Detection of agricultural contraband in baggage
AssigneeThe United States of America as represented by the Secretary of Agriculture
InventorThomas F. Schatzki
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Abstract
A radiant energy imaging system for selectively enhancing the image of objects having circular cross section to distinguish them from the image of objects having rectangular cross section, such objects being contained in a material having a different density-absorption coefficient product than the objects. In the invention, the gradient image of the spatially resolved transmitted intensity of the radiation is calculated and eroded to preferentially remove the edges of images of objects having rectangular cross section. The invention finds particular use in detecting agricultural contraband contained in baggage or parcels.
Claims19
In a radiant energy imaging system, a method for distinguishing objects having circular cross section from objects having rectangular cross section, such objects being contained in a material having a different density-absorption coefficient product than the objects, comprising:
- (a) directing a beam of radiant energy through the objects;
- (b) measuring transmitted intensity of the radition while maintaining spatial resolution;
- (c) calculating a spatial gradient image of the transmitted intensity;
- (d) eroding the gradient image one or more times to preferentially remove edges of images of objects having rectangular cross section relative to edges of images of objects having circular cross section, said objects being contained in a material having a different density-absorption coefficient product than said objects;
- and
- (e) presenting the image of step (d).
In a radiant energy imaging system, a method for distinguishing objects having circular cross section from objects having rectangular cross section, such objects being contained in a material having a different density-absorption coefficient product than the objects, comprising:
- (a) directing a beam of radiant energy through the objects;
- (b) measuring transmitted intensity of the radiation while maintaining spatial resolution;
- (c) transforming the measured transmitted intensity of step (b) with a point transform selected from group consisting of full gamma correction, partial gamma correction, black/white reversal, and thresholding;
- (d) calculating the spatial gradient image of the transformed transmitted intensity;
- (e) eroding the gradient image one or more times to preferentially remove the edges of images of objects having rectangular cross section relative to the edges of images of objects having circular cross section, said objects being contained in a material having a different density-absorption coefficient product than said objects;
- (f) multiplying the eroded gradient image by a constant;
- (g) adding the eroded gradient image of step (f) to the image of the transformed spatially resolved transmitted intensity of step (c);
- and
- (h) visually displaying the image of step (g).
A radiant energy imaging apparatus for distinguishing objects having circular cross section from objects having rectangular cross section, such objects being contained in a material having a different density-absorption coefficient product than the objects, comprising:
- (a) a beam of radiant energy to irradiate the objects;
- (b) means for measuring transmitted intensity of the radiation after irradiation of the objects in step (a) while maintaining spatial resolution;
- (c) means for calculating a spatial gradient image of the transmitted intensity of step (b);
- (d) means for eroding the gradient image of step (c) one or more times to preferentially remove edges of images of objects having rectangular cross section relative to edges of images of objects having circular cross section;
- and
- (e) means for presenting the image of step (d).
Dependencies are inferred from the claim text.