JP2845472B2 - Moving image signal processing method and apparatus - Google Patents

Description

The present invention relates to a method and an apparatus for processing a moving image signal, in particular,
The present invention relates to a moving image signal processing method and apparatus capable of suppressing useless information.

[Conventional technology]

In conventional moving image signal coding, to reduce the coding efficiency due to noise included in the input image signal, the input moving image signal is coded after removing noise with a noise reducer. Had gone.

[Problems to be solved by the invention]

In conventional moving image signal encoding, even when the object of interest is not moving, a large amount of information is generated due to noise or large movement in the background portion, and encoding is often stopped. However, the movement of the object of interest has been discontinuous, which has sometimes been very unsightly. In such a case, the noise reducer was powerless.

An object of the present invention is to provide a moving image signal processing method and apparatus which can significantly suppress information generated from a background other than a point of interest, suppress generation of useless information, and solve the above-described problem. It is in.

[Means for solving the problem]

The present invention is a method of processing a moving image signal using a time filter, wherein a subject portion and a background portion are predetermined in a screen, and an amplification degree of an output with respect to an input is set to 1 or less for the subject portion. By providing a second time filter characteristic closer to zero than the first time axis filter characteristic to the background portion, the amplification degree of the output with respect to the input is given to the background portion. The bandwidth is narrower than the bandwidth of the object portion.

Further, the moving picture signal processing device of the present invention includes a plurality of predetermined background patterns, and selects one of the plurality of background patterns according to a first instruction for selecting the background pattern. A control circuit that outputs a second instruction indicating a subject portion and a background portion in a screen based on the selected background pattern and an input moving image signal;
A time filter having a plurality of bandwidths;
Indicates that the subject is a subject, a first time filter in which the amplification of the output with respect to the input is 1 or less is selected from a plurality of time filters, and the second time filter is selected.
Indicates the background, the second time filter characteristic whose amplification degree of the output with respect to the input is closer to zero than that of the first time filter is selected. And a time filter for suppressing the above.

[Action]

In the conventional low bit rate video coding, when the amount of generated information increases, the coding is temporarily stopped,
The encoding speed and the transmission line speed were matched. However, in such a method, discontinuity occurs in the encoded image when the encoding is stopped, and as a result, the motion becomes unnatural, which is very annoying.

Therefore, in the present invention, for a predetermined background portion,
By applying a time filter with a narrower bandwidth than the focused subject part, the amount of generated information is reduced by suppressing useless information generated from movements of the background, etc. other than the focused subject, and the amount of generated information is reduced. By removing discontinuities in the encoded image, the movement of the subject, which is the point of interest, is smoothed.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of a moving picture signal processing apparatus according to the present invention. This processing device stores a plurality of predetermined background patterns, selects one of the background patterns according to a first instruction, and indicates a subject portion and a background portion in a screen based on an input moving image signal. A control circuit constituting a means for outputting a second instruction, and a means for obtaining a moving image signal having a plurality of bandwidths and having a changed bandwidth with respect to the input moving image signal according to the second instruction are constituted. It has a time filter 2 and an encoder 3 for encoding a moving image signal with a changed bandwidth.

FIG. 2 shows an example of the configuration of such a control circuit 1, which comprises a sync separator 11, a counter 12, and a ROM (Read Only Memory) 13.

The control circuit 1 determines a background pattern as shown by hatching in FIG.
Store in 3. In a videophone or the like to which a low bit rate moving image coding is applied, a person is mainly watched, so a background pattern as shown by hatching in FIG. 4A is prepared. Alternatively, if attention is paid only to the face part, a pattern as shown in FIG. 4B may be used. In this way, a plurality of background patterns are prepared and selected according to the case. The bandwidth of the time filter 2 is switched by giving the background pattern to the time filter in synchronization with the input moving image signal.

FIG. 3 shows an example of the configuration of the time filter 2, which is composed of a subtractor 21, a ROM 22, an adder 23, and a frame memory 24.

The input video signal is input to a frame memory 24 by a subtractor 21.
Is subtracted from the signal of the previous frame given from.
The frame difference signal obtained by the subtracter 21 is stored in the ROM 22
Given to. The characteristics as shown in FIG. 5 are written in the ROM 22 in advance, and the characteristics of the time filter are switched according to the filter switching signal given from the control circuit 1. For the background part, a strong band limitation is performed in terms of time by using a characteristic in which the amplification of the output with respect to the input is much lower than 1 as shown in FIG. 5 (A). For the subject portion, a relatively light band limitation is performed by using a characteristic in which the amplification degree of the output with respect to the input as shown in FIG. ROM2
As the second characteristic, it is also possible to use a non-linear characteristic in which the amplification degree decreases as the frame difference value increases. The frame difference signal to which the output of the ROM 22 has been suppressed is added to the signal of one frame before by the adder 23 to become a moving image signal subjected to band limitation. The moving image signal subjected to the band limitation becomes an output signal of the time filter and is also supplied to the frame memory 24 to be used for filtering of the next frame.

Next, an embodiment of the moving image signal processing method of the present invention,
The description will be made based on the moving picture signal processing apparatus shown in FIGS.

The input moving image signal is supplied to the control circuit 1 and the time filter 2 via the line 100 in FIG. The input video signal supplied via line 100 is provided to sync separator 11. The synchronization separator 11 separates synchronization from an input moving image signal and generates a frame reset signal and a clock for resetting at the beginning of a frame. The frame reset signal generated by the sync separator 11 is supplied to the counter 12 via a line 14. The clock generated by the sync separator 11 is also supplied to the counter 12 via the line 15.

The counter 12 is reset at the beginning of the frame by the frame reset signal supplied from the sync separator 11,
It counts up by the clock supplied from the sync separator 11 and outputs a value indicating the coordinates in the screen. Counter 12
Are supplied to the ROM 13.

As described above, for example, a plurality of background patterns indicated by oblique lines in FIG. The area shown by the diagonal lines in FIG. 4 is defined as the background, "0" is written in the address of the background coordinate, and "1" is written in the address corresponding to the subject.
Is written.

When attention is paid to the entire subject, the fourth
A signal for selecting the pattern shown in FIG.
When mainly focusing on the face portion, a signal for selecting the pattern shown in FIG. ROM13 is line 11
The background pattern is selected in accordance with the background pattern selection signal supplied via 0, and the value written in advance is read in accordance with the coordinate value supplied from the counter 12. RO
The output signal of M13 is supplied to time filter 2 via line 120 as a selection signal for time filter 2.

In FIG. 3, an input moving image signal is supplied to a subtracter 21 of a time filter 2 via a line 100. Subtractor 21
Performs an operation on the input moving image signal and the signal one frame time earlier supplied from the frame memory 24 to obtain a frame difference signal. The frame difference signal obtained by the subtracter 21 is supplied to the ROM 22.

As described above, the value of the input / output relationship as shown in FIG. 5 is written in the ROM 22 in advance. When the selection signal of the time filter 2 supplied from the control circuit 1 via the line 120 indicates "0" to indicate the background, the ROM 22 selects the characteristic shown in FIG. Strict band limitation is applied to suppress background information. When the selection signal of the time filter 2 indicates "1" to indicate a subject, the characteristic shown in FIG. Also suppress the generation of information. The filtered frame difference signal of the output of the ROM 22 is supplied to the adder 23.

The adder 23 adds the filtered frame difference signal supplied from the ROM 22 and the signal one frame before supplied from the frame memory 24 to obtain a moving image signal subjected to background processing. The moving image signal subjected to the background processing obtained by the adder 23 is supplied to a frame memory 24 and output as a line signal as an output signal of the time filter 2.
It is supplied to the encoder 3 via 230. Frame memory 2
Reference numeral 4 denotes a subtractor 21 and an adder 23 which delay the moving image signal subjected to the background processing supplied from the adder 23 by one frame time and perform background processing of the next frame.
Supplied to

The encoder 3 encodes the moving image signal subjected to the background processing supplied from the time filter 2 by using the correlation between the screens or the correlation within the screen, and while matching the speed with the speed of the transmission path. Send the encoded signal to the receiving side.

As described above, according to the present embodiment, the background portion is determined in advance, and a significant band limitation is applied to the background.
Unauthorized information due to the movement of the background portion can be greatly reduced, and the still region of the background portion can be clearly encoded. In addition, for the subject part that is the point of interest,
By applying a relatively light band limitation, the movement can be naturally encoded while suppressing the occurrence of abrupt information of the subject portion.

〔The invention's effect〕

As described above in detail, by using the processing of the moving image signal of the present invention, it is possible to suppress useless information generated due to movement of the background other than the point of interest, and as a result, the movement of the subject which is the point of interest can be suppressed. Can be smooth. Therefore, when the present invention is put to practical use, the effect of improving the image quality in moving image coding is extremely large.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a moving picture signal processing apparatus according to the present invention, FIG. 2 is a diagram showing an example of a configuration of a control circuit of FIG. 1, and FIG. FIG. 4 is a diagram illustrating an example of a configuration of a time filter, FIG. 4 is a diagram illustrating an example of a background pattern, and FIG. 5 is a diagram illustrating an example of characteristics of a time filter. DESCRIPTION OF SYMBOLS 1 ... Control circuit 2 ... Time filter 3 ... Encoder 11 ... Sync separator 12 ... Counter 13,22 ... ROM 21 ... Subtractor 23 ... Adder 24 ... Frame memory

Claims (2)

(57) [Claims] 1. A processing method of a moving image signal using a time filter, wherein a subject portion and a background portion are predetermined in a screen, and an amplification degree of an output with respect to an input is set to 1 or less for the subject portion. Giving a first time filter characteristic and giving the background part a second time filter characteristic whose amplification degree of the output with respect to the input is closer to zero than the first time axis filter characteristic, The bandwidth of the moving image signal is narrower than the bandwidth of the subject portion. 2. A method according to claim 1, wherein a plurality of predetermined background patterns are provided, and one of the plurality of background patterns is selected by a first instruction for selecting the background pattern. A control circuit for outputting a second instruction indicating a subject portion and a background portion in the screen based on an input moving image signal; and a time filter having a plurality of bandwidths,
Indicates that the subject is a subject, a first time filter in which the amplification of the output with respect to the input is 1 or less is selected from a plurality of time filters, and the second time filter is selected.
Indicates the background, the second time filter characteristic whose amplification degree of the output with respect to the input is closer to zero than that of the first time filter is selected. And a time filter for suppressing the image signal.