JPH0443785A - Video signal processing unit - Google Patents

Abstract

PURPOSE:To realize a video signal processing unit whose picture quality is substantially eliminated by controlling the transfer characteristic of a spacial filter circuit applying 2-dimension spacial filter processing of horizontal - vertical conversion to an output signal of a scanning conversion circuit depending on the standard or nonstandard of an incident signal. CONSTITUTION:When an input television signal is a standard NTSC signal, an input signal reflection circuit 820 controls a spacial filter 810 so as to have a substantial broad band transmission characteristic and a signal from a sequential scanning conversion circuit 800 is sent to a D/A converter 51 without band limit. On the other hand, when the input signal is a nonstandard signal, the input signal reflection circuit 820 controls the spacial filter 810 so as to have a horizontal - vertical 2-dimension spatial frequency characteristic and eliminates a high frequency component in an oblique direction from a signal sent from the sequential scanning conversion circuit 800 and gives the result to a D/A converter 51. Thus, the deterioration in the picture quality is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a television signal processing device, and more particularly to a video signal processing device having a function of converting an interlaced scanning video signal into a progressive scanning signal.

Conventional technology A high-definition television signal having 1125 scanning lines is processed to approximately 8.1 MH by multiple sub-sampling processing.
A MUSE method has been proposed in which the signal is band-compressed and transmitted. This method is based on NHK Technical Research VOL39, No.
2. Development of the rMUSE System in 1987, offset subsampling is performed between fields, between frames, and between lines, so that the subsampling phase goes around in four fields.

It is desired that television signals of the above system can be viewed not only on standard receivers designed for high-definition television, but also on receivers designed for NTSC. A conversion device is required to convert the signal into a 525 scanning line signal. This conversion device is the sixth
As shown in the figure, from among the 16:9 aspect ratio signals of high-definition television signals, the range that is compatible with the current system with 525 scanning lines, that is, the aspect ratio of 4:3 is twice that of 525 lines. The area of 1050 lines is selected and finally converted to 525 lines. Also,
Easily processing the band-compressed signal by the MUSE method is effective in manufacturing this converter at low cost, and for this purpose, the signal processing device is configured to supply signals to the signal input terminal 1 as shown in Figure 7. After converting the MUSE signal into a digital signal in an AD conversion circuit 2, a spatial filter 3 performs low-pass filtering on the vertical-horizontal two-dimensional space, and a time axis conversion circuit 4 converts it into a digital signal for high-definition television. The signal specifications are converted into specifications for a 525-line system, and further encoded into a required composite NTSC signal by an NTSC encoder 6 via a DA conversion circuit 5 and sent to a signal output terminal 10.

The high-definition television image information converted by this MUSE signal conversion device is supplied to a receiving device as shown in FIG. 8, for example. This device has a signal input terminal 11
The converted NTSC signal supplied via the AD conversion circuit 2
After converting it into a digital signal in step 1, the NTSC decoder 7 demodulates it as a luminance signal/color difference signal or (BR) three primary color signals, and outputs it to the image display device 9 via the DA conversion circuit 51.
By converting the number of scanning lines to , a double-density image is displayed.

The configuration of the converter shown in FIG. 7 above adapts the basic scanning parameters, such as the number of scanning lines, image display range, and counts per second, to the current standard receiving system for viewing in a 525-line system. It is converted so that

Problems to be Solved by the Invention When receiving the above-mentioned converted high-definition television broadcast signal, it is possible to obtain a practically usable image quality with the currently widely used interlaced scanning receiving apparatus. However, when the apparatus shown in FIG. 8 described above is used to convert the signals into sequential scanning signals for display, there is a technical problem in that the image quality deteriorates significantly. Among the aliasing components in the temporal direction, that is, the time-frequency domain, caused by inter-frame and inter-field offset subsampling, especially the aliasing of inter-field offset sampling is caused by sequential scan conversion processing in the vertical-horizontal two-dimensional space. This is because it occurs on the screen as an alias.

Therefore, when converting high-definition television signals, it is desirable to avoid significant deterioration in image quality for any of these receiving devices. A spatio-temporal three-dimensional signal processing circuit similar to that designed in the above is required, and as a result, the scale of the conversion device increases, resulting in an economical problem in that it becomes expensive.

An object of the present invention is to substantially eliminate image quality deterioration caused by aliasing components due to inter-field offset subsampling even if the output signal of a simple high-definition television signal conversion equipment has an aliasing component due to inter-field offset subsampling. The objective is to provide a video signal processing device that can perform the following tasks.

Means for Solving the Problems The present invention includes a progressive scan conversion circuit that converts an input television signal of an interlaced scan type into a progressive scan signal, and a horizontal-vertical two-dimensional spatial filtering process for the output signal of this scan conversion circuit. The invention is characterized in that the transfer characteristic of the spatial filter circuit is controlled depending on whether the input signal is a standard signal or a non-standard signal.

Operation The progressive scan conversion circuit described above converts an input television signal of interlaced scanning type having N scanning lines and counting M frames per second to N scanning lines.
This converts into a progressive scanning image signal that counts M images per second. During conversion, it detects moving parts and still parts of the image in the input television signal, and detects the still image part. An interpolated scanning line is generated using a signal of a field adjacent to the processing field, and the spatial filter has a plurality of signal processing modes and performs necessary signal processing on the sequentially scan-converted video signal. The spatial filter is controlled so that the input television signal operates essentially as an all-pass filter or two-dimensional enhancer for standard signals and as a two-dimensional low-pass filter for non-standard signals.

EXAMPLES Below, the present invention will be described in detail with reference to the drawings. 1st
The figure shows a video signal processing device in an embodiment of the present invention.

In the figure, an interlaced scanning television signal supplied to a signal input terminal 110 is converted into a digital video signal by an AD conversion circuit 210, and then converted into a progressive scanning signal by a progressive scanning conversion circuit 800.

For example, in the case where the input television signal is a standard signal according to the known NTSC system, this progressive scan conversion circuit 800 has 525 scanning lines, a field frequency of 59.94 (Hz), and a frame frequency of 29.
97 (H2) signal, that is, the horizontal scanning frequency is 15.
734 (KH2) input signal with a horizontal scanning frequency of 31
．． 468 (KHz), the number of scanning lines is 525, and the frame frequency is 59.94 (Hx). When the input television signal is encoded using the NTSC system and frequency-multiplexed with a luminance signal (hereinafter referred to as Y signal) and a carrier color signal (hereinafter referred to as C signal), the progressive scan conversion circuit uses its input section. A Y/C separation circuit for performing Y/C separation and an NTSC color decoder for demodulating the separated C signal and returning it to a color difference signal are arranged, and sequential scanning conversion is performed for each of the Y signal and color difference signal. configured to perform processing.

The spatial filter 810 performs filter processing in a vertical-horizontal two-dimensional space on the video signal supplied from the progressive scan conversion circuit 800. C signal and 1
In the case of a precisely frequency interleaved relationship with a /2 line offset, input signal discriminator circuit 820 controls spatial filter 810 to maintain a substantially wideband transmission characteristic. This allows the Y signal and C signal supplied from the progressive scan conversion circuit 800 to be transferred to the conductor 8 without band-limiting.
11 to the DA converter 51.

On the other hand, if the input television signal is a non-standard signal,
That is, if the frequency interleave relationship between the Y signal and the C signal is not maintained, the input signal discrimination circuit 820 selects the spatial filter 810 so that the vertical-horizontal two-dimensional spatial frequency characteristics are as shown in FIG. After removing diagonal high-frequency signal components from the signal sent from the progressive scan conversion circuit 800, the D
It is supplied to the A conversion circuit 51 as a sequentially scan-converted video signal. In Fig. 2, the vertical axis is the vertical spatial frequency ν (book).
, the horizontal axis is the horizontal spatial frequency μ (MHz), and no band-limiting effect is applied to the vertical, horizontal, and horizontal signal components of the input television signal, and high-frequency signals in the diagonal direction on the screen are The signal passing characteristic is set to remove or suppress only the component. This can be obtained, for example, by cascading a vertical reduction pass filter and a horizontal reduction filter.

Vertical spatial frequency 525/2 (line) indicates the highest frequency in the vertical direction that can be reproduced without distortion with a video signal of 525 (line) scanning lines converted to a progressive scanning method, and the horizontal spatial frequency μm The highest frequency of the Y signal of the NTSC video signal is approximately 4 (MH), so it is approximately twice the highest frequency, 8 MH, and both the vertical and horizontal sampling frequencies are doubled by sequential scan conversion. This is because.

The two-dimensional low-pass characteristic shown in FIG. 2 shows an example of the characteristic of the spatial filter 810 when a non-standard signal is input, but in implementing the present invention, it is not necessarily limited to this characteristic. This is not necessary and can be realized in terms of the video signal bandwidth of the input television signal, circuit scale, manufacturing cost, etc.

The aforementioned AD conversion circuit 210 and DA conversion circuit 51 are for converting an analog input television signal into a digital signal, subjecting it to the above-described signal processing, and then supplying the signal to the display device 9 that is compatible with the analog signal. However, it is not essential for carrying out the present invention and can be selected as appropriate.

Next, another embodiment of the present invention will be described with reference to FIG. In the figure, the signal input terminal 111 is the AD conversion circuit 2.
11 input, and this AD conversion circuit 211
The output of is coupled to the input of Y/C separation circuit 812. This Y/C separation circuit 812 is connected to the signal input terminal 111.
When a TSC composite signal is supplied, the inter-line correlation or inter-frame correlation is performed independently or in combination to separate the Y signal and the C signal and send the Y signal to the lead 41813 and the C signal to the lead 814. . In the above case, the signal selection circuit 213 is connected to the conductor 81 as shown in the figure.
The C signal demodulation circuit 214 selects the terminal b to which C. 4 is coupled, that is, the dotted line side, and outputs color difference signals, such as I and Q signals. C signal scanning conversion circuit 21 to which this color difference signal is supplied
5 converts the interlaced scanning signal into a progressive scanning signal by signal processing within a field or between fields, and then removes oblique high frequency signal components with a C signal spatial filter 216 and supplies the signal to an inverse matrix circuit 817.

The Y signal sent to the aforementioned conducting wire 813 is converted from an interlaced scanning signal to a progressive scanning signal by a Y signal scanning conversion circuit 815, and after removing diagonally high frequency signal components by a Y signal spatial filter 816, GB is supplied to the aforementioned inverse matrix circuit 817 and subjected to inverse matrix processing with the color difference signal.
It is converted into the three primary color signals of R, and further sent to the DA conversion circuit 510.
is supplied to the display device 9 via. Signal input terminal 112
The AD conversion circuit 212 is for separating and combining the Y signal and the C signal, and in this case, the signal selection circuit 213 described above is sent out from the AD conversion circuit 212 on the a side, that is, as shown by the solid line. The C signal is selected and supplied to the C signal demodulation circuit 214. When performing this separation/combination, the YC separation circuit 812 substantially stops the inter-line correlation or inter-frame correlation processing and can supply the signal from the AD conversion circuit 211 as it is to the Y signal scanning conversion circuit 815.

FIG. 4 shows an example of the configuration of a spatial filter arranged according to the present invention, and a Y signal spatial filter 816 is a two-dimensional Y signal L P that constitutes a low-pass filter in a vertical-horizontal two-dimensional space. F8161 and a signal selection circuit 8162 that selects the input and output of this filter, and the C signal spatial filter 216 constitutes a low-pass filter in the vertical-horizontal two-dimensional space similarly to the Y signal. It has a C signal two-dimensional LPF 2161 and a signal selection circuit 2162 that selects the input and output of this filter.

These signal selection circuits 8162 and 2162 are controlled by the input signal discrimination circuit 820, and when the input signal is a standard signal, both select the a side so as not to substantially give a band limiting effect. In addition, when the input signal is a non-standard signal, the b side is selected and both the Y signal and the C signal are controlled to undergo two-dimensional low-pass filter processing.
The inverse matrix circuit 817 is configured to obtain three primary color signals of (1 and BR). Therefore, like the MUSE signal (
Only for converted high-definition television signals that are band-compressed by field offset subsampling, or for so-called quasi-NTSC signals in which the frequency interleaving relationship between the Y signal and the C signal is not maintained accurately, 2 is converted after sequential scan conversion. Since dimensional LPF processing is performed, optimal signal processing can be performed on each signal.

The Y signal spatial filter 816 described above may be configured as shown in FIG. area signal components are obtained. Signal selection circuit 81
62 has this two-dimensional high-frequency signal component on one terminal a side, and the other terminal a side is equivalently grounded, and the conductor 8201
A control signal supplied through selects side a for standard signals and side b for non-standard signals. When this signal selection circuit 8162 selects the a side, the two-dimensional high frequency signal component sent from the subtraction circuit 8163 is amplified by the amplifier circuit 8164, and the Y signal two-dimensional L
After being combined with PF, it is sent out on conductor 8166. Therefore, in this case, the two-dimensional high-frequency signal component is enhanced, so that the sharpness is improved with respect to the standard signal.

Further, when the signal selection circuit 8162 selects the b side, that is, for a non-standard signal, the input of the amplifier circuit 8164 becomes no signal, so the adder circuit 8165 effectively selects the Y signal 2.
Only the signal from dimension L P F8161 is connected to conductor 8166
sent to. Therefore, for non-standard signals, the image quality deterioration factor caused by undesirable field offset sub-samples can be removed, as shown in FIG. I can provide it.

Effects of the Invention As described above, when converting an interlaced scanning signal into a progressive scanning signal, the present invention arranges a spatial filter that inputs the signal after progressive scanning conversion, and uses two-dimensional low-pass characteristics for non-standard signals. This is a spatial filter that prevents deterioration of image quality by removing or suppressing two-dimensional high-frequency signal components, and performs broadband processing or two-dimensional high-frequency signal enhancement processing on standard signals. By simply adding a large-scale circuit, it is possible to perform optimal signal processing according to the condition of the input television signal supplied to this signal processing device, making it possible to reproduce high-quality images without sacrificing economic efficiency. It has great effectiveness.

Although the above explanation shows a configuration in which the progressive scan conversion and the spatial filter are arranged separately, it is of course possible to integrate them as a circuit configuration, and it is also possible to perform discrimination of input television signals. It goes without saying that the present invention is not limited to the configuration of the example and that various modifications can be made in implementing the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a video signal processing device according to an embodiment of the present invention, FIG. 2 is a characteristic diagram of a spatial filter suitable for implementing the present invention, and FIGS. FIG. 5 is a partial specific configuration diagram of the video signal processing device in the embodiment, and FIG. 6 shows an example of converting a high-definition television signal to a current standard television signal. FIG. 7 is a block diagram of a processing device for a MUSE high-definition television. 110...Signal input terminal, 210...
AD conversion circuit, 800... progressive scanning conversion circuit,
810... Spatial filter, 51...D
A conversion circuit, 9... Image display device, 820...
...Input signal discrimination circuit. Name of agent Patent attorney Shigetaka Awano 1 person Figure 1 DA Conversion Mouth Road AD Sleep/n Times n Q-th run distance @ circular g island 9 filter input No. 18 barely g 2nd rgJ Fig. 1 Figure Figure Figure

Claims (5)

[Claims] (1) In a device that performs inter-field interpolation processing on an input television signal of interlaced scanning type and converts it into an output television signal of progressive scanning type, a vertical-horizontal 2. A video signal which is effectively equipped with a spatial filter that performs signal processing in a dimensional space, and which functions as a two-dimensional low-pass filter when an input television signal is a non-standard signal. Processing equipment. (2) The video signal processing device according to claim 1, wherein the signal processing characteristics of the spatial filter are controlled by determining whether the input television signal is a standard signal or a non-standard signal. (3) Input television signal has 1125 scanning lines
2. The video signal processing device according to claim 1, wherein the spatial filter is a two-dimensional low-pass filter when the signal is a non-standard signal obtained by converting a USE system high-definition signal to 525 scanning lines. (4) Claim 2 characterized in that when the input television signal is a standard television signal based on the NTSC system, the spatial filter has substantially wideband transmission characteristics.
The video signal processing device described above. (5) The video signal processing device according to claim 4, wherein the spatial filter is formed by enhancing a two-dimensional high-frequency signal.