JPS62298289A - Videotex signal conversion circuit - Google Patents

Abstract

PURPOSE:To change an aspect ratio without deteriorating picture quality and without requiring a large-scale hardware by code-converting the character code of a videotex signal and a draing instruction respectively. CONSTITUTION:A conversion unit 3 has a conversion table that converts data that determine the aspect ratio of a PDI (picture description instruction) command and a text according to the aspect ratio of display 5, and data that determines the aspect ratio of videotex signals transmitted through a data circuit 1 is changed. Output data of the conversion unit 3 are decoded by a NAPLPS decoder 4 and converted to the video signals and projected on a display 5. Even when the aspect ratio of the display is other than 3:4, the output of the NAPLPS decoder 4 can be projected directly by the display 5, and no signal processing is executed on the output video signals of a NAPLPS decoder 4, and accordingly, the picture quality of an image projected on the display is not deteriorated.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to, for example, a NAPLPS type videotex signal conversion circuit.

[Summary of the invention]

This invention enables a videotex signal conversion circuit to convert character codes and drawing commands according to their respective aspect ratios, thereby making it possible to change the aspect ratio without degrading the image quality.

[Conventional technology]

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

By the way, there are cases where you want to use a display with a different aspect ratio than the normal one for your Videotex terminal. In such cases, conventional methods have been used to decode the sent signal, write the video signal formed into the memory, control the readout of the memory, and process the video signal to accommodate the difference in aspect ratio. Ta.

[Problem that the invention seeks to solve]

As described above, when video signals are processed to accommodate differences in aspect ratio, there is a problem in that image quality deteriorates. In other words, when the aspect ratio is changed by video signal processing, video signal data may need to be interpolated, or video signal data may become unusable.

Furthermore, when video signals are processed in this manner to accommodate differences in aspect ratio, memory and control circuits are required for this purpose, resulting in the problem of increased hardware scale.

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

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

[Means for solving problems]

The present invention provides a videotex signal conversion circuit that converts the character code and drawing command of a videotex signal and outputs the code-converted videotex signal, which includes an aspect ratio conversion table. This is a videotex signal conversion circuit that converts character codes and drawing commands based on the following.

[Effect]

Data that determines the aspect ratio of a PDI command is converted in a drawing table 11 according to the display aspect ratio, and data that determines the aspect ratio of text is converted in a text size table 12 according to the display aspect ratio. In this way, the code-converted Videotex signal is
The signal is supplied to the PLPS 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, the image quality of the display 5 does not deteriorate because no signal processing is performed on the output video signal of the N,A P L P S decoder 4.

〔Example〕

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

This embodiment is used, for example, to process a NAPLPS videotex signal. In the NAPLPS method,
Images are expressed using the PDI (Picture Description Instruction) description method. There are five basic PDr commands: point, line, arc, rectangle, and polygon, and by combining them, complex images can be expressed. These points, lines, arcs, and rectangles.

The designation of shapes such as polygons is called a geometric primitive. Also, location coordinates and size.

Information such as color and fill pattern is called attribute. Attribute specifications are also encoded and sent in the same way as geometric primitives.

The standard display screen for NAPLPS is a display with an aspect ratio of 3:4, with 200 dots vertically and 256 dots horizontally, each representing 4 bits of emotion. One screen can display 2'=16 colors at the same time. Additionally, you can freely set any of these 16 colors. That is, a color palette is used in which color numbers 0 to 15 are indicated by 4-bit information at each point, and which color each number corresponds to is determined by referring to another table. Depending on the system, it is possible to express between 512 colors and tens of thousands of colors, from which 16 colors are usually selected. Text is sent using ASCII codes.

In FIG. 1, N A transmitted via data line 1
The PLPS videotex signal is supplied to the conversion unit 3 via the modem 2. The conversion unit 3 converts PDI according to the aspect ratio of the display 5.
It has a conversion table for converting data that determines the aspect ratio of each command and text. In the conversion unit 3 data determining the aspect ratio of the videotex signal transmitted via the data line l is changed. The output data of the conversion unit 3 is fed to a NAP L P S decoder 4 . The NAP LPS decoder 4 decodes the output data of the conversion unit 3 and converts it into a video signal. A video signal output from the NAPLPS decoder 4 is displayed on a display 5.

The display 5 includes, for example, light emitting elements that integrate picture elements of three primary colors and are arranged in a two-dimensional array. This type of display has a light emitting element in each cell, so it can provide sufficient brightness even outdoors. Therefore, it is suitable for use as a large outdoor display. When the display 5 is enlarged, there may be cases where the aspect ratio cannot 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 the display 5 is other than 3:4, the NAP LPS The output of the decoder 4 can be directly displayed on the display 5, and there is no need 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 quality of the image displayed on the display 5 is not degraded.

Note that as the display 5, of course, a CRT display may be used.

As shown in the functional block diagram in FIG. 2, the conversion unit 3 includes a drawing table 11 that converts PDI command data according to the aspect ratio of the display 5, and a drawing table 11 that converts text data according to the aspect ratio of the display 5. It has a text size table 12.

For the operation code of the PDI command, the third
As shown in Figure A, there are drawing start coordinates (x s, y3) and drawing end coordinates (x e, y e) operands.

The drawing table 12 stores these drawing start coordinates (xs, y
s) and drawing end coordinates (xe.

By multiplying ye) by an appropriate coefficient according to the aspect ratio of the display 5, the aspect ratio of the PDI command is converted to match the aspect ratio of the display 5.

The text is sent as an ASCII code as described above, and the third
As shown in Figure B, data specifying the character size (dx
/dy) is being sent.

The text size table 12 is for converting this character size specification data (d x/d y) according to the aspect ratio of the display 5.

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

When text is being sent, terminals 14A and 14C of switch 14 are connected, and terminals 15A and 15C of switch 15 are connected. When text is sent, the text data is sent to the text size table 12 via the switch 14. Character size specification data d x in text size table 12
/dy is converted according to the aspect ratio of the display 5.

The converted text data is provided to the conversion table 13.

In this manner, the data that determines the aspect ratio of the videotex signal output from the modem 2 is converted according to the aspect ratio of the display 5. For the converted videotex signal, offset table 1
6, an appropriate offset is added to determine the display position, and this data is sent to the NAP LPS decoder 4.
supplied to

[Effects of the Invention] According to the present invention, the aspect ratio is converted by converting the character code and the drawing command of the videotex signal, respectively. In this way, the aspect ratio is converted without performing video signal processing, so there is no deterioration in image quality and no complicated hardware is required.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the case where this invention is used in a NAPLPS terminal, Fig. 2 is a block diagram of an embodiment of this invention, and Fig. 3 is a route used to explain an embodiment of this invention. It is a diagram. Explanation of main symbols in the drawings 3: Conversion unit, 4: NAPLPS decoder, 5:
Display, 11: Drawing table, 12: Text size table. Agent Patent Attorney Tadashi Sugiura Figure 1 - Actual Transportation J'l Figure 2 Figure 3 A Figure 3 B

Claims (1)

[Claims] The videotex signal conversion circuit that converts the character code of the videotex signal and the drawing command and outputs the code-converted videotex signal has an aspect ratio conversion table, and converts the aspect ratio based on the conversion table. A videotex signal conversion circuit that converts character codes and drawing commands.