Image recognition edge detection method and system

Claim 1

In a system in which an image frame formed of a two dimensional array of pixels is represented by a first plurality of values, each value representing the gray scale of a separate pixel in the image frame, means for determining the edges of an object in the image frame, comprising: means for determining a gray scale threshold value; means for producing a second plurality of values comprising a first value for each pixel whose gray scale value has a predetermined relationship to the threshold value and a second value for each pixel whose gray scale value does not have the predetermined relationship to the threshold value; and means for examining groups of values in the second plurality of values, the groups corresponding to square groupings of four adjacent pixels, each group including first and second pairs of values corresponding to pairs of pixels located along orthogonal diagonals respectively of a square grouping of four adjacent pixels, and producing a two dimensional array of values arranged to correspond to the arrangement of the square groupings of four adjacent pixels, each value in the array having either a third or fourth value, said means for examining compares one value in a pair with the other value in said pair, said comparison being performed in both pairs, the third value occurring only if both values in said first pair are the same and both values in said second pair are the same, whereby the fourth values are arranged to represent the edges of the object in the image frame.

Claim 6

A method for determining and representing the edges of an object in an image frame formed of a two dimensional array of pixels represented by a first plurality of values, each value representing the gray scale of a separate pixel in the image frame, the method comprising the steps of: determining a gray scale threshold value based o the gray scale values of the pixels; producing a plurality of values comprising a first value for each pixel whose gray scale value has a predetermined relationship to the threshold value and a second value for each pixel whose gray scale value does not have the predetermined relationship to the threshold value; and examining groups of values in the second plurality of values corresponding to square groupings of four adjacent pixels, each group including first and second pairs of values corresponding to pairs of pixels located along orthogonal diagonals respectively of a square grouping of four adjacent pixels and producing a two dimensional array of values arranged to correspond to the arrangement of the square groupings of four adjacent pixels by comparing one value in a pair with the other value in said pair, said comparison being done for each pair, each value in the array having either a third or fourth value, the third value occurring only if both values in the first pair are the same and both values in the second pair are the same, whereby the fourth values are arranged to represent the edges of the object in the image frame.

Claim 7

A method for determining and representing the edges of an object in an image frame formed of a two dimensional array of pixels represented by a first plurality of values, each value representing the gray scale of a separate pixel in the image frame, the method comprising the steps of: determining a gray scale threshold value based o the gray scale values of the pixels; producing a plurality of values comprising a first value for each pixel whose gray scale value has a predetermined relationship to the threshold value and a second value for each pixel whose gray scale value does not have the predetermined relationship to the threshold value; and examining groups of values in the second plurality of values corresponding to square groupings of four adjacent pixels, each group including first and second pairs of values corresponding to pairs of pixels located along orthogonal diagonals respectively of a square grouping of four adjacent pixels and producing a two dimensional array of values arranged to correspond to the arrangement of the square groupings of four adjacent pixels by comparing one value in a pair with the other value in said pair, said comparison being done for each pair, each value in the array having either a third or fourth value, the third value occurring only if both values in the first pair are the same and both values in the second pair are the same, whereby the fourth values are arranged to represent the edges of the object in the image frame.