Hand-written character recognition device with noise removal

A method of removing noise in a system for recognizing hand-written characters comprising the steps of:

• receiving a hand-writing of a character via an input portion;
• detecting coordinate points of a character written on said input portion in a written order thereon;
• specifying two noise candidate coordinate points consecutive in the written order, one of which is to be removed as a noise coordinate point;
• calculating vectors between one of the noise candidate coordinate points and coordinate points detected prior to and subsequent to the noise coordinate points in the written order, for each of the noise candidate coordinate points, respectively;
• calculating angles between the vectors calculated for each of the noise candidate coordinate points, respectively;
• analyzing positional variations of the noise candidate coordinate points from the coordinate points written prior to and subsequent to the noise coordinate points on the basis of a direct comparison of the angle calculated for one of the noise candidate coordinate points with the angle calculated for the other noise candidate coordinate point to determine one of the noise candidate coordinate points whose positional variation is greater than that of the other noise candidate coordinate point as a noise coordinate point;
• and
• removing the noise coordinate point determined as the noise coordinate point from the coordinate points detected.

A method of removing noise in a system for recognizing hand-written character comprising the steps of:

• (a) receiving hand-writing of a character by an input portion;
• (b) detecting coordinate points of the character written on said input portion in an order written thereon;
• (c) specifying four coordinate points Pi−1, Pi, Pi+1 and Pi+2 consecutive in the written order;
• (d) calculating vectors Vi−1, Vi, Vi+1, V0 and V1 between the coordinate points Pi−1, Pi, Pi+1 and Pi+2 as follows:
• Vi−1=Pi−Pi−1,
• Vi=Pi+1−Pi,
• Vi+1=Pi+2−Pi+1,
• V0=Pi+1−Pi−1,
• V1=Pi+2−Pi;
• (e) determining an area A defined by an extension line of the vector V0 and a line perpendicular to the extension line of the vector V0 and starting at the coordinate point Pi+1, and an area B defined by an extension line of the vector Vi−1 and a line perpendicular to the extension line of the vector Vi−1 and starting at the coordinate point Pi;
• (f) calculating an angle Θ1 between the vector Vi−1 and the vector Vi, an angle Θ2 between the vector Vi+1 and the vector V0 and an angle Θ3 between the vector V1 and the vector Vi−1;
• (g) removing the coordinate point Pi as noise coordinate point if both of the following conditions are satisfied and the coordinate point Pi+2 is located in the area A:
• 90°≦|Θ1|<180°, and 0°≦Θ2<90°;
• (h) removing the coordinate point Pi+1 as noise coordinate point if both of the following conditions are satisfied and the coordinate point Pi+2 is located in the area B:
• 90°≦|Θ1|<180°, and −90°≦Θ3≦0°;
• and
• (i) removing the coordinate points Pi and Pi+1 as noise coordinate points if neither of the coordinate points Pi and Pi+1 is removed in the above steps (g) and (h) and the following condition is satisfied:
• 90°≦|Θ1|<180°.

A method of removing noise in a system for recognizing hand-written character comprising the steps of:

• (a) receiving hand-writing of a character by an input portion;
• (b) detecting coordinate points of the character written on said input portion in an order written thereon;
• (c) specifying six coordinate points Pi−2, Pi−1, Pi, Pi+1 and Pi+2, Pi+3 consecutive in the written order;
• (d) calculating vectors Vi−1 and Vi between the coordinate points Pi−1, Pi, and Pi+1 and Pi+2 as follows:
• Vi−1=Pi−Pi−1
• Vi−Pi+1−Pi
• Vi+1=Pi+2−Pi+1
• V0=Pi+1−Pi−1
• V1=Pi+2−Pi;
• (e) determining an area C defined by an extension line of the vector V0 and a line perpendicular to the extension line of the vector V0 and starting at the coordinate point Pi−1, an area D defined by an extension line of the vector Vi−1 and a line perpendicular to the extension line of the vector Vi−1 and starting at the coordinate point Pi−1, an area E defined by an extension line of the vector Vi+1 and a line perpendicular to the extension line of the vector Vi+1 and starting at the coordinate point Pi+2, and an area F defined by an extension line of the vector V1 and a line perpendicular to the extension line of the vector V1 and starting at the coordinate point Pi+2;
• (f) calculating an angle Θ1 between the vector Vi−1 and the vector Vi;
• (g) removing the coordinate point Pi as noise coordinate point if the coordinate point Pi−2 is located in the area C, the coordinate point Pi+3 is located in the area E and the following condition is satisfied:
• 0°≦|Θ1|<90°;
• (h) removing the coordinate point Pi+1 as noise coordinate point if the coordinate point Pi−2 is located in the area D, the coordinate point Pi+3 is located in the area F and the following condition is satisfied:
• 0°≦|Θ1|<90°;
• and
• (i) removing the coordinate points Pi and Pi+1 as noise coordinate points if neither of the coordinate points Pi and Pi+1 is removed in the above steps (g) and (h) and the following condition is satisfied:
• 0°≦|Θ1|<90°.