JP3157706B2 - Video signal processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a special effect device for high-quality video signals, and more particularly to a video signal processing device for applying a special effect to interlaced video signals.

[0002]

2. Description of the Related Art In the case of special effects accompanied by image reduction,
A pre-filter for preventing aliasing is required before. In addition, in order to obtain high image quality particularly in a still area, it is necessary to perform frame processing using a video signal one field before rather than processing closed within a field.

In order to realize frame processing in the prior art, there is a method shown in FIG. In the figure, the input video signal 5
From 1, the motion detection circuit 2 detects a motion signal 52 representing a motion area of a video. The progressive scan conversion circuit 5 sequentially scans the input video signal 51 using the motion signal 52 and outputs a progressive scan video signal 61. The progressive scanning is realized by interpolating the signal of the previous field in the still area and the signal of the current field in the moving area. On the other hand, the type of the special effect is input as a signal 56, and a reduction ratio generation circuit 4 generates a reduction ratio 55 for each pixel from information indicating the reduction ratio therein. The filter coefficient generation circuit 9 generates a filter coefficient 62 according to the reduction rate 55. The filter circuit 8 performs a filtering process on the progressively scanned video signal 61 in accordance with the filter coefficient 62, and becomes a signal 63. Finally, in the special effect circuit 7, the signal 56
The signal 63 is transformed according to the formula (1) to obtain an output 64.

[0004]

In the above-mentioned prior art, since the filtering process is performed in the state of the sequential scanning, it is difficult to perform the vertical filtering process having the same characteristics as that of the interlaced scanning process. Double the number of taps is required.
Since it is necessary to process this for twice as many scanning lines, there is a problem that the processing amount becomes four times in total.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a video signal processing apparatus which alleviates the above-mentioned drawbacks of the conventional system and performs preprocessing without increasing the hardware scale.

[0006]

A video signal processing apparatus according to the present invention receives a video signal of interlaced scanning and reduces a video reduction ratio.
Filter that limits the bandwidth according to the
A progressive scan conversion circuit that converts an image signal into a progressively scanned video signal.
Path and the progressive scan conversion video signal from the progressive scan conversion circuit.
Changes the passband according to the movement of the video content
A vertical filter. In addition, the video signal processor of the present invention
Processing device detects the motion region of the input video signal
A circuit, a reduction ratio generating circuit for generating a reduction ratio of the image,
From the motion area and the reduction ratio, a folding distortion preventing flag is used.
Filter coefficients and static area correction filter coefficients are generated.
A filter coefficient generating circuit for preventing
Filter the input video signal according to a filter coefficient.
And a filter circuit for applying
A progressive scan conversion circuit for converting to scanning, and the progressive scan conversion
The output of the circuit is supplemented by the filter coefficient for the static region correction.
And a static area correction circuit for performing a normal process.

In the video signal processing apparatus according to the present invention, a filtering process for preventing aliasing is performed while taking the amount of motion into consideration while performing the interlaced scanning, and the image is sequentially scanned, and then the still area is corrected. In the filtering processing for preventing aliasing, a low-pass filter having a pass band twice as large as that of the moving region is applied to the stationary region. Therefore, the filtering process is applied to the still region only when the reduction ratio is 1/2 or less. If the reduction ratio is less than １ ／, the band is limited by the correction processing of the still area in the subsequent stage.

In the present invention, among the filter processing for preventing aliasing, the vertical filter is applied in an interlaced scanning state. A tap number of 2 is sufficient.
In addition, since it is only necessary to output by interlaced scanning, it is further reduced to 1/2.
, And the total processing amount is で. on the other hand,
Since the correction process after the sequential scanning only needs to correspond to a reduction ratio of up to 縮小, the number of taps may be 以下 or less as compared with a filter for preventing aliasing. That is, even when viewed as a whole, it is possible to reduce the hardware scale as compared with performing filtering processing for preventing aliasing after sequentially scanning.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS. In the present embodiment, as an example, it is assumed that the anti-aliasing filter has a configuration in which a horizontal filter and a vertical filter are connected in cascade.

FIG. 1 is a block diagram showing a basic configuration of an embodiment of the present invention. First, the input video signal 51 of the interlaced scanning is input to the motion detection circuit 2 and the filter circuit 1. The motion detection circuit 2 detects a motion area for each pixel from the video signal and outputs it as a motion signal 52.

On the other hand, the type of the special effect is input as a signal 56, and when reduction is involved, a reduction ratio 55 for each pixel is generated in the reduction ratio generating circuit 4. For example, when reducing an image vertically and horizontally to half, horizontal pixels are used for all pixels.
A value of 5, vertical 0.5 is generated. Next, the filter coefficient generation circuit 3 generates a filter coefficient 53 and a still area correction coefficient 54 according to the reduction rate 55 and the motion signal 52. The filter of the filter circuit 1 is represented by the following equation. When a filter coefficient Ak is given, the filter output Yj
Is calculated according to the following equation (1).

[0012]

(Equation 1) For example, when a reduction ratio of 0.5 is input, 7 taps (k
= 3), for example, the following coefficients are first generated.

[0013]

(Equation 2) Expression (2) is output as the filter coefficient 53 as it is for the filter coefficient of the horizontal filter. On the other hand, as for the filter coefficient of the vertical filter, the motion signal is considered with respect to the coefficient of the equation (2). That is, in the stationary region, the filter coefficient having a pass band twice as large as the moving region is output as the filter coefficient 53.
When the reduction ratio is less than 1/2, the filter coefficients of all bands are output in the stationary region. When the reduction rate is R, the filter coefficient generation circuit 3 generates a filter coefficient (still area correction coefficient) 54 that makes R in comparison with the case where the pass band after the sequential scan conversion is not reduced in the still area. When the reduction rate is 1/2, for example, the equation (2) may be output as the correction coefficient 54. Next, in the filter circuit 1,
The input video signal 51 is subjected to the filtering process determined by the filter coefficient 53, and the signal 57 is output. The filter circuit 1 is configured by cascade connection of a horizontal filter and a vertical filter, and each filter may be configured by a known FIR filter. The vertical filter unit does not use the signals of the preceding and following fields.

The signal 57 output from the filter circuit 1 is converted into a sequential scanning signal 58 in the sequential scanning conversion circuit 5. Further, the progressive scanning signal 58 is supplied to the static area correction circuit 6.
Is subjected to vertical filter processing determined by the correction coefficient 54, and becomes an output signal 59. The vertical filter of the static region correction circuit 6 may be an FIR filter capable of changing a filter coefficient for each pixel, and may be configured by a well-known technique. The image of the output signal 59 is transformed in accordance with the signal 56 in the special effect circuit 7, and is output as the effect output signal 60.

FIG. 2 is a diagram showing the vertical filter characteristics in the above embodiment. Each of them is expressed in a two-dimensional vertical / time frequency space, for example, with a field frequency of 60 Hz and a number of scanning lines of 525. FIG.
(A) in FIG. 7A represents the signal carrier position of the input interlaced video signal. FIG. 2B illustrates an example of the pass band characteristic of the filter circuit 1 when the reduction ratio is 1/2. In a region where the time frequency f is small, that is, in a stationary region, the pass band is extended, that is , the band is not limited . FIG. 2C illustrates an example of the overall passband characteristic up to the static region correction circuit 6. Equivalent to performing anti-aliasing filter processing after sequential scanning,
The band of the video signal is limited .

FIG. 3 is a diagram showing a horizontal filter and a vertical filter of the filter circuit 1 and a filter configuration of the still area correction circuit 6. The delay circuit 10, the multiplication circuit 11, and the addition circuit 1
The delay circuit 10 delays one pixel in the horizontal filter and one line in the vertical filter.

As described above, according to the present embodiment, it is possible to reduce the hardware scale without lowering the image quality, as compared with the case where the sequential scanning is performed and the filtering process for preventing the aliasing is performed. It is possible.

Although the present embodiment has been described on the assumption that interlaced video signals are input and output by sequential scanning at a reduction ratio of 0.5, the reduction ratio may be arbitrary.
In the filter circuit 1, horizontal and vertical filters are connected in cascade, but a two-dimensional filter may be used.

[0019]

As described above, according to the present invention,
Compared to performing anti-aliasing filter processing after performing sequential scanning by performing anti-aliasing filter processing while considering the amount of motion with interlaced scanning and performing sequential scanning and then correcting for still areas Thus, the hardware scale can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a video signal processing device according to the present invention.

FIG. 2 is a diagram illustrating pass band characteristics of the filter circuit in the embodiment of FIG. 1;

FIG. 3 is a diagram illustrating a configuration example of a filter circuit according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a basic configuration of a conventional video special effect device.

[Explanation of symbols]

 1, 8 filter circuit 2 motion detection circuit 3, 9 filter coefficient generation circuit 4 reduction rate generation circuit 5 progressive scan conversion circuit 6 static area correction circuit 7 special effect circuit 10 delay circuit 11 multiplication circuit 12 addition circuit

Claims (4)

(57) [Claims] 1. A interlaced receives the video signal of the scan, a filter for limiting the band in accordance with the reduction ratio of movies image, a sequential scanning conversion circuit for converting the video signal of the progressive scanning video signal band-limited, sequentially receiving a progressive scan converted image signal from the scanning conversion circuit, film image content video signal processing device to characterized by comprising a vertical filter to make changes in the passband corresponding to the movement of. 2. The video signal processing apparatus according to claim 1, wherein the filter for limiting the band is executed by a combination of a horizontal filter and a vertical filter. 3. A motion detection circuit for detecting a motion region of an input video signal, a reduction ratio generating circuit for generating a reduction ratio of an image, a filter coefficient for preventing aliasing and a still region correction from the motion region and the reduction ratio. A filter coefficient generation circuit for generating a filter coefficient of the above, a filter circuit for filtering the input video signal in accordance with the filter coefficient for preventing aliasing, and a progressive scan conversion for converting an output of the filter circuit into a progressive scan A video signal processing apparatus comprising: a circuit; and a static area correction circuit for performing an output process of the progressive scan conversion circuit with a filter coefficient for the static area correction. 4. The video signal processing apparatus according to claim 3, further comprising a special effect circuit that receives an output of said still area correction circuit and applies a special effect according to a reduction ratio of said video.