PURPOSE: To obtain a compression mode for letter and image data, which is capable of faithly coding and memorizing the smoothness of letter border, by a method in which even specific additional information other than coordinate values of the points provided on the letter border is used as memory data and between any adjacent two points is approximated by three-order curve.
CONSTITUTION: For bit pattern data obtained by dot-decomposing a letter image into a matrix form, a border extraction treatment is applied to obtain the position of borders on X- and Y-coordinates. A point P is set on the border and the border is divided into the sections of single-valued function with X as a variable to obtain each block B properly. Any one block B is further divided into plural segments Si, and in terms of three-order curve passing through the start point Pi(xi, yi) of each segment Si, a constant (σi) corresponding to 1/6 of two-order derived function value at each start point Pi is calculated. The coordinate values (xi, yi)(i=1Wn) of the constant σi and the point Pi are stored as border data corresponding to the block.
TAKASHIMA MASATAKE
FUKUDA SHINICHIROU
SHIBATA HIROYUKI
| JPS5579154A | 1980-06-14 |
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