Tips and limitations

Type and display of image

Recognition of image files is left over to the browser. JPG and GIF files were tested under recent versions of Internet explorer and Netscape communicator. BMP files are accepted only by Internet explorer.
Color images are averaged to gray scale images.
The gradient is shown scaled to 0-50% of black color and is actually negative: White means no gradient, 50% of black means maximal gradient.

Three types of Boundary conditions are supported

Closed curve: the active contour is constrained to form a closed loop.
Free end points: there is no conditions imposed on curve end points.
Fixed end points: coordinates of both end points of the curve are held fixed.

Parameter gamma and convergence

Small parameter gamma can cause the method to diverge, or get out of control and the applet's behaviour can become unpredictable. Small gamma can also mean that the matrix of the system of linear equations is not positive definite and Cholesky decomposition fails. But this condition is recognized by the applet.
On the other hand, too large parameter gamma means slow convergence.

Some parameters are limited for obvious reasons

gamma < 5	Larger gamma are extremelly time-consuming.
NPoints < 2000	The number of points aproximating the curve.
NIniPoints < 100	The number of points in initial polygonal aproximation.