Patent CA-2105125-C (CA)
Inventor: TORAICHI KAZUO
IPC: G06T9/20
Filed: 1993-08-30
Granted: 2000-04-18
Abstract: The present invention provides apparatus and methods for reading two dimensional object, e.g., characters, figures, drawings or illustrations optically and for providing reproduction data for out putting such two dimensional object on paper, plastic or other media. The apparatus includes an image scanner for reading in at least one of characters, illustrations, drawings or logomarks as an image on an image screen having pixels which are arranged in a matrix on which a two-dimensional coordinate is defined. An image memory is provided for memorizing the image as a binary image which is defined on the pixels. A peripheral point extraction device is provided for extracting peripheral points and a peripheral point series from the memorized image, and representing the peripheral points by a series number and by a two-dimensional coordinate which is defined on the pixels. A peripheral point memory is provided for memorizing the series number and the two-dimensional coordinate (X,Y) of the peripheral points. A first data approximation device is provided for approximating x-coordinates and y-coordinates of the peripheral points by piecewise polynomials Sx(t) and Sy(t) which are based upon Fluency functions having an intermediate variable t until an error between the coordinates and the approximating polynomials at the peripheral points decreases below a predetermined threshold. A curvature calculation device is provided for calculating curvatures at all the peripheral points by differentiating the piecewise polynomials Sx(t) and Sy(t). An integral circle extraction device is provided for extracting integral circles from the calculated curvatures. A joint position extraction device is provided for extracting temporary joint which are peripheral points having a larger curvature than a threshold. A second data approximation device is provided for approximating peripheral lines between two neighbouring joints, firstly by a straight line, and secondly by an arc, the second data approximating device approximating x-coordinates and y-coordinates of a peripheral line by piecewise polynomials Sx(t) and Sy(t) which are based on Fluency functions of dimension M with an intermediate variable t, if an error of approximation by a straight line or by an arc is larger than a predetermined constant, the second data approximation device approximating the same line by higher dimensional piecewise polynomials, if the error of approximation is still larger than the constant until said error decreases below a predetermined constant. A     compressed data memory is provided for memorizing coordinates of the joints and parameters approximating lines between neighbouring joints. A peripheral line reproduction device is provided for reproducing peripheral closed lines from the data of the joints and parameters approximating the lines between neighbouring joints.  A reproduction device for reproducing at least one of characters, illustrations, drawings and logomarks by giving different colours to inner regions within peripheral closed lines and to outer regions. Finally, a reproduction data output device is provided for outputting the reproduced data as at least one of real characters, drawings, illustrations or logomarks on paper, plastic sheet or other medium. By this invention, it has been found that approximation by Fluency functions heightens the quality of the reproduced objects.