Active contour segmentation

Takes a starting contour (snake) and uses active contours to optimise its shape. Takes a table(s) with coordinates of the initial contour, returns a table(s) with coordinates of optimised contour.

Definition

Input ports

source image

Source image

contours table

Starting contour

Output ports

result table

Resulting contour

Configuration

X or R column (X)

Column names with contour X coordinates

Y or C column (Y)

Column names with contour Y coordinates

Length parameter (alpha)

Snake length shape parameter. Higher values makes snake contract faster.

Smoothness parameter (beta)

Snake smoothness shape parameter. Higher values makes snake smoother.

Boundary condition (boundary_condition)

Boundary conditions for worm (first and last point). Periodic attaches the two ends, fixed holds them in place and free allows them to move.

Convergence (convergence)

Convergence criteria.

Coordinates type (coordinates)

Coordinate tpes for the input columns

Gamma parameter (gamma)

Controls attraction to edges. Use negative values to repel snake from edges.

Max iterations (max_iterations)

Maximum number of iterations

Max move (max_px_move)

Maximum distance in number of pixels to move per iteration.

Edge parameter (w_edge)

Controls attraction to edges. Use negative values to repel snake from edges.

Brightness parameter (w_line)

Controls attraction to brightness. Use negative values to attract to dark regions.

Examples

• Snake_contours.syx

Implementation

class node_contours.ActiveContourSegmentation