Polygon-based technique for the automatic classification of text and graphics components from digitized paper-based forms

Claim 1

A method of classifying components of an image into text or graphics comprising the steps of: a) digitizing the image to form a bit map representation of the image; b) extracting a set of contour vectors from the bit map image; and c) extracting from the set of contour vectors a set of polygon features; d) employing the set of polygon features to classify a first set of graphics components; e) separating the image contour vectors into inner and outer contours; f) sorting all of the inner and outer contours according to horizontal location in their respective group; g) employing the inner and outer contours and the row segregation to classify a second set of graphic components; h) employing the polygon features and row segmentation to detect space between polygons in a horizontal projection between two consecutive polygons to identify a group of object strings; i) extracting from the group of textual strings a third set of graphic components in the form of single like text strings.

Claim 2

A method of classifying components of an image into text or graphics comprising the steps of: a) digitizing the image to form a bit map representation of the image; b) extracting a set of contour vectors from the bit map image; and c) extracting from the set of contour vectors a set of polygon features; d) employing the set of polygon features to classify a first set of graphics components; e) separating the image contour vectors into inner and outer contours; f) sorting all of the inner and outer contours according to horizontal location in their respective group; g) employing the inner and outer contours and the row segregation to classify a second set of graphic components; h) employing the polygon features and row segmentation to detect space between polygons in a horizontal projection between two consecutive polygons to identify a group of object strings; i) extracting from the group of textual strings a third set of graphic components in the form of single like text strings.

Claim 3

A method for the automatic classification of text and graphics components on a paper document comprising the steps of: a) scanning the image to produce a bit map digital image; b) generating from the bit map image a set of contour vectors; c) extracting from the set of contour vectors a set of polygon features; d) employing the set of polygon features to classify a first set of graphics components; e) separating the image contour vectors into inner and outer contours; f) sorting all of the inner and outer contours according to horizontal location in their respective groups; g) employing the inner and outer contours and the row segregation to classify a second set of graphic components; h) employing the polygon features and row segmentation to detect space between polygons in a horizontal projection between two consecutive polygons to identify a group of object strings; i) extracting from the group of object strings a third set of graphic components; j) classifying the remaining objects in the object string as text; and k) extracting from the group of object strings a third set of graphic components in the form of single line text strings.

Claim 4

A method for the automatic classification of text and graphics components on a paper document comprising the steps of: a) scanning the image to produce a bit map digital image; b) generating from the bit map image a set of contour vectors; c) extracting from the set of contour vectors a set of polygon features; d) employing the set of polygon features to classify a first set of graphics components; e) separating the image contour vectors into inner and outer contours; f) sorting all of the inner and outer contours according to horizontal location in their respective groups; g) employing the inner and outer contours and the row segregation to classify a second set of graphic components; h) employing the polygon features and row segmentation to detect space between polygons in a horizontal projection between two consecutive polygons to identify a group of object strings; i) extracting from the group of object strings a third set of graphic components; j) classifying the remaining objects in the object string as text; and k) extracting from the group of object strings a third set of graphic components in the form of single line text strings.

Claim 5

A method for the automatic classification of text and graphics components on a paper document comprising the steps of: a) raster scanning said document; b) generating as the document is being scanned, a bit map representation of the document such that wherever a transition is detected contour vectorization is used to convert the bit representation into a collection of closed polygons formed by a series of vectors; c) calculating a plurality of features associated with the geometric parameters of the polygon; d) establishing a first threshold level to be applied to the collection of polygons such that the calculated value for that polygon is above said first threshold identifying the polygon as a large graphic; e) sorting the collection of polygons into inner and outer contours; f) sorting all of the inner and outer contours according to horizontal location in their respective groups; g) establishing polygon links for all polygons having a geometrical relationship in the horizontal direction; h) use contour linking to examine the geometrical relationship of the coordinates of both the outer and inner contours of a polygon to determine if they are geometrically overlapping; i) separate inner contour of polygons into either graphics or text after comparing the features of the polygon to a predetermined threshold; and j) comparing a subset of features of the remaining polygons which lie on the same horizontal level with predetermined threshold and remove single line text strings.

Claim 6

A method for the automatic classification of text and graphics components on a paper document comprising the steps of: a) raster scanning said document; b) generating as the document is being scanned, a bit map representation of the document such that wherever a transition is detected contour vectorization is used to convert the bit representation into a collection of closed polygons formed by a series of vectors; c) calculating a plurality of features associated with the geometric parameters of the polygon; d) establishing a first threshold level to be applied to the collection of polygons such that the calculated value for that polygon is above said first threshold identifying the polygon as a large graphic; e) sorting the collection of polygons into inner and outer contours; f) sorting all of the inner and outer contours according to horizontal location in their respective groups; g) establishing polygon links for all polygons having a geometrical relationship in the horizontal direction; h) use contour linking to examine the geometrical relationship of the coordinates of both the outer and inner contours of a polygon to determine if they are geometrically overlapping; i) separate inner contour of polygons into either graphics or text after comparing the features of the polygon to a predetermined threshold; and j) comparing a subset of features of the remaining polygons which lie on the same horizontal level with predetermined threshold and remove single line text strings.