Method of and apparatus for extracting dotted line, and storage medium thereof

A method of extracting a dotted line on a document, comprising:

• a first step of extracting isolated points from an image on the document;
• a second step of extracting the isolated points configuring a candidate of the dotted line on the basis of a positional relationship between the two adjacent isolated points;
• and
• a third step of judging a validity of the candidate of the dotted line from a positional relationship between groups of the extracted isolated points of the candidate of the dotted line,
• wherein said second step includes:
• a step of calculating a distance between the isolated points adjacent to each other;
• a step of comparing the distance with a predetermined threshold value;
• a step of calculating a deviation between the isolated points adjacent to each other;
• and
• a step of comparing the deviation with a predetermined threshold value.

A dotted line extracting apparatus for extracting a dotted line on a document, comprising:

• reading means for reading an image on the document;
• and
• a processor for extracting isolated points from the image, thereafter extracting the isolated points configuring a candidate for the dotted line on the basis of a positional relationship between the two adjacent points, and then judging a validity of the candidate of the dotted line from a positional relationship between groups of the extracted isolated points of the candidate of the dotted line,
• wherein said processor judges the validity of the candidate of the dotted line by judging a regularity of a spacing between the isolated points, and
• wherein said processor judges the validity of the candidate of the dotted line by calculating a gradient of a line segment configured by the group of the isolated points.

A dotted line extracting apparatus for extracting a dotted line on a document, comprising:

• reading means for reading an image on the document;
• and
• a processor for extracting isolated points from the image, thereafter extracting the isolated points configuring a candidate for the dotted line on the basis of a positional relationship between the two adjacent points, and then judging a validity of the candidate of the dotted line from a positional relationship between groups of the extracted isolated points of the candidate of the dotted line,
• wherein said processor calculates a distance between the isolated points adjacent to each other, and thereafter compares the distance with a predetermined threshold value, and
• wherein said processor calculates a deviation between the isolated points adjacent to each other, and thereafter compares the deviation with a predetermined threshold value.

A storage medium storing:

• a first information for extracting isolated points from an image on a document;
• a second information for extracting the isolated points configuring a candidate of the dotted line on the basis of a positional relationship between the two adjacent isolated points;
• and
• a third information for judging a validity of the candidate of the dotted line from a positional relationship between groups of the extracted isolated points of the candidate of the dotted line,
• wherein the third information is also for judging the validity of the candidate of the dotted line by calculating a gradient of a line segment configured by the group of the isolated points.

A storage medium storing:

• a first information for extracting isolated points from an image on a document;
• a second information for extracting the isolated points configuring a candidate of the dotted line on the basis of a positional relationship between the two adjacent isolated points;
• and
• a third information for judging a validity of the candidate of the dotted line from a positional relationship between groups of the extracted isolated points of the candidate of the dotted line,
• wherein the second information is also for calculating a deviation between the isolated points adjacent to each other, and