Contour of an object as chain code.
The operator ::get_region_chain returns the contour of a region. A contour is a series of pixels describing the outline of the region. The contour ``lies on'' the region. It starts at the smallest line number; in that line at the pixel with the largest column index. The rotation occurs clockwise. Holes of the region are ignored. The direction code (chain code) is defined as follows:
3 2 1
4 * 0
5 6 7
The operator ::get_region_chain returns the code in the form of a tuple.
In case of an empty region the parameters Row and
Column are zero and Chain is the empty tuple.
Holes of the region are ignored. Only one region may be passed, and it must have exactly one connection component.
|
Region (input_object) |
region -> Hobject: HRegion |
| Region to be transformed. | |
|
Row (output_control) |
chain.begin.y -> HTuple.long * |
| Line of starting point. | |
|
Column (output_control) |
chain.begin.x -> HTuple.long * |
| Column of starting point. | |
|
Chain (output_control) |
chain.code-array -> HTuple.long * |
| Direction code of the contour (from starting point). | |
| Typical range of values: 0 <= Chain <= 7 | |
The operator ::get_region_chain normally returns the value H_MSG_TRUE. If more than one connection component is passed an exception handling is caused. The behavior in case of empty input (no input regions available) is set via the operator ::set_system('no_object_result',<Result>). The behavior in case of empty region (the region is the empty set) is set via the operator ::set_system('empty_region_result',<Result>). If necessary an exception handling is raised.
::sobel_amp, ::threshold, ::skeleton, ::edges_image, ::gen_rectangle1, ::gen_circle
::approx_chain, ::approx_chain_simple
::copy_obj, ::get_region_contour, ::get_region_polygon
Region processing
