diff --git a/stim/image/image.h b/stim/image/image.h
index 28ce502..4a324b2 100644
--- a/stim/image/image.h
+++ b/stim/image/image.h
@@ -24,6 +24,8 @@ class image{
 	size_t Y() const { return R[2]; }
 	size_t C() const { return R[0]; }
 
+	size_t bytes(){ return size() * sizeof(T); }
+
 	void init(){								//initializes all variables, assumes no memory is allocated
 		memset(R, 0, sizeof(size_t) * 3);		//set the resolution and number of channels to zero
 		img = NULL;
@@ -31,6 +33,8 @@ class image{
 
 	void unalloc(){								//frees any resources associated with the image
 		if(img)	free(img);						//if memory has been allocated, free it
+		img=NULL;
+		
 	}
 
 
@@ -40,15 +44,17 @@ class image{
 	}
 
 	void allocate(){
-		img = (T*) malloc( sizeof(T) * R[0] * R[1] * R[2] );	//allocate memory
+		unalloc();
+		img = (T*) malloc( bytes() );	//allocate memory
+		memset(img, 0, bytes());
 	}
 
 	void allocate(size_t x, size_t y, size_t c){	//allocate memory based on the resolution
+		unalloc();
 		R[0] = c; R[1] = x; R[2] = y;				//set the resolution
 		allocate();									//allocate memory
 	}
 
-	size_t bytes(){ return size() * sizeof(T); }
 
 	size_t idx(size_t x, size_t y, size_t c = 0){
 		return y * C() * X() + x * C() + c;
@@ -89,36 +95,33 @@ public:
 	image(){ init(); }							//initialize all variables to zero, don't allocate any memory
 
 	/// Constructor with a filename - loads the specified file
-	image(std::string filename){				//constructor initialize the image with an image file
+	image(std::string filename) : image(){				//constructor initialize the image with an image file
 		load(filename);
 	}
 
 	/// Create a new image from scratch given a number of samples and channels
-	image(size_t x, size_t y = 1, size_t c = 1){
+	image(size_t x, size_t y = 1, size_t c = 1) : image(){
+		init();
 		allocate(x, y, c);
 	}
 
 	/// Create a new image with the data given in 'data'
-	image(T* data, size_t x, size_t y, size_t c = 1){
+	image(T* data, size_t x, size_t y, size_t c = 1) : image(){
+		init();
 		allocate(x, y, c);
 		memcpy(img, data, bytes());
 	}
 
 	/// Copy constructor - duplicates an image object
-	image(const stim::image<T>& I){
+	image(const stim::image<T>& I) : image(){
+		init();
 		allocate(I.X(), I.Y(), I.C());
-		//allocate(I.R[1], I.R[2], I.R[0]);
 		memcpy(img, I.img, bytes());
 	}
 
 	/// Destructor - clear memory
-//	~image(){
-//		free(img);
-//	}
-
-	void clear_exp(){								//clears all image data
-		unalloc();		
-
+	~image(){
+		free(img);
 	}
 
 	stim::image<T> operator=(const stim::image<T>& I){
@@ -142,24 +145,14 @@ public:
 		if(C() == 1)
 		{
 	//if this is a single-color image, just copy the data
-/*
-			THIS DOES NOT WORK PROPERLY.
-			YOU CANNOT DO MEMCPY LIKE THIS BECAUSE IT CORRUPTS THE POINTREF MECHANIC IN OPENCV AND NEVER ACTUALLY CREATES A DEEP COPY BUT TAKES UP THE MEMORY.
-			TO TEST run and compile pseudocode
-			stim::image<unsigned char> I;
-			for(int i = 0; i < file_list.size(); i++)
-				I.load(file_list[i].srt())
-
-			
-			You will run out of memory.
-*/			 
 			memcpy(img, cv_ptr, bytes());     
-//			img = cvImage.data;
 		}
-		if(C() == 3)														//if this is a 3-color image, OpenCV uses BGR interleaving
+		if(C() == 3)
+		{														//if this is a 3-color image, OpenCV uses BGR interleaving
 			set_interleaved_bgr(cv_ptr, X(), Y());
+		}
 
-//		cvImage.deallocate();
+		cvImage.release();	
 	}
 
 	//save a file
@@ -352,6 +345,17 @@ public:
 
 		return r;								//return the inverted image
 	}
+	
+	/// Invert an image by calculating I1 = alpha - I0, where alpha is the maximum image value
+	image<T> invert(){
+		size_t N = size();						//calculate the total number of values in the image
+		image<T> r(X(), Y(), C());				//allocate space for the resulting image
+		T white_val = maxv();
+		for(size_t n = 0; n < N; n++)
+			r.img[n] = white_val - img[n];		//perform the inversion
+
+		return r;								//return the inverted image
+	}
 
 	///crops the image from x1 to x0 and y1 to y0 and returns a new (smaller) image.
 	///Untested
@@ -361,12 +365,12 @@ public:
 		image<T> ret(x1-x0, y1-y0, C());
 		int newWidth = x1-x0;
 		int destidx, srcidx;
-//		for(int i = 0; i < (y1-y0); i++)
+		for(int i = 0; i < (y1-y0); i++)
 		{
 			destidx = i*newWidth*C(); ///destination index one per each row
 			srcidx = ((i+(y0))*X()+x0)*C(); ///source index, one per each row.
-			ret.set_interleaved_rgb(img[srcidx], newWidth, y1-y0, C());
-			memcpy(&ret.img[destidx], &buffer[srcidx], sizeof(T)*newWidth*C());
+//			ret.set_interleaved_rgb(img[srcidx], newWidth, y1-y0, C());
+			memcpy(&ret.img[destidx], &img[srcidx], sizeof(T)*newWidth*C());
 		}		
 	
 //		for(int i = 0; i < (x1 -x0); i++)
--
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