JPH04102375U - Contour correction circuit - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce unnecessary white spots that occur on the screen by contour correction. [Structure] A black side signal limiting circuit 3 is inserted between the vertical contour correction signal forming circuit 2 and the addition circuit 4 of the contour correction circuit 1 to limit the black side correction level during vertical contour correction. By inputting the signal to the horizontal contour correction circuit 5, it is possible to relatively reduce the brightness of unnecessary white spots that occur during horizontal contour correction.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a contour correction circuit in a television receiver or the like.

0002

[Conventional technology]

Contouring is one of the ways to increase the resolution of images on television receivers, etc. It is known that correction circuits can be used. FIG. 3 is a block diagram showing an example of a conventional contour correction circuit. , a vertical contour correction signal forming circuit that inputs the video signal S1 and corrects the contour in the vertical direction. 22, the output signal S11 of this vertical contour correction signal forming circuit 22, and the video signal S An adder circuit 23 that adds 1 and a water The horizontal contour correction circuit 24 corrects the contour in the square direction.

0003 FIG. 4 is an explanatory diagram of the operation of this contour correction circuit 21, as shown in FIG. 4(a) as an example. Explanation using a screen 27 with a white quadrilateral 26 filled with white on a black background 25 placed in the center. do. Of course, it goes without saying that any shape or color can be used as the screen. Nor. The purpose of the contour correction circuit 21 is to clarify the contour of this white quadrilateral 26. There are many things.

0004 For example, when performing contour correction on the black background 25 and the white quadrilateral 26 in the vertical direction 28, To explain the case, the output signal S11 of the vertical contour correction signal forming circuit 22 The waveform becomes as shown in the same figure (b). That is, the upper and lower two rings of the white quadrilateral 26 Correction signals are formed at the contour points 28u and 28v, and outside the white quadrilateral 26, becomes even blacker, and becomes even whiter inside the white quadrilateral 26. Emphasize white and black. Generally, the level of this correction is the same for both the white side and the black side. Next, this signal S11 is added to the video signal S1 in the adding circuit 23, and the signal S11 is added to the video signal S1 in the adding circuit 23 ( The corrected vertical video signal S12 is shown in waveform c). This vertical video signal S12 is further input to the horizontal contour correction circuit 24 to form contour points 29u, 29u in the horizontal direction 29, After the contour is corrected at 29V, the waveform is output and has the waveform shown in FIG. in this way The difference between black and white is strong at the contour points 28u, 28v and 29u, 29v. The contours become clearer as the edges are adjusted. Screen 2 in vertical and horizontal directions like this 7. Contour correction is performed over the entire area.

[0005]

[Problem that the idea aims to solve]

FIG. 5 is an explanatory diagram of the operation of the contour correction circuit 21 near the contour portion. FIG. 4A is an enlarged view of the white quadrilateral 26 on the screen 27. FIG. ABC in the same figure The quadrilateral surrounded by D corresponds to the white quadrilateral 26, and the line ABCD is connected to this quadrilateral 2. This corresponds to the contour line of 6. Also, the part sandwiched between ABCD and EFGH is highlighted in white. Corresponding to the part to be corrected, the part sandwiched between ABCD and IJKL is corrected in black. This corresponds to the part that is This will be explained by taking the quadrilateral MNBA as an example. This MNBA is a vertical contour correction signal This is the part where the black color is corrected by the shaping circuit 22. On the other hand, IMAP and NJQB The background color is black and will not be corrected. Therefore, this MNBA is It is even darker than NJQB.

[0006] First, the above IJQP section when only vertical contour correction is performed and horizontal contour correction is not performed. The waveform during horizontal scanning is as shown in FIG. 4(b). On the other hand, the horizontal contour correction circuit 24 The waveform of the IJQP portion subjected to the horizontal contour correction is shown in FIG. That is, In addition to the horizontal correction signal level (white side W and black side X2) in the figure, the MNQP section further A black video signal level (black side) X1 is added. This W and X2 are added What is created is that MP and NB in the figure are new outlines, that is, circles between black and darker black. This is because it becomes a contour line. Furthermore, since X1 is added to the black side, this MP and NB part The difference between white and black is +W on the white side and -(X1+X2) on the black side. The difference in color becomes even larger. In other words, a signal level of X1 is added to this black side. Therefore, +W on the white side becomes a relatively whiter white dot and appears on the black background 25. It will be done. However, this white point is originally unnecessary, and as a result, the white point appears on the screen 27. This will produce white points outside the four corners of the color quadrilateral 26. This white color stands out. In order to avoid this, the level of X1 on the black side can be lowered.

[0007]

[Means to solve the problem]

In order to solve the above problems, the present invention has developed a vertical contour correction method for correcting the vertical contour of a video signal. A straight contour correction signal forming circuit, an output signal of this vertical contour correction signal forming circuit, and the image an adder circuit that adds the image signal and the vertical ring output from the adder circuit; By using a horizontal contour correction circuit that corrects the horizontal contour of the video signal whose contour has been corrected. The contour correction circuit configured includes the vertical contour correction signal forming circuit and the addition circuit. A record of the black side output signal of the output signals of the vertical contour correction signal forming circuit is connected between the The present invention is characterized in that a black side signal limiting circuit is provided to limit the signal.

[0008]

[Effect]

Of the white side correction signal and black side correction signal formed by the vertical contour correction signal forming circuit, The magnitude of the black side correction signal is limited by a black side signal limiting circuit. By doing this, the ring For black points, the level of correction is lower for black than for white. The black side signal system The output signal of the limiter circuit is added to the video signal in the adder circuit to produce a vertically corrected video image. become. Furthermore, this vertically corrected video signal is input to a horizontal contour correction circuit. The resulting video signal has its vertical and horizontal contours corrected.

[0009]

【Example】

FIG. 1 is a configuration diagram of an example of a contour correction circuit according to the present invention. In addition, the same part as the conventional example The same numbers will be given to the minutes, and the explanation thereof will be omitted. Contour correction circuit according to the present invention 1 is a vertical contour correction signal formation that inputs the video signal S1 and corrects the contour in the vertical direction. circuit 2 and the black side correction signal of the output signal S2 of this vertical contour correction signal forming circuit 2. A black side signal limiting circuit 3 that limits the magnitude of the black side signal limiting circuit 3 and an output signal S of this black side signal limiting circuit. 3 and the video signal S1, and an output signal S of this addition circuit 4. 4, and a horizontal contour correction circuit 5 for correcting the contour in the horizontal direction.

0010 FIG. 2 is an explanatory diagram of the operation of the contour correction circuit 1. In addition, the same screen 27 as the conventional example However, it is possible to use any screen other than this screen 27. Needless to say. In the figure, (a) shows the waveform of the output signal S2, where the outline point is on the white side. A correction signal of signal level X is generated on the black side and the black side, respectively. On the other hand, the figure (b) shows the above The waveform of the output signal S3 is shown, and the signal level X of the white side correction signal does not change. , the level of the black side correction signal X is limited to Y. The same figure (c) shows the above output. The waveform of signal S4 is shown, and the correction signal on the black side is limited to Y as in the same figure (b). Ru.

[0011] That is, by reducing the magnitude of the correction signal on the black side, the white quadrilateral 26 Reduce the difference between the black IMAP and NJQB corner ground colors and the darker black MNBA after correction. When correcting the horizontal contour of this area, the amount of correction on the white side and the amount of correction on the black side can be It is possible to reduce the difference between Therefore, on the screen, four of the white quadrilaterals 26 The brightness of white spots that appear outside the two corners can be relatively reduced.

0012 The reason why we focused on the black side correction signal of the vertical contour correction signal forming circuit 2 is as follows. In general, the vertical contour correction effect is mainly determined by the white side correction signal on the screen. Therefore, even if the level of the correction signal on the black side is limited, there is little effect on the contour correction effect. This is for a good reason.

[0013]

[Effect of the idea]

The level of the black side correction signal of the vertical contour correction signal forming circuit has been reduced, so the Unnecessary white brightness that occurs can be relatively reduced.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an example of a contour correction circuit according to the present invention.

FIG. 2 is an explanatory diagram of the operation of the contour correction circuit.

FIG. 3 is a configuration diagram showing an example of a conventional contour correction circuit.

FIG. 4 is an explanatory diagram of the operation of the contour correction circuit.

FIG. 5 is an explanatory diagram of the operation near the contour portion of the contour correction circuit.

[Explanation of symbols]

1... Contour correction circuit, 2... Vertical contour correction signal forming circuit, 3
...black side signal limiting circuit, 4...addition circuit, 5...horizontal contour correction circuit.

Claims (1)

[Scope of utility model registration request] 1. A vertical contour correction signal forming circuit for correcting the vertical contour of a video signal, an adding circuit for adding an output signal of the vertical contour correcting signal forming circuit and the video signal, and an output from the adding circuit. and a horizontal contour correction circuit for correcting the horizontal contour of the video signal whose vertical contour has been corrected,
A black side signal limiting circuit is provided between the vertical contour correction signal forming circuit and the adding circuit to limit the level of the black side output signal of the output signals of the vertical contour correction signal forming circuit. Contour correction circuit.