Measuring angular rotation of an object

An image processing system comprising:

• a processor;
• a memory coupled with said processor, said memory having contained therein sequences of instructions which, when executed by said processor cause said processor to perform:
• performing a filtering operation on an image of an object to produce a filtered image containing enhanced edge information for said image;
• rotating the filtered image by an incremental angle to produce a rotated image;
• projecting the rotated image onto an x-axis and y-axis defined relative to said image to form projected pixels image from an intersection of said x-axis and said y-axis with said rotated image;
• computing a score for a projection of the rotated image, said score corresponding to a sum of differences of pixel values for said projected pixels;
• performing said rotating, said projecting and said computing for subsequent rotated images, each rotated image of said subsequent rotated images being rotated by a multiple of said incremental angle;
• determining a peak score from said score for the rotated image projection and subsequent scores for the subsequent rotated image projections;
• and
• deriving an angle corresponding to a rotational orientation of said object from said peak score.

A medium having stored thereon sequences of instructions which are executable by a digital processing system, and which, when executed by said digital processing system, cause said digital processing system to perform:

• capturing an image of an object in an image processing system;
• performing a filtering operation on said image to produce a filtered image containing enhanced edge information for said image;
• rotating the filtered image by an incremental angle through a range of angles to produce a series of rotated images;
• projecting each image of said series of rotated images onto an x-axis and y-axis defined relative to said image to form a group of projected pixels from an intersection of said x-axis and said y-axis with said each image;
• computing a score for each projection of said each image of said series of rotated images, said score corresponding to a sum of differences of pixel values for said group of projected pixels;
• determining a highest score from said score for each projection;
• and
• deriving an angle corresponding to a rotational orientation of said object from said highest score.