Edge detection using Hough transformation
AssigneeLockheed Martin Corporation
InventorDaniel R. Paquette
Life of this patent
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Abstract
A method identifies edges of an object in an image by analyzing an accumulator array produced via a Hough transformation of the image. The method includes the step of identifying a first cell in a first row of the array associated with a first edge of the object. The first is then searched for a second cell in the array associated with a second edge of the object, the second edge being parallel to the first edge. A second row shifted ninety degrees from the first row is then searched for a third cell in the array associated with a third edge of the object, the third edge being perpendicular to the first edge. The second row is then searched for a fourth cell in the array associated with a fourth edge in the image, the fourth edge being parallel to the third edge.
Claims16
A method for identifying edges of an object in an image by analyzing an accumulator array produced via a Hough transformation of the image, the array including a plurality of cells arranged in rows associated with an angle (θ) and columns associated with a distance (ρ), said method comprising the steps of:
- stepping through the cells in a first row of the array inward from opposite ends of the first row to identify a first cell in the first row associated with a first potential edge line of the object;
- stepping inward from the end of the first row opposite the end from which the first cell was identified to identify a second cell in the first row associated with a second potential edge line of the object opposite the first edge;
- stepping through the cells in a second row of the array shifted ninety degrees from said first row to identify a third cell in the second row associated with a third potential edge line of the object;
- and
- stepping inward from the end of the second row opposite the end from which the third cell was identified to identify a fourth cell in the array associated with a fourth potential edge line in the image.
A computer product for identifying edges of an object in an image by analyzing an accumulator array produced via a Hough transformation of the image, the array including a plurality of cells arranged in rows associated with an angle (θ) and columns associated with a distance (ρ), said computer product comprising:
- a portion for stepping through the cells in a first row of the array inward from opposite ends of the first row to identify a first cell in the first row associated with a first edge of the object;
- a portion for stepping inward from the end of the first row opposite the end from which the first cell was identified to identify a second cell in the first row associated with a second edge of the object opposite the first edge;
- a portion for stepping through the cells in a second row of the array shifted ninety degrees from said first row to identify a third cell in the second row associated with a third edge of the object;
- and
- a portion for stepping inward from the end of the second row opposite the end from which the third cell was identified to identify a fourth cell in the array associated with a fourth edge in the image.
A method for identifying edges of an object in a graphical image by analyzing a Hough image of the graphical image, said method comprising the steps of:
- searching the Hough image from a first edge of the Hough image towards the center of the Hough image for a first potential edge line of the object in the graphical image;
- searching the Hough image from a second edge of the Hough image opposite the first edge towards the center of the Hough image for a second potential edge line of the object in the graphical image, the first and second edge lines being opposite edges of the object;
- searching the Hough image from a third edge of the Hough image transverse the first and second edges towards the center of the Hough image for a third potential edge line of the object in the graphical image;
- searching the Hough image from a fourth edge of the Hough image opposite the third edge towards the center of the Hough image for a fourth potential edge line of the object in the graphical image, the third and fourth edge lines being opposite edges of the object.
Dependencies are inferred from the claim text.