JPS62125779A - Video signal processor - Google Patents

Abstract

PURPOSE:To realize simultaneously the function of a vertical preemphasis and the function for a comb-line filter for removing chrominance signal component by using only one 1H delay circuit by applying a required processing for adding an input signal A and a signal B obtained by delaying a signal B by 1 horizontal scanning period. CONSTITUTION:The input signal from an input terminal 101 and the output signal of a 1H delay circuit 105 are added in an addition circuit 102 and the signal multiplied by a prescribed coefficient (d) in a coefficient circuit 103 and the input signal from the input terminal 101 are added. Further, after the output signal of the 1H delay circuit 105 is subtracted, the output is multiplied by 1/2 in a coefficient circuit 107 and becomes the output of a feedback type comb- line filter 100. Thereby, by using only 1H delay circuit, the function for the vertical non-linear type preemphasis is performed with respect to a luminance signal below about 3MHz of a horizontal frequency of a passing band of a low-pass filter 108 and the function for the comb-line filter is performed in above about 3MHz of the horizontal frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal processing device used in a video signal recording and reproducing device such as a video tape recorder.

Conventional technology In recent years, it has been proposed to perform pre-emphasis in the vertical direction of the image during recording and de-emphasis during playback in order to reduce the noise associated with recording and playback in home video tape recorders, which are widely used in general. has been done.

An example of a conventional vertical pre-emphasis device will be described below with reference to the drawings.

FIG. 4 is a configuration diagram showing an example of a conventional vertical pre-emphasis device. In FIG. 4, a luminance signal to be recorded is input to an input terminal 1.

In the adder circuit 2, the input signal is delayed by an IH delay circuit 4 which delays the signal by one horizontal scanning period (IH), and is added to a signal multiplied by a predetermined coefficient in a coefficient circuit 5. The output signal of the adder circuit 2 is input to the IH delay circuit 4, and is led to the subtracter circuit 6 via the coefficient circuit 3, where it is subtracted from the input signal from the input terminal 1. The signal obtained by the subtraction circuit 6 is amplitude limited by a nonlinear input/output circuit 7, passes through a coefficient circuit 8, is added to the input signal in an addition circuit 9, and is outputted from an output terminal 10.

As a result of the above, the signal obtained from the output terminal 10 becomes a vertically nonlinear pre-emphasized signal in which the high frequency component in the vertical frequency of the small amplitude signal is emphasized. (for example,
Problems to be Solved by the Invention Incidentally, the signal input to such a vertical pre-emphasis device is a luminance signal obtained by removing the color signal from the color video signal to be recorded. . However, in recent VTRs, in order to maintain the horizontal resolution of the luminance signal and reduce interference between the brown signal and the luminance signal, the color signal is removed by a comb filter using an IH delay circuit.
In many cases, a configuration is adopted in which a luminance signal is obtained by removing a certain amount of color signal with a low-pass filter and then removing the color signal completely with a comb filter. Therefore, in this case, two expensive IH delay circuits using glass delay lines, CCDs, digital memories, etc. are required for the comb filter and the vertical pre-emphasis device, which inevitably increases costs. ing.

In consideration of these points, the present invention aims to provide a video signal processing device that simultaneously realizes a vertical pre-emphasis function and a comb filter for removing color signals using a single IH delay circuit. The purpose is

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention adds the input signal A and the signal C, which is obtained by delaying the signal B by one horizontal scanning period, to obtain a signal, and adds a signal to the signal by a predetermined value. After multiplying by a coefficient, the signal A is added to obtain the signal B, and the signal B and the signal C are
A feedback comb filter is provided which extracts the high frequency component of the vertical frequency by outputting the difference signal multiplied by 1/2, and the high frequency component of the horizontal frequency is extracted by the feedback comb filter. The high frequency components of the vertical frequencies extracted by the feedback comb filter are emphasized and the high frequency components of the horizontal frequencies extracted by the feedback comb filter are outputted.

As a result, the present invention uses only one IH delay circuit to function as a vertical pre-emphasis for luminance signals from OHZ to about 3 MHz, and as a chrominance signal component for signals with frequencies above 3 MHz. It functions as a comb filter that removes.

That is, the vertical pre-emphasis function and the comb filter for removing color signals can be simultaneously realized without increasing costs.

Examples Examples of the present invention will be described below. FIG. 1 is a block diagram of a video signal processing device in one embodiment of the present invention.

In FIG. 1, an input terminal 101 receives a signal from which a color signal to be recorded has had its color signal removed to some extent by a low-pass filter, or a color image signal from which the color signal has not been removed.

The part 100 surrounded by the broken line constitutes a feedback comb filter, and the input signal from the input terminal 101 and the IH
The output signal of the delay circuit 105 is added in the adder circuit 102, and the resulting signal is multiplied by 4 by a predetermined coefficient in the coefficient circuit 103, and the input signal from the input terminal 101 is added in the adder circuit 104. The output of the adder circuit 104 becomes an input signal of the IH delay circuit 105 and is led to the subtracter circuit 106, where the output signal of the IH delay circuit 105 is subtracted, and then multiplied by 1/2 in the coefficient circuit 107 to form a feedback comb. This becomes the output of filter 100. As a result, by appropriately setting the coefficient d in the coefficient circuit 103, the frequency characteristic of the feedback comb filter 100 from the input terminal 101 to the coefficient circuit 107 can be changed to a vertical frequency of 131.25 (ay/ ph) (N
In the case of the TSC method), it has the characteristic of extracting nearby signals. Moreover, if this characteristic is expressed in a two-dimensional frequency domain, it is a characteristic that extracts a signal in the combined area of area A and area B in FIG. 3.

Now, the output of the feedback comb filter 100 is Qllz
~3MI (Low pass filter 1 with pass band around Z
Guided to 08. At this time, the output signal of the low-pass filter 108 becomes a signal in area A in FIG. On the other hand, in the subtraction circuit 109, the output signal of the feedback comb filter 100 is subtracted from the input signal from the input terminal 101. It is added to the output of the low-pass filter 108 at the step .

As a result, the output of the subtraction circuit 109 becomes a signal in which the frequency components of region A and region B in FIG. It becomes. The output signal of the low-pass filter 108, that is, the signal in area A in FIG. 1) Area B in Figure 3 in 4
The signal is added to the output of the adder circuit 1) 1, which is a signal with the frequency component suppressed, and is output from the output terminal 1) 5.

As a result of the above, the video signal processing device of this embodiment uses the IH delay circuit of one tatami to process the luminance signal in the region A of FIG. It functions as a vertical nonlinear pre-emphasis that nonlinearly enhances the signal of the luminance signal, and also functions as a comb filter that suppresses the component of region B in Fig. 3 at horizontal frequencies of about 3M Ilz or higher, degrading the horizontal resolution of the luminance signal. It is possible to reduce interference between the color signal and the luminance signal by removing unnecessary color signal components without causing any interference.

Effects of the Invention As described above, according to the present invention, the function of vertical pre-emphasis and the function of a comb filter for removing color signal components can be simultaneously realized using only one IH delay circuit. This allows for low-cost, high-performance VTRs.
can be obtained.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a configuration diagram of a video signal processing device according to an embodiment of the present invention, FIGS. 2 and 3 are schematic diagrams illustrating the operation in the frequency domain of an embodiment of the present invention, FIG. 4 is a configuration diagram showing an example of a conventional vertical pre-emphasis mounting surface. 100... Feedback comb filter, 105.
...IH delay circuit i, 108...Low pass filter, 109. IIL1) 4... Arithmetic circuit, 1) 0... Delay circuit. Agent's name: Patent attorney Toshio Nakao Only one name left 2! Watarukyoku Rōkazu [烙h]

Claims (2)

[Claims] (1) Signal D is obtained by adding input signal A and signal C which is obtained by delaying signal B by one horizontal scanning period, and after multiplying said signal D by a predetermined coefficient, said signal A is added to said signal B. obtained,
A feedback comb filter is provided which extracts high frequency components of vertical frequencies by outputting a difference signal between the signal B and the signal C multiplied by 1/2, and the feedback comb filter extracts high frequency components of vertical frequencies. It is characterized by suppressing the high frequency components of the vertical frequency extracted by the feedback comb filter, and emphasizing and outputting the high frequency components of the vertical frequency extracted by the feedback comb filter for the low frequency frequency. A video signal processing device. (2) When the input signal of the feedback comb filter is A and the output signal is E, a first arithmetic circuit that subtracts the signal E from the signal A to obtain the signal F; and a first arithmetic circuit that receives the signal E and outputs the signal; a low-pass filter for obtaining signal G; a second arithmetic circuit for obtaining signal H by adding the signal G to a signal obtained by delaying the signal F by a predetermined time determined by the low-pass filter; A video signal processing device according to claim (1), comprising a nonlinear input/output circuit that obtains a signal I, and a third arithmetic circuit that adds the signal H and the signal I. .