Measurement module
#include "diplib/chain_code.h"

dip::ChainCode struct

struct CodeTable

Provides data that are helpful when processing chain codes.

The table is prepared using the dip::ChainCode::PrepareCodeTable method. The method takes a stride array, which is expected to have exactly two elements (as chain codes only work with 2D images). The returned table contains a value pos[code] that says how the coordinates change when moving in the direction of the code, and a value offset[code] that says how to modify the image data pointer to reach the new pixel.

pos[code] is identical to code.Delta8() or code.Delta4() (depending on connectivity).

No checking is done when indexing. If the CodeTable is derived from a 4-connected chain code, only the first four table elements can be used. Otherwise, eight table elements exist and are valid.

using dip::ChainCodeArray = std::vector<ChainCode>

A collection of object contours.

void Push( dip::ChainCode::Code const& code)

Adds a code to the end of the chain.

dip::ChainCode::CodeTable PrepareCodeTable( dip::IntegerArray const& strides) const

Returns a table that is useful when processing the chain code

static dip::ChainCode::CodeTable PrepareCodeTable( dip::uint connectivity, dip::IntegerArray const& strides)

Returns a table that is useful when processing the chain code

dip::ChainCode ConvertTo8Connected( ) const

Creates a new chain code object that is 8-connected and represents the same shape.

bool Empty( ) const

A chain code whose start value hasn’t been set is considered empty.

dip::dfloat Length( dip::String const& boundaryPixels = S::EXCLUDE) const

Returns the length of the chain code using the method by Vossepoel and Smeulders.

If the chain code represents the closed contour of an object, add π to the result to determine the object’s perimeter.

Any portions of the chain code that run along the image edge are not measured by default. That is, for an object that is only partially inside the image, the portion of the object’s perimeter that is inside of the image is measured, the edge created by cutting the object is not. To include those portions of the perimeter, set boundaryPixels to "include".

dip::FeretValues Feret( dip::dfloat angleStep = 5.0/180.0*pi) const

Returns the Feret diameters, using an angular step size in radian of angleStep. It is better to use dip::ConvexHull::Feret.

dip::dfloat BendingEnergy( ) const

Computes the bending energy.

Computes the bending energy directly from the chain code. The algorithm is rather imprecise. It is better to use dip::Polygon::BendingEnergy.

dip::dfloat Area( ) const

Computes the area of the solid object described by the chain code. Uses the result of dip::ChainCode::Polygon, so if you plan to do multiple similar measures, extract the polygon and compute the measures on that.

dip::VertexFloat Centroid( ) const

Computes the centroid of the solid object described by the chain code. Uses the result of dip::ChainCode::Polygon, so if you plan to do multiple similar measures, extract the polygon and compute the measures on that.

dip::BoundingBoxInteger BoundingBox( ) const

Finds the bounding box for the object described by the chain code.

dip::uint LongestRun( ) const

Returns the length of the longest run of identical chain codes.

dip::Polygon Polygon( dip::String const& borderCodes = S::KEEP) const

Returns a polygon representation of the object.

Creates a polygon by joining the mid-points between an object pixel and a background pixel that are edge-connected neighbors. The polygon follows the “crack” between pixels, but without the biases one gets when joining pixel vertices into a polygon. The polygon always has an area exactly half a pixel smaller than the solid binary object it represents.

If borderCodes is "keep" (the default), then the output polygon will have vertices for the full chain code. If it is "lose", then the chain codes that go along the image border will be ignored; the polygon will still follow that edge of the object, but there will be no vertices along that edge.

dip::ConvexHull ConvexHull( ) const

Returns the convex hull of the object, see dip::ChainCode::Polygon.

void Image( dip::Image& out) const

Paints the pixels traced by the chain code in a binary image. The image has the size of the dip::ChainCode::BoundingBox.

dip::CoordinateArray Coordinates( ) const

Returns the pixel coordinates for each of the pixels represented in the chain code.

Very large coordinate values will be returned if the chain code runs outside the image on the left or top (i.e. if the pixels encoded by the chain code have negative coordinates) because the output object uses unsigned integers.

dip::ChainCode Offset( ) const

Create a new chain code that goes around the object in the same direction, but traces the background pixels that are 4-connected to the object. That is, it grows the object by one pixel. Only defined for 8-connected chain codes.

std::vector<Code> codes

The chain codes

dip::VertexInteger start = {-1,-1}

The coordinates of the start pixel, the default value is outside the image to indicate there’s no chain code here

dip::LabelType objectID = 0

The label of the object from which this chain code is taken

bool is8connected = true

Is false when connectivity = 1, true when connectivity = 2