function ContourFinder() {
	
	this.pixelsWidth; 	// pixels width
	this.pixelsHeight;	// pixels height
	this.pixels;				// pixels (single array of r,g,b,a values of image)
	this.fColor; // foreground color
	this.bColor; // background color
	this.threshold;
	this.maxContourPoints = 500*10; //was 500*4
  this.allpoints = [];

	this.findContours = function(image,foregroundColor,backgroundColor,threshold) {
		var w = this.pixelsWidth = image.width;
		var h = this.pixelsHeight = image.height; 
		this.fColor = foregroundColor;
		this.bColor = backgroundColor;
		this.threshold = threshold;

		// create a new pixel array
		var imageCtx = image.getContext('2d');


		alert(imageCtx);
		
		var imageData = imageCtx.getImageData(0,0,w, h);
		//console.log("imageData: ",imageData);
		var pixels = this.pixels = imageData.data;
		//console.log("pixels: ",pixels);
		var prevValue = 0;
		
		for (var y = 0; y < h; y++) {
			for (var x = 0; x < w; x++) {
				var index = y*w*4+x*4; //(y*w + x)*4;
				
				/*r = pixels[index+0];
				g = pixels[index+1];
				b = pixels[index+2];
				a = pixels[index+3];*/
				var factor = ((pixels[index] *.3 + pixels[index+1]*.59 + pixels[index+2]*.11) )
				//console.log(index+": "+r+" "+" "+g+" "+b+" "+a);
				
				//var value = g; 
				var value = (factor > threshold)? 255 : 0; // threshold
				
				//console.log(" > "+value);
				
				pixels[index+0] = value;
				pixels[index+1] = value;
				pixels[index+2] = value;
				//pixels[index+3] = value;
			}
		}
		
		//console.log("pixels: ",pixels);
		
		// copy the image data back onto the canvas
		//imageCtx.putImageData(imageData, 0, 0); // at coords 0,0
		//return; 
		
    var counter = 0;

		for (var y = 0; y < h; y++) {
			for (var x = 0; x < w; x++) {
				var index = y*w*4+x*4; 
				
				r = pixels[index+0];
				g = pixels[index+1];
				b = pixels[index+2];
				a = pixels[index+3];
				
				var value = g; 
				value = (value > threshold)? 255 : 0;
				// if we enter a foreGround color and red isn't 0 (already stored as contour)
				if(prevValue == backgroundColor && value == foregroundColor && r != 0) {
					var points = this.followContour([x,y]);
          this.allpoints.push(points);
          counter++;
				}
				
				//r = 255;
				pixels[index+0] = r;
				pixels[index+1] = g;
				pixels[index+2] = b;
				pixels[index+3] = a;
				prevValue = value;
			}
		}

    // console.log("counter: " +counter);

    //  console.log(this.getPoints(points));
    // console.log("======================================");

		
		/*for (var i = 0, n = pixels.length; i < n; i += 4) {
			var grayscale = pixels[i  ] * .3 + pixels[i+1] * .59 + pixels[i+2] * .11;
			
			alpha = pixels[i+3];
			//console.log("alpha: ",alpha);
			var value = (alpha > threshold)? 255 : 0;
			//console.log("value: ",value);		
			/*pixels[i  ] = value; 	// red
			pixels[i+1] = value; 	// green
			pixels[i+2] = value; 	// blue
			pixels[i+3] = value; 	// alpha*/
			/*
			if(alpha > threshold) {
				pixels[i  ] = 255; 	// red
			}
		}*/
		
		/*for (var y = 0; y < height; y++) {
			inpos = y * width * 4; // *4 for 4 ints per pixel
			outpos = inpos + w2 * 4
			for (var x = 0; x < w2; x++) {
				r = imageData.data[inpos++] / 3; // less red
				g = imageData.data[inpos++] / 3; // less green
				b = imageData.data[inpos++] * 5; // MORE BLUE
				a = imageData.data[inpos++];     // same alpha
				
				b = Math.min(255, b); // clamp to [0..255]
				
				imageData.data[outpos++] = r;
				imageData.data[outpos++] = g;
				imageData.data[outpos++] = b;
				imageData.data[outpos++] = a;
			}
		}*/
		
		// copy the image data back onto the canvas
		imageCtx.putImageData(imageData, 0, 0); // at coords 0,0
	}
	this.followContour = function(startPoint) {
		//console.log("followContour @",startPoint);
	  points = []; // start new contour
	  points.push(startPoint);
	  var w = this.pixelsWidth;
	  var h = this.pixelsHeight;
	  
	  //console.log("w :",w," h: ",h);
	  
	  var point = startPoint;
	  var numPoints = 0;
	  
	  // define neighborhood (array of 4, with:
	  //   x offset, y offset, index offset
	  var neighborhood = [
	  	[1,0,1,3], // east 
	  	[0,1,w,0], // south
	  	[-1,0,-1,1], // west
	  	[0,-1,-w,2] // north
	  ];
	  
	  var prevIndex;
	  var nextNeighbor = 0; // starting point for neighborhood search (index for neighborhood array)
	  do {
	  	//console.log("  point: ",point[0],point[1]);
	 	  var x = point[0];
	 	  var y = point[1];
	 	  
	 	  
	    // go clockwise trough neighbors (starting at east side)  
	    var index = y*w*4+x*4;
	    this.pixels[index] = 0; // r
	    this.pixels[index+2] = 0; // b
	    var newPoint;
	    //console.log("  index: ",index);
	    var i = nextNeighbor;
    	//console.log("    nextNeighbor: ",nextNeighbor);
	    for(var j=0;j<neighborhood.length;j++) {
	    	
	    	//console.log("    neighbor: ",i);
	    	var nIndex = index+neighborhood[i][2]*4;
	    	//console.log("      neighbor index: ",nIndex);
	    	//console.log("      neighbor g index: ",nIndex+1);
	    	//console.log("      value: ",this.pixels[nIndex+1]);
	    	// todo: check if in range
	    	if(this.pixels[nIndex+1] == this.fColor && nIndex != prevIndex) { 
		    	//console.log("      == fColor");
		    	newPoint = [x+neighborhood[i][0],y+neighborhood[i][1]];
		    	nextNeighbor = neighborhood[i][3];
	 		 	  break;
	    	}
	    	
	    	i++;
	    	i = i%neighborhood.length;
	    	
	    }
	    if(newPoint == undefined) {
		  	break;
		  } else {
			  //console.log("      new point: ",newPoint[0],newPoint[1]);
		 		point = newPoint;
	 		 	points.push(point);
	 		 	//console.log("      points: ",this.getPoints(points));
	 		 	
		  }
		  
		  prevIndex = index;
		  
		  //var index = y*w*4+x*4; 
		  numPoints++;
		  //console.log(point[0],startPoint[0],"  ",point[1],startPoint[1]);
		  
	  } while(!(point[0] == startPoint[0] && point[1] == startPoint[1]) && numPoints < this.maxContourPoints);

	  this.closeContour(points);

    return points;
	}
	this.closeContour = function(points) {
		//console.log("pixels: ",this.pixels);
	}
	this.getPoints = function(points) {
	  var log = "";
		for(var i=0;i<points.length;i++) {
			var point = points[i];
			log += point[0]+","+point[1]+" > ";
		}
		return log;
	}
}