JPS62147897A - Color ooze removing circuit - Google Patents

Abstract

PURPOSE:To improve the quality of a picture by subtracting a signal generated by limiting the amplitude and the level of a reproduced signal from a reproduced signal in the amplitude varying section of the reproduced signal, mixing the subtraction result with a reproduced luminance signal, and thereby reducing the color ooze and the contour blurring of a reproduced picture. CONSTITUTION:The reproduced color signal 100 is inputted to a subtraction circuit 3. And after limiting its amplitude by an amplitude limitor 1, the signal is outputted to an attenuator 2 to attenuate its level, and then outputted to the circuit 3. Meanwhile, the reproduced luminance signal 200 is inputted to a differentiation circuit 4 and a mixing circuit 6. The circuit 4 differentiates the signal and its differential signal output is used to trigger a double trigger monostable multivibrator 5 to output a control signal 400. When the signal 400 comes to H, the circuit 3 subtracts the low level reproduced chrominance signal inputted from the attenuator 2 from the reproduced signal 100, and outputs a reproduced chrominance signal 500 to the mixing circuit 6. The signal 500 is mixed with the signal 200 to generate a video signal (a). In such a way, the deformed part of the waveform of a reproduced color signal is removed, and the color-blurring and the contour blurring of the reproduced picture that are noticeable in the amplitude varying section of the reproduced luminance signal 200, is decreased. Therefore, the quality of the picture is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a color fringing removal circuit suitable for use in a home video tape recorder (VTR).

[Technical Background of the Invention] Conventionally, in the color signal processing of a home VTR, a color signal (3.58 MH2) is frequency-converted during recording and recorded on a tape as a low-frequency converted color signal, and then the color signal obtained during playback is The low frequency converted color signal is frequency converted and used back to the original color signal. In this color signal processing process, the low frequency converted color signal is mixed with the luminance signal and recorded on the video track during recording, so the band of the low frequency converted color signal (approximately ±500 KH
z > cannot be made wide, and during reproduction, it is necessary to reduce the low frequency components of the low frequency converted color signal in order to eliminate the effects of low frequency noise, etc. Due to these effects, the reproduced color signal (3,58M )(z) waveform distortion occurs.

[Problems with the Background Art] When waveform distortion occurs in the reproduced color signal as described above, the distortion becomes noticeable, especially in the section where the amplitude change of the reproduced luminance signal occurs, causing outline blurring and color blurring in the reproduced image. This has the disadvantage of causing a decrease in image quality.

[Object of the Invention] In view of the above-mentioned drawbacks, an object of the present invention is to provide a color fringing removal circuit that can improve image quality by reducing color fringing and outline blurring of reproduced images caused by waveform rounding of reproduced color signals. It's about doing.

[Summary of the Invention] The present invention subtracts a signal in which the amplitude and level of the reproduced color signal is limited from the reproduced color signal in an amplitude change section of the reproduced luminance signal, and reproduces by mixing this subtraction result with the reproduced luminance signal. By using a color fringing removal circuit configured to obtain a video signal, the purpose of improving image quality is achieved by reducing color fringing and outline blurring of reproduced images caused by waveform rounding of reproduced color signals.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing an embodiment of the color fringing removal circuit of the present invention. 1 is input reproduction color signal (3,58MH2)
An amplitude limiter 2 limits the amplitude of the reproduced color signal 100, and an attenuator 3 reduces the level of the amplitude-limited reproduced color signal to produce a low level reproduced color signal. a subtraction circuit 4 that subtracts only when the control signal 400 is input and outputs the m calculation result 500;
5 is a differential circuit that differentiates the reproduced luminance signal 200 to generate a differential signal 300; 5 is a dual-trigger monomulti that generates a control signal 400 using the differential signal 300 as a trigger; and 6 is a reproduced color signal 500 output from the subtraction circuit 3. and playback brightness @2
This is a mixing circuit that mixes 00 to produce a video signal.

Next, the operation of this embodiment will be explained with reference to the operation timing chart of FIG. First, a reproduced color signal 100 as shown in FIG. 2(D) is input to the positive input terminal of the subtraction circuit 3 and the amplitude limiter 1'. The amplitude limiter 1 limits the amplitude of the input reproduced color signal and then outputs it to the attenuator 2. The attenuator 2 attenuates the level of the input reproduced color signal and outputs it to the negative input terminal of the subtraction circuit 3. On the other hand, a reproduced luminance signal 200 as shown in FIG. 2 (A>) is input to the differentiating circuit 4 and the mixing circuit 6. The differentiating circuit 4 differentiates the input reproduced luminance signal 200 as shown in FIG. 2 (8). A differential signal 300 like this is output to both trigger monomultis 5.

Both trigger monomultis 5 are triggered by the input differential signal and output a control signal 400 as shown in FIG. 2(C) to the subtraction circuit 3.

In the subtraction circuit 3, the reproduced color signal 100, which is normally input to the positive input terminal, is passed through the mixer 6 without undergoing any processing.
is input. However, when the control signal 400 output from both trigger mono multi 5 becomes high level, this subtraction circuit 3 converts the low level reproduced color input from the attenuator 2 from the reproduced color signal @100 inputted to the positive input terminal. The signals are subtracted, and the resulting reproduced color signal 500 as shown in FIG. 2(E) is output to the mixer 6. The mixer 6 mixes the input reproduced color signal with the reproduced luminance signal 200 to produce a video signal.

Here, as shown in FIG. 2(C) and (A>), the subtraction circuit 3
The control signal @400 that causes the subtraction operation to be performed is the reproduction brightness signal @2
When the amplitude changes to 00 (edge part), it becomes high level,
When this luminance signal becomes high level, the reproduced color signal becomes 10
A low level reproduced color signal (attenuator) is subtracted from 0.

Therefore, as shown in FIG. 2(E), the reproduced color signal 500 output from the subtraction circuit 3 is generated at time T1. As a result of the subtraction performed at the above-mentioned timing within the range of T2, the minute change portion of the reproduced color signal is eliminated, and the waveform becomes rounded.

According to this embodiment, since the dullness of the waveform portion of the reproduced color signal corresponding to the amplitude change timing of the reproduced luminance signal 200 is removed, color fringing and outline blurring of the reproduced image that are noticeable at the amplitude change portion of the reproduced luminance signal 200 are removed. can be reduced to improve image quality.

[Effects of the Invention] As described above, according to the color fringing removal circuit of the present invention,
A low-level reproduced color signal created from the reproduced color signal is reduced in the amplitude change section of the reproduced luminance signal, and the subtraction result is mixed with the reproduced 8 degree signal to generate a video signal. This has the effect of improving image quality by reducing color fringing and outline blurring of reproduced images caused by waveform rounding of reproduced color signals.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the color fringing removal circuit of the present invention, and FIG. 2 is an operation timing chart of the circuit shown in FIG. 1...Amplitude limiter 2...Attenuator 3...Subtraction circuit 4...Differential circuit 5...Dual trigger monomulti 6...Mixed circuit Agent Patent attorney Nori Chika Hiroshi Uji T'T2 Figure 2

Claims (1)

[Claims] a level reduction circuit that generates a low-level reproduced color signal from the reproduced color signal; a control signal generation circuit that outputs a control signal by capturing signal change timing of the reproduced luminance signal; and a level reduction circuit that generates a low-level reproduced color signal from the reproduced color signal. a subtraction circuit that subtracts and outputs the reproduced color signal only when the control signal is input, and outputs the reproduced color signal as is at other times, and a mixing circuit that mixes the luminance signal with the output signal of the subtraction circuit to create a video signal. A color blur removal circuit comprising: