US PATENT SUBCLASS 382 / 257
.~.~ Dilation or erosion (e.g., opening or closing)


Current as of: June, 1999
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382 /   HD   IMAGE ANALYSIS

254  DF  IMAGE ENHANCEMENT OR RESTORATION {7}
256  DF  .~ Object boundary expansion or contraction {2}
257.~.~ Dilation or erosion (e.g., opening or closing)


DEFINITION

Classification: 382/257

Dilation or erosion (e.g., opening or closing):

(under subclass 256) Subject matter in which pixel*s are added or deleted by a specific morphological operation that passes a structuring element over the entire image.

(1) Note. The structuring element may be implemented by a simple logic circuit such as an AND gate for erosion, which contracts the objects in an image, and an OR gate for dilation, which expands the objects. The morphological operation known as "opening", which consists simply of an erosion followed by a dilation, generally smooths the contours of the objects, breaks narrow isthmuses, and eliminates thin protrusions. The morphological operation known as "closing", which consists of a dilation followed by an erosion, tends to smooth sections of contours but, as

opposed to opening, it generally fuses narrow breaks and long thin gulfs, eliminates small holes, and fills gaps in the contours.