JPH0265471A - Contour correcting device - Google Patents

Abstract

PURPOSE:To correct a contour of a video image to be thin and steep and to obtain an easy to see pattern by retarding a differentiating signal, rectifying and multiplying the signal to obtain a thinner 2nd order differentiating signal. CONSTITUTION:In order to make the width of a 1st order differentiating signal (b) narrow, after the 1st order differentiating signal (b) is obtained by a conventional method, the 1st order differentiating signal (b) is retarded by a delay circuit 2 to obtain a delayed 1st order differentiating signal (c). The delayed 1st order differentiating signal (c) and the 1st order differentiating signal (b) are multiplied at positive and negative polarities respectively, the differentiating signals (h), (i) after the multiplication are restored to a form of the 1st order differentiating signal by a subtraction circuit 9 and a narrow 2nd order differentiating signal (k) is obtained by differentiating the signal by a differentiating circuit 10. Then the 2nd order differentiating signal (k) is subtracted from a signal l being the result of retarding the input video signal (a) by a subtraction circuit 12 for the time required for the arithmetic processing above to obtain an output video signal (m). Thus, a clear and sharp contour correction is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention can be used to make the rise or fall of the outline of a video signal of a television receiver, video tape recorder or video projector more steep. The present invention relates to a contour correction device.

2. Description of the Related Art In recent years, as color television receivers have become larger, contour correction devices have become more important in order to make the contours of images appear clearer.

Hereinafter, a conventional contour correction device as described above will be explained with reference to the drawings.

FIG. 4 shows the configuration of a conventional contour correction device, and FIG. 5 shows waveforms at various parts in FIG. In FIG. 4, reference numeral 1 denotes a differentiating circuit which generates a primary image signal from an input video signal. This is a first-order circuit that generates a second-order differential signal C from a second-order image component signal. 3 is a delay circuit that creates a delayed input video signal d from the input video signal a. 4 is an arithmetic circuit for subtracting the secondary image signal C from the delayed input video signal d to obtain the output video signal 6.

First, the differentiating circuit 1 generates a primary image signal indicating the outline of the input video signal B. The differentiating circuit 1 is generally constructed using a coil, a capacitor, or a delay element as shown in FIGS. 4A and 4B. Next, the primary image signal C is further differentiated by a differentiating circuit 2 to produce a secondary image signal C. By subtracting this signal C from the delayed input video signal d, which is obtained by delaying the input video signal 5 in the delay circuit 3 by the delay time of the differentiating circuit 1.2, in the arithmetic circuit 4, an output video signal e with sharper contours is created. ing.

Problems to be Solved by the Invention However, with the above configuration, when built into a large screen television receiver, the preshoot and overshoot caused by second-order differentiation appear thicker, and the outline portions become unsightly. had.

In view of the above-mentioned problems, the present invention provides a contour correction device that can make the pre/neat and overshoot caused by contour correction thinner and steeper to make the contour portion easier to see.

Means for Solving the Problem In order to achieve this object, the contour correction circuit of the present invention has the following features:
It is composed of a delay circuit that delays a differential signal (which may be a primary image signal or a secondary image signal), a rectifier circuit, and a multiplier circuit.

Effect With this configuration, the present invention delays the differential signal in the delay circuit, and then extracts the positive polarity side and the negative polarity side of the differential signal after one delay using the half-wave rectifier circuit, and outputs the positive polarity side before and after the delay. By multiplying the two signals together and the negative polarity side signals before and after the delay using a multiplier, a thinner differential signal can be obtained, and as a result, the purinet and overshoot can be made thinner and steeper. .

Embodiment Hereinafter, a contour correction device according to an embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 shows a block diagram of a contour correction device in one embodiment of the present invention. In FIG. 1, numeral 1 denotes a differentiating circuit, which obtains a primary image component signal from an input video signal 4. In FIG. A delay circuit 2 obtains a delayed primary image signal C from the primary image signal. 3.5 is a positive half-wave rectifier circuit, which receives the primary image signal b- or the delayed primary image signal C.
, extract only the positive polarity side signal and obtain the positive polarity primary image signal d
Alternatively, a positive delayed first-order differential signal f is obtained. 4.6 is a negative polarity half-wave rectifier circuit, which extracts only the negative polarity side signal from the primary image signal or delayed primary image signal C, and converts it to the negative primary image signal e or the delayed negative polarity 1. Obtain the next image component signal g. 7
, 8 is a multiplication circuit which multiplies the primary image signal and the delayed primary image signal for positive polarity and negative polarity, respectively, and generates a positive multiplied differential signal.

A negative multiplication differential signal 1 is obtained. 9 is a subtraction circuit which subtracts the negative multiplication differential signal i from the positive multiplication differential signal to obtain the multiplication differential signal j. 10 is a differentiating circuit which differentiates the multiplied differential signal k to obtain a secondary image signal k. A delay circuit 11 obtains a delayed input video signal l from the input video signal a. 12 is a subtraction circuit, which obtains an output video signal m by subtracting the secondary image signal k from the delayed input video signal l.

The operation of the contour correction device configured as described above will be explained below using FIG. 2.

First, the input video signal a is differentiated by a differentiating circuit to obtain a first-order differential signal S. If a differentiating circuit such as that shown in FIG. 6B is used, the width of this primary image signal will be wider than the width of the rising edge or falling edge of the contour of the input video signal. In this configuration, in order to narrow the width of the primary image signal, after obtaining the primary image signal in the usual way, the delay circuit 2
The primary image signal C is delayed to obtain a delayed primary image signal C.

The width of the primary image signal can be narrowed by the delay time of this circuit. The delayed first-order differential signal C and the first-order differential signal S are multiplied separately on the positive side and the negative side, respectively. This is because if this is not done, correct multiplication will not be performed. The differential signal 1 after multiplication is returned to the form of a first-order differential signal by the subtraction circuit 9.

By further differentiating this signal using a differentiating circuit 1o, a narrow quadratic annual signal k is obtained. Next, the subtraction circuit 12 subtracts this second-order differential signal k from the signal β obtained by delaying the input video signal a by the time required for the above calculation processing.
By subtracting the output image (ψ signal m is obtained. This signal m is contour-corrected by a narrow second-order differential signal, so
Pre-shoot, over/neat or thinner, resulting in cleaner contour correction.

As described above, according to this embodiment, by making the width of the differential signal for contour correction narrower and steeper using the delay circuit, the half-wave rectifier circuit, and the multiplication circuit,
The overshooter is thinner, allowing for steeper and narrower contour correction.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram of a contour correction device showing a second embodiment of the present invention. 1rJ1 The difference in the configuration from the configuration shown in FIG. 1 is that the differentiating circuit 10 is provided after the differentiating circuit 1. The operation of the contour correction device constructed as described above will be described below.

In Figure 1, the first-order differential signal is delayed, half-wave rectified, and multiplied before and after the delay to create a narrow first-order differential signal.
After that, differentiation was further performed to create a quadratic labor signal, but in this embodiment, the input video signal is immediately divided twice, and the
The difference is that the order differential signal is first processed.The subsequent processing is exactly the same as in Figure 1.As described above, 1
Instead of the second-order differential signal, the second-order differential signal is delayed, multiplied before and after the half-wave rectification delay, and a narrow second-order differential signal is obtained, which is subtracted from the input signal. A similar effect can be obtained.

Note that in the above embodiments, the multiplier circuits 7 and 8 may be replaced by switching circuits.

Effects of the Invention As described above, the present invention delays the differential signal, rectifies it, and converts the V
By calculating a thinner second-order differential signal, the outline of the image can be corrected to be thinner and steeper, making the screen easier to see, and the practical effects of this are impressive.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a contour correction device according to an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of FIG. 1, and FIG. 3 is a block diagram of a contour correction device according to a second embodiment of the present invention. Block diagram: Figure 4 is a block diagram of a conventional contour correction device; Figure 5 is a waveform diagram for explaining its operation; Figures 6A and B
is a circuit diagram of a normal differential circuit. 1 10-...- Differentiator circuit, 2, 11... Delay circuit, 35... Positive + l: Ten-wave rectifier circuit, 4.6...
Negative polarity half-wave rectifier circuit, 7.8... Multiplier circuit, 9
．． 12.--Subtraction circuit. Name of agent Patent attorney Shigetaka Kurino and 1 other list
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Claims (1)

[Claims] A first differentiation circuit that differentiates a video luminance signal and a first delay circuit that delays a first-order differential signal obtained thereby are provided, and a first differentiation circuit that extracts only the positive polarity signal of the first-order differential signal before this delay is provided. The positive half-wave rectifier circuit and the first circuit that extracts only the negative polarity signal.
a second positive half-wave rectifier circuit that extracts only the positive polarity signal of the delayed first-order differential signal after the delay;
a second negative half-wave rectifier circuit that extracts only the negative polarity signal; a first multiplier circuit that multiplies the output signals of the first and second positive half-wave rectifier circuits; The first delay is achieved by a second multiplier circuit that multiplies the output signals of the two negative half-wave rectifier circuits, and a first subtraction circuit that subtracts the respective outputs of the first and second multiplier circuits. a second differentiation circuit that obtains a first-order differential signal whose width is narrow by the delay time of the circuit, and further differentiates this signal to obtain a second-order differential signal; a second delay circuit that delays the input video luminance signal; A second circuit that subtracts the output of the second differentiating circuit from the output of the second delay circuit.
What is claimed is: 1. A contour correction device, comprising: a subtraction circuit, which obtains a narrow differential signal, and obtains narrow contour correction signals of preshoot and overshoot.