JPS61285872A - Vertical outline emphasizing circuit for television receiver - Google Patents

Abstract

PURPOSE:To emphasize the vertical outline part of the picture without increasing or decreasing the luminance level by providing the change-over means to select the second video signal when the vertical outline position is not detected. CONSTITUTION:When a video signal 102 is inputted, a video signal 109 is obtained which is the output of one horizontal period delaying circuit 103. Further, when the video signal 109 is delayed by one horizontal period delaying circuit 104, a video signal 110 is obtained. These video signals 102, 109 and 110 are respectively in order inputted to coefficient multipliers 105, 106 and 107, multiplied by -1/4 times, +1/2 times and -1/4 times, inputted to an adder 108 and added, and then, a vertical outline detecting signal 116 detected the vertical outline position in the video signal 109 is obtained. After the signal 116 is made to be an absolute value, the signal is compared with a special constant value level 113 in a comparator 112. Then, the signal is obtained which comes to be an 'H' level only at the vertical outline position. The output of a change-over circuit 114 comes to be a vertical outline emphasizing signal 115.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a vertical contour emphasizing circuit for enhancing the sharpness of an image by emphasizing the vertical contour portion of an image in a television receiver.

[Background of the invention]

As a means of obtaining high sharpness for color television images, there is a vertical contour enhancement circuit that emphasizes the vertical contour portion of the image by brisseat and overshoot, as shown in Japanese Patent Laid-Open No. 59-25973, for example. Widely used.

The vertical contour enhancement of an image according to such a conventional technique will be explained with reference to FIG.

FIG. 2 is a diagram 1012 showing a conventional vertical contour enhancement circuit. In FIG. 2, 201 is a vertical contour signal generation circuit;
02 is a video signal, 203, 204 is a coefficient unit that multiplies by 10, 207 is a coefficient book that multiplies by 11, 208 is an adder,
209 is a vertical contour correction signal, 210 is a delay compensation circuit that compensates for the delay amount of the vertical contour signal generation circuit 201, and 211
is an adder, and 212 is a vertical edge emphasis signal.

The operation of the circuit shown in FIG. 2 will be explained. First, as the video signal 202, consider an image obtained by converting an image as shown in FIG. 3(α) into a video signal. This signal has high brightness at the center of the screen and low brightness at the top and bottom edges. In FIG. 3 (α), the shaded area is a portion with a luminance gradient, and FIG.

As shown in FIG. 3(α)K, at the upper end of the screen, the brightness changes from low to high in the vertical direction of the screen, while at the bottom end of the screen, the brightness changes from high to low in the vertical direction of the screen. The state of the video signal 202 at the upper end of the screen is shown in Figure 4 (
α) and the state of the video signal 202 at the bottom edge of the screen are shown in FIG. 4 1b).

Now, as shown in FIG. 2, such a video signal 202 is input into two parts, one to the vertical contour signal generation circuit 201 and the other to the delay compensation circuit 210.

In the vertical contour signal generation circuit 201, the input video signal 202 is delayed by one horizontal period by delay circuits 205 and 204, and is also delayed by one horizontal period by a coefficient multiplier 205.
07K, both the input video signal and the delayed video signal are multiplied by 10 or -7 times, input to the adder 208, and then outputted as the vertical contour correction signal 209.

Furthermore, in the delay compensation circuit 210, the input video signal 20
2 is delayed by one horizontal period and output.

Now, for convenience of explanation, the waveforms of the output of the delay compensation circuit 210 will be explained below using FIGS. 4(α) and (A). Therefore, the signal obtained by advancing the waveform shown in FIG. 4 (αl, (b) by one horizontal period) is the consideration signal 202. In this way, the waveform of the consideration signal 202 is as shown in FIG. 4 (α).

Assuming that the waveform shown in ill is a waveform obtained by advancing one horizontal period, the waveform of the vertical contour correction signal 209, which is the output signal, is changed to the waveform shown in FIG. 4 (α) due to the operation of the vertical contour signal generation circuit 201 described above. For the waveform shown in Figure 4 (C1), and for the waveform shown in Figure 4 (1b1), the waveform shown in Figure 4 (d
The waveform is as shown in >.

Next, the output from the delay compensation circuit 210 and the vertical contour emphasizing signal g209 are each input to an adder 211, where they are added together and output as a vertical contour emphasizing signal 212. That is, when these signals are added by the adder 211, the signals shown in FIG.
A vertical edge emphasis signal 212 as shown in gl is obtained, and undershoot occurs in the portion where the brightness increases from low brightness, and overshoot occurs in the portion where the brightness increases from a slope to a constant high brightness. On the other hand, Fig. 4 1b1,
(For the di signal, a vertical edge emphasis signal 212 as shown in FIG. 4 J1 is obtained, and an overshoot occurs in the part where the brightness starts to decrease from a certain high brightness, and the brightness gradually decreases. Undershoot occurs in areas where the brightness is a certain level.This situation is shown on the screen as shown in Figure 5 (
α). In this way, conventionally, overshading and undersea color occur in the vertical contours of an image, resulting in changes in brightness as shown in FIG. 5, 1bI, and thereby emphasizing the image. In vertical contour enhancement of an image using such a conventional vertical contour enhancement circuit, the contour is visually clear and good for obtaining high sharpness, but the brightness is changed and the brightness level is Since it increases or decreases more than shown, there are disadvantages such as (1) bluing tends to occur and (2) the beam spot tends to become thicker.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a high-frequency emphasis circuit capable of emphasizing vertical contours of an image without increasing or decreasing the brightness level in a television receiver. There is a particular thing.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention includes a plurality of delay means each delaying a video signal by an integral multiple of one horizontal period, and a first delay means among the delay means. vertical contour detection means for detecting the vertical contour position of the image in the first video signal delayed by the luminance signal; and the first video signal delayed by the first delay means and other delay means. switching means for switching and outputting a delayed second video signal, and selecting and detecting the second video signal when the vertical contour means is not detecting a vertical contour position. By switching the switching means so as to select the first video signal when the image is displayed, a video signal in which the vertical contour portion of the image is emphasized is output.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

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

In FIG. 1, 101 is a vertical contour detection circuit, 102 is a video signal, 105, 104 is a coefficient unit that multiplies the delay by 1 horizontal period by 10, 107 is a coefficient unit that multiplies 17 times, 108 is an adder, and 109 is a video signal. A video signal obtained by delaying the signal 102 by one horizontal period, 110 a video signal obtained by delaying the video signal 102 by two horizontal periods, 111 an absolute value circuit that takes the absolute value of the output from the adder 108, and 112 a signal from the absolute value circuit 111. A comparison circuit that compares the output with a constant value 113, 114 a switching circuit that switches between the video signals 109 and 110 using the output of the comparison circuit 113, 115 a vertical contour emphasis signal that is the output of the switching circuit 114, 116 a vertical contour detection signal, It is.

Next, the operation of the embodiment shown in FIG. 1 will be explained using FIGS. 6 and 7.

As the video signal 102, as explained in the conventional example,
@3 Consider an image that is converted into a video signal as shown in Figure (α).

Therefore, first, a case where the brightness gradually increases from a low brightness as shown above in FIG. 3(α) will be described. That is, as the video signal 102, a signal waveform as shown in FIG. 6 (α1) is manually input.
2, the signal waveform shown in FIG. 6(b) is obtained as the video signal 109 which is the output of the one horizontal period delay circuit 105. Furthermore, this video signal 109 is
When delayed by the horizontal period delay circuit 104, a waveform as shown in FIG. 6 FCI can be obtained as the video signal 110. These video signals 102, 109.

110 respectively in order as coefficient multipliers 105, 106 and 107.
manually, multiply by -1, 10-, and -7, and then use adder 1.
As shown in FIG. After converting to an absolute value and removing the sign, the comparator 112 compares the specific constant value level 113, and as a result of the comparison, it is possible to obtain a signal that becomes 1HI level only at the vertical contour position.This comparator The output from 112 is switched and inputted to switching circuit 114. In switching circuit 114, comparator 1
When the output from 12 is at the IHI level, the video signal 109 is selected and output, and when it is at the LL1 level, the video signal 110 is selected and output. Then, the output of the switching circuit 114 has a waveform as shown in FIG. It is possible to make the vertical contour part of the image more steep, thereby emphasizing it.The above is an explanation of the case where the brightness gradually increases from low brightness as shown in the upper part of Fig. 3 (α).Furthermore, A case where the brightness gradually decreases from high brightness as shown in the upper part of FIG. 3 (α) will be described.

That is, this time, the (IT waveform) shown in FIG. 7 (α) is input as the video signal 102.
2 is input, the video signal 109 which is the output of the 1-horizontal period delay circuit 103 has the waveform shown in FIG. When connected to 104, video signal 1
10, a waveform as shown in FIG. 7(C) is obtained.

When these video signals 102, 109, and 110 are manually multiplied by coefficients 105, 106, and 107, respectively, and the respective outputs are added by an adder 108, a vertical contour detection signal as shown in FIG. 7(d) is obtained. 116 can be obtained.

Then, this vertical contour detection signal 116 is sent to the absolute value circuit 11.
After converting it to an absolute value with 1 and removing the sign, the comparator 112 converts it to a specific constant value and compares it with the pel 113. As mentioned above, the signal output from the comparator 112 becomes LH+ level only at the vertical contour position. This becomes a signal and is manually input to the switching circuit 114.

As described above, the switching circuit 114 selects and outputs the video signal 109 when the output from the comparator 112 is at 1H level, and selects and outputs the video signal 110 when it is at the 1L1 level, so the switching circuit 114 selects and outputs the video signal 109. The vertical contour emphasis signal 115 obtained has a waveform as shown in FIG. 7+g1. That is, in this case as well, it is possible to obtain a signal with a reduced brightness level transition region as the vertical contour emphasizing signal 115, and it is possible to emphasize the vertical contour portion of the image.

The wJs diagram (α) is an explanatory diagram schematically showing an image when the present invention is implemented. As you can see by comparing it with Figure 3 (α), the transient region of the brightness level has been reduced.
It can be seen that the vertical contour part is more emphasized. In addition, the brightness level is 1.6 in Figure 3 as shown in Figure 8 (bl).
It can be seen that there is no need to worry about pushing, since it does not increase or decrease beyond the values shown in . Furthermore, the beam spot size does not become large.

〔Effect of the invention〕

According to the present invention, the vertical ring portion of the image can be emphasized without increasing or decreasing the brightness level, thereby eliminating the blueing caused by increasing or decreasing the brightness level, which is a drawback of the prior art. This has the effect of achieving good sharpness improvement.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a conventional vertical contour enhancement circuit, and FIG. 3 (α
) is an explanatory diagram schematically showing the image before vertical contour enhancement, Figure 8g3 (b) is a graph showing the vertical brightness of the image, and Figure 4 shows the main signal waveform of Figure 2. Waveform diagram, Fig. 5 1eLl is an explanatory diagram schematically showing an image after vertical contour enhancement by conventional technology, Fig. 5 (side) is a graph showing the vertical brightness of the image, Fig. 6 and FIG. 7 are waveform diagrams showing the main signal waveforms of FIG. 1, and FIG.
I) is an explanatory diagram schematically showing an image after vertical contour enhancement according to the present invention, and FIG. 8 (bl is a graph showing the vertical brightness of the image) 6101... Vertical contour detection Circuit 102...Video signal 105, 104...1 horizontal period delay circuit 105,
106, 107...Coefficient unit 108...Adder
111... Absolute value circuit 112... Comparator
114...Switching circuit 115...Vertical contour emphasizing signal No. 1 (IL) (b) $4 (eJ u5)

Claims (1)

[Claims] 1) A plurality of delay means each delaying a video signal by an integer multiple of one horizontal period, and a vertical contour position of an image in the first video signal delayed by the first delay means of the delay means. vertical contour detection means for detecting from a luminance signal; a first video signal delayed by the first delay means; and a second video signal delayed by other delay means.
switching means for switching between and outputting a video signal, and selecting the second video signal when the vertical contour means is not detecting the vertical contour position, and selecting the second video signal when the vertical contour means is detecting the vertical contour position; A vertical contour emphasizing circuit for a television receiver, characterized in that the switching means is switched to select a video signal, thereby outputting a video signal in which a vertical contour portion of an image is emphasized.