Active Contour Toolbox: ac_area(acontour) - File Exchange

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Highlights from
Active Contour Toolbox

gi_acontour(task, varargin) gi_acontour: graphical interface for ac_segmentation
gi_shape(varargin) gi_shape: graphical interface for instantiating a polygon, a spline, or a mask
ac_area(acontour) ac_area: signed area of an active contour
ac_clipping(acontour, framesi... ac_clipping: clipping of an active contour
ac_deformation(acontour, defo... ac_deformation: deformation of an active contour with topology management
ac_energy(task, varargin) ac_energy: storage and plot of the energy of a set of active contours and
ac_evolution(task, about_acon... ac_evolution: storage, properties, and plot of the evolution of a set of active
ac_isocontour(frame, level, o... ac_isocontour: instantiation of an active contour describing a level set of a frame
ac_length(acontour) ac_length: length of an active contour
ac_mask(acontour, mask_size) ac_mask: conversion of an active contour into a binary mask
ac_plot(o_axes_handle, aconto... ac_plot: plot of an active contour in a window of given height
ac_resampling(acontour, resol... ac_resampling: approximately regular resampling of an active contour using a
ac_sampling(acontour, o_prope... ac_sampling: sampling of an active contour
ac_segmentation(...
ac_usage_mean ac_usage_mean: region competition of mean-based descriptors in grayscale
ac_usage_mean_basic ac_usage_mean_basic: region competition of mean-based descriptors in grayscale
ac_usage_minlength ac_usage_minlength: curvature flow
ac_validity(acontour) ac_validity: check for validity of an active contour
po_circle(center, radius, num... po_circle: instantiation of a closed polygon sampling a circle
po_ellipse(center, radii, til... po_ellipse: instantiation of a closed polygon sampling an ellipse
po_isocontour(frame, level, o... po_isocontour: instantiation of a (set of) closed polygon(s) sampling a level set of a frame
po_mask(polygon, mask_size) po_mask: conversion of a closed polygon into a binary mask
po_orientation(polygon, o_ori... po_orientation: orientation of a closed polygon as a positive or negative real number
po_plot(polygon, o_window_hei... po_plot: plot of an open or a closed polygon in a window of given height
po_rectangle(center, lengths,... po_rectangle: instantiation of a closed polygon sampling a rectangle
po_rouctangle(center, lengths... po_rouctangle: instantiation of a closed polygon sampling a chamfered rectangle
po_simple(polygon) po_simple: test of closed polygon (non) self-intersection
po_square(center, width, tilt... po_square: instantiation of a closed polygon sampling a square
Contents.m
Contents.m
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from Active Contour Toolbox by Eric Debreuve
This toolbox provides some functions to segment an image or a video using active contours

ac_area(acontour)

function acarea = ac_area(acontour)
%ac_area: signed area of an active contour
%   r = ac_area(a) computes the signed area, r, of an active contour, a, using
%   the Green's theorem. If a is oriented counterclockwise, r is positive.
%
%See also po_orientation, acontour.
%
%Active Contour Toolbox by Eric Debreuve
%Last update: June 20, 2006

acarea = 0;

for subac_idx = 1:length(acontour)
   [breaks, coefs, interval] = ppbrk(acontour(subac_idx), 'breaks', 'coefs', 'interval');

   %/!\ this might not be valid if the ppform structure changes
   first_coordinate  = mkpp(breaks, coefs(1:2:end,:));
   second_coordinate = mkpp(breaks, coefs(2:2:end,:));

   acarea = acarea + 0.5 * fnval(fnint(...
      fncmb(...
         fncmb(first_coordinate,  '*', fnder(second_coordinate)), ...
         '-', ...
         fncmb(second_coordinate, '*', fnder(first_coordinate))...
      )), interval(2));
end

Highlights from Active Contour Toolbox

Highlights from
Active Contour Toolbox