Method and apparatus for shelf edge detection

A computing device for detecting shelf edges, comprising:

• a memory;
• and
• an imaging controller, coupled to the memory, the imaging controller including:
• a preprocessor configured to obtain an image depicting a shelf and to increase an intensity of a foreground subset of pixels in the image, wherein each pixel in the foreground subset of pixels has an initial intensity that exceeds an upper intensity threshold, and decrease an intensity of a background subset of pixels in the image, wherein each pixel in the background subset of pixels has an initial intensity that is below a lower intensity threshold;
• a selector configured, responsive to the increasing and the decreasing, to (i) determine gradients for each of the pixels and (ii) select a candidate set of the pixels based on the gradients;
• a line generator configured to overlay a plurality of shelf candidate lines on the image derived from the candidate set of pixels by:
• assigning each pixel in the candidate set to one of a plurality of bins each corresponding to a line,
• selecting candidate subsets of the pixels assigned to respective bins having pixel populations exceeding a threshold, and
• generating a shelf candidate line from each candidate subset of pixels;
• a region generator configured to identify a pair of the shelf candidate lines satisfying a predetermined sequence of intensity transitions;
• and
• the imaging controller configured to generate a shelf edge bounding box corresponding to the pair of shelf candidate lines in the memory.

A method of detecting a shelf edge by an imaging controller, comprising:

• obtaining, by the imaging controller, an image depicting a shelf;
• increasing an intensity of a foreground subset of image pixels in the image, wherein each pixel in the foreground subset of pixels has an initial intensity that exceeds an upper intensity threshold, and decreasing an intensity of a background subset of pixels in the image, wherein each pixel in the background subset of pixels has an initial intensity that is below a lower intensity threshold;
• responsive to the increasing and the decreasing, (i) determining gradients for each of the pixels and (ii) selecting a candidate set of the pixels based on the gradients;
• overlaying a plurality of shelf candidate lines on the image derived from the candidate set of pixels;
• identifying a pair of the shelf candidate lines satisfying a predetermined sequence of a plurality of intensity transitions, wherein the identifying further comprises traversing the image in a predefined direction and evaluating successive pairs of the shelf candidate lines against the predetermined sequence of the plurality of intensity transitions;
• and
• generating a shelf edge bounding box corresponding to the pair of shelf candidate lines.