provide a luminance correction device that realizes a high-order function or a non-linear correction operation, which has been difficult to realize conventionally, by realizing and calculating a correction function by digital video signal processing. And

[0008]

According to the present invention, there is provided a luminance correcting apparatus comprising: (1) The present invention provides a luminance correcting apparatus which converts a digital image luminance signal subjected to A / D conversion into a pixel reference position and an image. It is possible to correct the luminance level for each pixel by a function using the distance from the display pixel position as an argument.

According to the present invention, a complicated function such as a higher-order function or a non-linear function can be easily realized as a correction function by digital signal processing, and desired characteristics can be realized as desired. Since the calculation is performed in units, it is possible to provide a luminance correction device capable of performing highly accurate and fine-grained correction calculation.

(2) According to the present invention, a parameter for pixel-level luminance level correction is determined based on the result of video type determination by the input video type determination circuit, so that pixel-level luminance suitable for the video type is determined. It is possible to provide a brightness correction device that performs level correction.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention uses a function in which the distance between a certain pixel reference position and a video display pixel position is used as an argument for an A / D converted digital video luminance signal. The brightness level is corrected for each pixel. In this case, a digital signal processing can easily realize a complicated function such as a higher-order function or a non-linear function as a correction function, achieve desired characteristics as desired, and perform a correction operation on a pixel-by-pixel basis. It is possible to perform highly accurate and detailed correction calculation.
Further, by using the time axis parameter as a parameter of the brightness correction function, there is an effect that the brightness correction depending on the screen display position such as, for example, brightening the brightness around the left and right screens can be easily performed.

The invention according to claim 2 of the present invention provides an A / D
A video pixel position detecting means for detecting a display pixel position with respect to the converted digital video luminance signal; a rewritable register for storing a value indicating a pixel reference position of the video; and a video display which is an output of the video pixel position detecting means. A correction parameter calculation circuit for obtaining a difference between the horizontal pixel position data of each pixel and the horizontal pixel reference position data output from the register, and a digital video luminance signal subjected to the A / D conversion and an output of the correction parameter calculation circuit A luminance level correction arithmetic circuit for correcting a luminance level of the digital video luminance signal symmetrically with respect to a pixel reference position in accordance with the luminance level correction parameter for each display pixel with a certain luminance level correction parameter as an input. And The second aspect describes a specific circuit configuration realized by the first aspect, and has the same operation as the first aspect.

According to a third aspect of the present invention, an A / D
Video pixel position detection means for detecting a vertical display pixel position in the converted digital video luminance signal, a rewritable register for storing a value indicating a vertical pixel reference position of the video, and the video pixel position detection means A correction parameter calculation circuit for obtaining a difference between the vertical pixel position data of each pixel of the video display output from the register and the vertical pixel reference position data output from the register, and the A / D converted digital video luminance signal and the correction A luminance level correction operation for correcting a luminance level of the digital video luminance signal symmetrically around a pixel reference position for each display pixel in accordance with the luminance level correction parameter with a luminance level correction parameter output from the parameter calculation circuit as an input. And a circuit.

According to a third aspect of the present invention, the luminance level is corrected on a pixel-by-pixel basis using a function using the distance between a certain pixel reference position in the vertical direction and the image display pixel position as an argument.
The use of the time axis parameter as a parameter of the brightness correction function has an effect that the brightness correction depending on the screen display position such as, for example, brightening the upper and lower screen peripheral brightness can be easily performed.

According to a fourth aspect of the present invention, there is provided an image pixel position detecting means for detecting horizontal / vertical display pixel positions from a certain reference pixel position with respect to an A / D converted digital luminance signal. A rewritable register that stores a value indicating the pixel reference position of the pixel, and a difference between the pixel position data of each pixel of the video display output from the video pixel position detecting means and the pixel reference position data output from the register. A correction parameter calculation circuit, a digital image luminance signal subjected to the A / D conversion, and a luminance level correction parameter output from the correction parameter calculation circuit are input, and the digital image is displayed for each display pixel in accordance with the luminance level correction parameter. A luminance level correction arithmetic circuit for symmetrically correcting the luminance level of the luminance signal around the pixel reference position is provided. By detecting the horizontal and vertical display positions from the reference video signal position, it is possible to perform point-symmetric luminance correction centering on the reference video signal pixel toward the periphery of the display screen.

The invention according to claim 5 is characterized in that the NTSC signal,
An image type discriminating circuit for discriminating the type of a video signal such as an HDTV signal and an EDII, and a switching circuit capable of automatically switching a correction parameter based on the discrimination result of the video type discriminating circuit are provided inside a luminance level correction arithmetic circuit. By switching the correction parameter and the correction function according to the sampling frequency unique to the input digital video, the correction pixel reference position in the peripheral direction of the screen independent of the type of the input digital video, and performing the brightness level correction. Features. In this case, claim 2, claim 3, or claim 4
It is possible to perform the optimum luminance correction independent of the type of the video signal using the correction parameter realized in the above.

(Embodiment 1) A first embodiment of the present invention described in claims 1 and 2 of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram of a luminance correction circuit according to the first embodiment of the present invention. In FIG. 1, 1 is an A / D converter for converting an input analog luminance signal into a digital signal, and 2 is a counter for counting the number of clocks of a pixel currently being calculated in units of an A / D sampling clock based on a synchronization signal. A video pixel position detecting means for calculating the relative positional relationship between the synchronization signal and the video pixel, a register for storing a value indicating a pixel reference position for performing a luminance correction operation of the video signal, After calculating the difference between the video signal pixel position data detected by the video pixel position detection means 2 and the corrected pixel reference position data stored in the register 8, its absolute value is calculated and the value is output as a correction parameter. Correction parameter calculation circuit, 4
Is a luminance level correction operation circuit for multiplying a correction parameter, which is an output signal of the correction parameter calculation circuit 3, by the video luminance signal to correct an input luminance signal in accordance with a pixel position; A D / A converter for converting the digital luminance signal after the luminance correction operation, which is the output of the D / A converter, into an analog signal. A YUV-> RGB conversion circuit 7 converts a signal into an RGB signal in a signal format. A CRT 7 performs video display using the RGB signal after the signal format conversion, which is an output signal of the YUV-> RGB conversion circuit 6, as an input. is there.

The operation of the luminance correction circuit having such a configuration will be described below. First, the input analog luminance signal is converted into a digital signal by the A / D converter 1.

The image pixel position detecting means 2 sets each pixel of the input luminance signal to 0, 1, 2,... In order from the pixel displayed at the left end of the screen with reference to the horizontal synchronization signal of the input luminance signal.
Pixel numbers such as 1, 2, 3,... Are assigned. The correction parameter calculation circuit 3 inputs the video pixel number corresponding to each pixel of the input luminance signal calculated by the video pixel position detection means 2 and the correction calculation pixel reference position data which is the pixel number of the center pixel stored in the register 8. After calculating the difference between the two input data, the absolute value is calculated for each pixel,
The value is output as a correction parameter. Here, the output timing of the correction parameter for each pixel of the input luminance signal from the correction parameter calculation circuit 3 is set to the same phase as the output luminance signal of the A / D converter 1 as the input phase to the luminance level correction calculation circuit 4. Designed.

Further, for example, when the correction calculation pixel reference position data is set to a value that is half of the total number of pixels of the input luminance signal,
In the brightness correction calculation performed in the subsequent stage for the value of the correction parameter, a brightness correction calculation symmetric about the center position of the display screen is performed.

Next, in the brightness level correction arithmetic circuit 4, A
With the output video luminance signal of the / D converter 1 and the output correction parameter of the correction parameter calculation circuit 3 as inputs, the two signals are multiplied for each pixel, and the input luminance signal is corrected and calculated according to the screen position. As a calculation result of the brightness level correction calculation circuit 4, a corrected brightness signal depending on the screen position can be obtained based on the correction function set by the brightness level correction calculation circuit 4.

Further, the output luminance signal of the luminance level correction operation circuit 4 is inputted to a D / A converter 5 and converted into an analog luminance signal, and is converted together with two kinds of color difference signals (U and V signals) into a YUV-> RGB conversion circuit 6. Is converted into an RGB signal and displayed on the CRT 7. FIG. 2 shows a signal waveform of each block of the luminance level correction arithmetic device.

Here, there are various methods for assigning a pixel position to each pixel of the input luminance signal based on the synchronization signal of the input luminance signal in the video pixel position detecting means 2. Can be achieved.

In addition to storing the corrected operation pixel reference position data in the register 8, there is a method of giving it as IIC data of the microcomputer 75 as shown in FIG. In FIG. 3, reference numerals 1, 2, and 4 to 7 have the same configuration as in FIG.

Reference numeral 10 denotes a memory which outputs a memory control signal by a microcomputer built in the television receiver, and reference numeral 11 denotes a memory which can read correction calculation reference position data in the IIC data format according to the memory control signal from the microcomputer. The correction parameter calculation circuit 3 calculates the difference between the correction calculation reference position data input from the memory 11 via the IIC data bus and the video pixel number calculated by the video pixel position detection means 2, and calculates the absolute value for each pixel. Then, the value is output as a correction parameter. Subsequent operations are the same as those described above, and will not be described.

(Embodiment 2) An embodiment of the invention described in claim 3 of the present invention will be described below with reference to FIG.

FIG. 9 is a block diagram of a luminance correction circuit according to a second embodiment of the present invention. In the circuit shown in FIG. 1, the A / D converter 1, D / A converter 5, YUV → RGB conversion circuit 6, and CRT 7 have the same configuration and operation as those in the first embodiment, and therefore description thereof will be omitted.

Reference numeral 2 denotes a counter which calculates the number of lines in which the pixel currently being calculated falls in units of an A / D horizontal synchronizing signal based on the vertical synchronizing signal, and calculates the relative position between the vertical synchronizing signal and the video pixel. A video pixel position detecting means 8 for detecting a positional relationship, a register 8 for storing a value indicating a pixel reference position for performing a vertical luminance correction operation of a video signal, and a correction parameter calculating circuit 3 for calculating a video pixel position detecting means 2 After inputting the video pixel number corresponding to each pixel of the input luminance signal and the correction operation pixel reference position data which is the pixel number of the center pixel in the vertical direction stored in the register 8, the difference between the input data is calculated. The absolute value is calculated for each pixel, and the value is output as a correction parameter. Reference numeral 4 denotes a luminance level correction calculation circuit that corrects an input luminance signal according to a pixel position in the vertical direction by multiplying a correction parameter, which is an output signal of the correction parameter calculation circuit 3, by the video luminance signal.

The operation of the luminance correction circuit having such a configuration will be described below. The image pixel position detecting means 2 indicates, for each pixel of the input luminance signal, the number of lines on which the horizontal synchronization signal is used as a counter clock, with reference to the vertical synchronization signal of the input luminance signal.
Pixel numbers such as 2, 3,... Are assigned. In the correction parameter calculation circuit 3, a video pixel number corresponding to each pixel of the input luminance signal calculated by the video pixel position detection means 2 and a correction calculation pixel reference position which is a pixel number of a center pixel in the vertical direction stored in the register 8 After calculating the difference between the input data and the input data, the absolute value is calculated for each pixel, and the value is output as a correction parameter. Here, the output timing of the correction parameter for each pixel of the input luminance signal from the correction parameter calculation circuit 3 is set to the same phase as the output luminance signal of the A / D converter 1 as the input phase to the luminance level correction calculation circuit 4. Designed.

For example, when the correction calculation pixel reference position data is set to a value that is half of the total number of vertical lines of the input luminance signal, the values of the correction parameters are the same at the upper end and the lower end of the display screen, and are performed in the subsequent stage. The brightness correction calculation is performed symmetrically with respect to the center position of the display screen.

Next, the luminance level correction calculation circuit 4 receives the output video luminance signal of the A / D converter 1 and the output correction parameter of the correction parameter calculation circuit 3 and multiplies both signals by each pixel to obtain an input luminance. The signal is corrected and calculated according to the vertical screen position. As a calculation result of the brightness level correction calculation circuit 4, a corrected brightness signal depending on the vertical screen position can be obtained based on the correction function set by the brightness level correction calculation circuit 4. As the correction function, for example, there is a fractional function such as the following (Equation 1).

K (n) = B / (A− | n−N |) (Equation 1)
K (n): complement parameter, A: denominator constant, B: numerator component n: vertical pixel position data of operation pixel,
N: Vertical pixel reference position data FIG. 4 shows signal waveforms of each block of the luminance level correction arithmetic device.

Here, there are various methods for assigning a pixel position to each pixel of the input luminance signal on the basis of the synchronizing signal of the input luminance signal in the image pixel position detecting means 2. Can be achieved.

In addition to storing the corrected operation pixel reference position data in the register 8, there is a method of giving it as IIC data of a microcomputer as shown in FIG. This has the same configuration as that shown in the second embodiment, and performs the same operation, so that the description is omitted.

(Embodiment 3) An embodiment of the invention described in claim 4 of the present invention will be described below with reference to FIG.

FIG. 10 is a block diagram of a luminance correction circuit according to a fourth embodiment of the present invention. In the circuit of FIG. 1, the A / D converter 1, the correction parameter calculation circuit 3, the D / A converter 5, the YUV → RGB conversion circuit 6, and the CRT 7 have the same configuration and operation as those of the first embodiment, and therefore, the description is omitted. I do.

Reference numeral 2 denotes the number of clocks at which the pixel currently being calculated is hit in units of an A / D sampling clock based on the horizontal synchronization signal, and A / D based on the vertical synchronization signal.
The counter means calculates the number of lines corresponding to the D horizontal synchronizing signal as a unit, and determines the relative positional relationship between the horizontal and vertical synchronizing signals and the video pixels using two parameters (the relative positional relationship between the horizontal synchronizing signal and the video pixels). , A relative position relationship between the vertical synchronizing signal and the video pixel), a register 8 for storing a value indicating a pixel reference position for performing a horizontal and vertical luminance correction operation of the video signal, a correction parameter The calculation circuit 3 receives the video pixel number corresponding to each pixel of the input luminance signal calculated by the video pixel position detection means 2 and the corrected operation pixel reference position data stored in the register 8 as inputs, and calculates the distance between the two points. Calculation is performed for each pixel, and the value is output as a correction parameter. Reference numeral 4 denotes a luminance level correction calculation circuit that corrects an input luminance signal according to a pixel position in the vertical direction by multiplying a correction parameter, which is an output signal of the correction parameter calculation circuit 3, by the video luminance signal.

The operation of the luminance correction circuit having such a configuration will be described below. The image pixel position detecting means 2 determines, for each pixel of the input luminance signal, the number of lines on which the horizontal synchronizing signal is used as a counter clock based on the vertical synchronizing signal, and the A / D sampling clock based on the horizontal synchronizing signal. (0,0), (0,1),... Depending on how many pixels the counter clock hits
Pixel numbers (1, 0) and (1, 1) are assigned.

In the correction parameter calculation circuit 3, a video pixel number corresponding to each pixel of the input luminance signal calculated by the video pixel position detection means 2 and a correction calculation pixel reference position which is a pixel number of a central pixel stored in the register 8. With the data as input, the distance between the two input data is calculated, and the value is output as a correction parameter. Here, the output timing of the correction parameter for each pixel of the input luminance signal from the correction parameter calculation circuit 3 is set to the same phase as the output luminance signal of the A / D converter 1 as the input phase to the luminance level correction calculation circuit 4. Designed.

Also, for example, when the correction operation pixel reference position data is set to half the number of all vertical lines and half the total number of horizontal pixels of the input luminance signal, the value of the correction parameter becomes the correction operation pixel reference position. And the brightness correction calculation performed in the subsequent stage is performed symmetrically from the center position of the display screen toward the periphery.

Next, the luminance level correction operation circuit 4 receives the output video luminance signal of the A / D converter 1 and the output correction parameter of the correction parameter calculation circuit 3 and multiplies both signals by each pixel to obtain the input luminance. The signal is corrected according to the screen position. As a calculation result of the brightness level correction calculation circuit 4, a corrected brightness signal depending on the vertical screen position can be obtained based on the correction function set by the brightness level correction calculation circuit 4. As the correction function, for example, the following (Equation 2)
There is a fractional function like

K (x, y) = B / (A− | (x, y) − (X, Y) |) (Equation 2) K (x, y): complement parameter, A: denominator constant , B: molecular component x: horizontal pixel position data of operation pixel X: horizontal pixel reference position data y: vertical pixel position data of operation pixel Y: vertical pixel reference position data FIG. 3 shows a signal waveform.

Here, there are various methods for assigning a pixel position to each pixel of the input luminance signal based on the synchronizing signal of the input luminance signal in the video pixel position detecting means 2. Optimization can be achieved.

In addition to the method of storing the corrected operation pixel reference position data in the register 8, there is a method of giving it as IIC data of a microcomputer as shown in FIG. This has the same configuration as that shown in the second embodiment, and performs the same operation, so that the description is omitted.

(Embodiment 4) Next, a fourth embodiment of the present invention will be described with reference to FIG.

FIG. 6 is a block diagram of a luminance correction circuit according to the present embodiment. In the circuit of FIG.
4, 6, and 7 perform the same configuration and operation as (Embodiment 1), and thus description thereof is omitted. Reference numeral 12 denotes a horizontal correction parameter calculation circuit for performing horizontal luminance correction described in the first embodiment of the present invention, and reference numeral 15 denotes a register for storing reference pixel position data in the calculation. Reference numeral 13 denotes a vertical direction correction parameter calculating circuit for performing vertical luminance correction described in the second embodiment of the present invention, and 16 denotes a register for storing reference pixel position data in the calculation. Reference numeral 14 denotes a vertical / horizontal correction parameter calculation circuit for performing vertical / horizontal luminance correction described in the third embodiment of the present invention, and 17 denotes a register for storing reference pixel position data in the calculation. Reference numeral 18 denotes a correction parameter selection unit that receives a determination result of the video signal determination circuit 9 and selects a correction parameter.

The operation of the video signal correction circuit having such a configuration will be described. For example, if the video signal of EDII is N
When displayed on a TSC 4: 3 CRT, there is a blanking level non- (video) signal period above and below. In the case of such a signal, the video type determination circuit 9 selects the output of the horizontal direction correction parameter calculation circuit, and the correction function is only in the horizontal direction. When displaying a 4: 3 video signal on a 16: 9 CRT, the video type determination circuit 9 selects the output of the correction operation parameter calculation circuit only in the vertical direction or the output of the vertical / horizontal correction parameter calculation circuit. Select The subsequent operation is the same as that of the first embodiment, and the detailed operation is omitted. However, the luminance level correction operation circuit 4 obtains a corrected luminance signal depending on the video signal based on the set correction function. Is displayed.

In this case, the registers 15, 16, 17
Alternatively, there is a method of outputting a pixel reference position to be used for each correction parameter calculation using a microcomputer or IIC data, and a method of using a microcomputer instead of the image type discriminating circuit.

[0050]

As described above, according to the luminance signal correction circuit of the present invention, the peripheral portion of the screen has a large screen size in which the luminance tends to be lower than the central luminance, or the aspect ratio is 16: 9. For display devices such as television receivers and displays that are prone to color unevenness on the displayed image, such as LCDs, which are long horizontally, (1) Conventionally realized by realizing and calculating a correction function by digital video signal processing It is possible to provide a brightness correction device that can realize a complicated function and a non-linear correction operation that are difficult to perform.

(2) It is possible to provide a brightness correction device capable of switching appropriate correction for each video format.

[Brief description of the drawings]

FIG. 1 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram in each block of the luminance signal correction device according to one embodiment of the present invention;

FIG. 3 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 4 is a signal waveform diagram in each block of the luminance signal correction device according to one embodiment of the present invention.

FIG. 5 is a signal waveform diagram in each block of the luminance signal correction device according to one embodiment of the present invention.

FIG. 6 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 7 is a block diagram of a conventional screen peripheral luminance correction device.

[Explanation of symbols]

 Reference Signs List 1 A / D converter 2 Image pixel position detecting means 3 Correction parameter calculation circuit 4 Brightness level correction operation circuit 5 D / A converter 6 YUV → RGB conversion circuit 7 CRT 8 Register 9 Image type determination circuit 10 Microcomputer 11 Memory 12 Horizontal direction Correction parameter calculation circuit 13 Vertical direction correction parameter calculation circuit 14 Vertical / horizontal correction parameter calculation circuit 15-17 Register 18 Correction parameter selection means 101 RGB image quality adjustment circuit 102 Parabolic waveform generation circuit 103-105 Modulator

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) BA35 BB03 CA82 CA85 CB01 DA51 MM01 MM10

Claims (5)

[Claims] 1. A brightness correction apparatus for correcting a brightness level of a video brightness signal on a pixel-by-pixel basis using a function having an argument of a distance between a certain pixel reference position and a video display pixel position. 2. A video pixel position detecting means for detecting a display pixel position with respect to a video luminance signal, a register storing a value indicating a pixel reference position of an image, and pixel position data output from the video pixel position detecting means. A correction parameter calculating circuit for obtaining a difference from the pixel reference position data output from the register; and inputting the video luminance signal and the output of the correction parameter calculating circuit to adjust the luminance level of the video luminance signal with respect to the pixel reference position. And a luminance level correction operation circuit for performing symmetric correction. 3. A video pixel position detecting means for detecting a vertical display pixel position for an A / D converted digital video luminance signal, and a rewritable register for storing a value indicating a vertical pixel reference position of the video. A correction parameter calculating circuit for obtaining a difference between vertical pixel position data of each pixel of the video display output from the video pixel position detecting means and vertical pixel reference position data output from the register;
The D / D converted digital video luminance signal and the luminance level correction parameter output from the correction parameter calculation circuit are input, and the luminance level of the digital video luminance signal is determined on a pixel basis in accordance with the luminance level correction parameter for each display pixel. A brightness correction device comprising a brightness level correction calculation circuit for performing correction symmetrically about a position. 4. A video pixel position detecting means for detecting a horizontal / vertical display pixel position from a certain reference pixel position with respect to the A / D converted digital luminance signal, and indicates a pixel reference position of the image. A rewritable register that stores a value, a correction parameter calculation circuit that takes a difference between the pixel position data of each pixel of the image display output from the image pixel position detecting means and the pixel reference position data output from the register, Inputting the A / D-converted digital video luminance signal and the luminance level correction parameter output from the correction parameter calculation circuit, the luminance level of the digital video luminance signal is determined for each display pixel in accordance with the luminance level correction parameter. A brightness correction device, comprising: a brightness level correction calculation circuit that performs correction symmetrically with respect to a pixel reference position as a center. 5. A brightness level correction arithmetic circuit comprising: a video type determination circuit for determining the type of a video signal; and a switching circuit capable of automatically switching a correction parameter based on a determination result of the video type determination circuit. Thus, the correction parameter and the correction function are switched according to the sampling frequency unique to the input digital video, that is, the correction pixel reference position in the peripheral direction of the screen independent of the type of the input digital video is realized, and the luminance level is corrected. Brightness correction device.