JPH0343795A - Display control method - Google Patents

Abstract

PURPOSE:To represent a slanting line as a smooth line which is not stepwise by regarding picture element data to be interpolated as the mean value of picture element data with the smallest density difference. CONSTITUTION:Data of every other line among image data stored on an image memory 5 is interpolated and a control circuit inserts complementary picture element between two lines stored on a line buffer 13 to generate an interpolation line. In this case, the density difference between picture element data right above and below the position of a picture element to be interpolated and the density difference between picture element data left above and left below the position are calculated and the means value of picture element data having the smallest density difference between the found density differences is regarded as the picture element data at the position of the picture element to be interpolated. Consequently, picture element data are interpolated according to the connection of the line and the slanting line can be represented as the smooth line without becoming stepwise.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a display control method in an image communication device such as a video telephone device that transmits still images using a communication line such as a subscriber line. .

(b) Conventional technology Recently, a videophone device that transmits still images using communication lines such as subscriber lines has been developed and put into practical use.
For example, see the article ``Unification of still image TV phone plans based on rTTC standard system'' published by Japan Broadcasting Publishing Association, Electronics Life J, August 19B8 issue).

The Telegraph and Telephone Technical Committee (abbreviated as TTC) is standardizing the standards for analog still image videophone devices, and the screen specifications of this TTC standard method include a horizontal screen (160 pixels, 100 lines) mode. A. There is a mode B in which the screen is vertically long (96 pixels x 100 lines).

Since the display screen is very small in its original size in mode A (or mode B), one pixel data is usually repeated twice horizontally and twice vertically (the same line twice), and then Data for pixels, if mode A is 320
Pixels x 200 lines (192 pixels x 20 for mode B)
0 line) image.

(c) Problems to be Solved However, if the image is enlarged by simply repeating the same pixel data, the displayed image will become rough and the shaded areas will become step-like. Especially when displayed on a relatively large screen such as an external monitor, the roughness becomes noticeable.

Further, even if the image is enlarged by taking the average value of the density of adjacent pixels, a very clear display image cannot be obtained.

The present invention has been made in view of these points, and enables the display of a relatively natural image in which the diagonal lines are not step-like and smooth when enlarging and displaying a low-resolution image. It is something.

(d) Means for Solving the Problems The present invention is a display control method for enlarging and displaying original image data by interpolating data between each pixel data of original image data, the method comprising: , the density difference between the pixel data directly above and the pixel data directly below, the density difference between the R pixel data at the top left and the painting work data at the bottom right, and the density difference between the pixel data at the top right and the pixel data at the bottom left, whichever is the smallest. The average value of pixel data of the density difference is inserted and interpolated at the interpolation position as pixel data to be interpolated.

(E) The pixel data to be interpolated is determined by the density difference between the pixel data directly above and below the M open position, the density difference between the top left pixel data and the bottom right pixel data, and the top right pixel data. By using the average value of the pixel data with the smallest density difference among the density differences of the lower left pixel data, the pixel data is interpolated according to the connection of the lines, and the diagonal line becomes a smooth line without becoming step-like. It is expressed as

(F) Embodiment FIG. 1 is a schematic bottom view of a video telephone device according to an embodiment of the method of the present invention.

(1) is a control circuit that interpolates the received image data using a line buffer (13) and also controls the entire device; (2) is a camera as an imaging means that captures images using an image sensor such as COD. , (3) is the camera (2
) is an A/D converter that converts the analog signal captured by The images are stored in the image memory (5).

This image memory (5) usually stores image data of at least 320 pixels and 200 lines, each of which is expressed in 64 gradations.

(6) Is the CRTJ capable of displaying an image of at least 320 pixels and 200 lines? ? A display (7) as a display means such as a liquid crystal panel reads image data stored in the image memory (5) under the control of the control circuit (1) and displays an image based on the read image data ( 6) is a display control circuit for displaying.

(8) is a switch circuit provided with a plurality of switches for determining the image taken in from the camera (2) to the control circuit (1) as a still image, and issuing operation commands such as transmitting a still image. For example, as shown in Fig. 4, the switch of the switch circuit (8) is arranged on the front of the main body of the device, and in addition to the power switch (8a), there is also a switch for viewing the video captured by the camera (2). View J (8b), "Take J (8C)" to make the image a still image, "Send" (8d) to transmit the still image, and use your own camera (2) to display the display (6). To switch between the captured image and the image sent and received from another videophone device, press “Me/Partner J (
8e) is provided.

(9) is a modem as a transmission means for modulating image data to be transmitted or demodulating received image data.

(10) is a telephone provided separately from the present videophone device, and is connected to the videophone device by a network control circuit (hereinafter referred to as NCU) (11). This NCU (11)
is connected to the telephone line (12), and switches and controls connection of audio signals for telephone calls by the telephone (10) and image data to be transmitted to the line.

In the case of a telephone call using the telephone (10), the voice signal from the telephone (10) is sent to the telephone line (12) via the NCU (11) while the telephone line with the other party's telephone is secured.
The voice signal from the telephone line (12) is sent to the telephone (io) via the NCU (11) and a call is made.

Now, with this device, regardless of whether a telephone line with the other party's device is secured or not, when the power is on, the camera (2) will capture image data of 320 pixels x 200 lines. be exposed.

Image data of analog signal from camera (2) is A/D
It is digitized in a converter (3) and written into an image memory (5) through a gate circuit (4).

The image data written in the image memory (5) is read out by the display control circuit (7), and an image based on the image data is displayed on the display (6). At this time, on the display screen of the display (6), a mirror image is displayed with the left and right sides reversed from the image taken by the camera (2). Furthermore, since the image data is written and read out every moment, the image is displayed as a moving image.

When sending image data, first make sure that the line with the other party's videophone device is secured, and then
) To make a still image from what is displayed as a moving image, press the "Take J" button (8C) in the switch circuit (8), and the control circuit (1) will control the gate circuit (4) to capture the image. If you instruct the memory (5) to stop inputting image data (or press Send J (8d) directly without pressing Capture J (8c), the video will be fixed as a still image. ).

The control circuit (1) closes the gate circuit (4) to prevent image data from being input to the image memory (5). As a result, the image data is fixed on the image memory (5),
A still image is displayed on the display (6).

After that, when "Send J" (8d) is operated (pressed), the control circuit (1) reads out the image data fixed in the image memory (5) in a predetermined order and modulates it with the modem (9). and sends it to the telephone number I! (12) via the NCU (11).

In addition, do not press ``Take J'' (8C), but directly ``Send'' (8d).
Similarly, when the modem (
9).

Image data sent from other videophone devices is
It is received and demodulated by the modem (9) via the CU (11) and stored in the image memory (5). At this time, the control circuit (
1) is because if the received image data is in mode A, there is only 160 pixels x 100 lines of image data (mode B
Then, in order to display it on the display (6), one pixel data is multiplied by 4 and 320 pixels x 200 lines (mode A) of image data is stored in the image memory (5). do.

The received images are sequentially displayed on the display (6) as the image data (pixel data) is stored in the image memory (5). The image displayed on the display (6) is a simple enlargement of the received image data, so the image is rough.

Therefore, when the control circuit (1) finishes receiving image data for one screen, it automatically re-interpolates the image data.

The interpolation process of the method of the present invention will be explained with reference to FIGS. 1 and 2. This interpolation process is performed by simply doubling the received image data of 160 pixels and 100 lines (mode A) by doubling the original 100 lines,
That is, interpolation processing is performed on every other line of image data (pixel data) stored in the image memory (5).

The control circuit (1) selects the first horizontal line (320 pixels in which each of the received 160 pixels is overlapped) from the image memory (5).
The pixel data of the pixel) is read out and sent to the line buffer (13
). Furthermore, the next horizontal line, i.e. the received 1
The pixel data of one horizontal line next to the pixel data of line 00 is read out and stored in the line buffer (13).

The control circuit (1) inserts pixel data to be supplemented between the two lines stored in the line buffer (13) by interpolation processing described below, thereby creating an interpolated line.

Regarding the first pixel and the last pixel (320th pixel) of the interpolation line, the pixel data of the line above them is used as the pixel data of the corresponding pixel of the interpolation line.

For the other pixels from the 2nd pixel to the 319th pixel, first, the density difference between the pixel data directly above and the pixel data directly below at the position of the pixel to be interpolated is 1, and the pixel data at the top left and the pixel at the bottom right. Calculate the density difference between the data and the density difference between the upper right pixel data and the lower left pixel data. The control circuit (1) checks the smallest density difference among the calculated density differences, and sets the average value of the pixel data having the smallest density difference as the pixel data at the position of the previous pixel to be interpolated. If all or two of the density differences are the same, the average value of any one of the pixel data from which the density differences are taken is used as the pixel data of the pixel to be interpolated. It is up to you which pixel data average value to give priority to, but for example, top and bottom, top left, bottom right,
The order is top right and bottom left.

By performing this process for each pixel, one horizontal interpolation line is created.

Furthermore, by similarly performing interpolation processing between each of the 100 received lines, interpolation for 99 lines can be achieved. Then, regarding the last line, the upper] line, that is, the last line of the received 100 lines (100
The pixel data of line 1) is used as interpolation data as is, and the received 100 lines of pixel data and the created 1,
With the interpolation line 00, 200 lines worth of pixel data have been created, so the interpolation process ends.

In the above interpolation process, the control circuit (1) stores the processed line in the image memory (5) every time one line of interpolation process is completed.
), the next horizontal line of pixel data is read into the line buffer (13), and the next interpolation process is performed. Then, by writing the data into the image memory (5), it is sequentially displayed on the display (6), and when the interpolation process for one screen's worth of image data is completed, the enlarged image is displayed on the display (6). The received image is displayed in high definition.

Examples of interpolation processing are shown in FIGS. 2A to 2C.

These figures show the state of a part of the image memory that stores pixel data, and show the state before and after interpolation processing. Before interpolation processing, the right side of the broken line is approximately black pixel data, and the left side of the broken line is approximately white pixel data. Also, the black numbers represent interpolated pixel data,
Others represent received pixel data.

In the case of Figure 2 A, O is the average value of the pixel data of ■ and ■, O
is the average value of the pixel data of ■ and ■, . is the average value of the pixel data of ■ and ■, and 0 is the average value of the pixel data of ■ and ■.

At this time, 0 and 0 become white pixel data, O and 0 become black pixel data, and the boundary line (broken line) becomes a straight line.

In the case of Figure 2B, O is the average value of the pixel data of ■ and ■, O is the average value of the pixel data of ■ and ■, 0 is the average value of the pixel data of ■ and ■, 0 is the average value of the pixel data of ■ and ■ The average value of pixel data, O
is the average value of the pixel data of ■ and ■, and Φ is the average value of the pixel data of ■ and ■.

At this time, O, @, @ and Φ become white pixel data, and O
and O become black pixel data, and the boundary line, which was step-like before the interpolation process, becomes a smooth diagonal line.

Similarly, in the case of Figure 2 C, O is the average value of the pixel data of ■ and ■, ・ is the average value of the pixel data of ■ and ■, O is the average value of the pixel data of ■ and ■, and O is the average value of the pixel data of ■ and ■. is the average value of the pixel data of ■ and ■, O is the average value of the pixel data of ■ and ■, and Φ is the average value of the pixel data of ■ and ■. At this time, O becomes white pixel data, @, e, @, and Φ become black pixel data, and the boundary line, which was step-like before the interpolation process, becomes a smooth diagonal line.

In this embodiment, the received image data is simply enlarged and stored in the image memory (5) for display, but there is no particular need to do so, and the received image data is sequentially interpolated and displayed. It may also be stored directly in the image memory (5) and displayed on the display (6).

(g) Effects of the Invention As is clear from the above description, the present invention allows pixel data to be interpolated to be calculated based on the density difference between the pixel data directly above and the pixel data directly below the interpolation position, the pixel data at the top left and the pixel data at the bottom right. By using the average value of the pixel data with the smallest density difference among the density difference between the pixel data of It becomes possible. As a result, diagonal lines are expressed as smooth lines without becoming step-like, and the enlarged screen is relatively smooth and a natural image is displayed. In particular, when viewing a received image on a large display such as an external monitor, image roughness can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a flowchart for explaining the operation of an embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of an embodiment of the present invention,
FIG. 3 is a schematic configuration diagram of a video telephone device according to an embodiment of the present invention, and FIG. 4 is a schematic front view of the video telephone device according to an embodiment of the present invention. (1)...control circuit, (2)...turtle, (3)
)...A/D converter, (4)...gate circuit, (5
)...Image memory, (6)...Display,
(7)...display control circuit, (8)...switch circuit, (8b)..."viewing", (8c)..."taking",
(8d)..."send", (9)...modem, (10
)...Telephone, (11)...NCU, (12)...
...Telephone line, (13)...Line buffer.

Claims (1)

[Claims] (1) In a display control method in which data is interpolated between each pixel data of the original image data to enlarge and display the original image data, the density of the pixel data directly above and the pixel data immediately below the position where the pixel data is interpolated. pixel data that interpolates the average value of the pixel data with the smallest density difference among the difference, the density difference between the upper left pixel data and the lower right pixel data, and the density difference between the upper right pixel data and the lower left pixel data. A display control method characterized in that interpolation is performed at the interpolation position as described above.