JPS63198490A - Video signal processor - Google Patents

Abstract

PURPOSE:To prevent variation in resolution and deterioration in quality of a picture due to flickering, etc., by forming a video signal of one field by interpolating the video signal in the other filed, and outputting by always switching the interpolated video signal. CONSTITUTION:A digital video signal is inputted from an input terminal 1 to a sampler 2. In the mean time, a clock pulse in synchronizing with an input video signal from a terminal 7 is inputted to a pulse generator 6, a pulse signal whose frequency is four times of vertical frequency Fv of an input video signal is inputted to the sampler 2, and a line consisting of three lines of zero data is inserted between the respective lines of input video signals. A video signal whose vertical frequency is 4Fv from the sampler 2 is inputted to a sampler 4 via a digital filter 3. The sampler 4 receives a pulse signal from a pulse generator 8, and selectively outputs a signal of group delay of Th/4(Th=1 horizontal period) or a signal whose group delay is 3Th/4 depending on the agreement/disagreement between the level of a field pulse 11 from an agreement detection circuit 9 and that of a reference field pulse 10.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to a video signal that is used to match the field sequentiality of a video signal reproduced by a VTR when the field sequentiality is not constant. It relates to a processing device.

[Summary of the invention]

In the present invention, when odd and even fields are not repeated alternately, such as in a still image reproduction signal of a VTR, in a video signal processing device that matches the repetition of attributes of these fields as a reference, one The video signal of the other field is formed by interpolating the video signal of one field, and the interpolated video signal is always switched and output, so fluctuations in the resolution of the interpolated video signal and deterioration of image quality such as flicker are prevented. Ru.

[Conventional technology]

As one type of VTR, one is known in which the position of a rotary head can be displaced in the height direction and reproduced images without noise can be obtained. A VTR is also being considered in which the tape speed is shifted by a factor of 1% relative to the 1x speed ()-multiple playback) so that the program playback time can be finely adjusted.

During these variable speed reproductions, a mismatch occurs between the field attributes of the reproduced video signal from the VTR and the reference field attributes.

FIG. 7A shows the standard field attributes, in which odd fields indicated by 0 and even fields indicated by E are alternately repeated. FIG. 7B shows field attributes during still playback. When switching from normal playback operation to still playback operation in the field indicated by *, only the same field, for example, even field E, continues and is different from the standard field attribute. Discrepancies occur in every other field.

FIG. 7C shows the field attributes during program playback, and in order to finely adjust the playback time, odd fields are removed or even fields are repeated, so the field attributes and standards of the subsequent playback signal are shown. field attributes will no longer match. When a mismatch occurs in the field attributes as described above, since the monitor receiver is operated using a reference signal, when the mismatch occurs, image quality deterioration such as flickering in which the image shakes in the vertical direction is caused.

In order to prevent this image quality deterioration, in conventional VTRs, when field attributes do not match, interpolation is performed using a field image formed by the average value of the upper and lower lines, while when they match, interpolation is performed. The input video signal is used as is.

[Problem that the invention seeks to solve]

However, in conventional video signal processing devices that interpolate only fields that do not match the reference field attributes,
During still playback, matches and mismatches occur alternately,
Therefore, a reproduced video signal and an interpolated video signal whose vertical resolution is inferior to that of the reproduced video signal are output alternately, resulting in flicker. Furthermore, during program playback, before a mismatch occurs, a reproduced video signal is output, and after a mismatch, an interpolated video signal is output. Therefore, there is a problem in that the vertical resolution of the reproduced image fluctuates before and after the mismatch occurs.

Therefore, it is an object of the present invention to match field attributes between an input video signal obtained by still playback, program playback, etc. of a VTR and a reference signal, and to prevent flickering.
It is an object of the present invention to provide a video signal processing device in which deterioration of image quality such as fluctuation in resolution is prevented.

[Means for solving problems]

In the present invention, a video signal whose field sequentiality is not constant is supplied, and in a video signal processing device for matching the field sequentiality of this video signal with a reference, the video signal of one field is interpolated to improve the field order of the other field. video signals are formed, and interpolated video signals are always output alternately.

[Effect]

If the field sequentiality no longer matches that of the standard,
The video signal of the interpolated field is always output, both for the match field and the non-match field. The digital filters used for field interpolation for coincidence and mismatch have the same frequency characteristics, and the group delay in the case of coincidence is (1/4) Th, and the group delay in the case of mismatch is (3/4). Th. By performing such interpolation, problems such as flickering and resolution fluctuations can be prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, for example, VT
A digital video signal reproduced by R and converted into a digital signal is supplied. This digital video signal is supplied to the sampler 2. If the vertical frequency of the input digital video signal is Fv, a pulse signal of 4Fv from the pulse generator 6 is supplied to the sampler 2. A clock pulse synchronized with the input digital video signal is supplied to the pulse generator 6, and the pulse generator 6 forms a pulse signal with a frequency of 4FV synchronized with the input digital video signal. The sampler 2 inserts three lines of zero data between each line of the input digital video signal. That is, if the field line spacing is H, then (1/4)H, (2/4)H, (3/4)
)H, zero data is inserted into the line at each interval position.

The digital video signal from the sampler 2 whose vertical frequency has been converted to 4FV is supplied to the digital filter 3. The output signal of this digital filter 3 is sampled by a sampler 4.
The output signal of the resampler 4 is taken out to the output terminal 5. The resampler 4 is supplied with a pulse signal from a pulse generator 8 .

Resampler 4 has a group delay of (1/4) Th or (3/4
) Th (Th: 1 horizontal period). The phase of the pulse signal supplied from the pulse generator 8 to the ressembler 4 is controlled by a control signal from the coincidence detection circuit 9, and switching between two signals having different group delays is performed depending on the phase of the pulse signal. - The reference field pulse is supplied to the multiple output circuit 9 from one input terminal 10, and the reproduced field pulse is supplied from the other input terminal 11. These field pulses have a high level in odd (0) fields and a low level in even (E) fields, for example. A reproduction field pulse and a reference field pulse are formed from the phase relationship between the vertical synchronization signal and the horizontal synchronization signal of the reproduction signal and the reference synchronization signal, respectively. - The control signal output circuit 9 generates a control signal indicating whether the logical levels of the field pulses match or do not match.

If the reference field pulse and the reproduced field pulse match, the pulse generator 8 generates a pulse signal that causes the resampler 4 to select a signal having a (1/4) Th0 group delay. Furthermore, if the reference field pulse and the reproduction field pulse do not match, the resampler 4 (3
/4) The pulse generator 8 generates a pulse signal for selecting a signal with a group delay of Th. The digital video signal obtained from the ressembler 4 has a vertical frequency of 4FVO.

FIG. 2 shows an example configuration that can be used as the digital filter 3. In FIG. 2, D1 to D6 indicate six unit delay elements connected in cascade. Unit delay element D1
~D6 each has a delay amount of (1/4) Th. The output signal of the sampler 2 is supplied from the input terminal 16 to the cascade connection of these unit delay elements D1 to D6. The output signals of the input terminal 16 and the unit delay elements D1 to D6 are taken out and supplied to the coefficient multipliers M1 to M7, respectively.
Ru. The coefficients of the coefficient multipliers M1 to M7 are - for example, the second
As shown in the figure, the settings are (1, 2, 3, 4 degrees 3.2.1).

The output signals of each of the coefficient multipliers M1 to M7 are supplied to an adder 17, and the output signal of the adder 17 is supplied to a divider 18 for scaling. The divider 18 is the adder 17
This is provided to reduce the output signal to (1/16). The output signal of the divider 18 is taken out to the output terminal 19.

The transfer function H(
z) is H(z)=H1(z) ・H2(z)−−(1+Z−
') ” (1+Z-”) ”, therefore, the second
The digital filter shown in the figure is as shown in FIG.
Impulse response 20(1) corresponding to transfer function H1(2)
There is an impulse response 22 (indicated by a solid line) which is a composite of the impulse response 21 (indicated by a broken line) corresponding to the transfer function H2(Z). This impulse response 22 removes harmonic components (generated around the frequencies of Fv, 2Fv, 3Fv, 4Fv, etc.) generated after sampling.

Further, the frequency transfer characteristic of the digital filter shown in FIG. 2 is shown by 23 in FIG. The conventional interpolation digital filter has a configuration that uses data at corresponding sampling positions of the upper and lower lines, and has (z(1+Z-1)) as a transfer function. In Figure 4, 24
As shown, there are null points where the amplitude is zero at (525/4) vertical frequencies. On the contrary,
As is clear from the frequency characteristic 23, the digital filter shown in FIG. 2 has the advantage that there is no null point and that the signal band in the vertical direction can be widened.

The characteristics of the digital filter 3 shown in FIGS. 3 and 4 are such that the group delay selected by the resemblance 4 is (1/
4) The same applies to both Th and (3/4)Th signals. Therefore, the interpolated field signals formed when the reference field and the reproduced digital video signal field match in terms of attributes and when they do not match have the same frequency characteristics and impulse response characteristics. It is something.

The interpolation operation performed by this embodiment during still playback will be described with reference to FIG. FIG. 5 shows an interpolation operation when the field attribute of the reproduced video signal is fixed to an even field E, as shown in FIG. 7B. In FIGS. 5 and 6, solid lines indicate lines of even fields, broken lines indicate lines of odd fields, . indicates samples originally existing in the input data,
O indicates interpolated data formed by the sampler 2 and digital filter 3, and ◎ indicates output data selected and output by the sampler 4.

When the field attribute of the reproduced digital video signal is an odd field and does not match the reference field, (
3/4) Interpolated data of the Th0 group delay is selected by the ressembler 4. Further, when the attribute of the field of the reproduced digital video signal is an even field and matches the reference field, the ressembler 4 selects interpolated data with a (1/4) Th0 group delay. Therefore, in any of these cases, an output image with proper IH spacing can be obtained.

FIG. 6 shows the interpolation operation during program playback. During program reproduction, the attributes of the field of the reproduced image and the attributes of the reference field always do not match. Therefore, as shown in FIG. 6, whether the input sample is an even field or the input sample is an odd field, interpolated data with a group delay of (3/4) Th is output by the ressembler 4. selected as.

Therefore, the output image becomes an image in which the IH interval is maintained appropriately.

The digital filter shown in FIG. 2 has an example configuration, and digital filters other than the configuration shown in FIG. The configuration may be such that it is applied only during variable-speed playback such as motion and program playback, and the original playback video signal is output during normal playback.

〔Effect of the invention〕

In this invention, when a mismatch occurs between the field attributes of an input video signal and the reference field attributes, such as in a VTR playback video signal, the same interpolation is always performed regardless of whether they match or do not match. A field interpolated image with the same frequency characteristics and with the line spacing properly maintained at IH between two fields is output. According to the present invention, unlike a conventional video signal processing device that outputs both a field-interpolated image and an original image, deterioration in image quality such as flicker and resolution fluctuation can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of this invention, Fig. 2 is a block diagram of an example of a digital filter used in this embodiment, and Figs. 3 and 4 are used to explain the characteristics of the digital filter. The graphs, FIGS. 5 and 6 are route maps used to explain the interpolation operation of this embodiment, and FIG. 7 is a route map used to explain the mismatch in field attributes between the reproduced video signal and the reference signal. It is. Explanation of main symbols in the drawings 1: input terminal, 2: sampler, 3: digital filter, 4: resampler, 9-matching detection circuit. Agent: Tadashi Sugiura, Patent Attorney: Figure 1, Figure 1, Figure 2

Claims (2)

[Claims] (1) In a video signal processing device which is supplied with a video signal whose field sequentiality is not constant and which matches the field sequentiality of the video signal with a reference, by interpolating the video signal of one field, the field sequentiality of the other field is A video signal processing device that forms a field video signal and always outputs interpolated video signals alternately. (2) In the video signal processing device according to claim 1, the interpolated video signal is vertically shifted by an amount of 1/4 interval from each line of the video signal of the one field. A video signal processing device comprising an interpolated signal.