JPH04180470A - Ghost removing device - Google Patents

Abstract

PURPOSE:To execute efficient ghost removing by making the relation between a phase to sample a GCR signal or a vertical synchronizing signal and the sampling phase of a reference signal to execute the ghost removing constant. CONSTITUTION:A CPU 7 compares the whole the waveform data of a waveform data memory 6 to have plural pieces of waveform information with a GCR signal or a vertical synchronizing signal fetched by a waveform memory A2. As the result of comparison, the CPU 7 judges the waveform data which has the largest correlation with the GCR signal or the vertical synchronizing signal among the waveform data of the memory 6 as proper and executed ghost removing by using a reference signal to execute the ghost removing of the waveform data to have the largest correlation. Thus, the relation between a phase to sample the GCR signal or the vertical synchronizing signal and the sampling phase of the reference signal to execute the ghost removing is made constant, ghost removing performance is prevented from changing and removing efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ghost removal device that performs ghost removal using a ghost removal reference signal (hereinafter abbreviated as GCR signal) or a vertical synchronization signal.

2. Description of the Related Art The first generation of HDTV broadcasting, which aims to improve image quality while maintaining compatibility with current television systems, is about to begin, and ghost removal is attracting a lot of attention. Among the required ghost removal performance items are the image quality evaluation value after improvement and the removal time. In other words, this means how quickly ghosts can be removed and the amount of ghosts remaining after removal can be reduced. An example of a conventional ghost removal device is the Technical Report RE80-6 of the Television Society of Japan.
There is a ghost canceller reported in , pp. 9-14, February 1980. This detects ghosts by using the differential signal of the leading edge of the vertical synchronization signal unique to television signals as a reference waveform, and performs correlation calculations on the time axis using the detected ghost signals to perform transformer detection. Ghosts are removed by sequentially correcting the tap coefficients of the versal filter.

Also, a ghost removal section using GCR signals! As for the Television Society Technical Report ROFT89-6, pp.31
There is a ghost canceller reported in -36. This uses a transversal filter in the ghost canceller like the ghost canceller described above, but inputs and outputs of the transversal filter are taken into CPtJ via memory, and synchronous addition is performed between fields according to the transmission sequence. Performs all ghost removal calculations including processing.

An example of a conventional ghost removal device will be described below with reference to the drawings. FIG. 2 is a schematic block diagram showing the configuration of a conventional ghost removal device. In Figure 2,
10 is an A/D converter that A/D converts the input video signal; 11 is a transversal filter that removes ghosts from the output of the A/D converter 10; 12 is an A/D converter that converts the output of the transversal filter 11; D/A converter to convert and obtain output video signal, 13.14 is A/D converter 1
0 is a waveform memory that stores the output waveform of the transversal filter 11; 15 is a CPU that controls the transversal filter 11 using the output of the waveform memory 13j4.

The operation of the ghost removal device configured as described above will be explained. The input video signal is sent to A/D converter 1
The output ffi is input to the transversal filter 11 and the waveform memory 13, respectively.
The output of No. 4 is input to the CPU 15.

In the first generation HDTV broadcasting, Figures 3(a) and (b)
The WRB signal and 0 pedestal signal shown in are the WRB signal - ○ Destal signal - W RB No. m - 0 Pedestal signal →
O pedestal signal → WRB (i number → 0 pedestal signal →
W RB (Sent in the same horizontal period in a sequence that goes around the 8 fields of F-. By performing the calculation shown in the following equation 1 on the signals of these 8 fields, the signal shown in Fig. 3 (C) is obtained. You can get a signal. However,
Fn (, n=1 to 8) represents the signal of the nth field. Hereinafter, the processing between fields according to the exit sequence as shown in the first equation will be referred to as field sequence processing.

F=1/4 ((Fl-F5j+(F6-F2)+
(F3-F7)-! -(F8-F4), )...(1) Actually, the signal shown in FIG. 3(d), which is obtained by differentiating the signal in FIG. 3(C), is used as the reference signal for ghost detection, and the following ghosts are detected. M S E (Me
an 5quare Error) method or Z F
There is a (Zero Forcing) method, etc., which sequentially corrects the IIL on the time axis according to a constant algorithm to obtain the optimal tap coefficient at the end of the IIL. The output signal of the transversal filter is +Ykl, the reference signal is (Rk), the difference signal between the output signal of the transversal filter and the reference signal is (Ek), and the total number of taps is MfN.
+1, the nth tap coefficient C(i l "" of the transversal filter is expressed by the following equation 2 in the MSE method:
In the ZF method, correction is performed based on the third equation. However, α,
β is a coefficient for determining the amount of correction.

((i l l-4th = (C1)+1(Cill-4
Mouth = (, Ci) 1m1-β・Ei...(3)
After performing the synchronous addition and field sequence processing shown in the first equation, the CPU 15 repeatedly corrects the tap coefficients by calculating the second or third equation. A series of these processes is performed by software, and this flowchart is shown in the fourth section.
As shown in the figure. In this process, the process is repeated until the amount of residual ghost in ghost detection becomes sufficiently small.

Problems to be Solved by the Invention When performing ghost removal with the configuration of a conventional ghost removal device, the phase relationship of the tarok signal used when converting an input video signal to a digital video signal with respect to the GCR signal or vertical synchronization signal is The waveform of the digital video signal converted to a digital signal by the A/D converter changes because it changes depending on the temperature characteristics of the generation circuit and the phase of the GCR signal or vertical synchronization signal inserted into the input video signal. The ghost removal performance changes due to the waveform change, and in particular, the characteristics of high frequency components of the video signal change.

The present invention solves the above problem, and aims to provide a ghost removal device whose ghost removal performance does not change.

Means for Solving the Problems In order to solve the above-mentioned problems, the ghost removal device of the present invention uses a GCR signal, a vertical synchronization signal, or a signal obtained by processing these signals to generate a new phase that has been corrected and stored in a memory. The CPU compares the multiple reference signal waveform data for ghost detection sampled by the CPU, and selects the GCR from among the waveform data in the waveform data memory that is considered to be the most appropriate.
The configuration is such that reference signal waveform data having the highest correlation with the signal or vertical synchronization signal is selected and ghost removal is performed using that waveform data.

Effect of the present invention With the above-described configuration, the sampling phase of the reference signal for ghost detection and the video signal are A/D
The phase relationship between the clock and GCR signal or vertical synchronization signal during conversion is kept within a certain range, and the ghost removal performance is A
, / Prevents changes due to the phase of D conversion.

EXAMPLE Hereinafter, a ghost removal device according to an example of the present invention will be described with reference to the drawings. Figure 1 shows the ghost removal device in the first embodiment of the present invention! It is a block diagram of the time #@ configuration of. In Figure 1, 1 converts the input video signal into an A/D converter.
2 is a waveform memory A into which the output of A/D converter 1 is input; 3 is a transversal filter that removes ghosts from the output of A/D converter 1; 4 is the output of transversal filter 3. 5 is a D/A converter that converts the output of the transversal filter 3 into D/A, and 6 is waveform data having multiple waveform information for ghost detection sampled at different sampling phases. A memory 7 inputs the outputs of the waveform memory 2.4 and the waveform data memory 6 having a plurality of waveform information, and is used as a transversal filter 3.
The CPU 8 generates a clock signal based on the input video signal, and controls the A/D converter 1 and the D/D converter 1.
This is a clock recovery circuit that controls the A converter 5.

The operation of the ghost removal device configured as described above will be described below. Initially, waveform memory A2 is A/D
A GCR signal or a vertical synchronization signal is taken in from the output digital video signal of the converter 1 and inputted to the CPU 7.

The CPU 7 compares all of the waveform data in the waveform data memory 6, which has a plurality of pieces of waveform information, with the GCR signal or vertical synchronization signal taken in by the waveform memory A2. CPU7
As a result of this comparison, among the waveform data in the waveform data memory 6 that has multiple pieces of waveform information, it is determined that the one with the highest correlation with the GCR signal or vertical synchronization signal is appropriate, and the waveform data with the highest correlation is selected. Ghost removal is performed using the reference signal that performs ghost removal.In this way, 0C
The relationship between the sampling phase of R(i) or the vertical synchronization signal and the sampling phase of the reference signal from which ghost removal is performed is kept constant to prevent changes in ghost removal performance.

Effects of the Invention As described above, according to the present invention, by keeping the relationship between the sampling phase of the GCR signal or the vertical synchronization signal and the sampling phase of the reference signal from which ghost removal is constant, the input video signal is converted into a clock signal. This solves the problem that the ghost removal performance changes due to changes in the waveform when converted to a digital video signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a ghost removing device according to an embodiment of the present invention, FIG. 2 is a block diagram of a conventional ghost removing device, FIG. 3(a) is a waveform diagram of the WRB signal, and FIG. 3(b) is a 0 FIG. 4 is a waveform diagram of a pedestal signal, (C) is a signal waveform diagram after field sequence processing, (d) is a signal waveform diagram obtained by differentiating (C), and FIG. 4 is a flowchart of conventional ghost removal processing. 1... A/D converter, 2... Waveform memory A, 3
...Transversal filter, 4...Waveform memory B, 5...D, /A converter, 6...Waveform data memory with multiple waveform information, 7...CPt
, ', 8... Tarokku reproducing circuit. Agent Yoshihiro Morimoto Figure 1 δ % Compa-7 Figure 2 Figure 3

Claims (1)

[Claims] 1. A ghost removal device that performs ghost removal using a ghost removal reference signal or a vertical synchronization signal, which includes a clock recovery circuit that generates a clock signal based on an input video signal, and a clock signal generated by the clock recovery circuit. an A/D converter that converts an input video signal into a digital video signal using a clock signal; a transversal filter that receives the digital video signal and performs ghost removal under the control of a CPU; A waveform memory A that supplies the output of the transversal filter to the CPU; a waveform memory B that captures the output of the transversal filter and supplies it to the CPU; and D that converts the output of the transversal filter into an analog output video signal using the clock signal. /A converter, and a waveform data memory having a plurality of waveform information that supplies a plurality of reference signals for ghost detection sampled at different sampling phases to the CPU,
Before the CPU performs the ghost removal operation, the CPU detects a plurality of ghosts sampled at different sampling phases supplied from the digital video signal captured by the waveform memory A and the waveform data memory having the plurality of waveform information. The reference signal that has the highest correlation with the GCR signal or vertical synchronization signal is selected from among the waveform data in the waveform data memory, and the ghost removal operation is performed using that reference signal. The configured ghost removal device.