JPS6166492A - Correction circuit of chrominance signal profile - Google Patents

Abstract

PURPOSE:To correct the profile of a chrominance signal and to sharpen the color profile by differentiating secondarily and full-wave rectifying a luminance signal so as to obtain a correction signal and controlling gains of an input chrominance signal based on the correction signal. CONSTITUTION:A luminance signal (a) is secondarily differentiated in a secondarily differentiating circuit 1 in accordance with a changing amount, and correction signals (b) of the same polarity can be formed in a full-wave rectifier circuit 5. This signal controls gains of a chrominance signal as the control signal of a voltage control amplifier 6, and emphasizes the profile of color to obtain a sharp video. A delay circuit 4 is provided in order to take the timing between signals.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to contour correction of color signals in television receivers.

(Conventional technology) The configuration of a conventional device of this type is shown in FIG.

In FIG. 3, the input luminance signal is second-order differentiated by a differentiating circuit 3, polarity inverted by an inverting circuit 2, and then added to a signal obtained by delaying the original signal by a delay circuit 4 and an adder circuit 3. The waveforms of each part at this time are shown in FIGS. 4(a) to 4(e). For the input signal of Fig. 4(a), the inverted output 4
The signal shown in FIG. 4(d) is added, and overshoot and preshoot are added as shown in the waveform shown in FIG. 4(e). Note that the timing of the two signals is determined by the delay circuit 4.

In conventional contour correction, the brightness signal is contour-corrected as described above, but nothing is done to the color signal. Therefore, the brightness outline was sharp, but the color outline was not.

(Objective) The present invention was made in order to eliminate the drawbacks of the conventional method, and its purpose is to correct the outline of a color signal.

FIG. 1 shows the configuration of color signal contour correction according to the present invention.

The luminance signal is made into a second-order differentiated liquid according to the amount of change in a second-order differentiator circuit 1, and the polarity is made the same in a double-wave rectifier circuit 5 to become a correction signal. This signal is used as a control signal for the voltage control amplifier 6 to control the gain of the color signal, emphasizing color outlines and producing a sharp image. Note that a delay circuit 4 takes timing between signals.

The above is the luminance signal input in Figure 2 (a) and Figure 2 (d).
Considering the color signal input in Figure 2 (a), the signal in Figure 2 (a) is second-order differentiated and double-wave rectified to become the correction signal in Figure 2 (b), and this signal is the color signal in Figure 2 (d > and Figure 2(d)
Emphasize the outline and make it steeper.

Note that the above configuration can be applied to devices that use video signals.

(Effects) As described above, according to the present invention, the outline of a color can be sharpened.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the circuit according to the present invention, FIG. 2 is a diagram showing waveforms of each part of FIG. 1, FIG. 3 is a diagram of a conventional circuit, and FIG. 4 is a diagram of each part of FIG. 3. FIG. 3 is a diagram showing waveforms.

Claims (1)

[Claims] A color signal contour correction circuit comprising: a voltage control amplifier that controls the gain of an input color signal using a correction signal; and a circuit that performs second-order differentiation and double-wave rectification of a luminance signal to produce the correction signal.