BORDER LINE DESCRIPTION SYSTEM FOR BINARY IMAGE DATA

PURPOSE:To express the feature of a border line properly by setting up a point of which scanning direction is changed in both the X and Y axis directions as a changing point and recording the differences between a current point and the changing point in respective coordinate axes at the time of scanning from the starting point to the end point in a description system for a border line. CONSTITUTION:Since both the X and Y axes are changed when scanning is started from the starting point 4 of the border line 4-5 and scanning is executed up to the succeeding point 6, DELTAX=1 and DELTAY=-1 are recorded. When the scanning is executed by setting up the point 6 as the current point, the scanning arrives at a point 8 of which X and Y axes are changed and DELTAX=3 and #Y=1 are recorded by using the point 8 as the changing point. When the succeeding scanning is executed by using the point 8 as the current point, the scanning arrives at a point 9 of which X and Y axes are changed and DELTAX=-1 and DELTAY=2 are recorded by using the point 9 as the changing point. Points 10, 11 are adopted as the succeeding changing points, and finally the scanning arrives at the end point 5.