Method of optical character recognition

Claim 3

The method according to claim 1 wherein said reading sequence circumnavigates said character.

Claim 6

The method according to claim 3 wherein said parameter data is comprised of data corresponding to the height and width of said character.

Claim 7

The method of claim 3 wherein said parameter data is comprised of data corresponding to the height, width, perimeter and area within the periphery of the character.

Claim 8

The method of claim 3 wherein said parameter data is comprised of a series of contour numbers representative of the shape of the contour of the character.

Claim 9

The method according to claim 3 wherein said parameter data is comprised of data corresponding to the height, width, perimeter and area within the periphery and a series of contour numbers representative of the shape of the contour of the character.

Claim 10

The method according to claim 3 wherein said parameter data is comprised of data corresponding to the height, width, perimeter and area within the periphery of the character and the maximum and minimum X for each Y and the maximum and minimum Y for each X of said character.

Claim 11

The method according to claim 3 further comprising circumnavigating the character.

Claim 12

The method of claim 3 wherein the data in a cell being read is a factor used to determine which cell will be read next.

Claim 13

The method of claim 10 further comprising generating a compass heading number indicative of a relationship between sequentially read black cells.

Claim 14

The method of claim 11 wherein said reading sequence is comprised of a) reading cells until a black cell is read b) storing the address of said first black cell as a reference cell c) determining an initial compass heading number for said first black cell d) reading a second cell at address location X1 Y1 with respect to said reference cell and storing the address of said second cell as the reference cell when said second cell is black. f) reading a third cell at address X2 Y2 with respect to said reference cell when said second cell is white and storing the address of said third cell as the reference cell when said third cell is black g) retaining said first cell as the reference cell when both said second and third cells are white h) determining a current compass heading number based on the relationship between sequentially determined reference cells i) repeating steps d-h until said first black cell becomes the reference cell and said current compass heading number is the initial compass heading number.

Claim 15

The method according to claim 3 further comprising a) storing reference data in a second memory representative of a set of parameters for reference character b) comparing said test character parameters with corresponding reference character parameters and c) providing an output corresponding to said comparison results.

Claim 18

The method according to claim 14 wherein said first memory is comprised of a random access memory arranged in columns and rows of cells and circumnavigating the test character comprises a) beginning on a starting cell b) reading the location of a reference cell the initial reference cell being the starting cell c) reading a first cell located ahead and to the left of said reference cell to determine if said first cell is black or white d) moving to said first cell when it is black and recording its location as the reference cell and repeating steps c-h e) reading a second cell located directly ahead of said reference cell to determine if said second cell is black or white when said first cell is white f) moving to said second cell when it is black and recording its location as the reference cell and repeating steps c-h g) remaining on said reference cell if both said first and second cells are white but turning to the right so that unread cells are located in said first and second cell locations and repeating steps c-h. h) stopping the reading of cells when said starting cell is returned to as the reference cell and i) providing an output indicating that the circumnavigation of the test character is complete.

Claim 19

The method according to claim 15 further comprising a) storing the minimum and maximum values of the X coordinate encountered for reference cells during the circumnavigation b) storing the maximum and minimum values of the Y coordinate encountered for reference cells during the circumnavigation c) subtracting the minimum X from the maximum X and outputting the difference as the width of the test symbol d) subtracting the minimum Y'value encountered from the maximum Y value encountered and outputting that difference as the height of the test symbol.

Claim 20

The method according to claim 16 wherein said certain parameters are comprised of the width and height of the test character in cells.

Claim 21

The method according to claim 15 wherein said certain parameters are comprised of the width, height, perimeter' and area within the periphery of the test character in cells.

Claim 22

The method according-to claim 18 further comprising a) incrementing a first counter N1 each time the movement from one reference cell to the next is straight b) incrementing a second counter N2 each time the movement from one reference cell to the next is a turn c) providing an output as an approximation of the perimeter using the formula when the circumnavigation is completed.

Claim 23

The method according to claim 18 further comprising a) incrementing an L register by one each time the direction of motion to the next reference cell is to the right and decrementing said L register by one each time the direction of motion to the next reference cell.is to the left b) incrementing an A register by the value in the L register each time a direction of motion is down- . ward and decrementing said A register by the value in the L register each time the direction of motion is upward c) providing the output of the A register as the area within the periphery of the test symbol when the circumnavigation is completed.

Claim 24

The method according to claim 18 wherein said certain parameters are further comprised of a series of contour numbers.

Claim 25

The method according to claim 21 wherein said series of contour numbers is comprised of a series of numbers representing the difference between adjacent headings as the character is circumnavigated.

Claim 26

The method according to claim 22 wherein each heading number represents a difference of forty-five degrees or a multiple thereof such that eight numbers completely define the possible heading numbers.

Claim 27

The method according to claim 22 wherein said series of contour numbers is further comprised of a series of numbers representing the number of cells encountered between changes of headings.

Claim 28

The method of claim 24 wherein said series of contour numbers are grouped in pairs, the first number of each pair representing the number of reference cells encountered since the most recent heading change and the second number representing the heading change occurring at the end of that number of cells.

Claim 29

The method according to claim 22 wherein a new heading number is generated only if the new heading number exceeds the old heading number by a predetermined amount and the new heading is maintained for a predetermined distance as the test character is circumnavigated.

Claim 30

The method according to claim 22 wherein said series of numbers representing the difference between adjacent headings is generated by the steps comprising a) averaging the prior N heading numbers b) if the average of the prior N heading numbers is greater than the most recently encountered transition vector outputting that average as the new heading number and repeating steps a, band c until the circumnavigation is completed c) if the average of the prior N heading numbers is less than the most recently encountered transition vector continuing the circumnavigation without a change in heading number and repeating steps a, b and c until the circumnavigation is completed.

Claim 31

The method according to claim 27 wherein N=4.

Claim 32

The method according to claim 21 wherein the certain parameters of the test character are compared with the parameters of a first reference character to determine if each of the test character's parameters matches a. corresponding parameter of said first reference symbol and rejecting said first reference character as not a match as soon as a single parameter of the reference character fails to match a parameter of the test character and comparing the parameters of the test character to the next reference character's parameters to determine if each of the parameters of the test character match each of the parameters of the reference character and continuing the comparison until a match is found or until all reference characters have been compared.

Claim 33

The method according to claim 29 wherein said certain parameters are further comprised of a filling factor F which is determined by the formula

Claim 34

The method according to claim 29 wherein said certain parameters are further comprised of the width, height, perimeter and area within the periphery of any holes within the test symbol.

Claim 37

The method according to claim 32 wherein said series of contour numbers represents the direction of curvature of the periphery of the test symbol.

Claim 38

The method according to claim 32 wherein the series of contour numbers represents the distance between curves in the periphery of the test symbol.

Claim 39

The method according to claim 33 wherein said contour numbers are determined by circumnavigating the test character.

Claim 40

The method according to claim 35 wherein a number representing the direction of curvature is provided only if a new direction of curvature exceeding the current direction of curvature by a predetermined amount is maintained for a predetermined distance as the test symbol is circumnavigated.