JPH043000B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a handwritten figure transmission device that can realize easy-to-see line figures and a high compression rate.

[Conventional technology]

FIG. 3 is a block diagram showing the structure of a conventional device of this type.
The coordinate detection unit 2 samples the coordinate position signal of the pen at a constant cycle and detects the coordinate position signal Xi, Yi at each time ti and the pen up/down signal (Z) at each time ti. An A/D converter section for obtaining up/down signals Zi, and 3 a chain detection section for monitoring changes in the X and Y coordinates at each sampling time ti to obtain an 8-connected chain figure. When a displacement of magnitude 1 occurs as shown, the displacement is displayed as an 8-direction Freeman chain (codes 0 to 7) of magnitude 1. This eight-way Freeman chain code is determined by the direction of the line segment connecting the center position AO and the nearest grid points A1 to A8 in eight directions from the center position AO. 4 is a differential chain calculation unit that calculates the difference between the chains and outputs a differential chain sequence;
As shown in the figure, for the chain immediately after the start of the stroke, the Freeman chain code is encoded as is, and for the subsequent chains, a differential chain as shown in Figure 6 appears for each differential chain. In a differential chain encoding unit that assigns and encodes a Huffman code based on probability, for example, when the differential chain encoding format is D1, a code of 3 bits in code length "0, 0, 0" is assigned.
And at the end of the stroke, the end signal (En)
Assign and encode. Furthermore, at the start of a stroke, the starting point coordinates are encoded as is. 6 is a communication control unit that performs communication control for transmitting or receiving data encoded by the differential chain encoding unit 5 through the line 10; 7 is a communication control unit that decodes data related to handwritten figures received by this communication control unit 6; A differential chain decoding unit develops the data into an 8-way Freeman chain sequence. Reference numeral 8 denotes an image storage unit such as a video memory that stores an eight-direction Freeman chain sequence related to an input or received handwritten figure as a dot image, and 9 a CRT display or the like that displays the information stored in this image storage unit 8. This is the image display section.

[Problem that the invention seeks to solve]

As is clear from the above, conventional handwritten figure transmission devices only have a mode of transmitting handwritten figures as they are, so line figures such as drawings are difficult to see, and handwritten figures cannot be transferred to files. There was a problem that a sufficient compression ratio could not be obtained when storing data as .

The present invention was made to solve these problems, and provides a handwritten figure transmission device that approximates the figure to shape the line figure to obtain an easy-to-read line figure and also enables a high compression rate. The purpose is to obtain.

[Means for solving problems]

In addition to the conventional device shown in FIG. 3, the handwritten figure transmission device of the present invention transmits these signals based on the pen coordinate signals and pen up/down signals at each sample point obtained in the A/D converter. A command encoding unit is provided to express a command as a command, and handwritten figures are transmitted in two modes: a differential chain encoding mode and a command encoding mode.

[Effect]

In the figure command mode, line figures are approximated using straight lines or circular arcs, and only command information and coordinate information required for that expression are encoded, thereby formatting line figures such as drawings to make them easier to see. , achieves high compression ratio.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a handwritten figure transmission device according to the present invention. In the figure, 0 is a mode selection section that selects between normal mode and graphic command mode, 1 is a coordinate detection section that detects the coordinate position (X, Y) of the pen and the up/down state (Z) of the pen, and 2 3 is an A/D conversion unit that A/D converts and samples the signal (X, Y, Z) obtained by the coordinate detection unit 1; a chain detection unit that monitors changes in the X coordinate Xi and Y coordinate Yi at each time ti obtained by the A/D conversion unit 2, and detects an 8-direction Freeman chain of size 1 to obtain an 8-connected chain figure; Reference numeral 4 denotes a differential chain calculation unit that calculates the difference between the eight-direction chain array obtained by this chain detection unit 3 and generates a differential chain array, and 5 encodes the differential chain obtained by this differential chain calculation unit 4. a differential chain encoding unit that converts
6 is a communication control unit that controls data transmission or reception through the line 10, and 7 is a mode signal sending/determination unit that will be described later, when the normal mode is determined, the data received by the communication control unit 6 is transmitted to 8. A differential chain decoding section 8 decodes the data into a connected chain string, and 8 is an image storage for storing figures received by the differential chain decoding section 7 and the command decoding section 14 (to be described later) or handwritten figures as dot images. 9 is an image display section for displaying the contents of the image storage section 8, 10 is a line, and 11 is a mode selection section 0 for identifying what command is selected when the graphic command mode is selected. , a command identification unit 12 extracts coordinate information necessary to express the command based on the information of the command identification unit 11, adds it to the command code, and encodes the command expression. The command encoding unit 13 sends out a signal of the mode to be transmitted prior to data transmission, and the mode signal sending/determination unit 1 to 10 determines whether it is a graphic command mode or a normal mode upon reception. This is the same as in the conventional device described with reference to FIG. Note that the above-mentioned command decoding unit 14, when the mode is determined to be the graphic command mode,
Decode the received data.

The operation of the handwritten figure transmission device of the present invention configured as described above is as follows.

First, prior to inputting a handwritten figure, the mode selection section 0 selects whether to enter the figure command mode or the normal mode, and when in the figure command mode, also selects a command. In either mode, the coordinate position of the pen at ti (Xi, Yi) and the signal (Zi) indicating the up/down state of the pen are input to the coordinate detection unit 1 at a predetermined sampling frequency, and these signals are /D converter 2 quantizes and converts into discrete values. Next, processing is performed according to the mode specified by the mode selection unit 0.

In the case of normal mode specification, in order to obtain an 8-connected chain figure, X coordinates Xi, Y coordinates at each sampling time ti are
Changes in the coordinate Yi are monitored by the chain detection unit 3,
When a change of magnitude 1 occurs, the displacement is magnitude 1
It is expressed as an 8-way Freeman chain (codes from 0 to 7). Then, the differential chain calculating section 4 calculates the difference between the chains, and the differential chain encoding section 5 encodes the Freeman chain code as it is for the chain immediately after the start of the stroke, and for the subsequent chain strings. assigns and encodes each difference chain with a Huffman code based on the probability of appearance of the difference chain.

Next, when the graphic command mode, which is a feature of the present invention, is specified, the command selected in the mode selection section 0 is identified and identified by the command identification section 11.
It makes a determination, sets a command identification code, extracts the coordinates necessary to express the command based on the information of the command identification code, and adds them to the command identification code. As an example shown in Figure 2, when drawing a straight line from the starting point coordinates (Xi, Yi) to the ending point coordinates (Y _i+3 , Y _i+3 ), in normal mode, P1, P2, P3 , P4, but in the graphic command mode, as shown in the figure, it is expressed by a command identification code representing a straight line command, starting point coordinates, and ending point coordinates. When this straight line command mode is specified, a straight line is drawn from the starting point to the ending point, regardless of the actual trajectory from the starting point to the ending point. Therefore, it is suitable for inputting figures such as drawings. In addition, by having a circle or arc command, you can use the circle command to calculate a circle with the least error by writing it freehand, or to specify two points and create a circle with the diameter at that point. One possible method is to create a circle by specifying the center and a point on the circumference.

As described above, the data encoded in the normal mode or the graphic command mode is transmitted to the line 10.
Before being sent to the other party, a mode signal sending/determining section 13 that specifies the mode sends a mode specifying signal to the other party's handwritten figure transmission device, and then the data is sent to the line 10 through the communication control section 6.

Also, from the other party's handwritten figure transmission device to line 1.
The data sent through 0 is determined by the mode designation signal sent from the other party, and in the case of normal mode, it is decoded by the differential chain decoding section 7.
In the graphic command mode, the command decoder 14 decodes the command. Then, the image storage unit 8 stores the Freeman chain sequence of size 1 obtained by the chain detection unit 3 or the command encoding unit 1.
The command-expressed figure obtained in step 2, or
The data obtained by the differential chain decoding section 7 or the command decoding section 14 is stored as a handwritten figure, and the contents are displayed on the image display section 9.

In addition, in the above example, as a graphic command,
Although we have only shown straight lines, curved lines (circular arcs), etc., it goes without saying that if you want to draw a group of continuous straight lines, you can use the broken line command or add other appropriate commands as necessary. .

〔Effect of the invention〕

As described above, in the handwritten figure transmission device of the present invention, in addition to the normal mode in which data obtained by sequentially sampling handwritten figures and differential chain encoding is transmitted, straight line and curved line approximation processing is also performed. By adding the graphics command mode, if you want to draw a straight line neatly, by instructing the graphics command mode, the line graphics will be formatted and input, making it easier to see. Also, when transmitting complex figures, figures with significant changes, or characters, you can specify the normal mode.
This has the effect of allowing the optimum mode to be selected depending on the scope of use, and also has the effect of achieving a higher compression rate using the graphic command mode.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a handwritten figure transmission device of the present invention, FIG. 2 is a diagram showing an example of the figure command mode, FIG. 3 is a block diagram showing the configuration of a conventional device, and FIG. 4 is a block diagram showing the configuration of a conventional device. An explanatory diagram of an 8-connected chain, Fig. 5 is an explanatory diagram of differential chain encoding, and Fig. 6 is an explanatory diagram of the differential chain encoding.
The figure shows an example of a Huffman code table for a freeman chain and a differential chain. In the figure, 0 is a mode selection section, 1 is a coordinate detection section, 2 is an A/D conversion section, 3 is a chain detection section, and 4
5 is a differential chain calculation unit, 5 is a differential chain encoder, 6 is a communication control unit, 7 is a differential chain decoder, 8 is an image storage unit, 9 is an image display unit, 10 is a line, 11 is a command identification unit, 12 is a command encoding section, 13 is a mode signal sending/determination section, and 14 is a command decoding section. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A coordinate detection unit that detects the coordinates indicated by a pen and the up/down state of the pen, and an A/D that samples the coordinate signals regarding the position of the pen obtained by this coordinate detection unit at a constant cycle and performs A/D conversion. a conversion unit, a chain detection unit that detects an 8-direction Freeman chain of size 1 from the pen coordinate signals and up/down signals at each sample point obtained by the A/D conversion unit; a differential chain calculation unit that calculates the differential chain from the 8-way Freeman chain code; a differential chain encoding unit that encodes the differential chain sequence obtained from the differential chain calculation unit for data compression; and a command encoding unit that expresses these signals as a command based on the pen coordinate signal and up/down signal at each sample point obtained from the A/D conversion unit, and has a differential chain encoding mode and a command encoding mode. A handwritten figure transmission device characterized by being able to transmit handwritten figures in two modes.