JPS62299180A - Adaptable type outline correcting device - Google Patents

Abstract

PURPOSE:To correct the outline of the whole of a video signal by minimizing the correcting quantity of an outline correction to the video signal near the upper limit and near the lower limit of the dynamic range of the video signal, increasing a video signal gain to emphasize the outline. CONSTITUTION:The first fixed memory circuit 11 outputs, to the second adding circuit 12, an outline correcting signal G to convert an outline correcting signal F, which is the output of a subtracting circuit 9, to a nonlinear by the value of a control signal S outputted from a level detecting circuit 10. Namely, the correcting quantity of the outline correcting signal is minimized to the video signal near the upper limit and near the lower limit of a dynamic range. The second adding circuit 12 adds a video signal B outputted from the first delaying circuit 2 and the outline correcting signal G outputted from the first fixed memory circuit 11, and outputs an outline correcting video signal H to the second fixed memory circuit 13. The second fixed memory circuit 13 makes the video signal gain larger than 1' to the video signal near the upper limit and near the lowe limit and makes the video signal gain smaller than '1' to the video signal at the middle area.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a contour correction device for correcting the contour of a video signal in a television receiver.

[Conventional technology]

FIG. 2 shows a conventional contour correction device, where 1 is an input terminal for inputting a video signal A, 2 is a first delay circuit that delays the video signal A input from the input terminal 1 by a predetermined time, and 3 is a first delay circuit. A second delay circuit delays the video signal B output from the delay circuit 2 for a predetermined time; 4 is a first delay circuit that adds the video signal A input from the input terminal 1 and the video signal C output from the second delay circuit 3; Addition circuit 5 is a division circuit that divides the video signal D (=A + C) outputted from the first addition circuit 4 to 1k, 6
is the image @! output from the first delay circuit 2. A multiplier circuit converts signal B into 2@, 7 is video signal 2 which is the output of multiplier circuit 6
A subtraction circuit that subtracts the video signal D/2, which is the output of the division circuit 5, from B, and 8 is a contour correction circuit that is output from the subtraction circuit 7.
This is an output terminal that outputs a video signal E (= 2 B - (A+C)/2).

Next, the operation will be explained. The video signal A shown in FIG. 3 (81) inputted from the input terminal 1 is inputted to the first delay circuit 2 and the first addition circuit 4.The first delay port gII2
outputs the video signal B shown in FIG.

The second delay circuit 3 is a third delay circuit which delays the video signal B by a predetermined time.
The video signal C shown in FIG. The division circuit 5 outputs the video signal D/2 shown in FIG. The subtraction circuit 7 outputs the video signal D/D from the video signal 2B.
2 is subtracted, and the contour-corrected video signal E(
=2B-(A+C)/2) is output to the output terminal 8.

[Problem that the invention seeks to solve]

Conventional contour correction devices are configured as described above, and when the video signals near the upper and lower limits of the dynamic range of the video signal are subjected to contour correction to become a contour-corrected video signal, the dynamic range of the video signal is exceeded. ,
Since the overlapping portion is clipped, the effect of contour correction will be reduced.

Further, when contour correction is applied to noise near the black level, that is, noise near the lower limit of the dynamic range, there is a problem that it becomes an eyesore.

This invention was made in order to solve the above-mentioned problems, and it is possible to effectively perform contour correction of a video signal without exceeding the dynamic range of the video signal, and also to correct the outline of the video signal without exceeding the dynamic range of the video signal. An object of the present invention is to obtain an adaptive contour correction device that can suppress nearby noise.

[Means for solving problems]

The adaptive contour correction device according to the present invention includes a level detection circuit for detecting signals near the upper limit and near the lower limit in the dynamic range of the image signal, and a contour correction signal for the video signal detected by the level detection circuit. A first fixed storage circuit that performs conversion to reduce the amount of correction of A second fixed storage circuit is provided for converting the video signal gain to less than 1.

[For production]

In this invention, a level detection circuit detects a video signal near the upper limit vj8 and near the lower limit in the dynamic range, converts this into a control signal for varying the amount of correction of the contour-corrected video signal, and outputs the signal.

The first fixed memory circuit uses this control signal to reduce the correction amount of the contour correction signal for the image signal near the lower limit and the lower limit. The video signal gain is set larger than 1 for nearby video signals, and the video signal gain is set smaller than 1 for mid-range video signals.This allows the contour to be adjusted without exceeding the dynamic range of the video signal. It is possible to emphasize the outline of the video gIi signal near the upper limit and near the lower limit in the dynamic range of the corrected video signal.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1st
In the figure, 9 is a subtraction circuit that subtracts the video signal D/2, which is the output of the division circuit 5, from the video signal B, which is the output of the first delay circuit 2, and 10 is the video signal, which is the output of the first delay circuit 2. A level detection circuit, circuit 11, detects from the signal B a video signal near the upper limit and near the lower limit in the dynamic range of the video signal, converts this into a control signal S for varying the correction amount of the contour correction signal, and outputs the control signal S. A first fixed circuit that outputs a contour correction signal G obtained by nonlinearly converting the contour correction signal F (=B − (A+C) /2), which is the output of the subtraction circuit 9, according to the value of the control signal S output from the level detection circuit 10. A storage circuit 12 is a second addition circuit that adds the video signal B output from the first delay circuit 2 and the contour correction signal G output from the first fixed storage circuit 11; l3 is a circuit from the second addition circuit 12; A second fixed storage circuit 8 non-linearly converts the output contour-corrected video signal H (, B+G) and outputs the contour-corrected video signal J, and 8 is an output terminal that outputs the contour-corrected video signal J.

Next, the operation will be explained. The subtraction circuit 9 is shown in FIG.
As shown in e), a contour correction signal F (=B-(A+C)/2) is obtained by subtracting the video signal D/2, which is the output of the division circuit 5, from the video signal B, which is the output of the first delay port #+2. The first
The output signal is output to the fixed storage circuit 11 of. The level detection circuit 10 has several threshold values near the upper limit and the lower limit in the dynamic range of the video signal, and when a video signal B of a certain length exists for a certain time in a certain area divided by the threshold values, for example, , the control signal S specific to this area is stored in the first fixed storage circuit 11 for that period of time.
Output to. For example, as shown in FIG. 5, if there are seven regions divided by threshold values, P1 to P7, and when video signal B exists in regions P, , P, control signal S is set to S=S+
ain, and the video signal B is in the area P2. When the Z control signal S = S2 exists in the area P, the video signal B is in the area P.
3. When present in P, the control signal S = S.

Then, when the video signal B exists in the area P4, the control signal 5 is set as SIIaχ. The first fixed memory circuit 11 and the sixth
As shown in the figure, a contour correction signal G obtained by nonlinearly converting the contour correction signal F, which is the output of the subtraction circuit 9, according to the value of the control signal S output from the level detection circuit 10 is output to the second addition circuit 12. That is, the amount of correction of the contour correction signal is reduced for video signals near the upper and lower limits of the dynamic range. The second addition circuit 12 adds the video signal B output from the first delay circuit 2 and the contour correction signal G output from the first fixed storage circuit 11, and sends the contour correction video signal H to the second fixed storage circuit. Output to 13.

As shown in FIG. 7, the second fixed storage circuit 13 applies a video signal gain to the contour-corrected video signal H output from the second addition circuit 12 for video signals near the upper limit and near the lower limit in the dynamic range. 1, and non-linear conversion is performed so that the video signal gain is made smaller than 1 for mid-range video signals, and a signal J is output.

As a result of the above, conventionally, a contour-corrected video signal clipped near the upper and lower limits of the dynamic range was obtained from the video signal shown in FIG. As shown in FIG. 8 tc+, the contour-corrected video signal near the upper and lower limits of the dynamic range is not clipped by exceeding the dynamic range, and the contour can be emphasized.

〔Effect of the invention〕

As described above, according to the present invention, the contours are emphasized by reducing the amount of contour correction and increasing the video signal gain for video signals near the upper and lower limits of the dynamic range of the video signal. Therefore, the contour-corrected video signal will not exceed the dynamic range of the video signal and be clipped, and the contour correction of the entire video signal can be performed. This has the effect of suppressing the emphasis of noise caused by

[Brief explanation of the drawing]

Figure 1 is a block diagram of this invention device, Figures 2 and 3.
The figures are a block diagram and an operating waveform diagram of a conventional device, respectively.
5 is an explanatory diagram of the control signal of the level detection circuit according to the invention, FIG. 6 is an output characteristic diagram of the first fixed memory circuit according to the invention, and FIG. is an output characteristic diagram of the second fixed storage circuit, and FIG. 8 is a waveform diagram of the contour-corrected video signal according to the conventional method and the present invention. 2.3...Delay circuit, 4,12...Addition circuit, 5...
Division circuit, 9. Subtraction circuit, 10. Level detection circuit,
11...First fixed memory circuit, 13...Second fixed memory circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A delay circuit that delays the input video signal, an addition circuit that adds the input video signal and the output of the delay circuit, a division circuit that divides the output of the addition circuit, and a division circuit that divides the output of the delay circuit. Equipped with a subtraction circuit that subtracts the output of the circuit,
In a contour correction device that outputs a contour correction signal, a level detection circuit detects a signal near the upper limit and a lower limit in the dynamic range from the video signal output from the delay circuit, and a a first fixed storage circuit that performs nonlinear conversion to reduce the amount of correction of the contour correction signal; and a video signal gain circuit for signals near the upper and lower limits of the dynamic range of the contour-corrected video signal. What is claimed is: 1. An adaptive contour correction device comprising: a second fixed storage circuit that performs non-linear conversion to make the video signal gain smaller than 1 for signals in the middle range and to make the video signal gain smaller than 1.