JPS6243989A - Video adaptive scanning line interpolating device - Google Patents

Abstract

PURPOSE:To prevent the fading of a vertical outline by detecting the degree of the correlation of original video signals adjacent vertical direction and diagonal direction on adjacent scanning lines and controlling a weighting in an equalizing direction between the adjacent scanning lines. CONSTITUTION:When the absolute value ¦a-f¦ of a diagonal differential signal outputted from an absolute value circuit 43 is selected as a minimum value, a minimum value selecting circuit 44 changes over switches 51, 52 to positions of lower steps, supplies video signals (f), (a) to coefficient multipliers 46, 47. When a rightward and downward diagonal line appears in a screen, an interpolating signal (i) by the synthesis of the video signals (a), (f) existing on the diagonal line is outputted from an interpolating signal output terminal 3. When any minimum value is selected, if the value is larger than a certain value, outputs (d), (e) or (f) of the coefficient multiplier 46 are outputted as they are as the interpolating signal (i) from the output terminal 3. Thereby, the fading of a vertical outline is effectively avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning line interpolation device that interpolates scanning lines of a television video signal to improve image quality, and in particular to a scanning line interpolation device that interpolates scanning lines of a television video signal to improve image quality. The present invention relates to a video adaptive scanning line interpolation device that changes a signal synthesis method.

2. Description of the Related Art A scanning line interpolation device is known that interpolates scanning lines of a television video signal to improve image quality.

As one of the scanning line interpolation devices, as shown in FIG. 6(A), an original video signal input terminal 1. Original video signal output terminal 2
There is a so-called double writing device which is equipped with an interpolated video signal output terminal 3 and outputs the same signal as the original video signal as an interpolated video signal.

As another scanning line interpolation device, as shown in the same figure (B),
Original video signal input terminal 1. Original video signal output terminal 2. Interpolated video signal output terminal 3. 1 scanning line delay circuit 4 that delays the original video signal by 1 (horizontal) scanning line, addition circuit 5 and 1/2
Some devices include a coefficient unit 6 and output an arithmetic average value between adjacent scanning lines as an interpolated video signal.

Furthermore, as another scanning line interpolation device, the original video signal input terminal l
, original video signal output terminal 2. It is equipped with an interpolation video signal output terminal 3 and an l field delay circuit 7 that delays the original video (No. 8 by one field), and outputs the video signal one field before as an interpolation video signal by using the correlation between fields. There is.

"Problems to be Solved by the Invention" - In the scanning line interpolation device written twice, the seventh
When a diagonal line appears on the screen as shown in Figure (A), a stair-like line segment is displayed on the screen after interpolation, as shown in Figure (B), and the line segment is There is a problem that smoothness is lost.

Furthermore, in a scanning line interpolation device that uses an arithmetic average value between adjacent scanning lines as an interpolated video signal, there is a problem in that the contour in the vertical direction becomes blurred, as shown in FIG.

Furthermore, devices that use the video signal from one field before as an interpolated video signal not only require an expensive, large-capacity field memory, but also suffer from poor image quality when the screen moves large and the correlation between fields is small. There is also the problem of deterioration.

Structure of the Invention Means for Solving the Problems The scanning line interpolation device of the present invention solves the problems of the prior art as described above. a correlation detection circuit that detects the degree of correlation between original video signals adjacent in the vertical and diagonal directions on adjacent scanning lines, and the higher the degree of correlation detected by this correlation detection circuit, the more and a weighting control circuit that controls the weighting of the circuits in a direction that equalizes the weighting of the circuits.

The scanning line interpolation device according to the invention in Bookcase 2 has the following features:
A synthesis circuit that creates a controllable weighted interpolation signal from vertically and diagonally adjacent original video signals on an adjacent scanning line, and a correlation that detects the degree of correlation between vertically and diagonally adjacent original video signals on adjacent scanning lines. and a detection circuit.

Furthermore, as the degree of vertical correlation detected by the correlation detection circuit increases, the scanning line interpolation device weights the vertical direction of the synthesis circuit to be greater than that in the diagonal direction and equalizes the weighting between adjacent scanning lines. As the degree of correlation in the diagonal direction detected by the correlation detection circuit increases, the weighting in the diagonal direction of the synthesis circuit is controlled to be greater than that in the vertical direction and equalized between adjacent scanning lines. and a weighting control circuit.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

Embodiment FIG. 1 is a block diagram showing the configuration of a scanning line interpolation device according to an embodiment of the present invention.

This scanning line interpolation device includes an original video signal input terminal 1, an original video signal output terminal 2, and an interpolated video signal output terminal 3.

In addition, this scanning line interpolation device converts the video signal into 1 (horizontal)
A one-scan line delay circuit 10 that delays the video signal by one pixel, and one-pixel delay circuits 21, 22, and 23 that delay the video signal by one pixel.
and 24, and subtractors 3], 32, and 33.

Furthermore, this scanning line interpolation device includes absolute value circuits 41, 42 and 43, a minimum value selection circuit 44, a coefficient generator 45,
It is provided with a synthesis circuit consisting of coefficient multipliers 46 and 47 and an adder 48.

The original video signal supplied to the input terminal 1 is delayed by the time of one scanning line in the one scanning line delay circuit IO, and at the same time the subsequent scanning line 112 starts to be supplied to this one scanning line delay circuit IO, the original video signal is delayed by one scanning line delay circuit IO. It is output from here as scanning cotton H1. This advance scan 1! H1 is further delayed by one pixel in the one-pixel delay circuits 23 and 24, and is supplied to one input terminal of the subtracter 33.

When realizing this scanning line interpolation device in a digital format, one scanning line delay circuit 10 and one pixel delay circuit 23, 24 are used.
etc. are constituted by a RAM or the like, and readout is started after a time period of one scanning line or one pixel has elapsed after the writing of the video signal is completed.

On the other hand, the original video signal supplied to the input terminal 1 is delayed by one pixel time in the one pixel delay circuits 21 and 22 as the subsequent scanning line H2, and is supplied to one input terminal of the subtracter 32. The other input terminal of the subtracter 32 is supplied with the previous scanning line Hl output from the one-scanning line delay circuit 10. Further, the subsequent scanning line H1 is supplied to the other input terminal of the subtracter 33. Furthermore, the outputs of the one-pixel delay circuits 21 and 23 are supplied to both terminals of the subtracter 31, respectively.

FIG. 2 is a conceptual diagram for explaining the operation of FIG. 1. In the figure, H1 and H2 are adjacent scanning lines in the original video signal,
is an interpolated scanning line synthesized from original video signals on these adjacent scanning lines. Also, a.

b and C are adjacent pixels on the previous scanning line H1; d;

e and f are adjacent pixels on the subsequent scanning line H2, and l is an interpolated pixel on the interpolated scanning line IF. Scanning line H in Figure 2 above
1, H2, and pixel a%f correspond to the video signals at the locations with the same reference numerals in FIG.

From the subtracter 31, a difference output b-e between the video signal on the preceding scanning line 1 and the video signal e on the subsequent scanning line H2 is obtained.
It is output as a vertical difference signal between adjacent scanning lines. Further, from the subtracter 32, a difference output c-d between the video signal C on the preceding scanning line Hl and the video signal d on the succeeding scanning line H2 is output.
is output as a diagonal difference signal between adjacent scanning lines. Further, the subtracter 33 outputs a difference output a-r between the video signal number a of the preceding scanning line Hl and the video signal f of the succeeding scanning line H2-L as a diagonal direction difference signal between adjacent scanning lines. be done.

The difference outputs of the subtracters 3I to 33 are sent to the corresponding absolute value circuit 41.
The absolute value is taken at ~43, and the absolute value of the difference output is 1c
The signals are supplied to the minimum value selection circuit 44 as mdi, 1b-el, and 1a-fl. - Each absolute value indicated in the box indicates the degree of correlation between adjacent scanning lines in the diagonal direction and the vertical direction, and the smaller the corresponding absolute value, the greater the degree of correlation in the diagonal direction or the vertical direction. .

When implementing this scanning line interpolation device in a digital format, the minimum value selection circuit 44 is composed of a combination circuit of a subtracter and a logic gate, and selects the three differential outputs supplied from the absolute value circuits 41 to 43. The smallest absolute value, ie, the one with the largest correlation between adjacent scanning lines, is selected and supplied to the coefficient generator 45.

When realizing this scanning line interpolation device in a digital format, the coefficient generator 45 is composed of a ROM or the like that stores the corresponding coefficient at the address of the minimum value, and generates a coefficient according to the minimum value supplied from the minimum value selection circuit 44. The coefficient k of the magnitude
6.47 and an adder 48.

The coefficient multiplier 46 supplies a signal obtained by multiplying the video signal e on the subsequent scanning line H2 to one input terminal of the adder 48. Further, the coefficient multiplier 47 supplies a signal obtained by multiplying the video signal S on the previous scanning line Hl by (1-k) to the other input terminal of the adder 48.

The minimum value supplied to the coefficient generator 45 and the coefficient generator 45
As illustrated in FIG. 3, the relationship between the coefficients output from and the coefficients is 0.5 when the minimum value is 0, that is, when the correlation in the diagonal direction or the vertical direction is 100%. The coefficient approaches 1 as the minimum value increases (correlation between adjacent scanning lines weakens), and becomes 1 in a range where the minimum value is large to some extent (range where there is no correlation between adjacent scanning lines).

Therefore, if the correlation in the diagonal or vertical direction is 100%, the video signal on the preceding scanning line H1 will be
An interpolated video signal i is outputted from an interpolation signal output terminal 3 by equally weighting the video signal 1 on 2 (and the video signal e on 2).

Further, as the correlation in the diagonal direction or the vertical direction becomes smaller, the specific weight of the video signal e on the subsequent scanning line H2 increases. Furthermore, when there is almost no correlation between adjacent scanning lines, the value becomes 1, and the video signal e of the subsequent scanning line H2-
Only the scan line is supplied to the interpolation output terminal, and scanning line interpolation by so-called double writing is performed to avoid blurring of the vertical contour.

When there is almost no correlation between adjacent scanning lines by exchanging the coefficient units 46 and 47, it may be possible to write twice using the video signal on H1 on the previous scanning line.

FIG. 4 is a block diagram showing the configuration of a scanning line interpolation V device according to an embodiment of the invention in Bookcase 2.

Components in FIG. 4 denoted by the same reference numerals as those in FIG. 2 are the same as the components already described in connection with FIG.

In the scanning line interpolation device shown in FIG. 4, switches 51 and 52 are added to the device shown in FIG.
4 has an added function of controlling switching of the switches 51 and 52 according to the selected minimum value.

That is, when the minimum direct selection circuit 44 selects the absolute value Ib-el of the vertical difference signal output from the absolute value circuit 41 as the minimum value, it switches the switches 51 and 52 to the middle position in the figure. The video signals e and b are supplied to coefficient multipliers 46 and 47, respectively, and a coefficient k corresponding to the degree of correlation between video signals e and b is supplied to each coefficient multiplier 46 and 47.

The relationship between the minimum value and the coefficient in this coefficient generator 45 is as follows:
This is almost the same as that in FIG. 3, and in the limit where the minimum value is 0, equal weighting is performed, and as the minimum value increases, weighting is gradually applied to one side.

Therefore, as illustrated in FIG. 5(A), when a vertical line segment appears in the screen, as shown by the dotted line in the same figure,
An interpolated signal i is outputted from an interpolated signal output terminal 3 by uniformly combining the video signals S and e existing on this vertical line segment.

Further, when the minimum value selection circuit 44 selects the absolute value 1 cmdl of the diagonal difference signal outputted from the absolute value circuit 42 as the minimum value, it switches the switches 51 and 52 to the upper position in the figure to Signals d and C are supplied to coefficient multipliers 46 and 47, respectively, and a coefficient k corresponding to the degree of correlation between video signals d and C is supplied to each coefficient multiplier 46 and 47. Therefore, when a diagonal line slanting downward to the left appears on the screen, as illustrated in FIG. Interpolation signal i is output from interpolation signal output terminal 3.

Further, when the minimum value selection circuit 44 selects the absolute value 1a-fl of the diagonal difference signal outputted from the absolute value circuit 43 as the minimum value, the minimum value selection circuit 44 switches the switches 51 and 52 to the lower position in the figure. , video signals f and a are supplied to coefficient multipliers 46 and 47, respectively, and a coefficient k corresponding to the degree of correlation between video signals a and f is supplied to each coefficient multiplier 46 and 47. Therefore, when a diagonal line slanting downward to the right appears on the screen, as illustrated in FIG. Interpolation signal i is output from interpolation signal output terminal 3.

As is clear from FIG. 5, smooth diagonal lines and vertical line segments are displayed depending on the type of line segment appearing on the screen, that is, the video signal.

Incidentally, no matter which minimum value is selected, if the value is larger than a certain degree, that is, if the correlation in the diagonal or vertical direction is high to a certain extent, the output d of the coefficient circuit 46
.

As in the case of FIG. 2, by exchanging the coefficient units 46 and 47, the video signal on the preceding scanning line 111 is written twice instead of writing the video signal on the subsequent scanning line H2-to twice. It may be configured to write.

Note that in the scanning line interpolation device shown in FIG.
It is also possible to install a continuously variable weighting circuit for video signals in the vertical direction and diagonal direction in place of .

Effects of the Invention As explained in detail above, the scanning line interpolation device of the present invention detects the degree of correlation between original video signals that are adjacent to each other in the vertical and diagonal directions on adjacent scanning lines, and the greater the degree of correlation, the higher the degree of synthesis. This is because it is configured to perform scanning line interpolation that adapts to the screen situation by equalizing the weighting of the circuit, or by controlling the weighting to be equalized between adjacent scanning lines while giving greater weighting in the direction of greater correlation. The effect of this method is that it can effectively solve all of the problems that occur with conventional devices, such as loss of smoothness of diagonal lines, blurring of vertical contours, and deterioration of image quality due to lack of correlation between fields. It is played.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention. FIGS. 2 and 3 are conceptual diagrams that do not provide detailed explanations of the present invention, and FIG. 4 is a block diagram of the configuration of an embodiment of the invention in the bookcase 2.
FIG. 5 is a conceptual diagram explaining the operation of the scanning line interpolation device shown in FIG. 4, and FIG. 6 is a block diagram of the configuration of a conventional scanning line interpolation device.
FIG. 7 is a conceptual diagram for explaining the problems of the conventional device shown in FIG. 1.. Original video signal input terminal, 2.. Original video signal output terminal, 3.. Interpolation signal output terminal, 10.. l scanning line delay circuit, 21-24.. 1 pixel delay circuit, 31-33.. Subtractors 141-43...absolute value circuit, 45...coefficient generation circuit, 46.47...coefficient unit, 48...adder, 51.52
··switch.

Claims (2)

[Claims] (1) A synthesis circuit that creates a controllable weighted interpolation signal from vertically adjacent original video signals on adjacent scanning lines, and detects the degree of correlation between vertically and diagonally adjacent original video signals on adjacent scanning lines. and a weighting control circuit that controls the weighting in a direction that equalizes the weighting of the combining circuit as the degree of correlation detected by the correlation detection circuit increases. type scan line interpolator. (2) A synthesis circuit that creates a controllable weighted interpolation signal from vertically and diagonally adjacent original video signals on adjacent scanning lines, and a correlation between vertically and diagonally adjacent original video signals on adjacent scanning lines. a correlation detection circuit that detects the degree of correlation in the vertical direction, and a direction in which the higher the degree of correlation in the vertical direction detected by the correlation detection circuit, the greater the weighting in the vertical direction of the synthesis circuit than in the diagonal direction and equalization between adjacent scanning lines; The weighting is controlled in a direction such that the greater the degree of correlation in the diagonal direction detected by the correlation detection circuit, the more the weighting in the diagonal direction by the combining circuit is made larger than in the vertical direction and equalized between adjacent scanning lines. A video adaptive scanning line interpolation device comprising: a weighting control circuit that controls weighting.