anchor.diff:  					(loop for i below height do
   						(loop for j below width do
   							(setf neighbors 0)
  -							(setf v 0)
   							(dolist (f (multiple-value-list-remove-nulls (8-neighbors img i j)))
   									(multiple-value-bind (_r _g _b)
   										(pixel img i j)
  
positive.code: 
  ;; Perform an edge thinning algorithm;
  ;; http://homepages.inf.ed.ac.uk/rbf/HIPR2/thin.htm
  (defun edge-thin-means (img)
  	(typecase img
  		(8-bit-rgb-image
  			(locally (declare (type 8-bit-rgb-image img))
  
negative.code: 										(multiple-value-bind (r1 g1 b1)
  											(pixel img (first f) (second f))
  											(declare (type (unsigned-byte 8) r1 g1 b1))
                                      (setf v r1)
  												(if (not (eq r1 _r)) (setf neighbors (+ neighbors 1))))))
  							(multiple-value-bind (r g b)
  								(pixel img2 i j)
  								(declare (type (unsigned-byte 8) r g b))
                             (if (> neighbors 0)
     									(setf (pixel img2 i j)
     										(values v v v)))))))))))
  
  ;; Perform a threasholding operation on the image
  (defun threashold-image (img amount)
  