5. MORPHOLOGICAL AND OTHER AREA OPERATIONS Morphology Defined The word morphology means "the form and structure of an object", or the arrangements and interrelationships between the parts of an objects. Morphology is related to shape, and digital | There is also a way, similar to that of global erosion, to encode all possible openings as one gray-level image, and all possible closings can be computed at the same time. First, as in global erosion, the distance map of the image is found. Then all pixels that do NOT have at least one neighbor nearer to the background and one neighbor more distant are located and marked: These will be called nodal pixels. Figure shows the nodal pixels associated with the object of Figure . If the distance map is thought of as a three-dimensional surface where the distance from the background is represented as height, then every pixel can be thought of as being the peak of a pyramid having a standardized slope. Those peaks that are not included in any other pyramid are the nodal pixels. One way to locate nodal pixels is to scan the distance map, looking at all object pixels; find the minimum (or MIN) and maximum (or MAX) value of all neighbors of the target pixel, and compute MAX-MIN. If this value is less than the maximum possible, which is 2 when using 8-distance, then the pixel is nodal.
