Patent ID: 6888966

Claim:
A method of identifying a target pattern in an image, said method comprising: a) establishing an inventory of characteristic pattern points within said target pattern and establishing a first record of relative distances between selected characteristic pattern points, said relative distances being recorded as the square of the actual distances between said selected characteristic pattern points; b) partitioning said image into a plurality of sub-image points; c) identifying at least two sub-image points having attributes substantially similar to a corresponding two of said characteristic pattern points; d) calculating the square of the distance between said identified two sub-image points and comparing said calculated square to the recorded relative distance of said corresponding two characteristic pattern points; e) determining that said target pattern has not been identified in response to no match being found in step (d); wherein step(a) further includes: grouping characteristic pattern points into three-point sets defining a first angle having a characteristic pattern point at a vertex and two characteristic pattern points at side-ends of said first angle, the square of the distance between said vertex and each of the side-ends being part of said first record; establishing a second record of first angle parameters proportional to a corresponding first angle within said three-point sets; assigning an identification indicator to all three characteristic pattern points in each three-point set specifying which characteristic pattern point is at the vertex position and which are at either of the side-end positions of said first angle; each first angle parameter being defined as the product of its corresponding first angle's side-lengths multiplied by the cosine of its corresponding first angle; wherein said identified sub-image points are given the identification indicator of their correspondingly matched characteristic pattern points, and further including; f) calculating a second angle parameter of a second angle defined by three identified sub-image points corresponding to a complete three-point set of characteristic pattern points, the vertex of said second angle being the sub-image point whose identification indicator corresponds to the characteristic pattern point that is the vertex of said first angle; and comparing said second angle parameter with said first angle parameter of said corresponding three-point set; wherein said sub-image points forming the side-ends of said second angle are defined by X,Y coordinates of a cartesian plane having positional value relative to the sub-image point identified as the vertex of said second angle; said second angle parameter being defined as the sum of the product of the X coordinates and the product of the Y coordinates of said sub-image points at the side-ends of said second angle.