Positioning method and apparatus for line scanned images

A computer program for use in a line scanning system, said line scanning system comprising:

• a scanner for scanning an image and generating image information in the form of a plurality of horizontal scan lines representative of said image, said image information having background elements and image elements;
• storage connected to said scanner for storing said elements as they are received from said scanner, said storage organizing said elements as a map representative of said image;
• said computer program comprising:
• first programmed instructions responsive to said scanner for selecting horizontal lines of information received during each kth scan;
• second programmed instructions responsive to said first programmed instructions for detecting the location on said map of a left-most intersection of each of said kth horizontal scan lines with an image element;
• third programmed instructions responsive to the detection of said left-most intersections for logically overlaying each of said intersections with a search area;
• fourth programmed instructions responsive to said third programmed instructions for detecting the location on said map of a left-most image element within each of said areas and substituting said detected location as said left-most image element;
• fifth programmed instructions responsive to said fourth programmed instructions for generating a best-fit line through said locations on said map of said left-most image elements;
• sixth programmed instructions responsive to said fifth programmed instructions for calculating an angle between said best-fit line and a vertical line;
• seventh programmed instructions responsive to said sixth programmed instructions for rotating said map through said angle.

The method of correcting for skew in a line scanning system comprising the steps of:

• receiving image information from a scanner which scans a field and generates said image information in the form of a plurality of horizontal scan lines representative of an image, said image information having background elements and image elements;
• storing said elements as they are received from said scanner, said storage organizing said elements as a map representative of said image;
• selecting from said image information received from said scanner, horizontal lines of information received during each kth scan;
• listing the location in said image of a left-most image element of each of said kth horizontal scan lines;
• generating a best-fit line through said listed locations in said image of said left-most image elements;
• calculating an angle between said best-fit line and a line perpendicular to said kth horizontal scan lines;
• and
• rotating said map through said angle.

The method of correcting for skew in a line scanning system comprising the steps of:

• receiving image information from a scanner which scans a field and generates said image information in the form of a plurality of horizontal scan lines representative of an image, said image information having background elements and image elements;
• storing said elements as they are received from said scanner, said storage organizing said elements as a map representative of said image;
• selecting from said image information received from said scanner, horizontal lines of information received during each kth scan;
• detecting the location on said map of a left-most intersection of each of said kth horizontal scan lines with an image element;
• generating a best-fit line through said locations on said map of said left-most image elements;
• calculating a standard deviation of each of said locations of said left-most image elements from said best-fit line;
• calculating a new best-fit line through only those locations that have a standard deviation less than a predetermined value;
• calculating an angle between said best-fit line and a line perpendicular to said horizontal lines;
• rotating said map through said angle.

In a line scanning system, the combination comprising:

• a scanner for scanning an image and generating image information in the form of a plurality of horizontal scan lines representative of said image, said image information having background elements and image elements;
• storage connected to said scanner for storing said elements as they are received from said scanner, said storage organizing said elements as a map representative of said image;
• first programmed instructions responsive to said scanner for selecting horizontal lines of information received during each kth scan;
• second programmed instructions responsive to said first programmed instructions for detecting the location on said map of a left-most intersection of each of said kth horizontal scan lines with an image element;
• third programmed instructions responsive to said second programmed instructions for generating a best-fit line through said locations on said map of said left-most image elements;
• fourth programmed instructions responsive to said third programmed instructions for calculating a standard deviation of each of said locations of said left-most image elements from said best-fit line;
• fifth programmed instructions responsive to said fourth programmed instructions for calculating a new best-fit line through only those locations that have a standard deviation less than a predetermined value;
• sixth programmed instructions responsive to said fifth programmed instructions for calculating an angle between said best-fit line and a line perpendicular to said horizontal lines;
• seventh programmed instructions responsive to said sixth programmed instructions for rotating said map through said angle.