JPH1155598A - Luminance correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize correction of luminance with high accuracy through the use of a high-degree function or a nonlinear function in the configuration of a device for correcting a luminance around a screen. SOLUTION: The device is provided with an A/D converter 1 which converts a video luminance signal into a digital signal to apply unified amplitude correction processing to the video luminance signal and with a YUV->RGB conversion circuit 6 at its post-stage so as to reduce the circuit scale in comparison with signal correction for an RGB signal. Furthermore, the device is provided with a correction parameter calculation circuit 3 and a luminance level correction arithmetic circuit 4 so as to attain detailed correction with high accuracy in the unit of pixels by means of a function that uses a distance between a reference position in a horizontal direction and a video image display pixel position for an argument.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display having a large screen size such that the luminance of the peripheral portion of the screen tends to be lower than the central luminance, or a horizontally long screen having an aspect ratio of 9:16, or a display such as 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 an 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. 21 is a block diagram of a conventional screen peripheral luminance correction device. In FIG. 21, 10
Reference numeral 1 denotes an R for performing image quality adjustment such as contrast adjustment, gamma correction, and color saturation adjustment on an analog RGB signal.
A GB image quality adjustment circuit; 102, a parabolic waveform generation circuit that outputs a parabolic waveform with a horizontal synchronization signal as input;
A modulator 3 modulates an analog R signal after image quality adjustment, which is an output signal of the RGB image quality adjustment circuit 101, with a parabolic waveform generation circuit 102, and 104 a RGB image quality adjustment circuit 101
A modulator for modulating the analog G signal after image quality adjustment, which is the output signal of
A modulator that modulates an analog B signal after image quality adjustment, which is an output signal of the GB image quality adjustment circuit 101, by a parabolic waveform generation circuit 102. Reference numeral 7 denotes an RGB signal, which is an output signal of the modulators 103 to 105, and displays an image. This is a CRT that performs the following.

[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, the modulators 103 to 105 modulate the output RGB signals of the RGB image quality adjustment circuit 101 with the output parabolic waveforms of the parabolic waveform generation circuit 102, respectively, and make corrections so that the peak amplitudes increase along the periphery of the screen. Analog RGB corrected by modulators 103 to 105
The signal is displayed as an image on the CRT 7.

[0005]

However, in the above-described conventional screen peripheral brightness correction apparatus, since the video signals are respectively subjected to the image modulation processing, the modulation is performed when the RGB signals are corrected by the same function. And the circuit size increases. 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 provides a method for correcting a RGB signal using the same function to perform luminance correction.
Correction processing is performed centrally on the 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

[0007]

According to the present invention, there is provided a luminance correcting apparatus comprising: (1) The present invention provides a luminance correcting apparatus for converting an A / D converted digital video luminance signal into a pixel reference in a horizontal direction. It is possible to correct the luminance level for each pixel by a function using the distance between the position and the image display pixel position as an argument.

According to the present invention, complicated functions such as higher-order functions and non-linear functions can be easily realized as correction functions 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.

Further, (2) the present invention provides a multiplier for multiplying an arithmetic output signal of a luminance level correction arithmetic circuit by two types of A / D-converted color difference signals, respectively, and an arithmetic output signal of the multiplier. A which is also the input of the brightness level correction arithmetic circuit
And a divider for dividing by the / D-converted digital luminance signal, thereby performing the amplitude correction of the color difference signal at the same ratio as the luminance level correction, and performing the luminance level correction while keeping the Y / C ratio constant. It is possible to do that.

According to the present invention, when the luminance is corrected by the means of the present invention, particularly when the correction is performed in the direction of increasing the luminance level, a color called a color jump due to a Y / C ratio shift with respect to the input image is changed. It is possible to provide a brightness correction device that can correct the phenomenon of thinning and maintain the Y / C ratio constant even when the brightness is corrected.

(3) The present invention provides an image signal position detecting means common to RGB signals for detecting a horizontal display pixel position with respect to an A / D converted digital RGB image signal, and a horizontal pixel signal for each of the RGB signals. A rewritable register for storing a value indicating a pixel reference position in the direction, horizontal pixel position data of each pixel of the video display output from the video pixel position detecting means, and horizontal pixels for each RGB signal output from the register A correction parameter calculating circuit for obtaining a difference from the reference position data, and the A / D converted digital RGB
Signal and each RG output from the correction parameter calculation circuit.
Using the correction parameter unique to the B signal as an input, the amplitude level of the digital RGB signal is displayed for each display pixel in accordance with the correction parameter, and symmetrically around the pixel reference position set for each of the RGB signals using the same correction function as the RGB signal. When the RGB signal is individually corrected by moving the same correction function on the time axis by having the RGB signal amplitude correction operation circuit for correction, the register in which the horizontal pixel reference position data of each RGB signal is stored is switched. This makes it possible to multiplex each signal with a clock at least three times the sampling frequency of the RGB signal and process it using a common correction parameter calculation circuit and an RGB signal amplitude correction calculation circuit.

According to the present invention, the processing clock for the signal correction operation and the parameter calculation operation is set to be higher than the sampling frequency of the video signal to perform the processing, so that one correction parameter calculation circuit common to the RGB signals, the RGB signal amplitude It is possible to provide a luminance correction device that can correct the amplitude of each of the RGB signals with its own function with a small circuit scale of a correction operation circuit.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a distance between a pixel reference position in a horizontal direction 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 by the function described above. 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.

According to a second aspect of the present invention, an A / D
Video pixel position detection means for detecting a horizontal display pixel position with respect to the converted digital video luminance signal, a rewritable register for storing a value indicating a horizontal pixel reference position of the video, and the video pixel position detection means A correction parameter calculating circuit for obtaining a difference between the horizontal pixel position data of each pixel of the image display which is the output of the pixel and the horizontal pixel reference position data which is the output of the register, and the A / D-converted digital image 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. 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, the NTS
A video type determination circuit for determining the type of video signal including the C signal and the HDTV signal; a rewritable register for storing a value indicating a horizontal pixel reference position in a number corresponding to the video type; A switching circuit for selecting and switching the storage register of the horizontal pixel reference position data according to the determination result of the video type determination circuit is provided inside the luminance level correction arithmetic circuit, so that the sampling frequency unique to the input digital video, that is, the number of horizontal pixels is reduced. The horizontal pixel reference position data storage register is switched accordingly to realize corrected pixel reference positions for the left and right ends independent of the type of input digital video, and perform luminance level correction. In this case, in addition to the operation of claim 1, in this case, by switching the horizontal pixel reference position data depending on the type of the video signal, the video signal having a different number of horizontal pixels does not depend on the number of horizontal pixels of the video signal. This has the effect of making it possible to perform brightness correction at a fixed correction pixel reference position.

According to a fourth aspect of the present invention, an NTS
A video level discriminating circuit for discriminating the types of video signals such as the C signal and the EDTV-II signal, and a switching circuit for selecting and switching the characteristics of a luminance level correction function based on the discrimination result of the video type discriminating circuit are provided. It is characterized in that it is provided inside an arithmetic circuit.

According to the fourth aspect of the present invention, the provision of a new video type determination circuit makes it possible to perform a luminance level correction using an optimum correction function according to the type of the input video signal using the result of the determination. It has the action of:

According to the fifth aspect of the present invention, the A / D
By providing a luminance level correction operation circuit that divides the converted digital luminance signal by a luminance level correction parameter output from the correction parameter calculation circuit, it is possible to correct the luminance level of each pixel using a fractional function curve. Features. This claim 5 has, in addition to the function of claim 1,
For example, in order to correct that the peripheral luminance level of the screen is lowered due to the light emission characteristic of the CRT, when the correction is performed in advance by the function of the inverse characteristic by the video signal processing, the luminance correction is performed using the fractional function curve as the correction function. This has the effect of enabling smooth luminance correction in the display time axis direction, that is, in the horizontal direction of the display screen.

According to a sixth aspect of the present invention, there is provided a horizontal pixel position data of each image display pixel output from the image pixel position detecting means and a horizontal pixel reference position of the image stored in the rewritable register. An absolute value calculating circuit for calculating an absolute value of data after taking a difference from data; a rewritable register A for storing a denominator constant; a rewritable register B for storing a numerator constant; A correction parameter calculation circuit includes an adder that adds a denominator constant and absolute value data output from the absolute value calculation circuit, and a divider that divides the numerator constant of the register B by the added data calculated by the adder. It is characterized by having it inside. Claim 6 describes a specific circuit configuration realized by claim 5, and has the same function as claim 5. Here, the characteristic of the brightness correction function is determined by the ratio between the denominator constant of the register A and the absolute value data output from the absolute value calculation circuit. The gain of the brightness correction function is determined by the denominator constant of the register A and the denominator constant. It can be determined by the ratio with the molecular constant of the register B.

According to a seventh aspect of the present invention, there is provided a rewritable register for storing a threshold value for comparison with a luminance level correction parameter output from a correction parameter calculation circuit; A correction processing control circuit for comparing with a luminance level correction parameter and a switching circuit for selectively switching an input luminance signal to the luminance level correction operation circuit and an output luminance signal after correction by an output signal of the correction processing control circuit are newly provided. It is characterized by having. According to a seventh aspect of the present invention, in addition to the operation of the first aspect, the brightness level correction parameter, which is a difference between the horizontal pixel reference position and the display pixel position on the display screen, is compared with a threshold value. By outputting the output and switching the processing algorithm of the correction calculation, it is possible to perform a non-linear brightness correction calculation process such as performing correction only in a period delimited by a threshold value.

An eighth aspect of the present invention is characterized in that a correction gain of a correction operation of each pixel of an A / D-converted digital video luminance signal is controlled in accordance with a luminance level.
According to the eighth aspect of the present invention, for example, the luminance level of each pixel of a video to be subjected to a correction operation in addition to the luminance correction based on the display screen position, that is, the time axis parameter, which is the operation of the first aspect, is used as a parameter to perform the arithmetic processing. The limited dynamic range of the display device is reduced, such as lowering the gain of the luminance level correction amount for high pixels, and increasing the correction gain for video with an intermediate luminance level, especially by giving the gain of the luminance level correction amount a gamma characteristic. This has the effect that it is possible to use it effectively and to perform optimal brightness correction according to the visual characteristics of the viewer.

According to a ninth aspect of the present invention, a rewritable register A for storing a denominator constant, a rewritable register B for storing a numerator constant, and an A / D conversion of the denominator constant of the register A are performed. An adder A for adding the luminance level of the digital video luminance signal, a divider for dividing the numerator constant of the register B by the post-addition data calculated by the adder, an output data of the divider, and A / By providing an adder B for adding the luminance level of the D-converted digital video luminance signal inside the correction parameter calculation circuit, the adder B is used to calculate the ratio between the denominator constant of the register A and the luminance level of the digital video luminance signal. In addition to determining the characteristics of the brightness correction function, the gain of the brightness correction function is determined by the ratio of the output data after addition of the adder A to the molecular constant of the register B. The features. The ninth aspect of the present invention describes a specific circuit configuration realized by the eighth aspect, and uses a fractional function as a characteristic of a correction function that uses a luminance level of a display pixel as a parameter, thereby displaying images of different luminance levels. This has the effect that the gain control for smooth luminance correction can be performed between the two. Here, the gain control characteristic of the luminance correction function between images of different luminance levels is determined by the ratio between the denominator constant of the register A and the luminance level of the corrected pixel, and the gain of the luminance correction function is determined by the denominator constant of the register A. And the molecular constant of the register B.

The invention according to claim 10 of the present invention provides an A / D
Multiplier A and multiplier B for multiplying the converted digital video signal by a luminance signal of each pixel and two types of color difference signals, respectively.
And a divider that divides the operation output signals of the multipliers A and B by the operation output signal of the luminance level correction operation circuit, thereby performing the amplitude correction of the color difference signal at the same ratio as the luminance level correction, It is characterized in that the luminance level is corrected while keeping the Y / C ratio constant. Claim 10
Is, in addition to the effect of claim 1, when performing the brightness correction,
In particular, when the correction is performed in the direction in which the luminance level increases, the phenomenon called color skipping due to the Y / C ratio deviation with respect to the input image is corrected, and the luminance correction is performed.
This has the effect that the C ratio can be kept constant.

According to the eleventh aspect of the present invention, A / D
In a video signal in which the sampling frequency of the luminance signal of each pixel of the converted digital video signal is twice or four times the sampling frequency of the two types of color difference signals, 2 of each pixel of the A / D converted digital video signal is used. A multiplex processing circuit for performing multiplexing processing on one color signal by switching and selecting a type of color difference signal at a sampling frequency of a luminance signal, and a digital luminance of 2 or 4 pixels having the same phase as the two types of color difference signals A multiplier for multiplying a luminance level of a luminance signal obtained by selecting a certain pixel in the signal by an output color signal of the multiplex processing circuit;
A divider that divides the operation output signal of the multiplier by the operation output signal of the luminance level correction operation circuit, and a decoding circuit that separates again into two types of color difference signals by inverse conversion of the multiplexing processing of the multiplex processing circuit. With this configuration, the amplitude correction of the color difference signal is performed at the same ratio as the brightness level correction, and the brightness level correction is performed while keeping the Y / C ratio constant.

According to an eleventh aspect of the present invention, two types of color difference signals are multiplexed into one color signal in place of a set of multipliers and dividers for calculating a luminance signal and a color difference signal. By providing a multiplex processing circuit for performing the multiplexing processing and a decoding processing circuit for separating again into two kinds of color difference signals by inverse conversion of the multiplexing processing of the same circuit, the same operation as in claim 10 can be realized with a small circuit scale. It has the effect that it becomes possible.

According to a twelfth aspect of the present invention, a horizontal contour correction circuit for controlling a gain of a horizontal contour correction amount by gain control data, and a control signal in conjunction with a luminance level correction gain by a luminance level correction operation circuit. A contour correction gain control signal generation circuit to be generated; and an adder for adding an output control signal of the contour correction gain control signal generation circuit and gain control data for horizontal contour correction processing given to the horizontal contour correction circuit. Thereby, the gain control of the horizontal contour correction processing is performed in conjunction with the luminance level correction gain by the luminance level correction operation circuit. According to a twelfth aspect of the present invention, in addition to the operation of the first aspect, the luminance level correction and the outline correction are performed in conjunction with the same parameter called the screen position by controlling the correction amount of the horizontal contour correction in conjunction with the luminance level correction. Therefore, when an image is displayed on the display device, it is possible to realize uniform image quality setting for the entire screen.

The invention according to claim 13 of the present invention provides an A / D
A video pixel position detecting means common to RGB signals for detecting a horizontal display pixel position with respect to the converted digital RGB video signal, and a rewritable register for storing a value indicating a horizontal pixel reference position for each of the RGB signals When,
A correction parameter calculating circuit for obtaining a difference between horizontal pixel position data of each pixel of the image display output from the image pixel position detecting means and horizontal pixel reference position data output from the register; An RGB signal and a correction parameter unique to each RGB signal output from the correction parameter calculation circuit are input, and the amplitude level of the digital RGB signal is set for each display pixel in accordance with the correction parameter on a pixel basis. By having an RGB signal amplitude correction operation circuit for correcting the RGB signal symmetrically with respect to the position using the same correction function as the RGB signal,
When the horizontal pixel reference positions are different from each other in the RGB signals while performing the correction operation on the RGB signals with the same correction function,
In other words, when performing an amplitude correction operation on each of the RGB signals using a correction function in which a certain function is moved on a time axis basis by a specific time for each of the RGB signals, the respective signals are multiplexed with a clock having a frequency three times or more the sampling frequency of the RGB signals, and then the correction operation is performed. Do R
It is possible to switch the register in which the horizontal pixel reference position data for each of the RGB signals is stored in accordance with the signal, the G signal, and the B signal, and to perform processing using a common correction parameter calculation circuit and an RGB signal amplitude correction calculation circuit. It is characterized by doing. According to a thirteenth aspect of the present invention, the correction parameter calculation circuit and the RGB signal amplitude correction calculation circuit are related to correction of each of the RGB signals by increasing the processing clock of the signal correction calculation and the parameter calculation calculation with respect to the sampling frequency of the video signal and performing the processing. RG while realizing with a common circuit
This has the effect that the B signal can be corrected and calculated with its own amplitude correction characteristics.

According to a fourteenth aspect of the present invention, an A / D
A video pixel position detecting means common to RGB signals for detecting a horizontal display pixel position with respect to the converted digital RGB video signal, and a rewritable register for storing a value indicating a horizontal pixel reference position for each of the RGB signals A, B and C, the horizontal pixel position data of each pixel of the image display which is the output of the image pixel position detecting means, and the register A
And a correction parameter calculation circuit for obtaining a difference between horizontal pixel reference position data output from B and C, and a correction specific to each of the RGB signals output from the A / D converted digital RGB signal and the correction parameter calculation circuit. With the parameters as inputs, the amplitude levels of the digital RGB signals are displayed symmetrically around the pixel reference position set for each of the RGB signals in accordance with the correction parameters for each display pixel.
The input RGB signal, the correction parameter, and the
An RGB signal amplitude correction operation circuit for switching and correcting the correction function is provided. According to a fourteenth aspect of the present invention, in addition to the configuration of the thirteenth aspect, a correction operation circuit that individually processes only a correction operation that realizes a unique correction characteristic for an RGB signal into an RGB signal is provided. This has the effect that the correction operation can be performed with the correction function characteristics having no correlation.

(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, reference numeral 1 denotes an A / D converter for converting an input analog luminance signal into a digital signal, and reference numeral 2 denotes the number of clocks at which a pixel currently being calculated is in units of an A / D sampling clock based on a horizontal synchronization signal. Video pixel position detection means 8 which is calculated by the counter means and detects the relative positional relationship between the horizontal synchronizing signal and the video pixels, and 8 stores a value indicating a pixel reference position for performing a horizontal luminance correction operation of the video signal. The register 3 calculates a difference between the video signal pixel position data detected by the video pixel position detection means 2 and the corrected operation pixel reference position data stored in the register 8, calculates an absolute value thereof, and calculates the value. The correction parameter calculation circuit 4 for outputting as a correction parameter and the correction parameter calculation circuit 3
A luminance level correction arithmetic circuit 5 for multiplying the video luminance signal by the correction parameter, which is an output signal of the above, to correct the input luminance signal in accordance with the horizontal pixel position, and an output 5 of the luminance level correction arithmetic circuit 4 A D / A converter for converting the digital luminance signal after the luminance correction operation into an analog signal. Reference numeral 6 denotes two types of color difference signals of the same phase of the output analog luminance signal of the D / A converter 5 and the output analog luminance signal. To convert signal format to YU
A V-> RGB conversion circuit 7 is a CRT 7 that performs image display using the RGB signal after signal format conversion, which is the output signal of the YUV-> RGB conversion circuit 6, as an input.

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. 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 horizontal 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. Further, for example, when the correction calculation pixel reference position data is set to a value that is half of the total number of horizontal pixels of the input luminance signal, the value of the correction parameter becomes the same value at the left end and the right end of the display screen, and the luminance correction calculation performed at the subsequent stage is performed. Performs a luminance correction operation symmetrical about the center position of the display screen.

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 an input luminance. The signal is corrected according to the horizontal screen position. As a calculation result of the brightness level correction calculation circuit 4, a corrected brightness signal depending on the horizontal 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 input to the D / A converter 5, converted into an analog luminance signal, and input to the YUV-> RGB conversion circuit 6 together with two kinds of color difference signals (U and V signals). , RGB signals are converted to CRT7
Is displayed. FIG. 17 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 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 the method of storing the correction calculation 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. In FIG. 2, reference numerals 1, 2, and 4 to 7 have the same configuration as that of FIG. 75
Outputs a memory control signal by a microcomputer built in the television receiver, and II denotes a memory control signal from the microcomputer.
This is a memory from which correction calculation reference position data can be read in the C data format. The correction parameter calculation circuit 3 calculates I
The difference between the correction calculation reference position data input from the memory 76 via the IC data bus and the video pixel number calculated by the video pixel position detection means 2 is calculated, and the absolute value is calculated for each pixel, and the value is corrected. Output as parameters.
Subsequent operations are the same as those described above, and will not be described.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described with reference to FIG.

FIG. 3 is a block diagram of a luminance correction circuit according to the second embodiment of the present invention. In the circuit of FIG. 3, reference numerals 1 to 8 have the same configuration as that used in the first embodiment, and perform the same operation, so that the description will be omitted. Reference numeral 9 denotes a register for storing a horizontal pixel reference position value of an image with respect to an input video signal having a signal format different from that of the register 8. Reference numeral 10 denotes a type of an input video signal such as an NTSC signal or an HDTV signal and outputs a result of the determination. And a selector 11 for switching and selecting the registers 8 and 9 using the output determination signal of the video type determination circuit 10 as a control signal. In the second embodiment, the register for storing the horizontal pixel reference position value of the video used when the NTSC signal is selected using the register 8 as the input luminance signal, and the HDTV signal is selected using the register 9 as the input luminance signal. A description will be given as a register for storing a horizontal pixel reference position value of an image used sometimes. The operation of the luminance correction circuit having such a configuration will be described below.
For example, when the sampling frequency of the A / D converter at the time of inputting the NTSC signal is 4 fsc and the sampling frequency of the A / D converter at the time of inputting the HDTV signal is 48.6 MHz, the number of horizontal pixels of each signal is 910 pixels for the NTSC signal and HDTV. The signal becomes 1440 pixels. Hereinafter, a process in the case where video signals having different numbers of horizontal pixels according to the sampling frequency of the A / D converter are input to the same luminance correction circuit will be described.

First, when an NTSC signal is input as an input luminance signal, the video type determination circuit 10 determines that the input luminance signal is an NTSC signal, and the selector 11 uses the output control signal of the video type determination circuit 10 as a control signal. NT
The register 8 storing the image horizontal pixel reference position data for the SC signal is selected. The correction parameter calculation circuit 3 receives the image pixel position corresponding to each pixel of the input luminance signal calculated by the image pixel position detection means 2 and the correction calculation pixel reference position data stored in the register 8 as input and calculates the input data of both. After calculating the difference, the absolute value is calculated for each pixel, and the value is output as a correction parameter. 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 horizontal screen position based on the set correction function. Displayed by CRT7.

When an HDTV signal is input as an input signal, the video type determination circuit 10 determines that the input luminance signal is an HDTV signal, and the selector 11 uses the output control signal of the video type determination circuit 10 as a control signal. HDT
The register 9 storing the video horizontal pixel reference position data for the V signal is selected. The correction parameter calculation circuit 3 receives the image pixel position corresponding to each pixel of the input luminance signal calculated by the image pixel position detection means 2 and the correction operation pixel reference position data stored in the register 9 as input and calculates the input data of both. After calculating the difference, the absolute value is calculated for each pixel, and the value is output as a correction parameter. 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 horizontal screen position based on the set correction function. Displayed by CRT7.

Here, assuming that the image horizontal pixel reference position data stored in the register 8 is 455 and the image horizontal pixel reference position data stored in the register 9 is 720, NTS
In both the luminance correction processing of the C signal and the luminance correction processing of the HDTV signal, by switching and selecting the registers 8 and 9 according to the type of the input signal, the reference position of the video horizontal pixel due to the difference in the frequency band of the digital video signal is determined. The deviation is eliminated, that is, the luminance correction is performed symmetrically with respect to the horizontal center line of the screen. FIG. 18 shows a signal waveform of each block of the luminance level correction arithmetic device.

The video horizontal pixel reference position data may be provided by IIC data of a control microcomputer built in the television receiver, instead of being stored in the registers 8 and 9. FIG. 4 shows a case where the video horizontal pixel reference position is given by the IIC data of the microcomputer.

In FIG. 4, first, when an NTSC signal is input as an input signal, the microcomputer 75 in the television receiver determines that the input signal is NTSC, and a memory control signal for NTSC video horizontal pixel reference position data. Is output to the memory 76. The memory 76 receives a control signal from the microcomputer and outputs NTSC video horizontal pixel reference position data as IIC data. The image horizontal pixel reference position data is input to the correction parameter calculation circuit 3, and the luminance level correction calculation circuit 3 calculates the image pixel position corresponding to each pixel of the input luminance signal calculated by the image pixel position detection means 2. After calculating the difference between the input data of the correction operation pixel reference position data and the correction operation pixel reference position data input as the IIC data of the microcomputer, the absolute value is calculated for each pixel, and the value is output as a correction parameter. Subsequent operations are the same as in the first embodiment, and detailed operations are omitted.

When an HDTV signal is input as an input signal, the microcomputer 75 in the television receiver determines that the input signal is HDTV, and stores a memory control signal for HDTV video horizontal pixel reference position data. 76. The memory 76 receives the control signal of the microcomputer as input,
The video horizontal pixel reference position data for DTV is output as IIC data. The video horizontal pixel reference position data is input to the correction parameter calculation circuit 3, and the brightness level correction calculation circuit 3 calculates the video pixel corresponding to each pixel of the input luminance signal calculated by the video pixel position detection means 2. After calculating the difference between the input data of the position and the corrected operation pixel reference position data input as the IIC data of the microcomputer, the absolute value is calculated for each pixel, and the value is output as a correction parameter. Subsequent operations are the same as in the first embodiment, and detailed operations are omitted.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a block diagram showing a luminance correction circuit according to the third embodiment of the present invention. In the circuit of FIG. 5, reference numerals 1 to 8 and reference numeral 10 have the same configuration as those used in the first embodiment, and the same operation is performed, so that the description is omitted. Reference numeral 12 denotes a luminance level correction operation circuit that performs a luminance correction operation using a correction parameter on a signal of a type different from a video signal on which correction operation is performed by the luminance level correction operation circuit
Reference numeral 13 denotes a selector for selecting a correction operation output signal of the luminance level correction circuit 4 or a correction operation output signal of the luminance level correction circuit 12 according to the result of the determination of the input video signal format output from the video type determination circuit 10. In the third embodiment, the correction operation circuit used when the luminance level correction operation circuit 4 is selected as the input luminance signal and the NTSC signal is selected, and the EDTV-II signal is selected using the luminance level correction operation circuit 11 as the input luminance signal. A description will be given of a correction arithmetic circuit used sometimes.

The operation of the luminance correction circuit having such a configuration will be described below. First, as an input luminance signal, NT
When the SC signal is input, the video type discriminating circuit 10 determines that the input luminance signal is an NTSC signal, and the selector 13 uses the output control signal of the video type discriminating circuit 10 as a control signal and the luminance level correction arithmetic circuit 4 uses the NTSC signal. An output luminance signal obtained by performing a luminance level correction operation on the NTSC signal using a signal-specific correction function is selected. here,
Similar to the first embodiment, the brightness level correction calculation is performed on a pixel-by-pixel basis.

As an example of an NTSC signal-specific correction function, an NTSC signal having an aspect ratio of 4: 3 is displayed at a circularity of 1 on a CRT having a wide aspect ratio, and side blanking is added to both left and right ends of the screen. Function characteristics for performing luminance correction on the input image. Subsequent operations are displayed on the CRT 7 at the last stage, but detailed operations during that period are the same as in the first embodiment, and a description thereof will be omitted.

When an EDTV-II signal is input as an input luminance signal, the video type discriminating circuit 10 judges that the input luminance signal is an EDTV signal, and the selector 13 outputs an output control signal of the video type discriminating circuit 10. As a control signal, an output luminance signal obtained by performing a luminance level correction operation on the EDTV-II signal by the luminance level correction operation circuit 12 using an intrinsic correction function for the EDTV-II signal is selected. Here, in the brightness level correction calculation, a correction calculation process is performed in pixel units, as in the first embodiment. Further, as an example of a unique correction function for an EDTV-II signal, an aspect ratio of 16:
Function characteristics for performing brightness correction when the EDTV-II signal of No. 9 is displayed at a roundness of 1 are listed. Subsequent operations are displayed on the CRT 7 at the last stage, but detailed operations during that period are the same as in the first embodiment, and a description thereof will be omitted. FIG. 19 shows a signal waveform of each block of the luminance level correction arithmetic device.

With the above configuration, the brightness level correction calculation can be performed with a different correction function according to the type of the input signal only by adding the brightness level correction calculation circuit and the selector. For example, at the left and right ends of the CRT, it is not necessary to perform luminance correction for the NTSC signal during the side blanking period. Therefore, a correction function having a characteristic of not performing correction during the side blanking period is selected, and the EDTV-II signal is input. When a video signal having a different aspect ratio is displayed on the same CRT by selecting a correction function having a characteristic of performing correction up to the left and right ends of the video signal, brightness correction is performed according to the aspect ratio. be able to. Here, the switching control signal of the selector 13 is transmitted to the video type determination circuit 10.
A wide variety of brightness correction functions can be realized by using different discriminating means such as an APL (average brightness level) of a video, a video display aspect ratio on a display device, and the like from an input signal format such as described above.

In addition, a digital HDTV signal with a sampling frequency of the A / D converter of 48.6 MHz,
When displaying input signals having different frequency bands such as a digital EDTV-II signal having a sampling frequency of 4 fsc for the / D converter on the same CRT, a plurality of correction functions are prepared, and the frequencies of the HDTV signal and the EDTV-II signal are prepared. It is possible to select an optimal complement function from the relationship between the characteristics and the pixel pitch of the CRT to be displayed, or to select and display an optimal complement function depending on the signal source to be displayed.

Also, instead of adding a new luminance level correction operation circuit, an internal change of the luminance level correction operation such as a change of a parameter of a correction function by control by an output control signal of the video type discriminating circuit 10 is also possible. It is feasible.

(Embodiment 4) Next, a fourth embodiment of the present invention described in claims 5 and 6 of the present invention will be described with reference to FIGS.

FIG. 1 shows a block diagram of a luminance correction circuit according to the fourth embodiment of the present invention. The circuit of FIG. 1 performs the same configuration and the same operation as the first embodiment, and the description is omitted. FIG. 6 is an internal block diagram of the correction parameter calculation circuit in FIG. 1 according to the first embodiment of the present invention. Reference numeral 25 denotes a subtractor for performing a difference operation between the output horizontal pixel position data of the video pixel position detecting means 2 and the output horizontal pixel reference position data of the register 8, and 21 calculates the absolute value of the output operation result of the subtracter 25. An absolute value calculating circuit 22 is a rewritable register A for storing a constant called a denominator constant to be added to the absolute value calculating circuit 21, and 26 is an output operation result of the absolute value calculating circuit 21 and a denominator constant stored in the register A22. Is a rewritable register B for storing a constant called a molecular constant to be divided by the output operation result of the adder 26, and 24 is a calculation result of the adder 26 for the molecular constant stored in the register B23. This is a divider that divides by.
The operation of the luminance correction circuit having such a configuration will be described below. The correction calculation described below is based on the following equation (Equation 1).

K (n) = B / (A− | nN |) (Equation 1) K (n): complement parameter, A: denominator constant, B: numerator component n: horizontal pixel position data of operation pixel , N: horizontal pixel reference position data In FIG. 6, first, the output horizontal pixel position data of the video pixel position detection means 2 and the output horizontal pixel reference position data of the register 8 are input to a subtractor 25, and a difference operation is performed. Is input to the absolute value calculation circuit 21 to calculate the absolute value. As a result, the distance from the output horizontal pixel reference position data of the register 8 to each of the calculated pixels is obtained in pixel units. The adder 26 adds a register A2 to the absolute value data of each pixel.
The denominator constant (constant A of (Equation 1)) stored in 2 is added to perform scaling of the function characteristics.

Next, using the output operation result of the adder 26 as a denominator, the numerator constant ((Equation 1)) stored in the register B23
The constant B) is divided by the divider 24 as a numerator to calculate a correction parameter. Here, the characteristic of the brightness level correction function is determined by the ratio of the calculation result of the absolute value calculation circuit 21 to the denominator constant stored in the register A22. The subsequent output result is the absolute value calculation circuit 21
Is small, that is, as the denominator constant takes a larger value, a correction characteristic independent of the pixel position can be obtained.

The gain of the correction function is determined by the ratio of the output operation result of the adder 26 to the molecular constant stored in the register B23, and the correction characteristic of the output operation result is determined. The correction parameter calculated by the divider 24 is then multiplied by the input digital luminance signal in the luminance level correction operation circuit 4 in FIG. 1 to correct the luminance level.

For example, if the input signal is an NTSC signal,
When the sampling frequency of the / D converter is 4 fsc, the number of video horizontal pixels is 910. If the horizontal pixel reference position data at this time is 455, and both the denominator constant and the numerator constant take the value of 2000, the complement parameter will be a minimum value of 1 (horizontal pixel position data = 0) to a maximum value of 1.29 (horizontal pixel position data). Data = 455), and the D / A converter 5
Output is 1 to 1.29 times the input video signal.
A video signal having a double amplitude level can be obtained.

If the result of the fractional function of (Equation 1) is used as a correction parameter, an output of the fractional function characteristic shown in FIG. 17 for the horizontal pixel position is obtained. In digital signal processing, a fractional function operation using the difference between the horizontal pixel position data and the horizontal pixel reference position data as an argument can be easily performed. This is possible for input luminance signals. As a result, the characteristics of the luminance correction for the periphery of the obtained screen can be obtained smoothly using a fractional function.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIGS. 7 and 8.

FIG. 7 is a block diagram showing a luminance correction circuit according to the fifth embodiment of the present invention. In FIG.
Reference numerals 2 and 4 to 8 perform the same configuration and operation as those of the block diagram of the luminance correction circuit in FIG. Reference numeral 103 denotes a circuit obtained by adding a calculation control parameter calculation circuit to the correction parameter calculation circuit 3 of FIG. 1 according to the first embodiment, and 14 receives a calculation control parameter from the correction parameter calculation circuit 103,
The selector selects an image luminance signal before luminance correction, which is an output of the A / D converter 1, and a luminance-corrected image luminance signal output from the luminance level correction operation circuit 4.

FIG. 8 is an internal block diagram of the correction parameter calculating circuit 103 in FIG. 7 according to the fifth embodiment of the present invention. Reference numerals 21 to 26 are the same as those in FIG.
Since the operation is performed, the description is omitted. 28 is a register storing a threshold value for comparing the output operation result of the subtractor 25 with the magnitude comparison, and 27 is a magnitude comparison between the output computation result of the subtracter 25 and the threshold value stored in the register 28, and performing an operation according to the comparison result. This is a magnitude comparison circuit that generates a control signal as a control parameter.

The operation of the luminance correction circuit having such a configuration will be described below. 8, first, the output horizontal pixel position data of the video pixel position detection means 2 and the output horizontal pixel reference position data of the register 8 are input to a subtractor 25 to perform a difference operation, and the calculation result and a threshold value stored in a register 28 are obtained. Is input to the magnitude comparison circuit 27 to perform magnitude comparison. This calculation is performed for each pixel. The calculation result of the magnitude comparison circuit 27 is output as a calculation control parameter, and the signal is output as it is from the correction parameter calculation circuit as the same signal. As shown in FIG.
A before the luminance level correction calculation
The output luminance signal of the / D converter 1 and the output luminance signal of the luminance level correction operation circuit 4 after the luminance level correction operation are selected and used as an input signal to the D / A converter 5. Subsequent operations are the same as those in the first embodiment until they are displayed on the CRT 7 at the last stage, and a description thereof will be omitted.

With the above configuration, the difference between the horizontal pixel reference position and the operation pixel is compared with a certain threshold value, and the result is switched between performing and not performing correction operation. Rather than performing the correction, it is possible to perform selective luminance level correction such as performing correction with respect to a certain region in the horizontal direction, for example, the center of the screen, and performing correction centering on the pixel reference position only at the left and right ends. .

(Embodiment 6) Next, Embodiment 6 of the present invention will be described with reference to FIGS. 9 and 10.

FIG. 7 is a block diagram showing a luminance correction circuit according to the sixth embodiment of the present invention. In FIG.
2 and reference numerals 4 to 7 perform the same configuration and operation as those of the block diagram of the luminance correction circuit in FIG. FIG. 10 is an internal block diagram of the correction parameter calculation circuit 103. In FIG. 10, reference numeral 22 denotes a rewritable register for storing a constant called a denominator constant to be added to the output digital luminance signal of the A / D converter 1 in FIG. 9, and reference numeral 26 denotes the digital luminance signal and the denominator constant stored in the register 22. , And 23 is an adder 2
6, a rewritable register for storing a constant called a molecular constant to be divided by the output operation result, 25 a subtractor for taking the difference between the horizontal pixel position data and the horizontal reference position data, and 29 an output of the subtractor 25 and the adder 26 Subtracter to take the difference of the result,
24 is a subtractor 29 which subtracts the numerator constant stored in the register 23.
Is a divider for dividing by the operation result of.

The operation of the luminance correction circuit having such a configuration will be described below. In FIG. 10, first, A / D of FIG.
The denominator constant stored in the register 22 is added to the output digital luminance signal of the converter 1 by the adder 26 of the correction parameter calculation circuit 203 to perform scaling of the function characteristic. Next, the output operation result of the subtracter 29 is used as a denominator, and the numerator constant stored in the register 23 is used as a numerator.
By dividing by 4, a correction parameter is calculated. Here, the characteristic of the gain correction function is determined by the ratio between the output digital luminance signal of the A / D converter 1 in FIG. 9 and the denominator constant stored in the register 22. In practice, the denominator constant is the output of the A / D converter 1. A large value is set for the digital luminance signal. Further, the gain of the gain correction function is determined based on the ratio between the output operation result of the subtractor 29 and the numerator constant stored in the register 23, and is practically determined by the ratio between the denominator constant and the numerator constant. Thereafter, the correction parameter calculated by the divider 24 is added to the input digital luminance signal by the luminance level correction operation circuit 4 in FIG. 9 to perform amplitude correction according to the luminance level. The above correction operation is expressed by the following equation (Expression 2).

Vout = Vin × B / (A + Vin− | nN |) (Equation 2) A: denominator constant, B: numerator component Vin: input luminance signal, Vout: output luminance signal n: horizontal of calculation pixel Pixel position data N: horizontal pixel reference position data In the above (Equation 2), B / (A + Vin− | nN |) represents a gain correction amount, and when | nN | takes a constant value, the luminance level Vin is large. The smaller the brightness level Vin, the larger the gain correction amount. By performing correction using this gain correction function,
When the luminance level correction is performed for each pixel, the luminance level correction gain is reduced for pixels having a large luminance level, so that the correction is not performed so much. For example, it is possible to perform a luminance level correction depending on a luminance level within a limited dynamic range of a display device, such as a low luminance part gradation correction and a gamma correction.

For example, 0 to 255 by an A / D converter
, The numerator component B is 3200 and the denominator component A is 294 for an NTSC input signal of 910 horizontal video pixels sampled by the digital clock width of 4 fsc.
5. Assuming that the horizontal reference pixel position data N is 455, the output luminance signal Vout has a minimum ratio of 1.0 times the luminance level of the input luminance signal (when the input luminance signal is 255 and the horizontal pixel position data is 0) to a maximum ratio. The luminance level correction of 1.29 times (when the input luminance signal is 0 and the horizontal pixel position data is 455) is performed.

Further, in the sixth embodiment, the use of the fraction function as the gain correction function makes it possible to realize a correction curve between luminances with a smooth function characteristic. In digital signal processing, a fractional function operation using the difference between the horizontal pixel position data and the horizontal pixel reference position data as an argument can be easily performed, so that the correction function for each pixel has the smooth characteristic shown in (Equation 2). Correction is possible for the input luminance signal.
As a result, the characteristics of the luminance correction for the periphery of the obtained screen can be obtained smoothly using a fractional function.

(Embodiment 7) Next, claim 10 of the present invention will be described.
The seventh embodiment of the invention described in the above will be described with reference to FIGS. 11 and 12. FIG.

FIG. 11 is a block diagram showing a luminance correction circuit according to the seventh embodiment of the present invention. In FIG. 11, 1,
2 and 4 to 8 perform the same configuration and operation as those of the block diagram of the luminance correction circuit in FIG. In FIG. 11, reference numeral 31 denotes an A / D converter for converting an input analog color difference U signal into a digital signal;
Denotes an A / D converter for converting an input analog color difference V signal into a digital signal, and 33 denotes A / D converters 31 and 3
2. The correction ratio of the luminance signal obtained by inputting the color difference signal digitized in step 2 and dividing the signal after correcting the luminance level of the luminance signal having the same phase as the color difference signal by the signal before correction is used as the color difference signal. A color difference signal correction operation circuit which outputs a color difference signal obtained by multiplying the luminance signal of the same phase and an amplitude correction of the same ratio with respect to each pixel by multiplication, and a digital after correction operation which is an output of the color difference signal correction operation circuit 33 A D / A converter 35 converts the color difference U signal into an analog signal, and a D / A converter 35 converts the corrected digital color difference V signal output from the color difference signal correction operation circuit 33 into an analog signal.

FIG. 12 shows a color difference signal correction operation circuit 33.
It is an internal block diagram of. In FIG. 12, 36 is A /
A multiplier for multiplying the output chrominance U signal of the D converter 31 by the output luminance signal of the luminance level correction operation circuit 4; a divider 37 for dividing the output luminance signal of the multiplier 36 by the output luminance signal of the A / D converter 1; 38 is a multiplier for multiplying the output chrominance V signal of the A / D converter 32 and the output luminance signal of the luminance level correction operation circuit 4, and 39 is dividing the output luminance signal of the multiplier 38 by the output luminance signal of the A / D converter 1. Divider.

The operation of the luminance correction circuit having such a configuration will be described below. In FIG. 12, first, input color difference signals (U, V) are converted into digital signals by A / D converters 31, 32, respectively. Next, inside the color difference signal correction calculation circuit 33, two types of digital color difference signals and A /
Multipliers 31 and 3 in FIG. 11 receive a luminance signal (digital luminance signal before correction) output from the D converter 1 as an input.
Multiplied by three. Further, the calculation results of the multipliers 31 and 33 are divided by a luminance signal (corrected digital luminance signal) output from the luminance level correction operation circuit 4 and output as a corrected color difference signal. Here, since the correction operation of the color difference signal is performed for each pixel of the color difference signal, and the correction function of the amplitude correction of the luminance signal and the color difference signal is the same, the Y / C
The ratio remains constant after the correction. Color difference signal correction arithmetic circuit 3
The calculation of the color difference signal in 3 is represented by Expression 3.

Vout = Yout / Yin × Vin (Equation 3) Vin: color difference signal before correction Vout: color difference signal after correction Yin: luminance signal before correction Yout: luminance signal after correction The signals (U and V signals) are D
YUV together with the output signal of the D / A converter 5 which is input to the A / A converters 34 and 35 and is a corrected luminance signal.
-> The RGB signal is converted by the RGB conversion circuit 6 into an RGB signal.
7 is displayed.

(Eighth Embodiment) Next, an eleventh embodiment of the present invention will be described.
Embodiment 8 of the present invention described in FIG. 11 will be described with reference to FIG. 11 and FIG.

FIG. 11 is a block diagram of a luminance correction circuit according to the seventh embodiment of the present invention. Since the configuration and operation are the same as those of the luminance correction circuit of the seventh embodiment shown in FIG. 11, a description thereof will be omitted. . FIG. 13 shows an internal block diagram of the color difference signal correction operation circuit of FIG. In FIG. 13, reference numerals 41 and 42 denote D flip-flops for latching output color difference signals (U and V signals) of the A / D converters 31 and 32 with a sampling clock of the A / D converter.
D flip-flops which connect the sampling clock of the / D converter to the clock input and connect the data inversion output and the data input to generate a clock divided by two of the sampling clock of the A / D converter. Output luminance signal of circuit 4 and A
This is a D flip-flop that latches the output luminance signal of the / D converter 1 with the inverted data output of the D flip-flop 43 (divided clock of the sampling clock of the A / D converter).

Reference numeral 44 denotes the output data of the D flip-flops 41 and 42 as A / D
A selector 47 that alternately switches and selects the luminance signal by a pixel unit of a luminance signal as a switching signal by using the frequency-divided clock of the converter as a switching signal. Latched by a multiplexed color signal (hereinafter referred to as a color signal) output from the selector 44 and a D flip-flop 45. A multiplier for multiplying the corrected digital luminance signal after the correction, a divider 48 for dividing the color signal as an output result of the multiplier 47 by the digital luminance signal before correction sampled by the D flip-flop 46, and a divider 49 A D flip-flop latches the corrected color signal, which is the output result of 48, with the sampling clock of the A / D converter, 50 a D flip-flop latching the data output of the D flip-flop 49 with the sampling clock of the A / D converter, 51 , 52 are the outputs of D flip-flops 49 and 50, respectively. The corrected color signals are D flip-flop for latching an inversion data output of the D flip-flop 43 (A / D converter 2 divided clock of the sampling clock).

The operation of the luminance correction circuit having such a configuration will be described below. Here, in the luminance correction circuit according to Embodiment 8 of the present invention, in the input video signal format, the A / D sampling clock of the color difference signal has the same phase as the A / D sampling clock of the luminance signal, and the clock frequency is Has a relationship of 1/2 or 1/4 with respect to the clock for luminance signal processing. In FIG. 13, a case will be described in which the A / D sampling frequency of the luminance signal of the video signal is twice the sampling frequency of the two types of input digital color difference signals.

The input digital color difference signal is multiplex-processed into one color signal (hereinafter referred to as a color signal). Explaining the multiplexing process, the input two types of color difference signals are sampled by the D flip-flops 41 and 42 in synchronization with the luminance signal by the luminance signal sampling clock. Also,
A sampling clock, which is a frequency division of the luminance signal sampling clock input by the D flip-flop 43, is generated, and switching of the selector 44 is controlled as a selection control signal of the selector 44. Here, since the sampling clock is a half of the luminance signal sampling clock, for example, the digital U signal output from the D flip-flop 41 as U1, U2, U3... The digital V signals output as V1, V2, V3,.
1, V1, U2, V2, U3, V3... Are output as color signals multiplexed into one. FIG. 20 shows a timing chart of the multiplex processing circuit.

Next, the amplitude correction calculation performed on the multiplexed color signals is as follows.

The input digital luminance signal after correction is input by the D flip-flop 45, and the input digital luminance signal before correction is input by the D flip-flop 46 by dividing the luminance signal sampling clock by two (the inverted data of the D flip-flop 43). Output).

The multiplexed color signal is multiplied by a multiplier 47.
Is multiplied by the above-mentioned sampled digital luminance signal after correction, and the output result of the multiplier 47 is divided by the above-mentioned sampled digital luminance signal before correction by the divider 48. Equation 4 shows the color signal amplitude correction by the above calculation.

Vout = Yout / Yin × Vin (Equation 4) Vout: Color signal after correction Vin: Color signal before correction Yout: Luminance signal after correction Yin: Luminance signal before correction Further, the color signal after correction is performed. The inverse transformation of the multiplexing process is described below. The corrected color signal output from the divider 48 is delayed by one clock of the luminance signal sampling clock by the D flip-flop 49, and is sampled by the D flip-flop 52 with the sampling clock which is the frequency signal divided by two. Is output as a color difference signal of only the digital V signal. Further, the color signal delayed by two clocks of the luminance signal sampling clock by the D flip-flops 49 and 50 is sampled by the D flip-flop 51 with the sampling clock which is the frequency signal divided by two, so that only the digital U signal is obtained. Is output as a color difference signal.

With the above operation, when the sampling frequency of the luminance signal is twice the sampling frequency of the two types of input digital color difference signals, the color difference amplitude correction synchronized with the luminance correction is performed.

Next, a case will be described in which the sampling frequency of the luminance signal of the video signal is four times the sampling frequency of the two types of input digital color difference signals.

When the sampling frequency of the digital chrominance signal is １ ／ of the sampling frequency of the luminance signal, for example, D is synchronized with the sampling frequency of the digital chrominance signal luminance signal.
The digital U signal output as U1, U1, U2, U2... From the flip-flop 41 and the digital V signal output as V1, V1, V2, V2. Are output from the selection means 44 as color signals which are multiplexed into U1, V1, U1, V1, U2, V2, U2, V2,... FIG. 20 shows a timing chart of the multiplex processing circuit. Further, the subsequent color signal correction calculation and decoding processing circuit performs the same operation as when the sampling frequency of the luminance signal is twice the sampling frequency of the two types of input digital color difference signals, and the amplitude correction is performed. Thus, two types of color difference signal outputs are obtained.

With the above configuration, the signal format 4: between the input video signal (luminance signal and color difference signal)
When certain relations such as 1: 1, 4: 2: 0, 4: 2: 2, and the like are satisfied, a multiplier and a divider that require a large circuit scale are realized by a multiprocessing circuit and a decoding processing circuit, and a smaller circuit is realized. Video amplitude correction depending on the screen position, in which the Y / C ratio is kept constant even after the correction on the circuit scale, is realized.

Embodiment 9 Next, a twelfth aspect of the present invention will be described.
The ninth embodiment of the invention described in the above will be described with reference to FIG. FIG. 14 shows a block diagram of a luminance correction circuit according to Embodiment 9 of the present invention. Note that, in the circuit of FIG. 14, 1 to 8 perform the same configuration and operation as in the first embodiment, and a description thereof will be omitted.

In FIG. 14, reference numeral 53 denotes a luminance level correction gain by obtaining the luminance signal after the luminance level correction and the luminance signal after the correction and dividing the luminance signal after the correction by the luminance signal before the correction. A contour correction gain control signal generation circuit for generating a signal for controlling the contour correction gain in conjunction with the correction gain; 54 is a rewritable register for storing data for determining the contour correction amount of the horizontal contour correction circuit;
Reference numeral 6 denotes an adder for adding the output contour correction gain control signal of the contour correction gain control signal generation circuit 53 and data for determining the contour correction amount stored in the register 56. Reference numeral 55 denotes an output of the adder 56 as contour correction gain data. This is a horizontal contour correction circuit that performs horizontal contour correction on the digital luminance signal after the luminance correction.

The operation of the luminance correction circuit having such a configuration will be described below. Here, in the brightness correction circuit according to the ninth embodiment of the present invention, first, the corrected data of the digital brightness signal is divided by the pre-correction digital brightness signal in the contour correction gain control signal generation circuit 53, and the result is linked to the result. And outputs the contour correction gain control signal. For example, data proportional to the division result is output as the contour correction gain control signal, such as 0.1 when the division result is 1 and 0.2 when the division result is 2 and 2. The contour correction gain control signal and the contour correction control data stored in the register 54 are added by an adder 56 to obtain a contour correction gain. The horizontal contour correction circuit performs horizontal contour correction on the signal after the luminance level correction with a contour correction gain linked to the luminance level correction amount.

With the above configuration, the horizontal contour correction in which the correction amount changes in accordance with the screen position is realized in conjunction with the brightness level correction, and the horizontal contour correction amount together with the contrast can be controlled in accordance with the screen position. .

(Embodiment 10) Next, Embodiment 1 of the present invention will be described.
Embodiment 10 of the invention described in 3 will be described with reference to FIG. FIG. 15 shows a block diagram of a video signal correction circuit according to Embodiment 10 of the present invention.

In the circuit of FIG.
Performs the same configuration and operation as in the first embodiment, and a description thereof will be omitted. A / D converters 61, 62 and 63 convert input analog RGB video signals into digital signals, respectively.
64, 65, and 66 are registers for storing a value indicating a pixel reference position for performing a horizontal correction operation on each of the RGB video signals, and 67, 68, and 69 are D / Ds for analog-converting each of the RGB corrected video digital signals. A converter.

The operation of the video signal correction circuit having such a configuration will be described. First, the input analog video signals RGB are converted into digital signals by A / D converters 61, 62, and 63. In the correction parameter calculation circuit, a video pixel position corresponding to each pixel, which is an output of the video pixel position detection means, and correction calculation pixel reference position data stored in the registers 64, 65, and 66 are input, and a difference is calculated. Outputs the absolute value of the difference result. Here, the output timing of the correction parameter for each pixel of the input video signal from the correction parameter calculation circuit 3 is set as the input phase to the video level correction calculation circuit 4 as A / D converters 61 and 6.
It is designed to be in phase with the output video signals of 2, 63. Further, for example, when the correction calculation pixel reference position data is set to a value that is half of the total number of horizontal pixels of the input RGB video signal, the value of the correction parameter becomes the same value at the left end and the right end of the display screen, The correction calculation is performed symmetrically about the center position of the display screen.

Next, the video level correction operation circuit 4 receives the output video signals of the A / D converters 61, 62 and 63 and the output correction parameter of the correction parameter calculation circuit 3 and inputs the correction parameter and the output video signal. A multiplication is performed for each pixel, and a correction operation is performed on the input video signal according to the horizontal screen position. As the calculation result of the video level correction calculation circuit 4, corrected RGB signals depending on the horizontal screen position can be obtained based on the same correction function for each signal set by the video level correction calculation circuit 4.

With the above-described configuration, the corrected operation pixel reference position data has a register for each of the RGB signals and data can be set.
The signal is at 1/3 from the left of the screen, the G signal is at the center of the screen, the B signal is at 1/3 from the right of the screen, and so on.
When it is necessary to make different correction operation pixel reference position data different from each other while maintaining the same characteristics of the correction function with respect to the amplitude correction of the RGB signal, for example, it is easy to perform the case where the light emission position of the RGB signal is different as in a projection video projector. In addition, the amplitude correction is realized with high accuracy.

(Embodiment 11) Next, Embodiment 1 of the present invention will be described.
Embodiment 11 of the invention described in FIG. 4 will be described with reference to FIG. FIG. 16 shows a block diagram of a video signal correction circuit according to Embodiment 11 of the present invention.

In the circuit of FIG.
Performs the same configuration and operation as in the tenth embodiment, and a description thereof will be omitted. 70, 71 and 72 are correction parameter calculation circuits 3
A video level correction arithmetic circuit which receives the correction parameters of the output RGB and the output digital video signals of the A / D converters 61, 62 and 63, and performs a calculation by a correction function adapted to the signal characteristics of each of the RGB on a pixel-by-pixel basis.

The operation of the video signal correction circuit having such a configuration will be described. Video level correction arithmetic circuit 70,
The digital video signal RGB and RGB-specific correction parameters output from the correction parameter calculation circuit 3 are input to 71 and 72, respectively, and the amplitude correction calculation is performed by the respective correction functions adapted to the luminance characteristics of the RGB signals. Therefore, the amplitude level of the digital RGB signal is changed to RGB
The correction can be performed symmetrically with respect to the pixel reference position set for each signal by using a correction function different for each RGB signal in the same phase as the correction parameter unique to each RGB signal. The correction function at this time utilizes digital signal processing to make use of its characteristics, facilitates realization of complicated functions such as higher-order functions and non-linear processing, and makes it possible to realize optimal amplitude correction processing.

[0100]

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 a television receiver and a display, such as an LCD or the like, which are likely to be uneven in color on a display image, such as an LCD, (1) when the RGB signal is corrected by the same function, luminance correction is performed. In this case, the correction processing can be performed on the luminance signal in a unified manner.

(2) To provide a brightness correction device capable of realizing and calculating a correction function by digital video signal processing, thereby realizing a complicated function and a nonlinear correction calculation which have been difficult to realize conventionally. Becomes possible.

(3) The provision of a new video type discriminating circuit allows smooth luminance in the horizontal direction of the display screen by using the result of the discrimination and using an optimal correction function such as a fractional function according to the type of the input video signal. Level correction can be performed.

(4) By using a fractional function as the characteristic of a correction function that uses the luminance level of a display pixel as a parameter, it is possible to perform smooth luminance correction gain control between images of different luminance levels.

(5) When the luminance correction is performed, particularly when the correction is performed in the direction of increasing the luminance level, the phenomenon called the color skip caused by the Y / C ratio shift with respect to the input image is corrected to be reduced. The Y / C ratio can be kept constant even when the luminance correction is performed.

(6) By controlling the correction amount of the horizontal contour correction in conjunction with the luminance level correction, the luminance level correction and the contour correction can be performed in conjunction with the same parameter called the screen position, and the image is displayed on the display device. , It is possible to realize a uniform image quality setting for the entire screen.

(7) The correction parameter calculation circuit and the RGB signal amplitude correction calculation circuit perform correction of each of the RGB signals by performing processing by increasing the processing clock of the signal correction calculation and parameter calculation with respect to the sampling frequency of the video signal. The RGB signals can be corrected and calculated with their own amplitude correction characteristics while being realized by a common circuit.

(8) By providing a correction operation circuit for individually processing only the correction operation for realizing the correction characteristics for the RGB signals into the RGB signals, even if the correction function characteristics have no correlation between the RGB signals at all, Correction calculation can be performed.

[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 block diagram of a luminance signal correction device according to an 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 an internal block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 5 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

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

FIG. 7 is an internal block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 8 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 9 is an internal block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 10 is an internal block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 11 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 12 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 13 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 14 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 15 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 16 is a block diagram of a luminance signal correction device according to an embodiment of the present invention.

FIG. 17 is a signal waveform diagram in each block of the luminance signal correction device according to one embodiment of the present invention;

FIG. 18 is a signal waveform diagram in each block of the luminance signal correction device according to one embodiment of the present invention.

FIG. 19 is a signal waveform diagram in each block of the luminance signal correction device according to one embodiment of the present invention.

FIG. 20 is a timing chart of a chrominance signal multiplexing processing circuit inside the chrominance signal correction circuit of the luminance signal correction device according to one embodiment of the present invention;

FIG. 21 is a block diagram of a luminance signal correction device according to the related art of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 A / D converter 2 Image pixel position detecting means 3 Correction parameter calculation circuit 4 Luminance level correction operation circuit 5 D / A converter 6 YUV → RGB conversion circuit 7 CRT 8, 9 register 10 Video type determination circuit 11 Selector 12 Luminance level Correction calculation circuit 13, 14 Selector 21 Absolute value calculation circuit 22 Register 23 Register 24 Divider 25 Subtractor 26 Adder 27 Large / Small comparator 28 Register 31, 32 A / D converter 33 Color signal correction calculation circuit 34, 35 D / A Converters 36, 38 Multipliers 37, 39 Dividers 41 to 43, 45, 46, 49 to 52 D flip-flops 47 Multipliers 48 Dividers 53 Contour correction gain control signal generation circuits 54 Registers 55 Horizontal contour correction circuits 56 Adders 61 ~ 63 A / D converter 64 ~ 66 cash register Data 67 to 69 D / A converters 70-72 luminance level correction calculating circuit 75 microcomputer 76 memory 101 RGB image quality adjusting circuit 102 parabolic waveform generating circuit 103-105 modulator

Claims (14)

[Claims] 1. A luminance level is corrected for each pixel of an A / D-converted digital video luminance signal by a function using a distance between a pixel reference position in a horizontal direction and a video display pixel position as an argument. Brightness correction device. 2. A video pixel position detecting means for detecting a horizontal display pixel position for an A / D converted digital video luminance signal, and a rewritable register for storing a value indicating a horizontal pixel reference position of the video. A correction parameter calculating circuit for obtaining a difference between horizontal pixel position data of each pixel of the video display output from the video pixel position detecting means and horizontal 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 that performs correction symmetrically with respect to a position. 3. A video type determination circuit for determining the type of a video signal such as an NTSC signal or an HDTV signal, and a rewritable memory for storing values indicating the number of horizontal pixel reference positions corresponding to the number of video types. And a switching circuit for selecting and switching the storage register of the horizontal pixel reference position data according to the determination result of the video type determination circuit, inside the luminance level correction arithmetic circuit, so that the sampling frequency unique to the input digital video is provided. That is, the horizontal pixel reference position data storage register is switched according to the number of horizontal pixels,
3. The brightness correction apparatus according to claim 2, wherein a correction pixel reference position for both left and right ends independent of the type of the input digital video is realized and brightness level correction is performed. 4. An image type discriminating circuit for discriminating types of image signals including an NTSC signal and an EDTV-II signal;
A switching circuit for selecting and switching the characteristics of the brightness level correction function based on the determination result of the video type determination circuit is provided inside the brightness level correction calculation circuit. 3. The brightness correction apparatus according to claim 2, wherein: 5. A luminance level correction operation circuit for dividing an A / D-converted digital video luminance signal by a luminance level correction parameter output from a correction parameter calculation circuit. 3. The brightness correction device according to claim 2, wherein the brightness level of the pixel is corrected. 6. A data obtained by taking a difference between horizontal pixel position data of each pixel of a video display, which is an output of a video pixel position detecting means, and horizontal pixel reference position data of a video stored in a rewritable register. , A rewritable register A for storing the denominator constant, and a rewritable register B for storing the numerator constant
An adder for adding the denominator constant of the register A to the absolute value data output from the absolute value calculation circuit; and a divider for dividing the numerator constant of the register B by the post-addition data calculated by the adder. Is provided inside the correction parameter calculation circuit, and the output signal of the correction parameter calculation circuit is multiplied by the input digital video brightness signal by the brightness level correction calculation circuit, whereby the denominator constant of the register A and the absolute value Determine the characteristics of the luminance correction function based on the ratio to the absolute value data output from the calculation circuit, and determine the gain of the luminance correction function based on the ratio between the denominator constant of the register A and the numerator constant of the register B. 3. The brightness correction device according to claim 2, wherein 7. Data obtained by taking the difference between the horizontal pixel position data of each pixel of the video display output from the video pixel position detection means and the horizontal pixel reference position data of the video stored in the rewritable register. A rewritable register storing a threshold value for comparison with the absolute value of the signal, a magnitude comparison circuit for comparing the threshold value stored in the register with the absolute value, and an input luminance signal and a correction signal to a luminance level correction operation circuit. 3. The luminance correction apparatus according to claim 2, further comprising a switching circuit for selectively switching a subsequent output luminance signal according to an output signal of the correction processing control circuit. 8. The brightness correction apparatus according to claim 2, wherein a correction gain of a correction operation of each pixel of the digital video brightness signal subjected to the A / D conversion is controlled according to a brightness level. 9. A rewritable register A for storing a denominator constant, a rewritable register B for storing a numerator constant, and a denominator constant of the register A and a luminance level of an A / D-converted digital video luminance signal. Adder A to add
A divider for dividing the numerator constant of the register B by the added data calculated by the adder; and adding the output data of the divider and the luminance level of the A / D-converted digital video luminance signal. And a luminance level correction operation circuit that adds an output signal of the correction parameter calculation circuit to the input digital video luminance signal, thereby obtaining a denominator constant of the register A and a denominator constant of the register A. The characteristic of the luminance correction function is determined by the ratio of the luminance level of the digital video luminance signal to the luminance level, and the gain of the luminance correction function is determined by the ratio of the output data after addition of the adder A to the molecular constant of the register B. 3. The brightness correction device according to claim 2, wherein: 10. A multiplier A and a multiplier B for respectively multiplying an arithmetic output signal of a luminance level correction arithmetic circuit and two types of A / D converted color difference signals, and arithmetic outputs of the multipliers A and B. A divider that divides the signal by an A / D-converted digital luminance signal that is also an input of the luminance level correction operation circuit, thereby correcting the amplitude of the color difference signal at the same ratio as the luminance level correction, 3. The method according to claim 2, wherein the luminance level is corrected while keeping the ratio constant.
The brightness correction device according to any one of the preceding claims. 11. A video signal in which the sampling frequency of a luminance signal of each pixel of an A / D-converted digital video signal is twice or four times the sampling frequency of two types of color difference signals,
A multiplexing circuit for multiplexing a single color signal by switching and selecting two types of color difference signals of each pixel of the A / D-converted digital video signal at the sampling frequency of the luminance signal; Multiplying an arithmetic output signal of a luminance level correction arithmetic circuit based on a luminance signal obtained by selecting a certain pixel from digital luminance signals of 2 or 4 pixels having the same phase as a signal and an output color signal of the multiplex processing circuit , A divider for dividing the operation output signal of the multiplier by an A / D-converted digital luminance signal which is also an input of the luminance level correction operation circuit, and an inverse conversion of the multiplexing processing of the multiplex processing circuit And a decoding processing circuit for separating into two types of color difference signals again, thereby performing amplitude correction of the color difference signals at the same ratio as that of the luminance level correction, and compensating the luminance level while keeping the Y / C ratio constant. And performing Claim 2
The brightness correction device according to any one of the preceding claims. 12. A horizontal contour correction circuit for controlling a gain of a horizontal contour correction amount based on gain control data, and a contour correction gain control signal generation circuit for generating a control signal in conjunction with a luminance level correction gain by a luminance level correction arithmetic circuit. And an adder for adding the output control signal of the contour correction gain control signal generation circuit and the gain control data of the horizontal contour correction processing given to the horizontal contour correction circuit, so that the luminance level correction arithmetic circuit 3. The brightness correction device according to claim 2, wherein the gain control of the horizontal contour correction process is performed in conjunction with the brightness level correction gain. 13. An RGB for detecting a horizontal display pixel position with respect to an A / D converted digital RGB video signal.
Image pixel position detecting means common to signals, rewritable registers A, B and C for storing values indicating horizontal pixel reference positions for each of the RGB signals, and an image which is an output of the image pixel position detecting means A correction parameter calculating circuit for obtaining a difference between horizontal pixel position data of each pixel and horizontal pixel reference position data output from the registers A, B, and C; the A / D-converted digital RGB signal and the correction parameter; A correction parameter unique to each RGB signal, which is an output of the calculation circuit, is input and the amplitude level of the digital RGB signal is symmetrically set for each display pixel in accordance with the correction parameter with respect to a pixel reference position set for each of the RGB signals. An RGB signal amplitude correction arithmetic circuit for correcting the RGB signal with the same correction function. Positive apparatus. 14. RGB for detecting a horizontal display pixel position for an A / D-converted digital RGB video signal.
Image pixel position detecting means common to signals, rewritable registers A, B and C for storing values indicating horizontal pixel reference positions for each of the RGB signals, and an image which is an output of the image pixel position detecting means A correction parameter calculation circuit for obtaining a difference between horizontal pixel position data of each pixel and horizontal pixel reference position data output from the registers A, B, and C; an A / D-converted digital RGB signal and the correction parameter; A correction parameter unique to each RGB signal, which is an output of the calculation circuit, is input, and the amplitude level of the digital RGB signal is symmetrically set for each display pixel in accordance with the correction parameter with respect to a pixel reference position set for each RGB signal. Input RGB using different correction functions for each RGB signal in phase with the correction parameters unique to each RGB signal
R for switching and correcting signals, correction parameters, and correction functions
R having a GB signal amplitude correction operation circuit
GB signal amplitude correction device.