JPS62154880A - Method for interpolating video signal - Google Patents

Abstract

PURPOSE:To display an enlarged picture more naturally by calculating the difference of data between picture elements adjacent to a part to be enlarged and interpolating the adjacent picture elements like a step function in accordance with the increase of the difference of the data or linearly at the small difference of data. CONSTITUTION:A window position selecting circuit 6 selects the position and range of a window 2a of a frame memory 2 and determines the position and range of a part to be expanded by a keyboard or the like while observing the video screen 5a of a TV image receiver 5. The number of picture elements in the window 2a is set up to an integer to simplify the processing, and at the time of enlargement, the most outside picture elements of the screen in both the horizontal and vertical directions are made to coincide with the most outside picture elements of the window 2a, the data of the picture elements in the window 2a are read out and supplied to a microprocessor 8, the adjacent picture elements are interpolated, and the interpolated data are supplied to a frame memory 9. At the interpolation of the adjacent picture elements, the picture elements are interpolated linearly when the difference DELTA of data between the adjacent picture elements is small, or like a step function when the difference DELTA is large.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of interpolating a video signal used when enlarging a part of a video screen.

[Summary of the invention]

In the video signal interpolation method used when enlarging a part of the video screen, the present invention selects the part of the video screen to be enlarged and calculates the difference in data between neighboring pixels of the part to be enlarged. As the data difference increases, interpolation is performed between adjacent pixels in a step function manner, and when the data difference is small, interpolation is performed linearly between neighboring pixels, thereby eliminating unnaturalness in the enlarged screen.

[Conventional technology]

Generally, when enlarging a part of a video screen, the distance between adjacent pixels increases and the video screen becomes difficult to see, so interpolation is performed between the adjacent pixels.

Conventionally, the interpolation method for this video signal is the same as for the previous pixel.
Previous value interpolation, which interpolates using data, or average value interpolation, which interpolates using the average value of the preceding and following pixels, was performed.

[Problem that the invention seeks to solve]

However, such previous value interpolation has the disadvantage that as the image is enlarged, the picture on the screen changes discontinuously, making it unnatural and difficult to see. In addition, average value interpolation has the disadvantage that image contour information is lost, resulting in many unnatural scenes.

In view of this point, the present invention aims to make an enlarged screen look more natural.

[Means for solving problems]

The video signal interpolation method of the present invention selects a portion of the video screen to be enlarged, calculates the difference in data between neighboring pixels of the portion to be enlarged, and as the difference in data becomes larger, the data is increased in a step function. When the difference is small, interpolation is performed linearly between adjacent pixels.

[Effect]

According to the present invention, when the data difference between neighboring pixels is large, interpolation is performed in a step function manner, so that the outline information of the image is not lost, and when the data difference between neighboring pixels is small, interpolation is performed linearly. Therefore, the picture on the screen does not change discontinuously, and a more natural enlarged picture can be obtained.

〔Example〕

Hereinafter, an embodiment of a display device using the video signal capturing method of the present invention will be described with reference to the drawings.

In FIG. 1, fl) indicates a video signal input terminal to which a digitized video signal is supplied, and the digital video signal supplied to this video signal input terminal is a frame memo!
J (2+), and the video signal obtained at the output side of this frame memory (2) is supplied to the normal image side fixed contact (3S) of the changeover switch (3) that changes whether or not to obtain an enlarged image, and this switch The video signal obtained at the movable contact (3a) of the switch (3) is supplied to the television receiver (5) via the D-A conversion circuit (4) that converts the digital signal into an analog signal. When the movable contact (3a) of 3) is connected to the normal image side fixed contact (3S), the video signal from the video signal input terminal is reproduced as in a general television receiver.

Further, in FIG. 1, (6) indicates a window position selection circuit, and this window position selection circuit (6) selects the position and range of the window (2a) of the frame memo January 2). In this case, the position and range to be enlarged is determined using this window (2a). In this example, the position and range to be enlarged is set to the television receiver R (5
) while viewing the video screen (5a) and making decisions using a keyboard or the like. (6a) is a window position selection signal input terminal. The output signal from the window position selection circuit (6) is supplied to the frame memory (2) via the address counter (7) to determine the window (2a) of this frame memory (2). In this case the window (2a)
The number of pixels in the window (2a) is set to be an integer to simplify processing, and when enlarging, the outermost pixels in both the horizontal and vertical directions of the screen are set to the outermost pixels in the window (2a). shall be taken as a thing. The data of the pixels within this window (2a) is read out and supplied to the microprocessor (8), which performs interpolation processing between the pixels according to this example and supplies it to the frame memo (January 9). Do as you like. For example, Figure 2 shows the frame memo January 2).
The ◯ indicates a pixel, and the ◯ indicates a pixel within the window (2a) that is enlarged. Further, FIG. 3 shows pixels written in the frame memo (January 9), where X is an interpolated pixel.

In this example, interpolation between neighboring pixels is based on the data difference Δ between neighboring pixels, and when this difference Δ is small, interpolation is performed linearly, and when this difference Δ is large, interpolation is performed using a step function. Do as you please.

To explain this in detail, as shown in FIG. 4, the larger data of two neighboring pixels in the horizontal direction, that is, the Assume that the coordinates increase in the positive direction toward dm. Now consider the shaded area in Figure 4. This y
(In this example, is used as xi. Here, 0≦Δ<256. This y(×)
The equation changes linearly when the difference Δ is small, and changes like a step function when the difference Δ becomes large. In this equation, theoretically, we would like to apply the value of x(, which makes y(xo) = 0, to the distance Nx1 between neighboring pixels dM and dm, but in that case, X. = prisoner, so Δ If we calculate XO such that y(xo) = ξ when -1, we get x o = 255j! n (--1)ξ, and since we actually compress XQ into the interval of Xl, this formula becomes 2Δ Therefore, the interpolated data at the interpolation point X is d fxl =
There is d mξ. In this case, this interpolated data is sent to the microprocessor (
8) at the corresponding pixel X position.

Also, interpolation data in the vertical direction, that is, in the y-axis direction and in the diagonal direction, is similarly calculated by the microprocessor (8) and written in the corresponding pixel X position of the frame memo (January 9).

Further, the output terminal of this frame memory (9) is connected to the enlarged image side fixed contact (3L) of the changeover switch (3).

In this case, when the movable contact (3a) of the changeover switch (3) is connected to the fixed contact (3L) on the enlarged image side, the neighboring pixels to be enlarged written in this frame memo (January 9) are interpolated. The video signal is supplied to the television receiver (5) via the DA conversion circuit (4), and the enlarged image can be viewed.

Since this example is configured as described above, the frame memory (
2) To view normal video images, press the selector switch (
If you connect the movable contact (3a) in 3) to the fixed contact (3S) on the normal picture side, you can receive the normal picture from the video signal terminal (1) on the TV! It can be seen by machine (5).

Also, the video screen (5a) of this television receiver (5)
When it is desired to enlarge and view a desired part of the image, the window position selection circuit (6) determines its position and range, and the pixel data within the determined window (2a) of the frame memo (January 2) is read out. It is supplied to the microprocessor (8), and the neighboring pixels are interpolated and stored in the frame memory (8).
9) and the movable contact (3) of the changeover switch (3)
By connecting a) to the enlarged image side fixed contact (3L), the enlarged image of the desired portion written in the frame memory (9) can be viewed on the television receiver (5). In this case, according to this example, when the data difference Δ between neighboring pixels is small, linear interpolation is performed, so the picture on the screen (5a) does not change discontinuously, and the data difference Δ between neighboring pixels
When the value is large, interpolation is performed in a step function manner, so that the contour information of the image is not lost and a more natural enlarged image can be viewed.

It goes without saying that the present invention is not limited to the above-described embodiments, and can take various other configurations without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, when the data difference Δ between neighboring pixels is small, interpolation is performed linearly, so the picture on the screen does not change discontinuously, and when the data difference Δ between neighboring pixels is large, interpolation is performed in a step function manner. Since the image is interpolated, the outline information of the image is not lost, and the advantage is that a more natural enlarged image can be viewed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a display device using an example of the video signal interpolation method of the present invention, and FIGS. 2, 3, 4, and 5 are diagrams for explaining the present invention. be. (1) is a video signal input terminal, (2) and (9) are frame memories respectively, (2a) is a window, (5) is a television receiver, (6) is a window position selection circuit, (8) is a microprocessor.

Claims (1)

[Claims] Select the part of the video screen that you want to enlarge, and calculate the difference in data between neighboring pixels of the part you want to enlarge, and as the difference in data increases, if the difference in data is small, the difference in data is calculated linearly. A video signal interpolation method characterized by interpolating between pixels.