Edge detection
AssigneeHewlett-Packard Development Company, L.P.
InventorsSerene Banerjee, Noushath Shaffi, Pulkit Parikh
Life of this patent
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Abstract
An edge detection method and apparatus is disclosed. The method comprises the steps of: calculating a pixel gradient value for each of a plurality of pixels of a digital image, the pixel gradient value representing the difference of a pixel value with respect to at least one neighboring pixel; for each of a plurality of binarization threshold values, determining a corresponding edge map representing the location of pixel gradient values exceeding the binarization threshold value with respect to a side of the digital image; for each edge map, computing a measure of linearity; determining an optimal binarization threshold value based on the computed measures of linearity; and selecting the edge map corresponding to the optimal binarization threshold value.
Claims15
An edge detection method for detecting a substantially linear edge in a digital image, the method comprising the steps of:
- calculating a pixel gradient value, at a processor, for each of a plurality of pixels of a digital image, the pixel gradient value representing the difference of a pixel value with respect to at least one neighbouring pixel;
- for each of a plurality of binarization threshold values, determining a corresponding edge map, at said processor, representing the location of pixel gradient values exceeding the binarization threshold value with respect to a side of the digital image;
- for each edge map, computing a measure of linearity, at said processor;
- determining an optimal binarization threshold value, at said processor, based on the computed measures of linearity;
- and
- selecting the edge map, at said processor, corresponding to the optimal binarization threshold value.
Edge detection apparatus for detecting an edge of a page in a digital image, the apparatus comprising:
- processing means adapted to calculate a pixel gradient value for each of a plurality of pixels of a digital image, the pixel gradient value representing the difference of a pixel value with respect to at least one neighbouring pixel;
- edge map calculation means adapted to determine, for each of a plurality of binarization threshold values, a corresponding edge map representing the location of pixel gradient values exceeding the binarization threshold value with respect to a side of the digital image;
- linearity calculation means adapted to compute a measure of linearity for each edge map;
- threshold determination means adapted to determine an optimal binarization threshold value based on the computed measures of linearity;
- and
- edge map selection means adapted to select the edge map corresponding to the optimal binarization threshold value.
A non-transitory computer-readable medium, when executed on a computer, execute the steps of:
- calculating a pixel gradient value for each of a plurality of pixels of a digital image, the pixel gradient value representing the difference of a pixel value with respect to at least one neighbouring pixel;
- for each of a plurality of binarization threshold values, determining a corresponding edge map representing the location of pixel gradient values exceeding the binarization threshold value with respect to a side of the digital image;
- for each edge map, computing a measure of linearity;
- determining an optimal binarization threshold value based on the computed measures of linearity;
- and
- selecting the edge map corresponding to the optimal binarization threshold value.
Dependencies are inferred from the claim text.