Graphics processing device

A method for recognizing a characteristic point of an image for a graphics processing device having an image data storing unit for storing image data;

• a graphic data storing unit for storing graphic data;
• a coordinate inputting unit for inputting coordinates;
• a display unit for displaying the image data and the graphic data;
• and a graphic operation processing unit for processing the image data and the graphic data;
• wherein the graphic data are processed with reference to the image data displayed on the display unit by designating a control point;
• comprising the steps of:
• designating an input point corresponding to the displayed image;
• defining a predetermined neighborhood region in the neighborhood of the input point in a constant range with the input point as a given center of the neighborhood region;
• scanning from the input point in the defied neighborhood region and thereby detecting an image tracing point;
• restricting the constant range, with the image tracing point detected as a given center, as a decision range in which a characteristic point of the image is recognized, and determining an image data region for the image as an object whose characteristic point is to be recognized;
• tracing the image points that constitute the image in the decision range beginning from the detected image tracing point and proceeding in a direction in which the image points are continuously and linearly disposed, and determining the shape of the image in the decision range from the result of tracing;
• determining whether a discontinuous end point of the image exists in the decision range as the characteristic point of the image as a result of tracing the image points in the direction in which the image points are continuously disposed in a linear form;
• determining whether a branch point exists, at which a continuous direction of the image in the decision range is branched into plural directions, as the characteristic point of the image as a result of tracing the image points in the direction in which the image points are continuously disposed in a linear form;
• determining whether a corner point exists, at which a continuous direction of the image in the decision range is changed, as the characteristic point of the image as a result of tracing the image points in the direction in which the image points are continuously disposed in a linear form;
• determining a center point, which lies in a center position in a line width of the image in the decision range and in a position nearest to the input point, as the characteristic point of the image when none of an end point, a branch point nor a corner point is detected as a result of tracing the image points in the direction in which the image points are continuously disposed in a linear form;
• and p1 substituting the given characteristic point for the input point.