JPH041400B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a handwritten figure transmission device that transmits handwritten figures.

[Prior art]

Conventionally, there has been a device of this type as shown in FIG. In the figure, 1 is a coordinate detection unit, 2 is an A/
The D converter 3 monitors changes in the x coordinate, x _i and y coordinate _{y i} at each time t i obtained by the A/D converter 2, and converts a Freeman 8 of size 1 to obtain an 8-connected chain figure. A chain detector 4 detects a directional chain; 4 a chain encoder encodes the 8-direction chain sequence obtained by the chain detector 3 for data compression; 6 is an image storage unit that stores handwritten and received graphics; a chain decoding unit that decodes the received handwritten figure signal into an 8-connected chain;
8 is an image display section for displaying the contents of the image storage section 6, and 9 is a line.

Next, the operation will be explained. A handwritten figure is detected by the pen position coordinates (x,
y) and a pen up/down signal z are input. Next, the A/D converter 2 samples the position coordinates at a constant cycle, and obtains the position coordinate signals x _{i and} y _i at each time t _i and the up/down signal z _i of the pen at this time. 8 in chain detection section 3
Each sampling time (t _i ) is used to obtain a connected chain figure.
When a displacement of magnitude 1 occurs as shown in Fig. 2, the displacement is converted into a Freeman 8-direction chain of magnitude 1 (from 0 to
7 code). The chain encoding unit 4 encodes the 8-direction chain sequence obtained from the chain detection unit 3 for data compression. For example, the chain encoding unit 4 encodes the 8-direction chain sequence obtained by the chain detection unit 3 for data compression. and for the first point of the stroke,
A code indicating the beginning and the absolute coordinates of x and y are shown, and at the end of the stroke, a code indicating the end is issued.
The communication control section 5 modulates and transmits the data encoded by the chain encoding section 4, performs demodulation when receiving the data, and performs overall communication control.
The chain encoding section 4 encodes the chain and at the same time writes the obtained chain sequence into the image storage section 6. The image display section 8 displays the contents of the image storage section 6. The chain decoding unit 7 decodes the received data demodulated by the communication control unit 5,
The obtained information regarding the chain row is stored in the image storage unit 6.
write to.

Since the conventional handwritten figure transmission device is configured as described above, very high-speed coordinate input, that is, very high-speed A/D, is required to always obtain 8-connected figures.
Conversion and chain detection were required. In addition, there are cases in which the eight-connected chain cannot be detected in time for high-speed writing, and in such cases, a situation occurs in which a normal figure cannot be input.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and instead of directly detecting an 8-connected chain, the coordinates of each sample point are linearly interpolated and decomposed into 8-connected chains. By encoding and transmitting the obtained 8-connected chain string, an 8-connected chain string can be reliably generated by slow A/D conversion, that is, slow sampling, and a handwritten figure can be input and transmitted. A handwritten figure transmission device is provided.

[Embodiments of the invention]

FIG. 3 shows an embodiment of the present invention. In this Fig. 3, 1 is the pen position coordinate,
(x, y) and a coordinate detection section 2 that detects the up/down state of the pen. A coordinate detection section 2 converts the position coordinate signal (x, y) obtained by the coordinate detection section 1 into A/D, and simultaneously detects the up/down state of the pen. A/D that also samples the down signal z
A conversion unit 10 decomposes the coordinates (x _i , y _i ) of each sample point obtained by the A/D conversion unit 2 and the up/down signal z _i of the pen into 8 consecutive chain sequences by linear interpolation processing. 11 is an interpolation chain encoding unit that performs encoding for data compression on the interpolation chain sequence generated in the interpolation chain generation unit 10; 5 is an interpolation chain encoding unit that performs encoding in the interpolation chain encoding unit 11; a communication control unit that modulates and transmits the converted handwritten figure signal, demodulates the received data, and controls the overall communication; 6 is an image storage unit that stores the handwritten figure and the received figure; , 8 is an image display section that displays the contents of the image storage section 6, and 7 is a chain decoding section that decodes the handwritten figure data received and demodulated by the communication control section 6 into an 8-connected chain.

Next, the operation will be explained in detail. After the pen position coordinates (x _i , y _i ) at each time t _i and a signal z _i indicating the up/down state of the pen are input to the coordinate detection unit 1 at a sampling frequency of about 30 Hz,
The A/D converter 2 quantizes and converts into discrete values. Next, the interpolation chain generator 10 finds the start and end of the stroke from x _i , y _i , z _i at each time t _i , and for the continuation point of the stroke, the previous sample point coordinates (x _i-1 ,
y _i-1 ) is determined, and an 8-connected chain sequence (interpolated chain sequence) is generated from the interpolation grid points obtained by linear interpolation processing.

Next, a method for realizing the process of finding interpolated grid points from relative coordinates at high speed will be described.

First, compare the positive and negative signs and absolute values of the relative x and y coordinates, as shown in Figure 4.
It is classified into eight octants. Figure 5 shows how octants are classified. From the relationships shown in Figures 4 and 5, relative coordinates belonging to octants other than the octant are projected onto the octant, and the interpolation grid points and interpolation chain are calculated for (dx, dy) at that time. and finally back-projected onto each corresponding octant to obtain actual interpolation grid points and interpolation chains.

Next, a method for obtaining interpolated grid points and interpolated chain sequences from the relative coordinates of the octant will be described.

In general, when examining the distribution of difference coordinates (difference between the previous sample point coordinates and the current sample point coordinates) when handwritten figures are sampled at about 30 Hz, most of them are within an absolute value of 16 dots. Therefore, the relative coordinates (dx,
It is sufficient to store an interpolation chain of up to an absolute value of 16 as a table for dy). Regarding the relative coordinates of the octant shown in FIG. 6, an interpolation chain table as shown in FIG. 8 is referred to.
For example, if the coordinates (3, 2) as shown in Figure 7 are given, the coordinates (3, 2) in the interpolation chain table in Figure 8 are adopted, and the corresponding chain length and interpolation chain row are calculated. demand. Chain length =
3, the upper three bits of the two bytes of the interpolation chain column, that is, 1, 0, and 1 are obtained. The actual interpolation grid points are determined as shown in FIG. 7 based on the chain direction relationship shown in FIG. 8. If the difference coordinates exceed the range of the table of the interpolation chain generation unit 10, the sizes Lx and Ly of the interpolation chain table in the x and y directions set in advance as shown in FIG. 9 (in the above explanation, Lx= 16,
Ly = 16), divide the difference coordinates, calculate the intermediate point coordinate sequence, and calculate the difference coordinates between the sample point and the relay points and between the relay points from the coordinates of the obtained relay points. , the interpolation chain generation unit 10 generates an interpolation chain using the method described above for each section.

In Fig. 9 _, after calculating the coordinates of one relay point _T1 , the generation of the interpolation chain in the section P _i ~ _T1 is
The interpolation chain sequence is searched based on the relative coordinates (dx ₁ , dy ₁ ) with respect to P _i , and the interpolation chain generation process in the interval T ₁ to P _i+1 is performed using the relative coordinates of P _i+1 with respect to T ₁ (dx ₂ , dy ₂ )
The interpolation chain sequence is searched and an interpolation chain is generated. For such large difference coordinates, the coordinates of the necessary relay points are determined, and the interpolation chain generation process for each of the obtained partial sections is repeated to realize the generation of the interpolation chain for the entire section.

The interpolation chain signal thus generated by the interpolation chain generation section 10 is processed for data compression in the interpolation chain encoding section 11 by, for example, assigning a Huffman code based on the appearance distribution of the difference chain to the difference chain. is encoded and transmitted by the communication control unit 5 to another handwritten figure transmission device through a line. On the other hand, the handwritten figure data received by the communication control section 5 is decoded into an 8-connected chain by the chain decoding section 7 and stored in the image storage section 6. The interpolation chain encoding unit 11 transmits graphic information to the communication control unit 5 and also writes the image to the image storage unit 6. The contents of the image storage section 6 are displayed by the image display section 8.

Note that in the above embodiment, the interpolation chain generating section 1
Although the case where the interpolation chain table is referred to in 0 is described, the interpolation chain may be directly determined by only adding and subtracting integers according to the flowchart shown in FIG.

Note that in the above embodiment, the interpolation chain generating section 1
0, a case has been described in which all interpolated chain sequences are converted to Freeman's 8-way chain and output, but the octant number, chain length, and intra-octant chain code (0or1) for each sample point may also be output. In such a case, coding can be most easily performed by applying segment division type chain coding in the interpolation chain coding section 11.

〔Effect of the invention〕

As described above, according to the present invention, an interpolation chain is generated by linearly interpolating sample point coordinates sampled at low speed at high speed, so a high-speed A/D converter is not required. This has the effect of being able to reliably generate an 8-connection chain no matter how fast the writing speed is.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional handwritten figure transmission device.
FIG. 2 is an explanatory diagram of an 8-connected chain, FIG. 3 is a configuration diagram of a handwritten figure transmission device according to an embodiment of the present invention, FIG. 4 is an explanatory diagram of octant numbers and chain codes within the octant, and FIG. A diagram explaining the classification of octants and the chain direction within an octant,
Figure 6 is an explanatory diagram of the coordinate range for which interpolation chain tables are prepared, Figure 7 is a diagram illustrating the correspondence between an example of differential coordinates, interpolation chain columns, and interpolation grid points, and Figure 8 is an illustration of the interpolation chain table. An explanatory diagram, Figure 9 is an explanatory diagram of the interpolation chain generation process when the difference coordinates exceed the range of the interpolation chain table, and Figure 10 is an illustration of the interpolation chain generation process when the difference coordinates exceed the range of the interpolation chain table. 1 is an overall flowchart for generating a chain. 1... Coordinate detection section, 2... A/D conversion section, 5...
...Communication control unit, 6...Image storage unit, 7...Chain encoding unit, 8...Image display unit, 10...Interpolation chain generation unit, 11...Interpolation chain encoding. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1 In a handwritten figure transmission device that encodes and transmits the sample point coordinates of a handwritten figure input from a tablet, there is a coordinate detection unit that detects the coordinates of the pen and the up/down state of the pen, and a coordinate detection unit that detects the coordinates of the pen and the up/down state of the pen, and An A/D converter that A/D converts coordinate signals related to the pen position, and linear interpolation processing from the above coordinate signals of the pen at each time t _i obtained in the A/D converter and signals related to up/down of the pen. an interpolation chain generation section that generates an interpolation chain sequence by the interpolation chain generation section; an interpolation chain encoding section that encodes the interpolation chain sequence generated in the interpolation chain generation section for data compression; and an interpolation chain encoding section that performs encoding for data compression. A communication control unit that performs communication control, a chain decoding unit that decodes a handwritten figure signal received through a line, and an image that stores a handwritten figure input as a figure and a signal related to the received and decoded handwritten figure as an image. A handwritten figure transmission device comprising a storage section and an image display section that displays the contents of the image storage section.