Method of and device for preparing characters for recognition

Claim 1

A method of preparing characters which are imaged on a twodimensional regular pattern of positions, a character position being distinguished from a background position by digital information present, the characters being skeletonized for removal of redundant information in that the information of a character position is changed into that of a background position until a skeleton character is obtained whose stroke elements consist of single series of character positions which succeed each other in accordance with an adjacency criterion, said skeletonizing being performed in cycles, in which the positions of the character field are considered according to a regular and fixed sequence, said method comprising the steps of: A. dividing said cycles into at least one cycle of a first mode, followed by at least one cycle of a second mode; B. marking in accordance with an edge criterion, first mode character positions that are situated at an edge of the character, by associating additional information with information of these character positions; C. deciding whether to remove or retain the marked character positions on the basis of an indispensability criterion; D. testing character positions during a cycle of said second mode against an indispensability criterion, and removing or retaining them on the basis of said test; E. counting how many of said series start from all character positions of said skeleton characters in order to determine end points, connection points, and junctions in said skeleton characters, said additional information being associated with the information of said character positions; F. removing at least one series of the series of character positions starting from a junction dependent upon whether a span length of that series, measured as a number of positions from an end point of said series to said junction, does not exceed a given value; and G. changing said additional information of the junction as originally existed prior to its removal, if said removal causes said junction to change over into a connection point.

Claim 2

A method of preparing characters which are imaged on a twodimensional regular pattern of positions, a character position being distinguished from a background position by digital information present, the characters being skeletonized for removal of redundant information in that the information of a character position is changed into that of a background position until a skeleton character is obtained whose stroke elements consist of single series of character positions which succeed each other in accordance with an adjacency criterion, said skeletonizing being performed in cycles, in which the positions of the character field are considered according to a regular and fixed sequence, said method comprising the steps of: A. dividing said cycles into at least one cycle of a first mode, followed by at least one cycle of a second mode; B. marking in accordance with an edge criterion, first mode character positions that are situated at an edge of the character, by associating additional information with information of these character positions; C. deciding whether to remove or retain the marked character positions on the basis of an indispensability criterion; D. testing character positions during a cycle of said second mode against an indispensability criterion, and removing or retaining them on the basis of said test; E. counting how many of said series start from all character positions of said skeleton characters in order to determine end points, connection points, and junctions in said skeleton characters, said additional information being associated with the information of said character positions; F. removing at least one series of the series of character positions starting from a junction dependent upon whether a span length of that series, measured as a number of positions from an end point of said series to said junction, does not exceed a given value; and G. changing said additional information of the junction as originally existed prior to its removal, if said removal causes said junction to change over into a connection point.

Claim 7

A device for skeletonizing characters imaged on a carrier, according to a two-dimensional regular pattern of positions, said device comprising: a detector and storage means associated therewith, said detector feeding information of the characters into said storage means so that the characters are stored as digital information of character positions and background positions, respectively; skeletonizing means for receiving and changing information of character positions into those of background positions until the information of character positions have been reduced to information of character positions of skeleton characters whose stroke elements consit of a single series of character positions which succeed each other in accordance with an adjacency criterion, said skeletonizing means comprising a control unit associated with said storage means for controlling skeletonizing of said characters in cycles, said control unit operative in two modes, a first mode having at least one cycle and a second mode having at least one cycle; a first deciding unit connected to said control unit for receiving during a cycle of the first mode, at least the information of the character positions together with information of positions neighboring thoSe character positions, said first deciding unit incorporating an edge criterion and associating additional information with the information of the character positions to compare whether said character positions satisfy said edge criterion; a second deciding unit connected to said first deciding unit for receiving the information of the character positions and those positions neighboring said character positions during said first mode, said second deciding unit incorporating a logic indispensability criterion and comparing the information of said character positions satisfying said edge criterion with said logic indispensability criterion, said second deciding unit receiving during a cycle of said second mode, information of remaining character positions, and comparing the remaining character positions with the logic indispensability criterion irregardless of whether said remaining positions satisfy said edge criterion; and a counter which compares positions of a ring of positions about a character position, said positions including void as well as neighboring positions about a central position, said counter counting how often a character position is directly followed by a background position or a void position during a cycle about said ring, said counter generating a signal corresponding to this count; a detector connected to said counter for detecting end points, connection points, and junctions, respectively, during a series of searches, and supplying an equality signal when a proper point is located, said control limit responsive to said equality signal and which interrogates information of a number of positions, said number possibly being zero, during at least one search series; and an isolation store connected to said detector and said control unit for isolating information of an end point during a search series of a first type, and isolating information of a connection point during a search series of a second type, said second type of search starting in response to receipt of an equality signal by said control unit during said first type of search series, said isolation store further comprising a span length defining unit having a capacity measured in a number of character positions, said defining unit supplying a signal when a span length of a series of character positions reaches a given value, said span length signal being supplied to said control unit in order to prevent the start of a next search series of the second type.

Claim 8

A device for skeletonizing characters imaged on a carrier, according to a two-dimensional regular pattern of positions, said device comprising: a detector and storage means associated therewith, said detector feeding information of the characters into said storage means so that the characters are stored as digital information of character positions and background positions, respectively; skeletonizing means for receiving and changing information of character positions into those of background positions until the information of character positions have been reduced to information of character positions of skeleton characters whose stroke elements consit of a single series of character positions which succeed each other in accordance with an adjacency criterion, said skeletonizing means comprising a control unit associated with said storage means for controlling skeletonizing of said characters in cycles, said control unit operative in two modes, a first mode having at least one cycle and a second mode having at least one cycle; a first deciding unit connected to said control unit for receiving during a cycle of the first mode, at least the information of the character positions together with information of positions neighboring thoSe character positions, said first deciding unit incorporating an edge criterion and associating additional information with the information of the character positions to compare whether said character positions satisfy said edge criterion; a second deciding unit connected to said first deciding unit for receiving the information of the character positions and those positions neighboring said character positions during said first mode, said second deciding unit incorporating a logic indispensability criterion and comparing the information of said character positions satisfying said edge criterion with said logic indispensability criterion, said second deciding unit receiving during a cycle of said second mode, information of remaining character positions, and comparing the remaining character positions with the logic indispensability criterion irregardless of whether said remaining positions satisfy said edge criterion; and a counter which compares positions of a ring of positions about a character position, said positions including void as well as neighboring positions about a central position, said counter counting how often a character position is directly followed by a background position or a void position during a cycle about said ring, said counter generating a signal corresponding to this count; a detector connected to said counter for detecting end points, connection points, and junctions, respectively, during a series of searches, and supplying an equality signal when a proper point is located, said control limit responsive to said equality signal and which interrogates information of a number of positions, said number possibly being zero, during at least one search series; and an isolation store connected to said detector and said control unit for isolating information of an end point during a search series of a first type, and isolating information of a connection point during a search series of a second type, said second type of search starting in response to receipt of an equality signal by said control unit during said first type of search series, said isolation store further comprising a span length defining unit having a capacity measured in a number of character positions, said defining unit supplying a signal when a span length of a series of character positions reaches a given value, said span length signal being supplied to said control unit in order to prevent the start of a next search series of the second type.