Pattern recognition apparatus

• US 4,556,985 A
• Filed: 06/14/1983
• Issued: 12/03/1985
• Est. Priority Date: 06/28/1982
• Status: Expired due to Fees

• Current Assignee: Fuji Electric Company Limited 1-1 Tanabeshinden Kawasaki-Ku Kawasaki-Shi Kanagawa Japan
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Hongo, Yasuo
• Primary Examiner(s): Boudreau, Leo H.
• Application Number:
  US06/504,263
• Time in Patent Office: 903 Days
• Field of Search: 382/30, 382/33, 382/34, 382/41, 382/54, 382/55, 381/41-43
• US Class Current: 382/220
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06V 10/20 Image preprocessing
• CPC Class Codes: G06V 10/32 Normalisation of the pattern dimensions
• CPC Class Codes: G06V 10/40 Extraction of image or video features

Abstract

A pattern recognition apparatus for identifying characters for example comprises a scanner and data extraction circuit which obtains a rectangular sized M×N bit pattern matrix B(i,j) representing the presence and configuration of an unknown scanned pattern in subregions (i,j) of a frame which substantially encloses the scanned pattern, wherein each bit in the pattern has a pattern present value when the scanned pattern falls at least partially within its associated subregion and a pattern absent value when the scanned pattern does not fall within its associated subregion. A processor compares the bit pattern matrix with a plurality of previously obtained bit pattern matrices B_S^K (i,j) for a respective plurality of known reference patterns K, and outputs for each reference pattern K a comparison quantity value D^K whose amplitude represents the degree of correspondence between the bit pattern matrix B(i,j) from scanning the unknown pattern and the bit pattern matrices B_S^K (i,j) for each reference pattern K. The processor then selects the lowest and next lowest comparison quantity values and outputs a pattern identification signal which identifies the unknown pattern as the reference pattern corresponding to the lowest quantity value if this value is less than a first preset value, and if the difference between the lowest and next lowest comparison quantity values is greater than a second preset value.

Claims

1. A pattern recognition apparatus comprising:

means for obtaining a M×

N bit pattern matrix B(i,j) representing the presence and configuration of an unknown scanned pattern in subregions (i,j) of a frame which substantially encloses the scanned pattern, and for determining the general center of a pattern and for forming a frame having a certain size generally centered on said pattern center, wherein each bit in the pattern has a pattern present value when the scanned pattern falls at least partially within its associated subregion or a pattern absent value when the scanned pattern does not fall within its associated subregion;

means for comparing the bit pattern matrix with a plurality of previously obtained bit pattern matrices B_S^K (i,j) for a respective plurality of known reference patterns K, and for outputting for each reference pattern K a comparison quantity value D^K whose amplitude represents the degree of correspondence between the bit pattern matrix B(i,j) for the unknown pattern and the bit pattern matrices B_S^K (i,j) for each reference pattern K according to the formula;

##EQU3## where;

D^K is a deformation matrix operator for the reference pattern K which replaces a pattern absent bit value in B(i,j) with a pattern present bit value for all subregion bits in each bit string, if at least one of the bits in the respective bit string which includes the bit under consideration has a pattern present value,

B_M^K (i,j) is a mask bit matrix for the reference pattern K which contains pattern absent bit values at positions which do not significantly aid in distinguishing the pattern K from another pattern, thereby enabling the identification process to ignore the value of this bit obtained directly from the scan, and

B_S^K (i,j) is a standard bit matrix for the reference pattern K which contains pattern present bits at positions where an ideal reference pattern K would at least partially occupy the corresponding subregion positions, and which contains pattern absent bits where an ideal reference pattern K would not have any of its portion occupying the corresponding subregion positions;

means for selecting the lowest and next lowest comparison quantity values and for outputting a pattern identification signal which identifies the unknown pattern as the reference pattern corresponding to the lowest comparison quantity value if this lowest comparison quantity value is less than a first preset value, and if the difference between the lowest and next lowest comparison quantity values is greater than a second preset value wherein the values of comparison quantity values are generally inversely proportional to the degree of correspondence between the bit matrix pattern and the reference pattern matrices.