System and method for image registration based on variable region of interest

A method executed by one or more processors for finding a region of interest in an image including the steps of:

• detecting features in said image;
• determining a location for said region of interest;
• determining a size of said region of interest based on a number of features contained within a region of said size and at said location in said image;
• and
• enlarging said size until a number of features contained in said region is larger than a predetermined lower bound or until said size is greater than a predetermined upper bound.

A method executed by one or more processors for aligning a first image and a second image including the steps detecting features in one of said images;

• determining a location for a region of interest;
• determining a size of said region of interest based on a number of features contained within a region of said size and at said location in said image;
• enlarging said size until a number of features contained in said region is larger than a predetermined lower bound or until said size is greater than a predetermined upper bound;
• applying said size and location to said first and second images to extract a region of interest from each image;
• and
• cross-correlating said regions of interest using a plurality of transforms to find a first transform that coarsely aligns said regions of interest.