JPH03133289A - Scanning line converter - Google Patents

Abstract

PURPOSE:To prevent generation of flicker or the like by generating all output scanning line signals while passing them through a vertical filter using the same number of coefficient devices, that is, of the same characteristic when new scanning lines after conversion are sequentially generated. CONSTITUTION:Plural input scanning line signals are made simultaneous and auxiliary signal corresponding to positions symmetrical in the vertical direction are generated by an output of an adder 35. A prescribed coefficient K1 is multiplied with the auxiliary signal. On the other hand, a selector 39 selects the plural signal among the signals processed simultaneously and a prescribed coefficient K2 is multiplied with the selected signal. The coefficients K1,K2 are set so as to be the unity in total and whether the generated new scanning line signal is placed upward or downward depends on the selection operation of the selector 39. Thus, the characteristic of the vertical filter is made identical in the process of generating all the scanning line signal and the generation of flicker or the like is prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention converts a high-definition television signal having a greater number of scanning lines and aspect ratio than a standard television signal into a standard television signal. The present invention relates to a scanning line conversion device used when

(Prior art) MU as a new transmission method for high-definition television signals
S E (Multiple 5ub-Nyquls
tSamping-Encordlng) method has been developed. However, in order to receive signals of this system, a separate receiver dedicated to the MUSE system is required since it is different from the conventional NTSC system transmission system. Currently, high-definition television receivers are expensive, so it is expected that it will take some time for them to become widespread. Therefore, the conventional N
There is a need for a device that receives high-quality signals using a TSC receiver and converts the signal format for viewing.

To obtain this format conversion device, a scanning line conversion device is required that converts 1125 scanning lines of a high-definition television signal into 525 scanning lines, which are the same as an NTSC signal.

FIG. 3 is a diagram shown to explain a method of converting 1125 scanning lines into 525 scanning lines.

FIG. 3(A) is the first field, FIG. 3(B) is the second field, and the solid lines are the input scanning lines that have been transmitted.
It is assumed that the dashed line is the output scanning line after conversion. For example, scanning line L5 is interpolated from scanning lines LL, L2, and L3, and scanning line L6 is interpolated from scanning lines L2, L3, and L4. In other words, a new scan line is created for every third scan line.

In the second field, the same principle applies to the scanning line Ll'
Scanning line L5' is interpolated from L2° and L3°, and L2°
, L3°, and L4″, the scanning line L6° is interpolated.

Here, the new scanning lines obtained in the first field and the second field need to be obtained at the same position in the vertical direction (vertical timing) when compared between the fields. Therefore, instead of simply adding the data of three scanning lines to make 1/3, the scanning lines are multiplied by a predetermined coefficient and added. For example, if we focus on scanning line L5, this scanning line L5
The signal at the position is almost equally influenced by Ll and L3, and the influence of L2 is the strongest. Also, scanning line L6
In this case, the effects of L3 and L4 are almost equal, and the effect of L2 is the weakest. Therefore, when adding each scanning line, it is necessary to multiply by an appropriate coefficient and add them to create the scanning line L5.

FIG. 4 shows an example of coefficients multiplied by data when one scanning line is created from three scanning lines. In this example, a new scanning line is created at the vertical center position, and for each scanning line data a, b, and c, 1/4,
By multiplying by l/2 and l/4, new scanning line data d is obtained. Such processing is filtering processing, and by changing the coefficients, the vertical frequency characteristics of the output signal can be changed. Hereinafter, this coefficient will be referred to as a filter coefficient.

As shown in FIG. 3, scanning line L6 is interpolated from scanning lines L2, L3, and L4. If the milter coefficients are made vertically symmetrical when obtaining this scanning line, the obtained scanning line will occur with contents adapted to the position of L3. However, since the content needs to be adapted to the position of scanning line L6, when obtaining this scanning line L6, L2, L
3. Perform filter processing on L4 and multiply by the filter coefficient) and interpolate. For example, (1/4) L2, (1/2
) L3, (1/2) L4.

FIG. 5 shows the above-mentioned scanning line conversion circuit.

The signal at the input terminal 11 is supplied to an IH (one horizontal period) delay memory 14 and coefficient multipliers 12 and 13. The output of the IH delay memory 14 is sent to the coefficient unit 15 and the IH delay memory 19.
is supplied to The output of the IH delay memory 19 is sent to the coefficient unit 20.
is supplied to the adder 16 via. The output of the coefficient multiplier 15 is also supplied to the adder 16 . The output of the adder 1B is supplied to the coefficient multiplier 17 and also to one input terminal of the selector 21. The output of the coefficient multiplier 17 is supplied to an adder 18. This adder 18 is also supplied with the output of the coefficient unit 12, and the addition output is supplied to the other input terminal of the selector 21.

In the figure, the fractional character shown adjacent to each coefficient unit is the magnification of each coefficient unit.

In the above circuit, a plurality of scanning line signals sequentially inputted from the input terminal 11 have coefficients rA12.13.15.
20 outputs will be synchronized. Moreover, the coefficients are multiplied by each coefficient unit. Now, if the selector 21 selects the direct output of the adder 1B based on the control signal from the control terminal 22, a signal obtained by adding the outputs of the coefficient multipliers 13, 15, and 20 will be derived. Such a processing form is formed when obtaining the scanning line L5 shown in FIG. 3. Next, the form in which the selector 21 derives the signal from the adder 18 is formed when obtaining the scanning line L6 shown in FIG. 3. This means that L2, L3, and L4 are used to create a signal at the position of L3 (the output of the adder 16), then the coefficient multiplier 17 halves this signal, and the coefficient multiplier 12 halves the signal, and then the coefficient multiplier 12 converts L4 into 1/2.
2 and add both. In this way, by switching the path through the coefficient multiplier, the vertical frequency characteristics can be changed.

FIG. 6 shows the relationship between the control signal supplied to the control terminal 22 of the selector 2.1 and the horizontal synchronization signal.

At timing a, for example, the output of the adder 16 is selected,
At timing b, the output of adder 18 is selected. At timing C, either is acceptable. This is this timing C
This is because the converted output of is not used.

(Problems to be Solved by the Invention) The conventional scanning line conversion circuit described above has the following problems. That is, when creating the scanning line L5 as shown in FIG.
．． It passed 15.20.

However, when creating scanning line L6, the signals of the three scanning lines pass through coefficient units 13, 15, and 20, are added in adder 1B, and further pass through coefficient unit 17. passes through the coefficient unit 12 once. Therefore, the converted scanning lines L5 and LB have different numbers of passes through the coefficient multiplier before being created. For this reason, the vertical frequency characteristics of the circuits from which the scanning lines L5 and LB are obtained cannot be considered to be the same. This is when comparing the upper and lower scanning lines within the same field, but when comparing the scanning lines of the first field and the second field, it is found that the vertical frequency characteristics required to obtain scanning lines generated at the same position are different. Become.

In this way, when a screen is formed using scanning line signals having different conversion characteristics, there is a problem that flicker and the like occur.

Figure 7 shows the filter coefficients l for the center scanning line.
/2, and the vertical filter characteristic Fv1 is shown when the upper and lower scanning lines are set to 1/4, respectively. This corresponds to the characteristic when obtaining the scanning line L5 in FIG. 4. However, since the vertical filter characteristic when obtaining the scanning line L6 is asymmetrically weighted in the vertical direction, it becomes a vertical filter characteristic FV2. As described above, if the vertical filter characteristics for obtaining the converted scanning line are different, flicker and the like occur as described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide a scanning line conversion device that can make the vertical filter characteristics the same for each scanning line when converting new scanning lines after conversion.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a delay means for simultaneously synchronizing N input scanning line signals, and a delay means for simultaneously controlling N input scanning line signals outputted from the delay means. a first coefficient multiplication means for multiplying, a first addition means for adding N signals outputted from the first coefficient multiplication means, and a second coefficient for multiplying the signal outputted from the addition means by a fixed value. doubling means; a signal switching means capable of selectively deriving M selected scanning lines from the N input scanning line signals output from the delay means; and a third coefficient for multiplying the output of the signal switching means by a fixed value. a doubling means; a second adding means for adding the output of the second coefficient multiplying means; and the output of the third coefficient multiplying means; and a position of the output scanning line signal derived from the second adding means. and means for controlling the input scanning line selection operation of the signal switching means so that the lines are vertically symmetrical when viewed from one line to another with respect to the position of the input scanning line.

(Function) According to the above means, all output scanning line signals are created using the same number of coefficient units, that is, by passing through vertical filters with the same characteristics. Alternatively, the output characteristics will not change between fields.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. A digital video signal is supplied to the input terminal 31, which is supplied to an IH delay memory 33 having a delay time of one horizontal period, a coefficient multiplier 32, and one terminal of a selector 39.

The output of the IH delay memory 33 is further transmitted to the IH delay memory 3
7 and is also input to the coefficient unit 34. IH
The output of the delay memory 37 is input to the coefficient unit 38 and is also supplied to the other input terminal of the selector 39. The block surrounded by the broken line simultaneously synchronizes three scanning line signals input sequentially to the input terminal 31. Of the synchronized signals, two signals are supplied to the selector 39.

The outputs of the coefficient multipliers 32, 34, and 38 are input to an adder 35 and combined. In the figure, each coefficient unit 32, 34, 38
The fractional character next to is the magnification of each coefficient unit.

The outputs of the adder 35 and selector 39 are input to coefficient units 36 and 40, respectively. And this coefficient unit 3B and 40
The outputs of are added in an adder 41 and output to an output terminal 42.

Here, the selector 39 selects the control 1 synchronized with the horizontal synchronization signal.
By supplying the engineering symbol to the terminal 43, one of the inputs is selected and derived.

The above circuit converts the number of scan lines and forms a vertical filter. Here, the operation will be explained with reference to FIG.

Now, let us consider the case where scanning line L5 is created using scanning lines Ll, L2, and L (in FIG. The location is
The position is set 174 upwards from the center position of the scanning line L2.

First, IH delay memory 33.37, coefficient multiplier 32.34.
38, the circuit of the adder 35 creates a signal corresponding to the position of the scanning line L2 (hereinafter such a signal will be referred to as an auxiliary signal). When creating a signal at a position shifted 1/4 upwards from this position (scanning line L5), scan line L
1 multiplied by a coefficient 174, the output of the adder 35 (auxiliary signal)
By multiplying by a coefficient 374 and then adding both, a signal at a position corresponding to scanning line L5 can be obtained. Therefore, in this case, the selector 39 selects the scanning line LL (IH
output of delay memory 37).

Next, consider the case where scanning line L6 is created using scanning lines L2, L3, and L4. The scanning line L6 is set at a position shifted downward by 1/4 from the central scanning line L3. In this case, the adder 35 first obtains a signal (auxiliary signal) at a position corresponding to the scanning line L3. To create scanning line L6 using this auxiliary signal and signals of other scanning lines, multiply the auxiliary signal from adder 35 by 374, multiply the signal of scanning line L4 from terminal 31 by 1/4, Both can be combined.

As described above, the selector 39 is switched according to the position of the scanning line by the control signal, and the operation timing is the same as that described in FIG. 6.

Looking at the interpolation signal generation path of the above scanning line conversion device, the number of coefficient multipliers used does not change when generating signals for scanning line L5 and scanning line L6.

Then, the selector 39 selects the input terminal 3 which does not pass through the coefficient unit.
1 signal or the output signal of the IH delay memory 37, the signal on the scanning line L2 (scanning, l
L5), a signal below scan line L3 (scan line L6) can be created. Therefore, when creating signals for the scanning lines L5 and L8, the vertical filter characteristics of the circuit do not change as in the conventional case.

The same holds true when converting scanning lines in the second field. However, the signal of scanning line L5° generated at the same position as scanning line L5 is located below scanning line L2'.
Occurs at a position shifted by /4. Moreover, the signal of scanning line L6° generated at the same position as scanning line L6 is the scanning! 1iL4°
It occurs at a position shifted 174 points below.

According to the above embodiment, the vertical filter characteristic becomes like the characteristic FV3 shown in FIG. 7, and it is possible to obtain a characteristic close to the ideal characteristic FVI.

As described above, in this embodiment, first, a plurality of input scanning line signals are synchronized to create an auxiliary signal (output of the adder 35) corresponding to a vertically symmetrical position, and a certain coefficient is applied to this auxiliary signal. Multiply by 1. On the other hand, a plurality of signals can be selected from the simultaneous signals by a selector 39,
Multiply the selected signal by a constant factor of 2. Here, the coefficients 1 and 2 are set so that the sum is 1, and whether the new scanning line signal to be created is shifted upward or downward is determined as described above. It is left to the selection operation of the selector 39. By doing so, it is possible to make the vertical filter characteristics the same in the process of creating all the scanning line signals, and it is possible to prevent factors such as flicker from occurring as in the prior art.

Note that in the above embodiment, a new interpolated scanning line signal was created using three scanning lines, but the number of scanning lines used is not limited to this, and the conversion rate of the number of scanning lines The selection will be made accordingly.

[Effects of the Invention] As described above, according to the present invention, when new scanning lines are sequentially created, the vertical filter characteristics at the time of conversion can be made the same for each scanning line.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a scanning line explanatory diagram shown to explain the operation of the device shown in FIG. 1, and FIG. 3 is a diagram showing a conventional scanning line conversion processing device. A scanning line explanatory diagram shown to explain the operation, Fig. 4 is an explanatory diagram showing the principle of scanning line conversion, Fig. 5 is a circuit diagram showing a conventional scanning line converting device, and Fig. 6 is a scanning line converting device. FIG. 7 is a diagram illustrating an example of the vertical filter characteristics of the scanning line conversion device. 31...input terminal, 32.34. 88.37...IH delay memory, selector. 38.8B, 40... Coefficient unit, 35.41... Adder, 39...

Claims (1)

[Scope of Claims] Delay means for synchronizing N input scanning line signals; first coefficient multiplication means for multiplying each of the N input scanning line signals outputted from the delay means by a fixed value; a first addition means for adding N signals outputted from the coefficient multiplication means; a second coefficient multiplication means for multiplying the signal outputted from the addition means by a fixed value; and N signals output from the delay means. a signal switching means capable of selectively deriving M selected scanning lines from an input scanning line signal; a third coefficient multiplication means for multiplying the output of the signal switching means by a fixed value; and an output of the second coefficient multiplication means. and a second addition means for adding the output of the third coefficient multiplication means; and a second addition means for adding the output of the third coefficient multiplication means; A scanning line converting device comprising: means for controlling the input scanning line selection operation of the signal switching means so that the input scanning line selection operation is vertically symmetrical when the input scanning line is selected.