JPH0316078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for improving the image quality of a color television receiver, particularly a projection display device for high definition television.

Conventional technology High-definition television displays high-definition television images on a large screen to give viewers a sense of impact and realism that cannot be obtained with existing television receivers. It is something.

A CRT projection display device is being developed as one of such high-definition television display devices. For details of such a CRT projection display device, please refer to the paper by Kubo et al. entitled ``Development of CRT type display for high-definition television'', lecture number SP1-15 of the 1982 National Conference of the Television Society.

In the above-mentioned CRT projection display device, it is considered essential to perform contour correction between the camera and the receiver in order to compensate for the decrease in resolution due to the increase in the size of the optical system. For more information on this type of contour correction, see
Television Society 1983 National Conference Lecture No. 12-2
"Digital contour corrector for high-quality television cameras"
Please refer to the paper by Okada et al.

Further, in the above-mentioned projection display device, large flare interference occurs due to reflected components caused by the projection light passing through the lens multiple times and the finite thickness of the screen. A video signal with large flare is accompanied by an increase in low frequency components. For more information on such flare disturbances, please refer to the Television Society
Please refer to the paper by Kanazawa et al. titled 1982 National Convention Lecture No. SP-14, "Improvement of Image Quality of High-Definition Television Projection Displays - Removal of Flare Interference by SAW Filters."

Problems to be Solved by the Invention An attempt was made to improve the image quality of a color television receiver such as a projection display device for high-definition color television by performing contour correction and flare correction in the horizontal and vertical directions. In this case, it is necessary to extract the following various problems and provide answers to each one, taking into account the relationship with other problems.

[A] The question of whether to implement it with analog circuits or digital circuits Video signals are supplied as analog signals, with some special exceptions, and analog circuits are generally simpler and simpler than digital circuits. It's cheap. Therefore, in terms of circuit scale and cost, it is desirable to implement the above image quality improvement device using an analog circuit.

On the other hand, analog
Considerable difficulty is expected in realizing the filter.

For example, according to the paper by Kanazawa et al. mentioned above, by amplitude modulating a video signal with a high frequency carrier frequency, it is first converted into a high frequency, wideband video signal of about 150 MHz ± 20 MHz, and the converted video signal is An attempt has been made to perform horizontal flare correction by attenuating only the frequency components of 1 MHz above and below 150 MHz by about 6 dB using a SAW filter and then demodulating them.

According to the above method, a reliable effect is achieved in that a simple and inexpensive analog circuit can be used. On the other hand, with this method, at least
There is a problem in that high-frequency signal processing of 100MHz or higher is required. Another problem is that if this method is applied not only to the horizontal component of flare but also to the vertical component, a large number of one-line delay circuits with extremely high precision, which is close to the limit of analog circuits, will be required. There is also.

[B] The question of whether everything can be realized with digital circuits If it is realized with digital circuits, [C]
Related to the question of whether or not to perform correction for the three primary colors independently, which will be discussed later, there is the question of whether or not to implement everything with digital circuits, that is, whether or not to include an analog part.

The above-mentioned paper by Okada et al. discloses a digital contour corrector based on a combined analog method. That is, of the analog three primary color video signals of R, G, and B, only the G signal is converted into a digital signal, and a digital contour correction signal is created based on this. The above-mentioned digital G signal is digitally added by the above-mentioned digital contour correction signal, and then converted into a corrected analog G signal.
Restored to signal. On the other hand, the digital contour correction signal is converted into an analog signal and then added to the original R signal and B signal as analog signals to obtain corrected analog R and B signals.

In this way, if the analog part coexists,
There is a certain effect that the circuit becomes simpler and cheaper. On the other hand, such a combined analog method has the problem that a delay compensation circuit and the like for compensating the processing time must be implemented using an analog circuit such as an LC circuit.
In other words, this type of analog circuit has lower adjustment accuracy than a digital circuit, and is more susceptible to temperature fluctuations, so unless high-precision stabilization measures are taken for such analog systems, the characteristics will not stabilize. This poses a problem in that there may be a difference in delay time, etc. between the digital system and the digital system, which may even deteriorate the image quality.

[C] The question of whether or not to perform correction independently for the three primary colors Create correction signals for each of the three primary colors R, G, and B, and use these correction signals to correct R, G, and B.
If the configuration is such that the G and B original signals are corrected, the best image quality improvement effect will be achieved.

However, it is expected that there is a considerable correlation between the appearance of contours and the occurrence of flare among video signals of the three primary colors, so if a certain degree of image quality deterioration is allowed when the correlation is broken, it is possible to A method of creating a correction signal may also be possible.

Taking this point into consideration, a configuration in which correction is performed independently for the three primary colors requires three independent correction signal generation circuits for R, G, and B, which poses a problem in that the scale and cost of the circuit become excessive. In particular, when implementing all of these correction signal generation circuits and delay compensation circuits digitally, there are problems in terms of circuit scale and cost.

[D] The problem of whether to create a correction signal from the G signal or the Y signal If correction is not performed independently for the three primary colors, there is a problem as to whether to create the correction signal from the G signal or the luminance signal Y. Input signal is R, G, B
If the three primary color signals are the three primary color signals, as described in the paper by Okada et al. mentioned above, if a correction signal is generated from the G signal that contributes the most to the luminance signal,
A reliable effect is achieved in that the step of creating the luminance signal Y by the matrix circuit can be omitted.

On the other hand, this method still has the problem that the correction effect decreases as the G signal component decreases.

[E] The question of whether to apply correction only to the Y signal When a correction signal is created from the Y signal, there is a problem whether to apply correction using this correction signal only to the Y signal. If the configuration is such that only the Y signal is corrected, the circuit configuration becomes simple. Particularly in a combined digital/analog system in which only the Y signal system is digitally processed, the effect of circuit simplification is significant.

On the other hand, a method in which a correction signal created from the Y signal is added to all three primary colors requires a more complicated circuit, but is more effective in improving image quality. In particular, in a system in which all three primary color systems are digitally processed, the addition of the digital addition circuit associated with the above-mentioned configuration is considered to have little effect on complicating the entire circuit.

[F] The issue of whether contour compensation and Frey compensation should be processed simultaneously by the same circuit Contour correction is performed by extracting a contour signal from the high-frequency components of an image and adding it to the original image. . Flare correction is performed by suppressing low frequency components of the video signal. Therefore, both contour correction and flare correction have a common aspect of emphasizing high-frequency components of a video signal. Therefore, if both correction processes are performed simultaneously by the same circuit, the number of stages of processing circuits can be halved.

On the other hand, the frequency range and frequency characteristics to be processed are quite different between the two, and processing both in the same circuit at the same time would make the design of the processing circuit difficult and increase the scale of the processing circuit. Ru. Furthermore, the above simultaneous processing method is expected to have a problem in that it becomes difficult to independently adjust the characteristics of contour correction and flare correction during assembly or use.

[G] The issue of whether to process contour correction and flare correction in the horizontal and vertical directions in parallel.If contour correction and flare correction are not performed simultaneously in the same circuit, contour correction and flare correction in the horizontal direction , vertical contour correction, and flare correction are required.

Assuming digital processing, a configuration in which all of the above four types of processing are performed in parallel has an excessive effect on improving the average image quality of the screen in that no rounding errors occur.

On the other hand, if you perform horizontal and vertical processing in parallel, you will end up with an angular window.
In patterns etc., the four corners are no longer processed,
It is expected that the image quality of that part will be relatively degraded compared to other parts, and that the uniformity of the image quality of the entire screen will be impaired.

Also, since the times required for the four types of processing above are all different, if all of these processes are performed in parallel, the processing will continue until the vertical flare processing (creating the flare correction signal), which takes the longest time, is completed. There is also the problem that the other three types of correction processing that have already been completed must be delayed, and that the scale of the delay compensation circuit within the correction signal generation circuit is large.

[H] The question of whether or not to process contour correction and flare correction in the horizontal and vertical directions all in series If the above four types of correction processing are all performed in series, as soon as one correction process is completed, the next correction process will be performed immediately. Since processing can be started, there is an advantage that a delay compensation circuit in the correction circuit is not required. Furthermore, if horizontal processing and vertical processing are performed in series and these processing circuits are configured with low-pass filter circuits, the problem of image quality deterioration at the four corners described above does not occur.

On the other hand, whether horizontally or vertically,
If the configuration is such that contour correction and flare correction are performed in series, there are disadvantages in that the design of the processing circuit becomes difficult and the scale of the processing circuit becomes large, as in the case of simultaneous processing using the same circuit described above.

Another disadvantage is that rounding errors associated with the four types of processing are accumulated.

[I] The question of whether or not to use a high-pass filter circuit As mentioned above, contour correction and flare correction both suppress low frequencies and emphasize high frequencies, so a configuration that uses a high-pass filter circuit is straightforward. It is true.

However, in order to prevent the problem that the four corners are not processed as described in [G] above, when performing horizontal processing and vertical processing in series, it is possible to use a high-pass filter circuit. New four-corner problems arise due to different causes. In other words, the level of the four outer corners of the window, whose level has decreased due to the horizontal contour correction, will increase in level due to the next vertical contour correction, and the image quality improvement effect of only the four corners will be relatively A problem arises in that it deteriorates and becomes an eyesore.

[J] The question of what kind of filtering circuit to use Especially when performing digital processing, it is necessary to use an acyclic filter (transversal filter) regardless of whether it is a high-pass filtering circuit or not. The problem is whether to use a recursive filter or a recursive filter.

[K] The question of whether to create a correction signal from the original signal that has been γ-corrected The video signal is subjected to γ-correction to compensate for the nonlinearity of the voltage/current characteristics of the CRT cathode. . If a correction signal is created from a video signal that has been subjected to this γ correction, the linearity of the correction signal itself may be lost, and the effect of the correction may be reduced.

The main problems encountered in improving image quality by performing contour correction and flare correction in the horizontal and vertical directions have been listed above. According to the inventor's estimates, thousands of different configurations will be reached depending on the answers to the various problems mentioned above.

Means for Solving the Problems of the Structure of the Invention The image quality improving device of the present invention which solves the problems of the prior art described above is based on a digital brightness signal of a digital video signal consisting of a digital brightness signal and two types of digital color signals. , an image quality improvement correction signal creation circuit that creates an image quality improvement correction signal including a contour correction signal and a flare correction signal; a delay compensation circuit that delays each of the digital video signals by a predetermined time; and the delayed digital video signal. A matrix circuit that converts each of these into digital three primary color signals of red, green, and blue, a digital addition circuit that adds the above-mentioned image quality improvement correction signal to each of the converted digital three primary color signals, and a three primary color signal after digital addition. The device is configured to include an A/D conversion circuit that converts the signal into an analog signal.

In a preferred embodiment of the present invention, the image quality improvement correction signal generation circuit includes contour correction signal generation means and flare correction signal generation means, and each signal generation means includes a low-pass filter for low-pass filtering the digital luminance signal. The digital luminance signal is configured to include a pass filter circuit, a delay circuit that delays the digital luminance signal by a predetermined amount, and a digital subtraction circuit that subtracts the low pass filtered digital luminance signal from the delayed digital luminance signal. .

In a preferred embodiment of the invention, separate contour correction signal generation means and flare correction signal generation means are installed in parallel with each other, each correction signal generation means comprising:
It is configured to include a low-pass filter circuit for creating a vertical correction signal and a low-pass filter circuit for creating a horizontal correction signal, which are installed in series with each other.

In a preferred embodiment of the present invention, each low-pass filtering circuit of the contour correction signal generating section comprises a transversal filter, and each low-pass filtering circuit of the flare correction signal generating section comprises a recursive filter. .

Hereinafter, the effects of the present invention will be explained in detail by way of examples.

Embodiment FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

In the image quality improvement device of this embodiment, 1a to 1c
are input terminals, 2a to 2c are A/D conversion circuits, 3 is a correction signal generation circuit, 4a to 4c are frame delay circuits, 5a to 5c are line delay circuits, 6 is a matrix circuit, 7a to 7c are addition circuits, 8a -8c are D/A conversion circuits, and 9a-9c are output terminals.

The input terminals 1a to 1c respectively receive an analog luminance signal Y for high-definition television and two types of color signals C1 (wideband color signal Cw) and C2 (narrowband color signal Cw).
C _N ) is supplied. These analog video signals Y, C1, and C2 are sampled at a predetermined sampling frequency by A/D conversion circuits 2a to 2c, and then converted into, for example, 8-bit digital signals. The luminance signal Y converted into a digital signal is supplied to the input terminal 3b of the correction signal generation circuit 3. On the other hand, digital video signals Y, C1, C
2 are delayed by the frame delay circuits 4a to 4c and the line delay circuits 5a to 5c by approximately one frame and several lines required for the correction signal generation circuit 3 to generate the correction signal. At this time, a part of the luminance signal Y delayed by approximately one frame time by the frame delay circuit 4a is supplied to the input terminal 3a of the correction signal generation circuit 3.

The delayed video signals Y, C1, and C2 are converted into three primary color digital video signals R, G, and B in the matrix circuit 6. Each of the digital video signals R, G, and B is added to a contour correction signal and a flare correction signal supplied from the output terminal 3a of the correction signal generation circuit 3 in addition circuits 7a to 7c. Through this addition, the digital video signals R, G, B are subjected to contour correction and flare correction.
are restored to analog video signals R, G, B in the D/A conversion circuits 8a to 8c, and output to the output terminal 9a.
~9c is output.

In preparation for receiving analog R, G, and B signals of three primary colors from a camera, the device of this embodiment includes a luminance signal Y, a color signal C1, a color signal C1, and a
The inverse matrix circuit 10 that creates C2 and the A/D
An input selection circuit 11 for selecting inputs to the conversion circuits 2a to 2c is provided as necessary.

In the device of this embodiment, both frame delay circuits 4a to 4c and line delay circuits 5a to 5c are RAM
The correction signal generation circuit 3 delays the input digital video signal by the time required for one frame and several lines to generate the correction signal, and then outputs the input digital video signal to one input terminal of each of the addition circuits 7a to 7c. supply

FIG. 2 is a block diagram showing the configuration of the correction signal generation circuit 3.

The correction signal generation circuit 3 includes a contour correction signal generation circuit 20, a flare correction signal generation circuit 30, and a digital addition circuit 40, which are connected in parallel.

The contour correction signal creation circuit 20 includes an inverse γ circuit 21 for canceling γ correction applied to the digital video signal R, a low-pass filter circuit (LPF) 22 for vertical contour correction connected in series, and a low-pass filter circuit (LPF) 22 for horizontal contour correction connected in series. Low-pass filter circuit 23 and digital subtraction circuit 26
and a delay compensation circuit 4 that delays the digital video signal R extracted from the center tap 22a of the vertical contour correction low-pass filter circuit 22 so that the phases of the two inputs of the digital subtraction circuit 26 match.
1, and a coring circuit 27 having a γ correction function.

Similarly, the flare correction signal generation circuit 30 also has an inverse γ
A circuit 31, a vertical flare correction low-pass filter circuit 32, a horizontal flare correction low-pass filter circuit 33, and a digital subtraction circuit 36, which are connected in series.
The coring circuit 37 includes a coring circuit 37 having a γ correction function.

The correction signal generation circuit 3 of this embodiment includes a low-pass filter circuit 2 for contour correction in the vertical and horizontal directions, respectively.
2, 23, and low-pass filter circuit 3 for flare correction
2 and 33, the low-frequency component of the luminance signal Y is extracted, and the extracted low-frequency component is subtracted from the original luminance signal Y of the same phase delayed by a predetermined time, thereby obtaining the contour correction signal and the flare correction signal. is configured to create.

The reason for this configuration, which extracts low-frequency components and subtracts them from the original signal, is to prevent image quality deterioration at the four corners that would occur when each correction signal is extracted from the luminance signal Y using a high-pass filter circuit. This is to do so.

The digital luminance signal Y supplied to the input terminal 3a is delayed by approximately one frame compared to the digital luminance signal Y supplied to the input terminal 3b. This is because the delay time occurring in the contour correction low-pass filter circuit 20 is shorter than the delay time occurring between the flare correction low-pass filter circuits 30.

Each luminance signal Y supplied to input terminals 3a and 3b
γ correction is applied to compensate for the nonlinearity of the voltage/current characteristics of the CRT cathode. If a correction signal is created from the luminance signal Y that has been subjected to this γ correction, there is a risk that the S/N ratio in dark areas of the screen will deteriorate and the effect of the correction will decrease.

Therefore, as shown in FIG. 2, the γ-corrected luminance signal Y is temporarily removed from the γ-correction by the inverse γ-addition correction circuits 21 and 31 consisting of ROM, and is linearly adjusted to the amount of light received by the imaging device. After the values are restored to values having the same relationship, the low-pass filter circuits 22 and 23 for contour correction and the low-pass filter circuit 3 for flare correction are applied, respectively.
2,33. The outputs of the low-pass filter circuit 23 for horizontal contour correction and the low-pass filter circuit 33 for horizontal flare correction are subtracted from the original luminance signal Y from which γ correction has been canceled in subtraction circuits 43 and 44, respectively, to form a correction signal. After that, in each of the coring circuits 27 and 37 equipped with a γ correction function, γ is
Correction and coring are performed.

The coring circuits 27 and 37 reduce high-frequency noise mixed into the correction signal by setting their respective outputs to zero when each of the created contour correction signal and flare correction signal is below a predetermined level. This prevents S/N deterioration in dark areas of the screen. An example of the predetermined levels is levels 2 to 6 with respect to the maximum level 256 expressed in 8 bits.

The adder circuit 40 includes each coring circuit 27, 37.
The contour correction signal and the flare correction signal that have passed through are added and synthesized.

Both the vertical contour correction low-pass filter circuit 22 and the horizontal contour correction low-pass filter circuit 23 are
It consists of a transversal filter as shown in the figure. This transversal filter includes delay circuits 51a to 51b connected in series to delay the digital luminance signal Y supplied to the input terminal 50 by a predetermined amount, and delay circuits 51a to 51b that delay each digital luminance signal Y by a predetermined amount by a predetermined amount. It is composed of coefficient circuits 52a to 52e that multiply values, and an adder group 53 that adds the outputs of each coefficient circuit according to a predetermined algorithm, and outputs the low frequency component for contour correction extracted from the digital luminance signal Y to an output terminal 54. Output to.

In the vertical contour correction low-pass filter circuit 22, the delay circuits 51a to 51d are composed of line memories that delay the digital luminance signal Y by one line. On the other hand, in the horizontal contour correction low-pass filter circuit 23, the delay circuits 51a to
51d is composed of a dot memory that delays the digital luminance signal Y by one sampling period.

The vertical flare correction low-pass filter circuit 32 and the horizontal flare correction low-pass filter circuit 33 each include two recursive filters 61 and 63 of the same configuration and two recursive filters 61 and 63 of the same configuration, as shown in FIG. The time axis reversing circuit 62 and 64 are configured.

In the above-mentioned contour correction, it is sufficient to perform signal processing between several adjacent sampling points, but the influence of flare generally extends to a very large number of adjacent sampling points. Therefore, if flare processing were to be performed by a transversal filter, an extremely large number of delay circuits, coefficient circuits, and adder circuits would be required, and the scale of the filter would be extremely large. Therefore, a recursive filter is used for flare correction.

In the vertical flare correction low-pass filter circuit 32, the time axis inversion circuits 62 and 64 perform field inversion that writes one field's worth of digital luminance signal Y and then reads it in the reverse order of the writing. Consists of memory. On the other hand, in the horizontal contour correction low-pass filter circuit 33,
The time axis inverting circuits 62 and 64 are constituted by line inverting memories in which one line of digital luminance signal Y is written and then read out in the reverse order of the writing. The phase characteristics are improved by inverting the time axis of the digital luminance signal Y passed through the recursive filter 61 and passing it through the recursive filter 63 again to achieve linear illusion characteristics.

The recursive filters 61 and 62, as exemplified by the recursive filter 61, include adder circuits 70a to 70c and delay circuits 71a to 71.
c, and coefficient circuits 72a to 72c. The delay circuits 71a to 71c are recursive filters for vertical flare correction, and are composed of line memories that provide a one-line delay to the digital luminance signal Y. On the other hand, the recursive filters for horizontal flare correction are configured to delay the digital luminance signal Y. It consists of a dot memory that provides a delay of one sampling period.

FIG. 5 shows an example of the contour correction signal output from the subtraction circuit 26 in FIG. 2 as a spatial frequency characteristic (MTF).
This is shown in . The level of the contour correction signal is
It is zero up to 100 TV books, and from 100 TV books
Up to 300 TV lines, as the spatial frequency increases,
Can increase linearly at a rate of 12dB/200 lines, 300TV
The signal can increase to a level 12 dB higher than the original luminance signal.

FIG. 6 shows an example of the flare correction signal output from the subtraction circuit 36 of FIG. 2 in terms of spatial frequency characteristics. Flare correction signal level is 15TV
From 12 TV lines to 30 TV lines, it can increase linearly at a rate of approximately 6 dB/15 TV lines as the spatial frequency increases, and above 30 TV lines it can increase to a level 6 dB greater than the original luminance signal. .

FIG. 7 is a block diagram showing an example of the configuration of a coefficient circuit used in the transversal filter of FIG. 3 and the recursive filter of FIG. 4.

This coefficient circuit is composed of a selector 81 and a RAM 82.

For example, the CPU selects the selector 81 during the vertical blanking period when the screen is not displayed.
A CPU that commands the selection of a CPU address and multiplies the CPU address whose value increases gradually by a predetermined coefficient to be set to this CPU address.
Output DATA repeatedly. This CPU DATA
is supplied to the data write terminal Din of the RAM 82 and written into 256 areas specified by the CPU address. When the CPU finishes writing the coefficients, it instructs the selector 81 to select DATA (luminance signal Y). After this, when the RAM 82 is addressed by the luminance signal Y, its data output terminal
From Dout, the luminance signal Y multiplied by the coefficient is
Output as DATA out.

In this way, by configuring the coefficient circuit with RAM, calculation speed is improved compared to configuring it with ROM or multipliers, etc., and correction can be made by changing the coefficient value at the adjustment stage during manufacturing or during use. Characteristics can be adjusted.

The case of a high-definition television signal has been illustrated above, but in the case of an NTSC television signal, two types of color signals C1 and C2 are (R-Y), respectively.
The (B-Y) signal or the I and Q signals may be used. In short, the two types of color signals C1 and C2 may be in any other suitable format as long as the three primary color signals of R, G, and B can be restored from these and the luminance signal Y.

In addition, although we have illustrated a configuration in which image quality is improved by converting an analog video signal into a digital video signal using an A/D conversion circuit, if the video signal whose image quality is to be improved has already been digitized, the above Of course, an A/D conversion circuit is not required.

Effects of the Invention As explained in detail above, the image quality improvement device of the present invention is configured to create an edge correction signal and a flare correction signal from the luminance signal Y, so the above correction is performed from each of the three primary color signals R, G, and B. The effect is that the circuit scale can be reduced to approximately one-third compared to the case where signals are created.

Furthermore, since the image quality improvement device of the present invention is configured to create an edge correction signal and a flare correction signal based on the luminance signal Y, the level of the G signal is reduced as in the case where each correction signal is created from the G signal. This is advantageous in that the problem that the effect of improving image quality deteriorates as the image quality increases increases.

Since the image quality improvement device of the present invention has a configuration in which all three systems of the luminance signal Y and color signals C1 and C2 are processed by digital circuits, a part of the frame delay circuit and line delay circuit is configured with analog circuits. This method has the effect of solving the problem that the effect of improving image quality is diminished or the image quality deteriorates due to the difference in delay time between the analog system and the digital system.

Since the image quality improvement device of the present invention is configured to correct not only the luminance signal Y but also the color signals C1 and C2 using the correction signal created from the luminance signal Y, compared to the case where only the luminance signal Y is corrected. Therefore, the effect of improving the image quality is improved.

Along with this, digital adder circuits 7b and 7c are required in the example of FIG. 1, but since these occupy a small proportion of the hardware in the entire image quality improvement device, they do not affect the complexity of the entire device. The impact is small.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing an example of the configuration of the correction signal generation circuit 3 shown in FIG. 1, and FIG. FIG. 4 is a block diagram showing an example of the configuration of the low-pass filter circuit 22 for vertical flare correction and the low-pass filter circuit 23 for horizontal contour correction shown in FIG. 2. A block diagram showing an example of the configuration of the low-pass filter circuit 33, FIG. 5 is a characteristic diagram showing an example of a contour correction signal, FIG. 6 is a characteristic diagram showing an example of a flare correction signal, and FIG. 7 is a characteristic diagram showing an example of a flare correction signal. FIG. 2 is a block diagram showing an example of the configuration of a coefficient circuit in a filter circuit. 1a-1c...input terminal, 2a-2c...A/D conversion circuit, 3...correction signal creation circuit, 4a-4c...frame delay circuit, 5a-5c...line delay circuit,
6... Matrix circuit, 7a-7c... Addition circuit, 8
a to 8c...D/A conversion circuit, 9a to 9c...output terminal, 20...contour correction signal creation circuit, 30...flare correction signal creation circuit, 21, 31...inverse γ correction circuit,
22...Low pass filter circuit for vertical contour correction, 32...
Low-pass filter circuit for vertical flare correction, 23... Low-pass filter circuit for horizontal contour correction, 33... Low-pass filter circuit for horizontal flare correction, 26, 36... Subtraction circuit, 27, 37... Coring circuit, 40 ...Addition circuit, 41...Delay compensation circuit.

Claims (1)

[Scope of Claims] 1. An image quality improvement correction signal generation circuit that generates a digital image quality improvement correction signal based on a digital luminance signal of a digital video signal consisting of a luminance signal and two types of color signals, which are connected in series. A low-pass filtering circuit for vertical flare correction and a low-pass filtering circuit for horizontal flare correction connected in series with a contour correction signal generating means consisting of a low-pass filtering circuit for vertical contour correction and a low-pass filtering circuit for horizontal contour correction. flare correction signal generating means consisting of circuits connected in parallel to each other, a delay circuit for matching the phase of the output of these correction signal generating means with the phase of the original digital luminance signal, and each correction signal having the matched phase. a subtraction circuit that subtracts the luminance signal from the original digital luminance signal; a delay circuit that delays each of the digital video signals by a predetermined time; and a subtraction circuit that delays each of the digital video signals by a predetermined time, and converts each of the delayed digital video signals into three digital primary colors of red, green, and blue. a matrix circuit for converting into signals; a digital addition circuit for digitally adding the image quality improvement correction signal to each of the converted digital three primary color signals; and a digital addition circuit for converting the digital three primary color signals after the digital addition into corresponding analog signals. - A color television image quality improvement device characterized by being equipped with an analog conversion circuit. 2. Claims characterized in that each low-pass filtering circuit of the contour correction signal generating means consists of a transversal filter, and each low-pass filtering circuit of the flare correction signal generating means consists of a recursive filter. 2. The color television image quality improvement device according to claim 1. 3. The contour correction signal generating means and the flare correction output generating means are provided with an inverse γ correction circuit at the front stage and a γ correction circuit at the rear stage, according to claims 1 and 2. color television image quality improvement device.