JP3470906B2 - Television receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver which automatically adjusts the image quality of various settings according to the video state of an input video signal so that an optimum video can always be obtained.

[0002]

2. Description of the Related Art Heretofore, in television receivers, attempts have been made to improve the display video signal in accordance with the viewing conditions and video contents of the user. In the most advanced example in recent years, there is a video control method in which the brightness and contrast of the video are automatically adjusted according to the grayscale histogram of the video of the input video signal to always obtain the optimum video state. As an example of the image control method for such a television receiver, there is JP-A-2-233068.

FIG. 2 shows an outline of the image control means of the television receiver in this already proposed example. In the figure, 2
Reference numeral 01 is a video signal input terminal, 202 is a video signal processing circuit (Y / C processing), 203 is a sampling means, 204 is a calculation means, 205 is a storage means, and 206 is a cathode ray tube.

A video signal input terminal 201 receives a video signal supplied from a television tuner, a video tape recorder (VTR) or the like, and a video signal processing circuit 202.
Then, the luminance signal (Y signal) and the color signal are processed. The luminance signal output from the video signal processing circuit 202 is supplied to the sampling means 203, while the CRT 20
Each video signal converted into RGB is supplied to 6. As shown in FIG. 3, the sampling means 203 is, for example, 1
N voltages are sampled in the frame, and each of the n sampling points is a representative value of each area obtained by dividing one screen image into n areas. The sampling data obtained by the sampling means 203 is taken into the arithmetic means 204, where it belongs to each group divided into several stages by the luminance signal level (IRE level) is discriminated and totaled for each group.

By performing an operation in accordance with a certain rule on the aggregated data of each group, or the storage means 2
By reading certain setting data from 05, the values indicating the distribution state of each brightness level on the screen, the brightness and darkness of the entire screen, and the like are set, and the data serving as the setting reference of the brightness level control signal is obtained. The control signal S converted into an analog signal by digital / analog (D / A) conversion of the added value of the data as the setting reference of the control signal thus obtained
Output as. Then, the video signal processing circuit 202 adjusts the luminance level according to the control signal S output from the calculating means 204.

By performing the above operation, this video control method automatically attempts to perform various output adjustments according to the video state on a screen-by-screen basis.

[0007]

However, in the above-mentioned proposed example, since the video control is performed based on the luminance level distribution state of the sampling data, that is, the grayscale histogram of the video, for example, in one frame of the input video signal. If the maximum value (hereinafter referred to as the white peak) or the minimum value (hereinafter referred to as the black peak) of the luminance signal exists in a small area, the data of the white peak and the black peak is The data of the white peaks and the black peaks are ignored in the video control because the ratio is low. Therefore, in such a case, the correct input image cannot be grasped, resulting in an erroneous control state such as a white crush or a black crush.

An object of the present invention is to solve the above-mentioned problems and to provide a television with a new function that always obtains the best picture state by automatic picture quality control according to the picture change using accurate picture information from an input picture signal. To provide John receiver.

[0009]

In order to achieve the above object, the present invention provides a noise detecting means for detecting noise from an input video signal, and a luminance according to the noise level detected by the noise detecting means. Change the pass band of the signal,
A low-pass filter for reducing the influence of noise contained in an input signal, a display means for displaying an image on a screen by the video signal, a data detection area setting means for setting a data detection area on the screen, and the low-pass filter. The brightness signal supplied from the feature detection means for detecting the feature of the brightness signal in a portion corresponding to the data detection area set by the data detection area setting means, and outputting the detection result as a detection signal. An ambient light detection unit that detects the ambient brightness of the television receiver and outputs the detection result as a detection signal, an image control unit that controls the image, and a detection signal that is output from the noise detection unit. Based on the detection signal output from the feature detection means and the detection signal output from the ambient light detection means, And control means for controlling the image control unit,
With the above, the image control is automatically performed according to the change of the image.

[0010]

The noise detecting means detects the magnitude of noise from the input video signal. The low-pass filter can adaptively reduce the influence of noise contained in the input signal by changing the pass band of the luminance signal according to the noise level detected by the noise detecting means and changing the pass band of the luminance signal. Then, the luminance signal in which the influence of noise is adaptively reduced can be supplied to the feature detection means.

The feature detecting means detects a feature of the input luminance signal. Since the feature detecting means is supplied with the luminance signal in which the influence of noise is adaptively reduced by the low-pass filter, it is possible to perform more accurate data detection.

Since the data detection area setting means can detect the size of the video image and arbitrarily set the data detection area according to the size of the video image, when a black band portion exists on the screen, the data detection area other than the black band is detected. Of the part corresponding to the part (video part),
Information on the video state can be obtained from any range such as the feature of the signal can be detected.

The control means, based on the detected luminance signal characteristics and noise, and image information of ambient light, color, bright,
The control signals for adjusting the contrast, the contour correction, the noise reduction, and the gamma correction are set, and the image control means is controlled so as to obtain the best image state without white crushing and black crushing.

[0014]

EXAMPLES Examples of the present invention will be described below. FIG. 1 is a block diagram showing a first embodiment of the present invention.
Is an antenna, 102 is a tuner, 103 is a luminance signal color signal separation circuit (Y / C separation circuit), 104 is a luminance signal noise reduction circuit (YNR circuit), and 105 is a contour correction circuit (EN
H circuit), 106 is a color signal noise reduction circuit (CNR circuit), 107 is a video chroma circuit, 108 is a gamma correction circuit, 109 is an RGB conversion circuit, 110 is a cathode ray tube,
Reference numeral 111 denotes a horizontal synchronizing signal (H synchronizing signal) input terminal, 112
Is a vertical sync signal (V sync signal) input terminal, 113 is a data detection area setting circuit, 114 is a low-pass filter (LP
F), 115 is a clock generation circuit, 116 is a noise detection circuit, 117 is a white peak detection circuit, 118 is a black peak detection circuit, 119 is an average brightness detection circuit, 120 is an ambient light detection circuit, 121 is a control circuit, and 122 is 122. Clock (CL
K) input terminal, 123 is a user setting input terminal.

The operation will be described below. Antenna 1
The radio wave received at 01 is tuned and demodulated by the tuner 102, and a baseband video signal is output. The demodulated baseband video signal is input to the Y / C separation circuit 103 and separated into a luminance signal and a chrominance signal. The luminance signal separated by the Y / C separation circuit 103 is supplied to the YNR circuit 104, and the color signal is supplied to the CNR circuit 106.

The YNR circuit 104 reduces noise from the input luminance signal according to the control signal sent from the control circuit 121, and supplies it to the ENH circuit 105. ENH circuit 1
Reference numeral 05 designates the input luminance signal contour portion to the control circuit 121.
The video signal is corrected according to the control signal output from the digital camera and supplied to the video chroma circuit 107.

On the other hand, the color signal input to the CNR circuit 106 is noise-reduced according to the control signal output from the control circuit 121, and then supplied to the video chroma circuit 107.

The video chroma circuit 107 is the ENH circuit 1
The luminance signal output from the CNR circuit 106 and the color signal output from the CNR circuit 106 are subjected to image adjustment such as color, bright, and contrast based on the control signal from the control circuit 121. Is supplied to the RGB conversion circuit 109 via the, and the color signal is converted into two or three color difference signals and supplied to the RGB conversion circuit 109.

The gamma correction circuit 108 performs gamma correction on the luminance signal output from the video chroma circuit 107 according to the control signal from the control circuit 121, and then RGB
It is supplied to the conversion circuit 109.

The RGB conversion circuit 109 includes a color difference signal output from the video chroma circuit 107 and the gamma correction circuit 10.
The luminance signal output from the converter 8 is converted into RGB primary color signals and supplied to the cathode ray tube 110.

The noise detection circuit 116 includes a tuner 102.
The noise level included in the video signal output from the is detected and supplied to the LPF 114 and the control circuit 121.

The LPF 114 according to the detection signal output from the noise detection circuit 116, the Y / C separation circuit 103.
The pass band of the luminance signal output from is changed. For example,
When the noise level detected by the noise detection circuit 116 is high, the LPF 114 lowers the cutoff frequency. This makes it possible to adaptively reduce the influence of noise included in the input video signal when detecting the white peak, the black peak, and the average luminance, and to perform more accurate data detection.

Further, from the LPF 114 to the white peak detection circuit 117, the black peak detection circuit 118, the average luminance detection circuit 1
Independent output signal path to 19 and white peak detection circuit 1
17, black peak detection circuit 118, average brightness detection circuit 11
Different low-pass filter bands may be used for the respective luminance signals supplied to the signal line 9. With such a configuration, for example, the black peak signal detected by the black peak detection circuit 118 is relatively narrowed in the low-pass filter band to reduce the change and stabilize the black level.
The white peak signal detected by the white peak detection circuit 119 is
By widening the low-pass filter band, the signal followability can be improved, and more stable and highly accurate video control can be performed as a whole.

The data detection area setting circuit 113 includes a video signal output from the tuner 102, a clock signal input from the clock input terminal 122, a horizontal sync signal input from the horizontal sync signal input terminal 111, and a vertical sync. A vertical sync signal input from the signal input terminal 112 sets a detection area in one screen for performing white peak detection, black peak detection, and average luminance detection, and the white peak detection circuit 11
7, black peak detection circuit 118, average luminance detection circuit 119
Output to. However, the output video signal from the tuner 102 input to the data detection area setting circuit 113 is LP
It may be the output signal of F114.

The clock generation circuit 115 receives the clock signal input from the clock input terminal 122, the horizontal synchronization signal input from the horizontal synchronization signal input terminal 111, and the vertical synchronization signal input from the vertical synchronization signal input terminal 112. Two types of clock pulses are generated and output to the white peak detection circuit 117, the black peak detection circuit 118, and the average brightness detection circuit 119.

The white peak detection circuit 117, the black peak detection circuit 118, and the average luminance detection circuit 119 detect the white peak, the black peak, and the average luminance from the output luminance signal of the LPF 114, and output them to the control circuit 121.

A concrete example of the white peak detection circuit 117 is shown in FIG. In the figure, 401 is a luminance signal input terminal, 402 is a clock 1 (CLK1) input terminal, 403
Is a clock 2 (CLK2) input terminal, 404 is a white peak comparison circuit, 405 is a white peak output circuit, 406 is a white peak output terminal, 407 is an input terminal to which the output signal of the data detection area setting circuit 113 is input, and 408 is It is an AND circuit.

The circuit operation will be described below. The white peak comparison circuit 404 compares the luminance signal input from the input terminal 401 and the signal output from the white peak comparison circuit 404 with A
Compared when the output of the ND circuit 408 changes from the low level to the high level, the signal with the higher brightness level is output. The AND circuit 408 outputs the clock signal input to the clock 1 input terminal 402 to the white peak comparison circuit 404 when the output signal of the data detection area setting circuit 113 input from the input terminal 407 is at a high level. The white peak output circuit 405, for example, performs white peak detection for one field period, and finally, the white peak comparison circuit 4
When the clock signal is input to the clock 2 input terminal 403, the value output from 04 is set as the maximum white peak value (that is, the maximum brightness level) of the field, and is output to the output terminal 406.

Next, a concrete example of the black peak detection circuit 118 is shown in FIG. In the figure, 501 is a black peak comparison circuit, 502 is a black peak output circuit, 503 is a black peak output terminal, and the same reference numerals as those in FIG. 4 are the same as those in FIG.

The circuit operation is the same as that of the white peak detection circuit of FIG. 4 except for the black peak comparison circuit 501.
The black peak comparison circuit 501 compares the luminance signal input from the input terminal 401 and the signal output from the black peak comparison circuit 501 when the output of the AND circuit 408 changes from the low level to the high level, and the luminance level Output the lower signal. The AND circuit 408 has an input terminal 407.
When the output signal of the data detection area setting circuit 113 input from the clock 1 is at the high level, the clock 1 input terminal 402
The clock signal input to is output to the black peak comparison circuit 501. The black peak output circuit 502 performs, for example, black peak detection for one field period, and then finally outputs the value output from the black peak comparison circuit 501 to the maximum black peak value of the field (that is, the lowest luminance level). ) As
When a clock signal is input to the clock 2 input terminal 403, the clock signal is output to the output terminal 503.

Next, a concrete example of the average luminance detection circuit 119 is shown in FIG. In the figure, 602 is an integrating circuit, and 603.
Is an integrated value output circuit, 604 is a multiplication circuit, 606 is a counter, 607 is a counter output circuit, 608 is an average luminance output terminal, and the same reference numerals as those in FIG. 4 are the same as those in FIG.

The circuit operation will be described below. The integrating circuit 602 cumulatively adds the level of the input luminance signal to the luminance signal input from the input terminal 401 every time the output of the AND circuit 408 changes from the low level to the high level. For example, the accumulated value for one field is input to the integrated value output circuit 603 as an output signal of the integrating circuit 602. The integrated value output circuit 603 outputs the cumulative value output from the integration circuit 602 to the multiplication circuit 604 for each pulse of the clock signal input from the clock 2 input terminal 403. The multiplication circuit 604 multiplies the cumulative value output from the integrated value output circuit 603 by (cumulative value / n) by the value n output from the counter output circuit 607, and outputs the execution result to the average luminance output terminal 608. Output to.

Although the example of detecting the average luminance of one field is shown here, the average luminance of several fields may be detected.

The AND circuit 408 outputs the clock signal input from the clock 1 input terminal 402 to the integration circuit 602 and the counter 606 when the output signal of the data detection area setting circuit 113 input from the input terminal 407 is at high level. To do. The counter 606 counts the number of input clocks and outputs it to the counter output circuit 607. The counter output circuit 607 outputs the output from the counter 606 to the multiplication circuit 604 for each pulse of the clock signal input from the clock 2 input terminal 403.

On the other hand, in FIG. 1, the ambient light detection circuit 12
0 detects the brightness around the television receiver and supplies the detection result to the control circuit 121.

The control circuit 121 includes the noise detection circuit 11
6, white peak detection circuit 117, black peak detection circuit 11
8, the YNR circuit 10 based on the respective data output from the average luminance detection circuit 119 and the ambient light detection circuit 120.
4. The control signals for controlling the contour correction circuit 105, the CNR circuit 106, the video chroma circuit 107, and the gamma correction circuit 108 are set and output to control the image. Furthermore, a signal input from the user setting input terminal 123 can be used to obtain an image according to the user's preference.

The control circuit 121 is composed of, for example, a microcomputer, fetches each input data into the microcomputer, performs the following arithmetic processing based on the fetched input data, and sets an output control signal.

The control signal from the control circuit 121 is
In order to control a screen for which image information such as noise, white peak, black peak, average brightness, and ambient light has been obtained, one field of input image signal for which image information has been obtained is temporarily stored in a field memory or the like. It can be realized by

The specific operation of the control circuit 121 is performed, for example, according to the flowchart shown in FIG.
In the figure, in step A2, it is determined which of several preset levels the detected average luminance level belongs to, and in step A3, the dynamic range is calculated from the detected white and black peaks. Then, it is determined which of several preset levels it belongs to. Similarly, in step A4, the detected ambient light data is determined, and in step A5, it is determined which of several preset levels the noise level belongs to. In step A6, the contrast control signal is set based on the result of the level judgment in steps A2, A3, A4, and A5, the bright control signal is set in step A7, and the gamma correction control signal is set in step A8. The contour correction control signal is set in step A9, and the YNR and CNR control signals are set in step A10. In the user setting in step A12, the contrast, brightness, and contour correction amount can be changed according to the user's preference.

Step A2, Step A3, Step A
4, the level preset in step A5 is set to, for example,
In step A2, the average brightness level is set to three levels of high, low, and intermediate thereof, in step A3, the dynamic range is set to three steps of wide, narrow, and intermediate, and in step A4, ambient light is set to bright and dark. Assume that the noise detection amount is set to two levels, that is, the noise detection amount is large and small in step A5.

At this time, as specific control signal settings, for example, when it is determined that the average luminance is high in step A2 and the dynamic range is wide in step A3, the contrast is greatly reduced in step A6, and the contrast is reduced in step A6.
In step 7, the brightness is lowered a little, in step A8 the gamma correction is weakly applied, and in step A9, the contour correction amount is set to be small. Further, if it is determined in step A4 that the ambient light is bright, the contrast and brightness lowering widths are set to be slightly smaller than the above settings, and if it is determined that the ambient light is dark, the contrast and bright lowering widths are set to be slightly larger. . Further, at this time, when it is determined in step A5 that the noise detection amount is large, in step A10, a control signal for slightly increasing YNR and CNR, and weakly increasing YNR and CNR is set.

Similarly to the above, when the average luminance is low and the dynamic range is wide, the contrast is lowered to a low level,
Raise the brightness a little, apply gamma correction slightly larger, and apply contour correction strongly. If the ambient light is bright,
Brightness and gamma correction amount increase range are set to be slightly larger than the above settings, and in dark conditions, the contrast decrease range is reduced and the gamma correction amount is further increased. YNR, CNR
Applies more when the noise detection amount is large, and weakly applies when the noise detection amount is less.

When the average luminance is high and the dynamic range is narrow, the contrast is greatly increased, the brightness is greatly reduced, and the gamma correction is applied small. In addition to this, when the ambient light is bright, the reduction range of the brightness is made slightly smaller than the above setting, and when it is dark, the reduction range of the bright is further increased.

When the average luminance is low and the dynamic range is narrow, the contrast is increased greatly, the brightness is increased slightly, and the gamma correction is applied greatly. Further, when the ambient light is bright, the increase range of the brightness and the gamma correction amount is set to be slightly larger than the above setting, and when it is dark, the contrast and the increase range of the brightness are reduced. When the noise detection amount is large, YNR and CNR are applied strongly, and when the noise detection amount is small, they are applied weakly.

The above description can be represented as shown in FIG. 8 only for the bright control when the ambient light is bright.

As described above, in step A2, the average brightness level is set to three stages of high, low, and intermediate, and in step A3, the dynamic range is set to three stages of wide, narrow, and intermediate. The characteristic points of the control amount of are 9 points, but in actual control, the innumerable points existing between the characteristic points are also calculated from the characteristic points by interpolation calculation so that smoother control can be performed. There is. It should be noted that the interpolation calculation method can be realized by using a method that can express the ambiguity of data or a non-linear function, such as fuzzy calculation processing or neuro calculation processing.

As described above, by using the flow chart shown in FIG. 7, the control settings of contrast, bright, gamma correction, contour correction, YNR, and CNR can be arbitrarily changed.

Although not shown in the flow chart shown in FIG. 7, color control can be similarly processed. For example, the color contrast can be linked with the brightness contrast, or the color temperature can be adjusted according to the ambient light. It can be changed.

In the flowchart shown in FIG. 7, the method of sequentially processing the input information is used. However, step A2, step A3, step A4, step A5
Since the processing of step A6, step A7, step A8, step A9, and step A10 can be performed at the same time,
It may be realized by using a parallel processing type microcomputer or a plurality of microcomputers.

Next, a concrete example of the gamma correction circuit 108 is shown in FIG. In the figure, 701 is a video chroma circuit 1
07, an input terminal for a luminance signal supplied from 07, 702, an input terminal for a control signal output from the control circuit 121, 703
Is a ROM table, and 704 is an output terminal.

The circuit operation will be described below. The luminance signal input from the input terminal 701 is stored in the ROM table 7
03 is read as an address, and the data according to the control signal inputted from the input terminal 702 is read out and outputted to the output terminal 704.

FIG. 10 is a characteristic diagram showing an example of the relationship between the input address and the output data. The output (vertical axis) corresponds to the input address (horizontal axis) according to the control signal input from the input terminal 702. , Curve 1, curve 2 and curve 3 selected.

If the gamma correction circuit 108 is composed of a ROM table, it is effective for high integration and reliability improvement when a television signal is handled digitally like a digital television.

Here, a circuit using a ROM table is shown as an example of the gamma correction circuit 108, but it can also be realized by a circuit using a non-linear element such as a transistor or a diode.

Next, a concrete example of the data detection area setting circuit 113 is shown in FIG. This circuit is a white peak detection circuit 1
17, black peak detection circuit 118, average brightness detection circuit 11
Reference numeral 9 sets a data detection area for performing white peak, black peak, and average luminance detection from the output video signal of the low-pass filter 114 according to the input video size, and outputs a signal limiting the data detection area to a white peak detection circuit 117. , A circuit for outputting to the black peak detection circuit 118 and the average luminance detection circuit 119.

In the figure, 122 is a clock input terminal, 111 is a horizontal synchronization (H synchronization) signal input terminal, and 112.
Is a vertical sync (V sync) signal input terminal, 901 is a horizontal sync signal counter (H counter), 902 is a vertical sync signal counter (V counter), 903 is an H decoder, 904 is a V decoder, 905 is an AND circuit, and 906 is Output terminal,
Reference numeral 907 is a video signal input terminal, 908 is a video size detection circuit, and 909 is a decode value switching circuit.

The circuit operation will be described below. H counter 9
01 counts the number of clocks input from the clock input terminal 122 starting from the horizontal synchronization signal input from the H synchronization signal input terminal 111. H decoder 903
Decodes the count number output from the H counter 901 and outputs a high level from a certain count value to a certain count value. The decode value of the H decoder 903 can be arbitrarily changed to the decode value set by the decode value switching circuit 909.

The V counter 902 uses the vertical sync signal input from the V sync signal input terminal 112 as a starting point,
The number of clocks is counted using the H synchronization signal input from the H synchronization signal input terminal 111 as a clock. The V decoder 904 decodes the count number output from the V counter 902, and outputs a high level from a certain count value to a certain count value. The decode value of the V counter 902 can be arbitrarily changed to the decode value set by the decode value switching circuit 909.

The AND circuit 905 receives the output of the H decoder 903 and the output of the V decoder 904, and outputs a high level to the output terminal 906 if both of its two inputs are at a high level, and otherwise outputs a low level. Is output.

As described above, the area setting in the horizontal direction of the data detection area is determined by the H decoder 903, and the area setting in the vertical direction is determined by the V decoder 904. In the determined data detection area, that is, while the H decoder and the V decoder are both outputting the high level, the AND circuit 905.
Outputs a high level to the output terminal 906, and outputs a low level outside the data detection area.

The video size detection circuit 908 receives the video signal, the output of the H counter 901, and the output of the V counter 902 from the video signal input terminal 907. For example, as shown in FIG.
The video size is detected from the video signal level in the video size detection range of five places as shown in 2 and output to the decode value switching circuit 909. In FIG. 12, a region A is an upper image size detection range, a region B is a lower image size detection range, a region C is a left image size detection range, a region D is a right image size detection range, and a region S is a center. The video size detection range of is shown.

Next, a concrete example of the video size detecting circuit 908 is shown in FIG. In this video size detection circuit 908,
The image size is detected by detecting the image size at two upper and lower positions (regions A and B) or the image size detection regions at two left and right regions (regions C and D) shown in FIG. The combination of S) is performed. For example, of the video signals in the two upper and lower video size detection ranges, the ratio of the total number of pieces of data having a predetermined brightness level or lower to a predetermined value or less and the video signals in the central video size detection range When the average brightness level is equal to or higher than a predetermined level, it is determined that the image size is such that the upper and lower parts of the screen are black and the center is bright, that is, the upper and lower parts of the screen are black bands. Further, when the video signals in the two upper and lower video size detection ranges and the video signals in the central video size detection range are both lower than a certain brightness level, it is determined that a dark scene is projected on the entire screen, and the normal size is determined. .

In FIG. 13, reference numerals 1, 2 denote input terminals, 3,
5, 7, 9, 11 are H decoders, 4, 6, 8, 10, 1
2 is a V decoder and 13, 14, 15, 16 and 17 are ANs
D circuit, 18, 19, 20, 21, 22 are switches, 2
3 is a luminance signal setting level d, 24 is a luminance signal setting level u, 25, 26, 27, 28 and 29 are comparison circuits, 30,
31, 32, 33, 34 are counters, 35, 36, 3
7, 38 and 39 are counter output circuits, and 40 and 41 are AN
D circuits, 42 and 43 are output terminals.

The circuit operation will be described below. 3, 5, 7,
The H decoders 9 and 11 are connected to the H terminal 9 from the input terminal 1
The output of 01 is input, and the output of the V counter is input from the input terminal 2 to the V decoders of 4, 6, 8, 10, and 12. The output signals of the H decoder 3 and the V decoder 4 are input to the AND circuit 13, and the output signal of the AND circuit 13 (signal A
However, the H decoder 3 and the V decoder 4 are arranged so that a high level is output in the upper video size detection range (area A) among the five video size detection ranges shown in FIG.
The decode value of is set.

Similarly, of the five image size detection ranges shown in FIG. 12, the output signal of the AND circuit 14 (denoted as signal B) by the outputs of the H decoder 5 and the V decoder 6 is the lower image size detection range. In the (region B), the output signal of the AND circuit 15 (referred to as the signal C) by the outputs of the H decoder 7 and the V decoder 8 is in the left image size detection range (region C), and the output signal of the H decoder 9 and the V decoder 10 is A depending on output
The output signal of the ND circuit 16 (referred to as a signal D) is in the right image size detection range (area D), and the output signal of the AND circuit 17 (referred to as a signal S) is at the center due to the outputs of the H decoder 11 and the V decoder 12. The decode value of each decoder is set so as to output a high level in the video size detection range (area S) of.

These decoders 3, 4, 5, 6, 7,
By changing the decoding values of 8, 9, 10, 11, and 12 or by adding or deleting the decoder, the five video size detection ranges shown in FIG. 12 and the number of video size detection ranges can be arbitrarily set. Can be changed to

The switch 18 supplies the video signal input from the input terminal 907 to the comparison circuit 25 only when a high level is input from the output of the AND circuit 13. Similarly, the switches 19, 20, 21 and 22 turn on / off whether or not the video signal from the input terminal 907 is supplied to the comparison circuits 26, 27, 28 and 29.

The comparison circuit 25 outputs a signal to the counter 30 if the brightness level of the video signal input via the switch 18 is lower than the signal output from the brightness signal setting level d23. The counter 30 is a comparison circuit 25
The number of times the signal is output from the counter is counted, and the count value is output to the counter output circuit 35. Counter output circuit 3
5 outputs a high level to the AND circuit 40 when the count value from the counter 30 is a certain value or more. Comparison circuits 26, 27, 28, switches 19, 20, 21, counters 31, 32, 33, counter output circuits 36, 37, 3
8 operates similarly. However, the counter output circuit 3
The outputs of 5 and 36 are sent to the AND circuit 40, and the outputs of the counter output circuits 37 and 38 are sent to the AND circuit 41.

The comparison circuit 29 outputs a signal to the counter 34 if the luminance level of the video signal input via the switch 22 is higher than the signal output from the luminance signal setting level u24. The counter 34 is a comparison circuit 29.
The number of times the signal is output from the counter is counted, and the count value is output to the counter output circuit 39. Counter output circuit 3
9 outputs a high level to the AND circuit 40 and the AND circuit 41 when the count value from the counter 34 is a certain value or more.

When the video size has black bands at the top and bottom of the screen, the AND circuit 40 inputs all to high level and outputs high level to the output terminal 42. Similarly, in the AND circuit 41, when the image size has a black band on the left and right of the screen, all the inputs are at the high level and the output terminal 43 outputs the high level. Under other conditions, a high level is not output to either of the output terminals 42 and 43, and it is determined that the size is normal. Therefore, in this circuit, from the video signal levels in the video size detection ranges of the five locations shown in FIG. 12, the video size has black bands at the top and bottom of the screen, or the video size has black bands at the left and right of the screen. Or
Detects whether the size is normal.

The decode value switching circuit 909 determines the H decoder 903 and the V decoder 904 according to the input screen size detection result supplied from the video size detection circuit 908.
A signal for determining each decode value is output to.

Here, when the video size detection circuit 908 determines that the input screen is a normal size, the data detection area set by the data detection area setting circuit 113 may be the entire video area of the input signal. Considering that the important information area of 1 is near the center of the input image, it is possible to consider a part as shown in FIG. 14 as the data detection area. Further, when it is detected that the screen has a black band at the upper and lower parts, an arbitrary region can be set by the decode value switching circuit 909, for example, the region excluding the black band is set as the data detection region. .

When a black band portion appears at the top, bottom, left or right of the input screen, it is divided into two areas, a black belt portion and a portion other than the black belt, and white and black peaks are detected from the black belt portion, and the black belt portion is detected. It is also possible to detect white peaks, black peaks, and average luminance from regions other than the above, and to separately control the respective regions by the control circuit 121 based on the respective detection data. In this case, the black peak / white peak detection of the black band can detect the black level of the black band and the white level of the subtitle character if there is a subtitle, and prevent black floating in the black band and blooming of the subtitle character. You can

Next, a second embodiment of the present invention will be described.

FIG. 15 is a block diagram showing a second embodiment of the present invention, in which 301, 302 and 303 are differentiating circuits,
The other circuits are the same as those in FIG.

The feature of this embodiment is that the differentiating circuits 301 and 30 are provided.
2, 303 can detect the amount of change in white peak, black peak, and average brightness for each detection time, so white peak, black peak,
When the average luminance changes abruptly, the delay of the response of each control by the control circuit 121 can be improved by applying a larger control set by the detected white peak, black peak, and average luminance, and the performance is further improved. Can be improved.

The differentiating circuits 301, 302, 303 are each composed of a delay element and a subtractor, and the white peak detecting circuit 11
7, black peak detection circuit 118, average luminance detection circuit 119
The output of is differentiated, and the differentiated result is output to the control circuit 121. The control circuit 121 considers the ambient light data and the outputs of the noise detection circuit 116, the white peak detection circuit 117, the black peak detection circuit 118, and the average luminance detection circuit 119 as well as the outputs of the differentiating circuits 301, 302, 303. YN
R circuit 104, contour correction circuit 105, CNR circuit 10
6. Set a control signal for controlling the video chroma circuit 107 and the gamma correction circuit 108. When the detected white peak / black peak / average brightness values are significantly different from the detected values one time before, each differentiator circuit increases the control set by the white peak / black peak / average brightness detected at that time. Call. By doing so, even when the white peak / black peak / average brightness of the screen suddenly changes greatly, the control circuit 1
It is possible to improve the delay of the response of each control by 21.

[0078]

As described above, according to the present invention, there is an effect that the video information is accurately detected from the input video signal and the best video state is always obtained according to the change of the video.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of video control means of the television receiver in the already proposed example.

FIG. 3 is an explanatory diagram showing an example of sampling points by the sampling means of FIG.

FIG. 4 is a block diagram showing a specific example of the white peak detection circuit of FIG.

5 is a block diagram showing a specific example of the black peak detection circuit of FIG.

6 is a block diagram showing a specific example of the average luminance detection circuit of FIG.

FIG. 7 is a flowchart showing a flow of control operation by the control circuit of FIG.

8 is an explanatory diagram showing an example of a bright control method by the control circuit of FIG. 1. FIG.

9 is a block diagram showing a specific example of a gamma correction circuit in FIG.

10 is a characteristic diagram showing an example of a relationship between an input address and output data in the gamma correction circuit of FIG.

11 is a block diagram showing a specific example of a data detection area setting circuit in FIG.

12 is an explanatory diagram showing an example of a video size detection range by the video size detection circuit of FIG.

13 is a block diagram showing a specific example of the video size detection circuit of FIG.

FIG. 14 is an explanatory diagram showing an example of a data detection range by the data detection area setting circuit of FIG.

FIG. 15 is a block diagram showing a second embodiment of the present invention.

[Explanation of symbols]

101 ... Antenna, 102 ... Tuner, 103 ... Video luminance signal color signal separation circuit (Y / C separation circuit), 104 ... Luminance signal noise reduction circuit (YNR circuit), 105 ... Contour correction circuit (ENH circuit), 106 ... Color Signal noise reduction circuit (C
NR circuit), 107 ... Video chroma circuit, 108 ... Gamma correction circuit, 109 ... RGB conversion circuit, 110 ... CRT, 111 ... Horizontal sync signal (H sync signal) input terminal,
112 ... Vertical sync signal (V sync signal) input terminal, 113
Data detection area setting circuit, 114 low pass filter (LPF), 115 clock generation circuit, 116 noise detection circuit, 117 white peak detection circuit, 118 black peak detection circuit, 119 average brightness detection circuit, 120 Ambient light detection circuit, 121 ... Control circuit, 122 ... Clock (CLK) input terminal, 123 ... User setting input terminal.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobufumi Nakagaki Nobufumi Nakagaki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside the Video Media Research Laboratory, Hitachi, Ltd. (72) Shigeru Hirabata Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa 292, Hitachi, Ltd., Video Media Research Laboratory (56) References JP-A-3-19527 (JP, A) JP-A-4-273669 (JP, A) JP-A-4-8068 (JP, A) Kaihei 3-188769 (JP, A) JP 4-127667 (JP, A) JP 4-342373 (JP, A) JP 3-123289 (JP, A) JP 4-215104 ( JP, A) JP-A-4-34594 (JP, A) Actual development: 4-43068 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 5/44

Claims (5)

(57) [Claims] 1. Noise detection means for detecting noise from an input video signal and outputting the detection result as a detection signal, and a luminance signal separated from the video signal are input, and a low frequency component of the luminance signal is input. And a low pass filter whose pass band changes in accordance with the detection signal output from the noise detection means, and a display means for displaying an image on the screen by the video signal, and on the screen. The maximum value of the signal in the portion corresponding to the data detection area set by the data detection area setting means, by inputting the signal output from the low-pass filter To
The white peak detecting means for detecting and the low-pass filter
Input the signal output from the
A section corresponding to the data detection area set by the step
Black peak detector for detecting the minimum value of the signal in minutes
Stage and the signal output from the low-pass filter is input
Before being set by the data detection area setting means
From the signal in the part corresponding to the data detection area
And an average brightness detecting means for detecting the average brightness level.
Made is a feature detection means for outputting a detection result as a detection signal, detects ambient brightness of the television receiver, and the ambient light detecting means for outputting a detection result as a detection signal, controls the video Image control means, controlling the image control means based on the detection signal output from the noise detection means, the detection signal output from the feature detection means, and the detection signal output from the ambient light detection means A control means, wherein the low-pass filter is configured as the pass band.
Independent according to the detection signal output from the noise detection means
Has at least two passbands that change to
The signal that has passed one of the pass bands is
The black peak detecting means passed through the other pass band.
The feature is that each signal is input.
Television receiver. 2. A noise detecting means for detecting noise from an input video signal and outputting the detection result as a detection signal, and a luminance signal separated from the video signal are inputted, and a low frequency component of the luminance signal. And a low pass filter whose pass band changes in accordance with the detection signal output from the noise detection means, and a display means for displaying an image on the screen by the video signal, and on the screen. The maximum value of the signal in the portion corresponding to the data detection area set by the data detection area setting means, by inputting the signal output from the low-pass filter To
The white peak detecting means for detecting and the low-pass filter
Input the signal output from the
A section corresponding to the data detection area set by the step
Black peak detector for detecting the minimum value of the signal in minutes
Stage and the signal output from the low-pass filter is input
Before being set by the data detection area setting means
From the signal in the part corresponding to the data detection area
And an average brightness detecting means for detecting the average brightness level.
Made, the feature detection means for outputting a detection result as a detection signal, a differentiating means for inputting a detection signal output from said character detector, by differentiating the detection signal and outputs as a differential signal, the television Ambient light detection means for detecting the ambient brightness of the image receiver and outputting the detection result as a detection signal, video control means for controlling the video, detection signal output from the noise detection means, and the feature detection based on the detection signal output from said ambient light detecting means detecting signal outputted to the a differential signal outputted from the differentiating means from the means, and control means for controlling said image control means, the low pass The filter has the
Independent according to the detection signal output from the noise detection means
Has at least two passbands that change to
The signal that has passed one of the pass bands is
The black peak detecting means passed through the other pass band.
The feature is that each signal is input.
Television receiver. 3. Noise is detected from an input video signal.
Noise detection that outputs the detection result as a detection signal
Means for inputting the luminance signal separated from the video signal,
The low frequency component of the signal is passed and output, and
Detection signal whose pass band is output from the noise detection means
Low-pass filter that changes depending on the image, and display means for displaying an image on the screen by the image signal
And a video size detecting means for detecting the size of the video.
Of the video detected by the video size detection means
Depending on the size, the data detection area on the screen
Input the signal output from the low-pass filter with the data detection area setting means to be set ,
The data set by the data detection area setting means.
The characteristics of the signal in the portion corresponding to the
And output the detection result as a detection signal.
And the ambient brightness of the television receiver,
Ambient light detection means for outputting a detection result as a detection signal, image control means for controlling the image , detection signal output from the noise detection means, and the characteristics
Detection signal output from detection means and ambient light detection means
Based on the detection signal output from
And a control means for controlling a step, wherein the video size detecting means controls the image on the screen.
Detects whether there is a black band at the top, bottom, left or right of the image,
If there is no black band, the size of the image is the first size.
If there is a black band, it is detected that
The video size is detected as the second size, and the video size detecting means detects the video size as the second size.
If it is detected, the data detection area setting
Means, the data detection area and the black band portion on the screen
The feature detection means is set separately for the video part and the data detection area setting means.
The data set for the black band on the screen
Maximum and minimum of the signal in the part corresponding to the detection area
Value and the data set for the video part on the screen.
The maximum value of the signal in the portion corresponding to the data detection area and
The minimum value and the minimum value are respectively detected, and the control means outputs at least the feature detection means.
Of the applied detection signal, the black band part and the image on the screen are
The maximum and maximum value of the signal detected for each image part
And the minimum value information, the black band on the screen and
Controls the video control means for controlling the video part
A television receiver characterized by being configured as described above. 4. Noise is detected from an input video signal.
Noise detection that outputs the detection result as a detection signal
Means for inputting the luminance signal separated from the video signal,
The low frequency component of the signal is passed and output, and
Detection signal whose pass band is output from the noise detection means
Low-pass filter that changes depending on the image, and display means for displaying an image on the screen by the image signal
And a video size detecting means for detecting the size of the video.
Of the video detected by the video size detection means
Depending on the size, the data detection area on the screen
Input the signal output from the low-pass filter with the data detection area setting means to be set ,
The data set by the data detection area setting means.
The characteristics of the signal in the part corresponding to the
And output the detection result as a detection signal.
Stage , and the detection signal output from the feature detection means is input, and the detection signal is detected.
Differentiating means for differentiating the output signal and outputting it as a differential signal, and detecting the ambient brightness of the television receiver,
Ambient light detection means for outputting a detection result as a detection signal, image control means for controlling the image , detection signal output from the noise detection means, and the characteristics
The detection signal output from the detection means and the detection signal output from the differentiation means
Output from the ambient light detection means and the applied differential signal
A control for controlling the image control means based on the detection signal.
Control means, and the image size detection means is configured to display the image on the screen.
Detects whether there is a black band at the top, bottom, left or right of the image,
If there is no black band, the size of the image is the first size.
If there is a black band, it is detected that
The's detected as the second size, the second site the image size detecting means the video size
If it is detected, the data detection area setting
Means, the data detection area and the black band portion on the screen
The feature detection means is set separately for the video part and the data detection area setting means.
The data set for the black band on the screen
Maximum and minimum of the signal in the part corresponding to the detection area
Value and the data set for the video part on the screen.
The maximum value of the signal in the portion corresponding to the data detection area and
The minimum value and the minimum value are respectively detected, and the control means outputs at least the feature detection means.
Of the applied detection signal, the black band part and the image on the screen are
The maximum and maximum value of the signal detected for each image part
And the minimum value information, the black band on the screen and
Controls the video control means for controlling the video part
A television receiver characterized by being configured as described above. 5. Noise is detected from an input video signal.
Noise detection that outputs the detection result as a detection signal
Means for inputting the luminance signal separated from the video signal,
The low frequency component of the signal is passed and output, and
Detection signal whose pass band is output from the noise detection means
Low-pass filter that changes depending on the image, and display means for displaying an image on the screen by the image signal
And input the signal output from the low pass filter,
White peak detection means for detecting the maximum value of the signal;
Input the signal output from the pass filter and select the maximum
A black peak detecting means for detecting a small value, and the low-pass filter
Input the signal output from the filter and average brightness from the signal
And an average brightness detecting means for detecting the level.
Feature detection means for outputting the detection result of as a detection signal, and detects the ambient brightness of the television receiver,
Ambient light detection means for outputting a detection result as a detection signal, image control means for controlling the image , detection signal output from the noise detection means, and the characteristics
Detection signal output from detection means and ambient light detection means
Based on the detection signal outputted from the movies image control hand
And a control means for controlling a stage, wherein the low-pass filter is the pass band.
Independent according to the detection signal output from the noise detection means
Has at least two passbands that change to
The signal that has passed one of the pass bands is
The black peak detecting means passed through the other pass band.
The feature is that each signal is input.
Television receiver.