A bit imperfect stickiness implementation resulted from aims of reproducing intelligent scissors, but making distance weights dynamic might help emulate what Mortensen aims at. Edge finding hardly helps though.

imperfect_sticky_scissors.js

/* Author: ideamonk

*/

window.scissors = {
	MAX_GRADIENT:179.606,
	GRADIENT_SEARCH:32,
	radius:16,
	MIN_GRADIENT:63,
	COST_WIDTH:2,
	distance_weights:[],
	TOLERANCE:3,
};

function clamp(x,l,u){
	return (x<l) ? l:( (x>u) ? u:x );
}

scissors.build_weights = function(){
	for (i=0; i<scissors.GRADIENT_SEARCH; i++){
		for (j=0; j<scissors.GRADIENT_SEARCH; j++){
			scissors.distance_weights.push(
				1.0 / (1 + Math.sqrt((i-scissors.radius)*(i-scissors.radius) + (j-scissors.radius)*(j-scissors.radius)))
			);
		}
	}
}

scissors.find_max_gradient = function(x,y){
	var cx = clamp(x,0,scissors.canvas2.width);
	var cy = clamp(y,0,scissors.canvas2.height);
	var sx = cx - scissors.radius;
	var sy = cy - scissors.radius;
	var x1 = clamp( cx-scissors.radius, 0, scissors.canvas2.width);
	var y1 = clamp( cy-scissors.radius, 0, scissors.canvas2.height);
	var x2 = clamp( cx+scissors.radius, 0, scissors.canvas2.width);
	var y2 = clamp( cy+scissors.radius, 0, scissors.canvas2.height);
	var max_gradient = 0, gradient=0, g=0;
	var rx = cx, ry=cy;
	//scissors.context.fillStyle="rgba(255,255,0,0.1)";
	//scissors.context.fillRect(x1,y1, x2-x1, y2-y1);
	for (var i = y1; i<y2; i++){
		for (var j = x1; j<x2; j++){
			gradient = scissors.distance_weights[(i-y1) * scissors.GRADIENT_SEARCH + (j-x1)] * scissors.context2.getImageData(j, i, 1, 1).data[1];
			if (gradient>max_gradient && gradient>scissors.TOLERANCE){
				max_gradient=gradient;
				rx=j;
				ry=i;
				console.log(gradient);
				//scissors.context.fillStyle="#00f";
				//scissors.context.fillRect(rx, ry, 1, 1);
			} 
		}
	}
	//scissors.context.fillStyle="#f00";
	//scissors.context.fillRect(rx, ry, 3, 3);
	//scissors.context.stroke();
	return [rx,ry];
}

$(document).ready( function(){
	var img = document.getElementById("myMap");
	scissors.canvas = document.getElementById("myCanvas");
	scissors.canvas2 = document.createElement("canvas");
	document.body.appendChild(scissors.canvas2);
	scissors.canvas2.width = scissors.canvas.width;
	scissors.canvas2.height = scissors.canvas.height;
	
	scissors.context2 = scissors.canvas2.getContext("2d");
	scissors.context = scissors.canvas.getContext("2d");
	
	img.onload = function(){
		scissors.context.drawImage(this,0,0);
	}

	Pixastic.process(img, "edges", {mono:true},function(){
		scissors.context2.drawImage(document.getElementById("myMap"),0,0);
	});
	//Pixastic.process(img, "blurfast", {amount:0.3});
	scissors.down = false;
	scissors.build_weights();
	
	// MOUSEDONE
	function canvas_mouseDown(e){
		scissors.down = true;
		var x = e.pageX - document.getElementById("myMap").offsetLeft;
		var y = e.pageY;
		var result = scissors.find_max_gradient(x,y);
		scissors._x = result[0];
		scissors._y = result[1];
		scissors.context.moveTo(scissors._x, scissors._y);
	}
	// MOUSEMOVE
	function canvas_mouseMove(e){
		if (scissors.down){
			var x = e.pageX - document.getElementById("myMap").offsetLeft;
			var y = e.pageY;
			var result = scissors.find_max_gradient(x,y);
			//scissors.context2.line(scissors._x, scissors._y, result[0], result[1]);
			scissors._x = result[0];
			scissors._y = result[1];
			scissors.context.lineTo(scissors._x, scissors._y);
			scissors.context.stroke();
		}
	}
	// MOUSEUP
	function canvas_mouseUp(e){
		scissors.down = false;
	}
	// setup events
	scissors.canvas.addEventListener("mousedown", canvas_mouseDown, false );
	scissors.canvas.addEventListener("mousemove", canvas_mouseMove, false );
	scissors.canvas.addEventListener("mouseup", canvas_mouseUp, false );
});

:D