get_region_chainT_get_region_chainGetRegionChainGetRegionChain (Operator)


get_region_chainT_get_region_chainGetRegionChainGetRegionChain — Contour of an object as chain code.


get_region_chainget_region_chainGetRegionChainGetRegionChainGetRegionChain is obsolete and is only provided for reasons of backward compatibility.


get_region_chain(Region : : : Row, Column, Chain)

Herror T_get_region_chain(const Hobject Region, Htuple* Row, Htuple* Column, Htuple* Chain)

void GetRegionChain(const HObject& Region, HTuple* Row, HTuple* Column, HTuple* Chain)

void HRegion::GetRegionChain(Hlong* Row, Hlong* Column, HTuple* Chain) const

static void HOperatorSet.GetRegionChain(HObject region, out HTuple row, out HTuple column, out HTuple chain)

void HRegion.GetRegionChain(out int row, out int column, out HTuple chain)


The operator get_region_chainget_region_chainGetRegionChainGetRegionChainGetRegionChain 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_chainget_region_chainGetRegionChainGetRegionChainGetRegionChain returns the code in the form of a tuple. In case of an empty region the parameters RowRowRowRowrow and ColumnColumnColumnColumncolumn are zero and ChainChainChainChainchain is the empty tuple.


Holes of the region are ignored. Only one region may be passed, and it must have exactly one connection component.

Execution Information


RegionRegionRegionRegionregion (input_object)  region objectHRegionHRegionHobject

Region to be transformed.

RowRowRowRowrow (output_control)  chain.begin.y HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Line of starting point.

ColumnColumnColumnColumncolumn (output_control)  chain.begin.x HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Column of starting point.

ChainChainChainChainchain (output_control)  chain.code-array HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Direction code of the contour (from starting point).

Typical range of values: 0 ≤ Chain Chain Chain Chain chain ≤ 7


The operator get_region_chainget_region_chainGetRegionChainGetRegionChainGetRegionChain normally returns the value 2 (H_MSG_TRUE). If more than one connection component is passed an exception is raised. The behavior in case of empty input (no input regions available) is set via the operator set_system('no_object_result',<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("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>)set_system("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>). If necessary an exception is raised.

Possible Predecessors

sobel_ampsobel_ampSobelAmpSobelAmpSobelAmp, thresholdthresholdThresholdThresholdThreshold, skeletonskeletonSkeletonSkeletonSkeleton, edges_imageedges_imageEdgesImageEdgesImageEdgesImage, gen_rectangle1gen_rectangle1GenRectangle1GenRectangle1GenRectangle1, gen_circlegen_circleGenCircleGenCircleGenCircle

Possible Successors

approx_chainapprox_chainApproxChainApproxChainApproxChain, approx_chain_simpleapprox_chain_simpleApproxChainSimpleApproxChainSimpleApproxChainSimple

See also

copy_objcopy_objCopyObjCopyObjCopyObj, get_region_contourget_region_contourGetRegionContourGetRegionContourGetRegionContour, get_region_polygonget_region_polygonGetRegionPolygonGetRegionPolygonGetRegionPolygon