US 5,809,171 A · Image processing method and apparatus for correlating a test image with a template

Abstract

The image correlation method and apparatus correlates or matches a test image with a template. The image correlation apparatus includes an image processor for partitioning the template into a number of labels, for determining the total number of pixels N.sub.T which form the template and for determining the number of pixels N.sub.i which form each of the labels i. The image correlation apparatus also includes comparator for comparing the test image to the template. The comparator respectively determines, for each predetermined gray level j, the number of pixels of the test image N.sub.j,i representative of a predetermined gray level j which correspond to a predetermined label i of the template. The comparator respectively also determines, for each predetermined gray level j, the number of pixels of the test image N.sub.j representative of a predetermined gray level j which correspond to the template. The image correlation apparatus further includes correlation means for determining the correlation X between the test image and the template according to a predetermined equation which is based, at least in part, upon N.sub.j,i, N.sub.j, N.sub.i and N.sub.T. The image correlation apparatus can also include an address generator for creating a number of relative offsets between the template and the test image. Thus, the test image can be compared to the template at each relative offset and the relative offset which provides the greatest correlation therebetween can be determined. Consequently, the test image and the template can be effectively matched such that a preselected object designated within the template can be located and identified within the test image.

Claims22

Dependent claims

A method for correlating a test image with a template to identify a specific object wherein both the test image and the template are comprised of a plurality of pixels representative of respective predetermined gray levels, the method comprising the steps of:

partitioning the template into a plurality of labels, wherein each label is comprised of at least one pixel;
determining the total number of pixels N.sub.T which comprise the template;
determining the number of pixels N.sub.i which form each of the plurality of labels i of the template;
comparing the template to the test image such that at least some of the pixels of the template correspond to respective pixels of the test image;
determining, for each of a plurality of predetermined gray levels j, the number of pixels of the test image N.sub.j,i representative of a predetermined gray level j which correspond to a predetermined label i of the template;
determining, for each of a plurality of predetermined gray levels j, the number of pixels of the test image N.sub.j representative of a predetermined gray level j which correspond to the template;
and
determining the correlation X between the test image and the template to identify said object according to:
##EQU4## wherein i.sub.min and i.sub.max are the minimum and maximum label designations, respectively, and wherein j.sub.min and j.sub.max are the minimum and maximum gray levels, respectively.

6 more elements

An apparatus for correlating a test image and a template to identify a specific object wherein both the test image and the template are comprised of a plurality of pixels representative of respective predetermined gray levels, the apparatus comprising:

template processing means for processing the plurality of pixels which comprise the template, wherein said template processing means comprises:
means for partitioning the template into a plurality of labels, wherein each label is comprised of at least one pixel;
means for determining the total number of pixels N.sub.T which comprise the template;
and
means for determining the number of pixels N.sub.i which form each of the plurality of labels i of the template;
and
comparison means, responsive to said template processing means, for comparing the test image to the template such that at least some of the pixels of the test image correspond to respective pixels of the template, wherein said comparison means comprises:
means for determining, for each of a plurality of predetermined gray levels j, the number of pixels of the test image N.sub.j,i representative of a predetermined gray level j which correspond to a predetermined label i of the template;
means for determining, for each of a plurality of predetermined gray levels j, the number of pixels of the test image N.sub.j representative of a predetermined gray level j which correspond to the template;
and
correlation means, responsive to said template processing means and said comparison means, for determining the correlation X between the test image and the template to identify said object according to:
##EQU5## wherein i.sub.min and i.sub.max are the minimum and maximum label designations, respectively, and wherein j.sub.min and j.sub.max are the minimum and maximum gray levels, respectively.

9 more elements

Dependencies are inferred from the claim text.

Image processing method and apparatus for correlating a test image with a template

Life of this patent

Image processing method and apparatus for correlating a test image with a template

Life of this patent

Abstract

Claims22