Region identification.

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• Region identification is necessary for region description. One of the many methods for region identification is to label each region (or each boundary) with a unique (integer) number; such identification is called labeling or coloring, also connected component labeling and the largest integer label gives number of regions in the image.

• Another method is to use smaller number of labels by ensuring that no two neighboring regions have the same label; then information about some region pixel must be added to the description to provide full region reference.

• This information is stored in a separate data structure.

• Goal of segmentation was to achieve complete segmentation, now, the regions must be labeled. R is segmented image consists of m disjoint regions Ri . The image R consists of objects and a background

image

Rc is the set of complement, Rb is background, and other regions are considered as objects. Either binary or multilevel image will be the input where background is represented by zero pixels, and objects by non-zero values.

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Fig 3: Masks for region identification (a) 4-connectivity (b) 8-connectivity (c) Label collision

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