JPH0446469A - Ghost removing device - Google Patents

Abstract

PURPOSE:To make a hardware exclusive for a correlation culculation unneeded and to enable arithmetic inexpensively and at high speed by using a transversal filter as a correlation culculating element. CONSTITUTION:First, a GCR signal is fetched from a output video signal, added synchronously corresponding to 8 field sequence by a CPU 4, and differentiated from a reference signal previously equipped inside. The tap coefficient of a transversal filter 3 is corrected here, and a difference Ek is written in a first waveform memory 1 as correlation data. After that, the input to the transversal filter 3 is switched by a switching circuit 2 to a (b) side (a first waveform memory side), and a fetched data Yk after a synchronous addition is written in the transversal filter 3 as the correlation data.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to Ghost Cancel Refer
The present invention relates to a ghost removal device that performs ghost removal using an ence (OCR) signal.

2. Prior 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 requirements for ghost removal performance are image quality evaluation after improvement and 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.

In addition, as a goth table device using OCR signals, the Technical Report of the Television Society of Japan ROFT89-6pp, 31-3
6. There is a ghost canceller reported in June 1989. 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 the CPU via memory, and synchronous addition is performed between fields according to the transmission sequence. Performs all ghost removal operations, including processing.

An example of a conventional ghost removal device will be described below with reference to the drawings. FIG. 3 is a schematic block diagram showing the configuration of a conventional ghost removal device. In Figure 3 I
, 5 is a waveform memory, 3 is a transversal filter, 4
is the CPU. Waveform memories 1 and 5 are inserted between the input end and output end of the transversal filter 30 and the CPU 4, respectively.

The operation of the ghost removal device configured as above will be explained. The input video signal is input to a transversal filter 3 and a waveform memory 1. The input and output of the transversal filter 3 are the waveform memory 1,
5 to the CPU 4. first generation HDTV
In broadcasting, the WRB signal and 0 pedestal signal shown in Figure 4 (a) and (b) are WRE signal => 0 pedestal signal → WRB signal → O pedestal signal → 0 pedestal signal →
The signal is transmitted in the same horizontal period in a sequence of 8 fields: WRB signal → 0 pedestal signal → WRB signal. The signal shown in FIG. 4(C) can be obtained by performing the calculation shown in equation 1 below on the signals of these 8 fields. However, Fn (n-1 to 8) represents the signal of the nth field.

Hereinafter, the processing between fields according to the transmission sequence as shown in the first equation will be referred to as field sequence processing.

F=1/4 ((Fl-F5)+ (F6-F2)+
(F3-F7)+ (F8-F4)) ...(1)
In practice, the signal shown in FIG. 4(d), which is obtained by differentiating the signal shown in FIG. 4(C), is used as the reference signal for ghost detection, and the following ghost removal calculation is performed. This is generally a method for determining the tap coefficients of a transversal filter. as MSE (Mean
5quare Error) method or ZF (Ze
r.

Forcing) method, etc., which sequentially correct on the time axis according to a certain algorithm to finally find the optimal tap coefficient. If the output signal of the transversal filter is (Yk), the reference signal is (Rkl), and the difference signal between the output signal of the transversal filter and the reference signal is (Ekl), and the total number of taps is M+N+1, then the Tap coefficient C(i)'”
) is modified based on the following equation 2 in the MSE method and equation 3 in the ZF method. However, α and β are coefficients for determining the amount of correction.

(Ci) ``”'= (Ci l '''-β・E
i... (3) After performing the synchronous addition and field sequence processing shown in the first equation, the CPU 4 repeatedly corrects the tap coefficients of the transversal filter 3 by calculating the second or third equation. . A series of these processes is performed by software, and the processes are repeated until the amount of residual ghost becomes sufficiently small in ghost detection.

In the conventional configuration, if the correlation calculation of the second equation is to be performed at high speed, dedicated hardware must be prepared separately or high-speed software processing is required.

Problems to be Solved by the Invention However, in the above configuration, the hardware configuration for performing the correlation calculation becomes complicated and expensive. Even when correlation calculation is performed by software processing, there is a problem in that the processing takes time and the ghost removal time becomes long.

The present invention solves the above-mentioned problems, and aims to provide a ghost removal device that is inexpensive and can perform high-speed processing.

Means for Solving the Problems In order to solve the above problems, the ghost removal device of the present invention includes a first waveform memory that captures the signal after passing through the transversal filter so that the transversal filter can be used as a correlation operator. , a second waveform memory serving as a signal source, and a switching circuit that switches between an output signal from the second waveform memory serving as a signal source and an input video signal and outputs the same to a transversal filter.

Effects According to the present invention, with the above-described configuration, correlation calculation can be performed between the first waveform memory and the tap coefficient by moving the switching circuit to the second waveform memory side, and the calculation result is taken in from the waveform memory.

Embodiment Hereinafter, a ghost removal device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram of the circuit configuration of a ghost removal device in an embodiment of the present invention. In FIG. 1, 1 is a first waveform memory, 2 is a switching circuit that switches between the input video signal and the output of the waveform memory 1;
3 is a transversal filter, 4 is a CPU, and 5 is a second waveform memory inserted between the output terminal of the transversal filter 3 and the CPU 4. The switching circuit 2 receives an input video signal and an output signal from the first waveform memory l. After the ghost removal is completed, the switching port B2 changes to the input video signal a side, and the ghost is removed through the transversal filter 3, and the signal is output as an output video signal. On the other hand, during the transition from the first waveform memory 1, the switching circuit 2 switches to the output signal side of the first waveform memory 1, and the switching circuit 2 switches to the output signal side of the first waveform memory 1.
The configuration is such that an output signal is inputted, a correlation calculation is performed through a transversal filter 3, and the output signal is taken into the CPU 4 through the first waveform memory 1.

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

FIG. 2 is a flowchart showing a specific embodiment of the present invention. First, in the first step 5, an OCR signal is captured from the output video signal. Imported GCR
The signal is synchronously energized in the CPU 4 according to an 8-field sequence, and a difference between the signal and a reference signal stored in the pre-warning unit is performed. Here, the tap coefficients of the transversal filter 3 are modified based on the second equation of the MSE method. In the second step 6, the difference E
k is written into the first waveform memory 1 as correlation data.

In the third step 7, the switching circuit 2 switches the input to the transversal filter 3 to the b side (first waveform memory side). In the fourth step 8, the captured data Yk after synchronous addition is written as correlation data to the transversal filter 3. In the fifth step 9, the results of the correlation calculations prepared in the second to fourth steps are written to the waveform memory 1.
can be taken in more. In the sixth step 10,
The input to the transversal filter 3 is set to a by the switching circuit 2.
side (input video signal side). In the seventh step 11, C1 is calculated based on the second equation, and the tap coefficients written in the transversal filter are corrected.

As described above, according to this embodiment, the transversal filter can also be used as a correlation operator.

Effects of the Invention As described above, according to the present invention, by using a transversal filter as a correlation operator, there is no need for hardware dedicated to correlation calculations, and inexpensive and high-speed calculations are possible.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a ghost removal device according to an embodiment of the present invention, FIG. 2 is a flowchart showing the process flow of the ghost removal device of the present invention, and FIG. 3 is a block diagram of a conventional ghost removal device. Fig. 4 a, b, c, d
is a waveform diagram for explaining the basic operation of ghost removal. l...Waveform memory, 2...Switching circuit,
3... Transversal filter, 4...
...CPU. Name of agent: Patent attorney Shigetaka Awano

Claims (1)

[Claims] A ghost removal device using a transversal filter, comprising: a first waveform memory that captures the signal after passing through the transversal filter; a second waveform memory that serves as a signal source; and the second waveform. A ghost removal device comprising a switching circuit that switches between an output signal from a memory and an input video signal and outputs the signal to a transversal filter, the transversal filter having a function of correlation calculation.