JPH0763186B2 - Video text signal conversion circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to, for example, a NAPLPS system videotex signal conversion circuit.

[Outline of Invention]

According to the present invention, in the videotex signal conversion circuit, the character code and the drawing command are code-converted according to the aspect ratio, so that the aspect ratio can be changed without degrading the image quality.

[Conventional technology]

For example, in NAPLPS videotex, the sender encodes the source data according to the syntax, and the receiver decodes the signal sent through the transmission system and displays it on the display.

By the way, there are cases where it is desired to use a display different from the normal aspect ratio as the display of the videotex terminal. In such a case, conventionally, the video signal formed by decoding the transmitted signal is written in the memory,
By controlling the reading of the memory and processing the video signal, the difference in aspect ratio is compared.

[Problems to be solved by the invention]

As described above, when a video signal is processed to cope with a difference in aspect ratio, there is a problem that image quality is deteriorated. That is, when the aspect ratio is changed by the video signal processing, the video signal data may have to be interpolated or the video signal data may become unused.

Further, when the video signal is processed in this way to cope with the difference in aspect ratio, a memory and a control circuit for this are required, which causes a problem that the hardware becomes large in scale.

Therefore, an object of the present invention is to provide a videotex signal conversion circuit capable of changing the aspect ratio without deteriorating the image quality.

Another object of the present invention is to provide a videotex signal conversion circuit which can change the aspect ratio without requiring large-scale hardware.

[Means for solving problems]

The present invention has a conversion table of aspect ratio in a videotex signal conversion circuit that performs code conversion of a character code of a videotex signal and a drawing command, and outputs the codex-converted videotex signal. Is a videotex signal conversion circuit for converting a character code and a drawing command based on the above.

[Action]

Data that determines the aspect ratio of the PDI command is converted in the drawing table 11 according to the display aspect ratio, and data that determines the text aspect ratio is converted in the text size table 12 according to the display aspect ratio. In this way, the code-converted videotex signal is supplied to the NAPLPS decoder 4. The output of the NAPLPS decoder 4 is supplied to the display 5 and an image is displayed on the display 5. Even if the aspect ratio of the display 5 is changed, no signal processing is performed on the output video signal of the NAPLPS decoder 4, so that the image quality of the display 5 does not deteriorate.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

This embodiment is used for processing a videotex signal of NAPLPS system, for example. The NAPLPS method uses a PDI (Picture Description Instruction) description method to express an image. Basic
There are five types of PDI commands: points, lines, arcs, squares, and polygons. By combining these, a bloated image can be expressed. The designation of these points, lines, arcs, rectangles, and polygons is called a geometric primitive. Information such as position coordinates, size, color, and fill pattern are called attributes. The attribute designation is coded and sent like the geometric primitive.

The standard NAPLPS display screen is 200 dots vertically, 256 dots horizontally, and a 4-bit information amount at each point on a display with an aspect ratio of 3: 4. 2 ⁴ at the same time on one screen
= 16 colors can be displayed. Also, these 16 colors can be set freely. In other words, the 4-bit information at each point is 0
A color palette is used which indicates the color numbers from No. 15 to each color and determines which color each color corresponds to by referring to another table. Depending on the system, it is possible to express from 512 colors to tens of thousands of colors, of which 16 colors are usually selected. The text is AS
Sent using a CII code.

NAPLPS transmitted via data line 1 in FIG.
The standard videotex signal is supplied to the conversion unit 3 via the modem 2. The conversion unit 3 has a conversion table for converting the data that determines the aspect ratios of the PDI command and the text according to the aspect ratio of the display 5. Data line 1 with conversion unit 3
The data that determines the aspect ratio of the videotex signal transmitted via the. The output data of the conversion unit 3 is supplied to the NAPLPS decoder 4. The NAPLPS decoder 4 decodes the conversion unit 3 and the blood pressure data and converts them into video signals. The video signal output from the NAPLPS decoder 4 is displayed on the display 5.

The display 5 is a display in which light-emitting elements in which picture elements of three primary colors are integrated are arranged in a two-dimensional array. Since a light emitting element is provided in each cell of this type of display, sufficient brightness can be obtained outdoors. Therefore, it is suitable for use as a large outdoor display. When the display 5 is enlarged, the aspect ratio may not be set to 3: 4. However, since the conversion unit 3 converts the data that determines the aspect ratio of the videotex signal according to the aspect ratio of the display 5,
Even if the aspect ratio of display 5 is other than 3: 4, N
The output of the APLPS decoder 4 can be directly displayed on the display 5, and it is not necessary to perform any signal processing on the output video signal of the NAPLPS decoder 4. Since no signal processing is performed on the output video signal of the NAPLPS decoder 4,
The image quality of the image displayed on the display 5 is not deteriorated.

As the display 5, of course, a CRT display may be used.

The conversion unit 3 converts the PDI command data according to the aspect ratio of the display 5 and the drawing table 11 and the text data according to the aspect ratio of the display 5, as shown in the functional block diagram of FIG. It has a text size table 12.

As shown in FIG. 3A, there are drawing start coordinate (x _s , y _s ) and drawing end coordinate (xe, ye) operands for the operation code of the PDI command. The drawing table 12 has these drawing start coordinates (xs, ys) and drawing end coordinates (xe, y).
By multiplying e) by an appropriate coefficient according to the aspect ratio of the display 5, the aspect ratio of the PDI command is converted so as to match the aspect ratio of the display 5.

The text is sent in ASCII code as described above, and in response to the operation code of the text display, FIG.
Data that specifies the character size (dx / dy) as shown in
Has been sent. The text size table 12 converts this character size designation data (dx / dy) according to the aspect ratio of the display 5.

In FIG. 2, the videotex signal from the modem 2 is sent to the conversion table 13. When the PDI command is sent, the terminals 14A and 14B of the switch 14 are connected, and the terminals 15A and 15B of the switch 15 are connected. When the PDI command is sent, this PDI command is sent to the drawing table 11 via the switch 14. In the drawing table 11, the drawing start coordinates (xs,
ys) and drawing end coordinates (xe, ye) are converted according to the aspect ratio of the display 5. The converted PDI command is given to the conversion table 13 via the switch 15.

When the text is being sent, the terminals 14A and 14C of the switch 14 are connected, and the terminals 15A and 15C of the switch 15 are connected. When the text is sent, the text data is sent to the text size table 12 via the switch 14. Text size table 12
The character size designation data dx / dy is converted according to the aspect ratio of the display 5. The converted text data is given to the conversion table 13.

In this way, the videotex signal output from the modem 2 is converted into data that determines the aspect ratio of the display 5 according to the aspect ratio. Offset table 16 for the converted videotex signal
In order to determine the display position, the offset is appropriately added, and this data is supplied to the NAPLPS decoder 4.

〔The invention's effect〕

According to the present invention, the aspect ratio is converted by converting the character code of the videotex signal and the drawing command. In this way, since the aspect ratio is converted without performing video signal processing, image quality is not deteriorated and complicated hardware is not required.

[Brief description of drawings]

FIG. 1 is a block diagram showing a case where the present invention is used in a terminal of NAPLPS system, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a schematic diagram used for explaining one embodiment of the present invention. It is a diagram. Description of main symbols in the drawing 3: Conversion unit, 4: NAPLPS decoder, 5: Display,
11: Drawing table, 12: Text size table.

Claims (1)

[Claims] 1. A videotex signal conversion circuit for converting a character code of a videotex signal and a drawing command into code and supplying the codex-converted videotex signal to a display device. A conversion table storing corresponding conversion data, and the conversion data stored in the conversion table allows the aspect ratio of the character indicated by the character code and the aspect of the figure indicated by the drawing command. Videotex signal conversion circuit that converts each ratio.