JPS60199272A - Profile correcting device of video signal - Google Patents

Abstract

PURPOSE:To avoid an unpleasant screen even when the number of profile correction signals per one vertical synchronizing period is comparatively large by providing a count means receiving the profile correction signal and counting it, an amplitude change means changing the amplitude of the profile correction signal in response to the count output and a synthesis means synthesizing the output of the amplitude change means into a video signal. CONSTITUTION:A voltage controlled gain variable circuit 9 has an input terminal 8a connected to a profile correction signal generating circuit 6, an output terminal 8b connected to an adder circuit 3 and a control terminal 8c. The profile correction signal shown in Fig. B is given to the voltage controlled gain variable circuit 9, where the amplitude is changed and the signal is outputted as an output signal E2 as shown in Fig. J. The gain A of the voltage controlled gain variable circuit 9 is controlled by an output voltage V2 of a control signal generating circuit 10. Further, the gain A of the voltage controlled gain variable circuit 9 is decreased as the output voltage V2 of the control signal generating circuit 10 increases. The signal E2 shown in Fig. J is synthesized with an original video signal S1 at the adder circuit 3 and the video signal S2 subject to profile correction as shown in Fig. K is outputted.

Description

[Detailed description of the invention] [FA Ming's technical field] The present invention relates to an improvement in a contour correction device for a video signal.

[Prior Art] FIG. 1 does not show a conventional image signal contour correction device. In the figure, the original v4Il signal S1 from the video signal $11 is
The signal is applied to one input of the adder circuit 3 via the amplifier circuit 2 as required. This original @image signal S1 is also given to the contour correction signal generation circuit 6.

The contour correction signal generation circuit r86G consists of two differentiating circuits 4 and 5 connected in series. Differential mouth w14 is cool taste I
Differentiate the component in ms + period of I Shintan S1, and use the differentiator circuit 5.
differentiates its output again. Therefore, the contour correction signal @E1, which is the output of the contour correction signal generation circuit 6, is the second-order differential of the component during the video period of the cool taste image signal @S1. The contour correction signal E1 is applied to the other input of the adding circuit 3, and is combined with the original video signal S1 applied from the other input. In this way, the adding circuit 3 outputs the contour-corrected video signal @S2.

Next, with reference to the waveform diagram of FIG. 2, the operation of the conventional 1iiiI shown in FIG. W41 will be explained. It is now assumed that the original video signal S1 from the video signal source 1 is obtained as a pulse wave in each horizontal synchronization interval, as shown in FIG. 2A. In this case, the contour correction signal E1 obtained from the contour correction signal generation circuit 6 is obtained as a second-order differential wave at the rising and falling positions of the original video signal S1, which is a pulse wave, as shown in FIG. 2B. It will be done.

The original video signal 81 (waveform A) and the contour correction signal El (waveform B) G are combined in the adder circuit 3, and the second
A video signal S2 whose waveform is contour-corrected as shown in FIG. C is obtained. As is clear from FIG. 2C, the contour-corrected video signal S2 is the original video signal S1 which is a pulse wave.
The second-order differential waves are synthesized at the rising and falling positions of .

If m images are obtained on a display device (not shown) using the contour-corrected video signal S2 obtained in this way, the contours of the m images will be the original! ! ! l! The image becomes clearer than the case where the image signal S1 is used as is and the image is of the stomach.

However, in such conventional devices, the original video signal S
Depending on the contents of item 1, performing contour correction may actually make the screen harder to see.

This is especially true for the 1f! This is noticeable when the number of direct synchronization zones is relatively large. In that case, the screen on the display device obtained using the contour-corrected video signal S2 becomes so-called "stirly" and becomes difficult to see.

[Summary of the Invention] Therefore, an object of the present invention is to provide a video signal contour correction device that eliminates the drawbacks of the conventional device as described above and does not make the screen difficult to view due to contour correction. be.

The contour correction @1 of a video signal according to the present invention includes contour correction signal generation means for receiving a video signal and generating a contour correction signal for contour correction of the video signal. The contour correction signal generated by the contour correction signal generating means is counted, and the amplitude of the contour correction signal is changed in response to the count output signal. The amplitude-changed signal is combined with the #-multiplied signal, thereby producing a video signal subjected to contour correction according to the present invention.

1 Embodiment of the invention] FIG. 3 shows contour correction of a video signal [111
FIG. 2 is a block diagram showing a preferred embodiment of No. 2;

The same parts as in the wi figure are given the same reference numerals, and their explanation will be omitted. The conventional device shown in Fig. 1 and its development,
The image signal contour correction apparatus according to the present invention includes a voltage-controlled variable gain circuit 9 between the contour correction signal generation circuit 6 and the addition circuit 13. The voltage-controlled variable gain circuit 9 has an input terminal 8a connected to the contour correction signal generation circuit 6, an output terminal 8b connected to the addition circuit 3, and a limiter 8C. A control signal generation circuit 10 is connected between the contour correction signal generation circuit 6 and the control t11 terminal 8C, which receives the contour correction 1g signal E1 and provides an output signal v2 for controlling the voltage-controlled variable gain circuit 9 1iilJ. has been done.

11JIJ-signal generation circuit 1o is configured as follows. That is, the contour correction signal E1, which is a binary differential wave of the original video signal S1, is given to the detection circuit 11, and among the pulses included in the contour correction signal E1, for example, only positive polarity pulses are detected. . The pulse P1 detected by the detection circuit 11 is sent to the counting pulse generation circuit 1.
2, is shaped, and is output as a counting pulse P2. The counting pulse P2 is counted by the counting circuit 15. The counting circuit 15 converts the N-bit binary numbers PC1, PO2, . . . PCN into the D, /A converter 1
6 as a count output. The counting circuit 15 receives the reset pulse P3 from the reset pulse generation circuit 13.
will be reset to zero.

The digital values of the binary numbers PC1, PO2, . The analog value ■1 is given to the sample and hold circuit 18. The sample hold circuit 18 samples the analog value ■1 at the time when the sampling pulse P5 from the sampling pulse generation circuit 17 is input, and continues to output the value V2 until the next sampling pulse P5 is input. . Reset pulse generation circuit 1
3 and the sampling pulse generation circuit 17 receive the vertical synchronizing pulse P4, so that the reset pulse P3 and the sampling pulse P5 are synchronized with the vertical synchronizing pulse P4. Vertical synchronization pulse P4 is II
It is given from a vertical synchronization pulse generation circuit 14 provided separately from the IJ@l signal generation circuit 10. The vertical synchronization pulse generation circuit 14 is configured to provide a vertical synchronization pulse P4 synchronized with the vertical synchronization of the original video signal $1. The output of the sample and hold circuit 18 (that is, the control signal generation circuit 10
The output) V2 is applied to the control terminal 8C of the voltage controlled variable gain circuit 9.

FIG. 4 is a waveform diagram for explaining the operation of contour correction of a video signal according to a preferred embodiment of the present invention shown in FIG. The operation of the *embodiment shown in FIG. 3 will be described below with reference to FIG. 4. For the sake of explanation, as shown in FIG. 4, attention will be paid to one vertical synchronization period of the original video signal S1 obtained from the video signal source 1, and further attention will be paid to one horizontal synchronization period within this vertical synchronization period.

j@4 As shown in FIG. 8, if the original video signal S1 includes N pulses in one horizontal period, the contour correction signal E1 returned by the contour correction signal generation circuit 6 is
As shown in FIG. B, the horizontal synchronization period includes 2N pulse phases of positive polarity and negative polarity. This contour correction signal E1 is given to the detection circuit 11 in the control signal generation circuit 10, and the detection circuit 11 outputs a positive polarity pulse P1 of 2Nm in the horizontal synchronization period, as shown in FIG. Output. These 2N positive pulses P
'I is shaped in the counting pulse generation circuit 12 to become the counting pulse 2 as shown in FIG. 4 C2.

The vertical synchronization pulse generation circuit 14 outputs a negative polarity pulse P4 synchronized with the vertical synchronization of the original video signal 81 to FIG. 4, as shown in the fourth diagram.

This pulse P4 is applied to the reset pulse generation circuit 13 and the sampling pulse generation circuit 17, and in response, the reset pulse P3 and the sampling pulse P5 shown in FIGS. 4E and F are output, respectively. Three pulses P3, P4. The timing of P5 is t 1. in FIG. 4G. t2. t3.
t4. t 5. and t6, and their relationship is as shown in the following equation.

t 1 < t 2 < t 3 < t 4 < t 5 < t 6th 4th
FIG. H shows the output 1 of the D/All converter 16. It can be seen that this output (1) is reset to zero in response to the reset pulse P3 shown in FIG. 4E. FIG. 4I shows the output v2 of the sample and hold circuit 18. It can be seen that this output V2 is obtained by sampling the output (1) of the D/A converter 16 in response to the sampling pulse P5.

The contour correction signal E 1 G,t shown in FIG. 4 is applied to the voltage-controlled variable gain circuit 9 to change its amplitude, and is outputted as an output signal @E2 as shown in FIG. 4J. When the amplitude of the contour correction signal E1 is VEl and the amplitude of the output signal E2 of the voltage-controlled variable gain circuit 9 is VE2, the gain A of the voltage-controlled variable gain circuit 9 is expressed as A-VE2/VEI.

The gain A of the voltage controlled variable gain circuit 9 is I11! IIl
*Jmj5 is given by the output voltage v2 of the signal generation circuit 10.

Figure 5 is l! Output voltage v of IJIIl signal generation circuit 10
2 and the gain of the voltage controlled variable gain circuit 9 is 1! It is a graph showing a preferable relationship of A. As shown in FIG. 5, the gain Δ of the voltage-controlled variable gain circuit 9 is
It is made to decrease as the output voltage v2 of 0 increases. In Figure 5, profit is 1! A and voltage v2
Although the relationship is shown as being inversely proportional, this relationship may be suitably varied to obtain the desired properties.

The signal E2 in FIG.
As a result, the adder circuit 3 outputs the contour-corrected video signal S2 shown in FIG. 4K.

According to the above operation, the pulse P1 shown in FIG.
If the number per vertical sync area increases, the clip will increase in proportion to it! EC also becomes larger. On the contrary, if the number of pulses P1 per vertical synchronization section becomes smaller, the clip width EC also becomes smaller in proportion to it. In this way, since the clip width EC changes in proportion to the number of pulses P1 per vertical synchronization section, the contour correction signal (signal E2>) with excellent clipping is the contour correction signal E before clipping.
1, the signal is almost constant. Therefore, it will be understood that the video signal S2 shown in FIG. 4K, which has been subjected to the contour correction according to the present invention, has always undergone appropriate contour correction.

In the above-described embodiment, the output of the contour correction signal generation circuit 6 is directly given to the detection circuit 11, but a clip circuit or an amplitude discrimination circuit is provided between the two, so that only pulses having a certain amplitude or more are sent to the detection circuit 11. 11. In this case as well, the same effects as in the above-mentioned embodiment can be achieved.

Further, a delay circuit may be inserted between the amplifier circuit 2 and the adder circuit 3, thereby making it possible to perform more appropriate contour correction. The delay may be, for example, one vertical synchronization period.

[Effects of the Invention] As described above, according to the present invention, even when the number of contour correction signals per vertical synchronization section is relatively large,
The effect is obtained that the screen obtained by the contour-corrected video signal does not become difficult to read.

[Brief explanation of drawings]

Figure 1 is the conventional movie II! FIG. 2 is a waveform diagram for explaining the operation of the conventional 11fil shown in FIG. 1, and FIG. 3 is a block diagram showing the outline correction device of 1@. 4 is a waveform diagram for explaining the dynamic IT of a preferred embodiment of the present invention shown in FIG. 3; FIG. 5 is a gain characteristic of the voltage controlled gain variable circuit 9. This is a graph showing. In the figure, 1 is a video signal source, 2 is an amplifier circuit, 3 is an adder circuit, 4 and 5 are differentiating circuits, 6 is a contour correction signal generation circuit, 9 is a voltage 11J11j type gain variable circuit, 10 is 11
The reference numeral 14 indicates four vertical synchronization pulse generation circuits. First FI! J Figure 2 + 4 Zhiyuan-ku; : -4!艮; A--111 old old once-←- ::: 5-T--111 moss one ha←→→←to: M Hill-Prefecture::: . 2 Upper Clothes and 1 Box-4-l, I:.・Moto---→"I ・-Atsushi 11" 4Kami 11112Kori 1:1... :II l+jlu, , . Figure 5 Showa Year, Month, Day 21 Name of the invention Video signal contour correction device 3, relationship with the person making the correction Case Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name Name
(601) Mitsubishi Electric Corporation Representative Hitoshi Katayama 4, Agent Address 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo, Claims column of the specification to be amended and detailed description of the invention No. 6, Contents of amendment (1) The scope of claims in the specification is amended as shown in the attached sheet. (2) The expression “increases in proportion to that” in lines 19 and 20 of page 12 of the specification means that the gain A of the voltage barrel type variable gain circuit 9 is inversely proportional to that number. becomes smaller. ”. (3) [Proportional to...] on page 13, line 1 of the specification
``Therefore,'' in line 7 of the same page is changed to ``gain A increases in inverse proportion to the number.'' In this way, the gain A changes in inverse proportion to the number of pulses P1 per vertical phase interval, so it is corrected as follows. 2 above, Claim (1) An apparatus for performing contour correction of a video signal, comprising: 11! a contour correction signal generating means for receiving an image signal and generating a contour correction signal for contour correction; a counting means for receiving and counting the contour correction signal; and a count means for receiving the contour correction signal and counting the contour correction signal. A contour correction device for a video signal, comprising: amplitude changing means for changing the amplitude of the contour correction signal in response to a count output; and combining means for combining the output of the amplitude changing means with the video signal. (2) The contour correction device for a video signal according to claim 1, wherein the amplitude changing means decreases the amplitude of the contour correction signal when the count output of the counting means increases. (3) The video signal contour correction device according to claim 1, wherein the counting means counts every vertical synchronization section of the video signal. (4) The contour correction signal generating means includes a differentiation circuit for differentiating the video signal (a contour correction device for a video signal according to claim 1). A contour correction device for a video signal according to claim 4, which includes a dividing circuit. (6) The output of the differentiating circuit includes pulses of positive and negative polarity, and the counting means includes pulses of positive and negative polarity. A contour correction side L of a video signal according to claim 4, wherein only one polarity of the pulses is counted. A contour correction side L(8) of the video signal according to claim 6, wherein the counting means includes a detection circuit for selecting the one-polarity pulse. 12. The image signal contour correction device according to claim 11, wherein the video signal contour correction device counts only those signals having an amplitude equal to or higher than a predetermined constant amplitude. (9) Only contour correction signals having an amplitude equal to or higher than the predetermined constant amplitude are counted. 9. The video signal contour correction device according to claim 8, wherein the counting means includes an amplitude discrimination circuit for discriminating the amplitude of the contour correction signal. 11. The video signal contour correction device according to claim 1, further comprising a delay means for delaying the No. 11 signal, and the output of the color means is combined with the No. 11 signal delayed by the delay means. f.

Claims (1)

[Scope of Claims] (1) An apparatus for performing contour correction of a video signal, comprising contour correction signal generation means for receiving the fIJ MIS signal and generating a contour correction signal for contour correction; counting means for receiving and counting the contour correction signal; amplitude changing means for receiving the contour correction signal and changing the amplitude of the contour correction signal in response to the count output of the counting means; and the amplitude carbonizing means. 2. A contour correction device for a IIi image signal, comprising: combining means for combining an output with the video signal. (2) The amplitude changing means is configured to reduce the amplitude of the contour correction signal when the count output of the counting means becomes larger. The video signal contour correction device according to item 1. (3) The image signal 1 @ contour correction device according to claim 11111, wherein the counting means counts every vertical synchronization section of the video signal. (4) The contour correction device according to claim 1, wherein the contour correction signal generation means includes a differentiation circuit that differentiates the video signal. (5) The differentiation circuit is a quadratic 1! An image contour correction device according to claim 4, comprising an image dividing circuit. (6) The output of the differentiating circuit includes positive and angular physical pulses, and the counting means [Yo, the The contour correction side L of the video signal according to claim 4, wherein only one polarity of pulses of positive and negative polarity is counted. The counting means configured to count only the - impulse pulses includes a detection circuit for selecting the impulse pulses, and the image signal contour correction IL(8) lll[I The contour correction device for a video signal according to claim 1, wherein the counting means counts only those of the contour correction signals that are equal to or larger than a predetermined certain amplitude. The Callan 1 means is configured to count only contour correction signals having a predetermined amplitude or more.
9. The image signal contour correction apparatus according to claim 8, further comprising an amplitude discrimination circuit for discriminating the amplitude of the contour correction signal. (10) The synthesis means includes a delay means for delaying the contour correction signal, and the output of the counting means is synthesized with the contour correction signal delayed by the delay means. The S-image signal contour correction device described above.