Add perceptualdiff program totest/pdiff.

The perceptualdiff program was written by Hector Yee with contributions
from Scott Corley and Mick Weiss. It is hosted at http://pdiff.sourceforge.net
The source code added here was obtained by:

	svn co https://svn.sourceforge.net/svnroot/pdiff/trunk pdiff

which gave revision 22 of the source code.

The perceptualdiff program is available under the terms of the GNU GPL,
so I've added a note to COPYING about this program, (and the fact that
it is auxiliary only, and does not affect the license of the implementation
of cairo itself).

13 files changed, 1341 insertions, 3 deletions

diff --git a/COPYING b/COPYING
index 145e62966..7019cd694 100644
--- a/COPYING
+++ b/COPYING
@@ -1,6 +1,6 @@
 Cairo is free software.
 
-Every source file in the implementation of cairo is available to be
+Every source file in the implementation[*] of cairo is available to be
 redistributed and/or modified under the terms of either the GNU Lesser
 General Public License (LGPL) version 2.1 or the Mozilla Public
 License (MPL) version 1.1.  Some files are available under more
@@ -13,5 +13,20 @@ conditions of either license:
 	COPYING-LGPL-2.1
 	COPYING-MPL-1.1
 
-Please see each file in the implementation for Copyright and licensing
-information.
+Please see each file in the implementation for copyright and licensing
+information, (in the opening comment of each file).
+
+[*] The implementation of cairo is contained entirely within the "src"
+and "pixman" directories of the cairo source distribution. There are
+other components of the cairo source distribution (such as the "test"
+and "perf") that are auxiliary to the library itself. None of the
+source code in these directories contributes to a build of the cairo
+library itself, (libcairo.so or cairo.dll or similar).
+
+These auxilary components are also free software, but may be under
+different license terms than cairo itself. For example, most of the
+test cases in the perf and test directories are made available under
+an MIT license to simplify any use of this code for reference purposes
+in using cairo itself. Other files might be available under the GNU
+General Public License (GPL), for example. Again, please see the
+opening comment of each file for copyright and licensing information.
diff --git a/test/pdiff/CMakeLists.txt b/test/pdiff/CMakeLists.txt
new file mode 100644
index 000000000..6e4fa7a8a
--- /dev/null
+++ b/test/pdiff/CMakeLists.txt
@@ -0,0 +1,55 @@
+PROJECT (PerceptualDiff)
+SET(DIFF_SRC PerceptualDiff.cpp LPyramid.cpp RGBAImage.cpp
+CompareArgs.cpp Metric.cpp)
+
+ADD_EXECUTABLE (perceptualdiff ${DIFF_SRC})
+
+# look for libtiff
+FIND_PATH(TIFF_INCLUDE_DIR tiff.h
+  /usr/local/include
+  /usr/include
+  /opt/local/include
+)
+
+FIND_LIBRARY(TIFF_LIBRARY tiff
+  /usr/lib
+  /usr/local/lib
+  /opt/local/lib
+)
+
+IF(TIFF_INCLUDE_DIR)
+  IF(TIFF_LIBRARY)
+    SET( TIFF_FOUND "YES" )
+    SET( TIFF_LIBRARIES ${TIFF_LIBRARY} )
+  ENDIF(TIFF_LIBRARY)
+ENDIF(TIFF_INCLUDE_DIR)
+
+IF(TIFF_FOUND)
+  INCLUDE_DIRECTORIES(${TIFF_INCLUDE_DIR})
+  TARGET_LINK_LIBRARIES(perceptualdiff ${TIFF_LIBRARY})
+ENDIF(TIFF_FOUND)
+
+# look for libpng
+FIND_PATH(PNG_INCLUDE_DIR png.h
+  /usr/local/include
+  /usr/include
+  /opt/local/include
+)
+
+FIND_LIBRARY(PNG_LIBRARY png
+  /usr/lib
+  /usr/local/lib
+  /opt/local/lib
+)
+
+IF(PNG_INCLUDE_DIR)
+  IF(PNG_LIBRARY)
+    SET( PNG_FOUND "YES" )
+    SET( PNG_LIBRARIES ${PNG_LIBRARY} )
+  ENDIF(PNG_LIBRARY)
+ENDIF(PNG_INCLUDE_DIR)
+
+IF(PNG_FOUND)
+  INCLUDE_DIRECTORIES(${PNG_INCLUDE_DIR})
+  TARGET_LINK_LIBRARIES(perceptualdiff ${PNG_LIBRARY})
+ENDIF(PNG_FOUND)
\ No newline at end of file
diff --git a/test/pdiff/CompareArgs.cpp b/test/pdiff/CompareArgs.cpp
new file mode 100644
index 000000000..25925f805
--- /dev/null
+++ b/test/pdiff/CompareArgs.cpp
@@ -0,0 +1,128 @@
+/*
+Comapre Args
+Copyright (C) 2006 Yangli Hector Yee
+
+This program is free software; you can redistribute it and/or modify it under the terms of the
+GNU General Public License as published by the Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with this program;
+if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include "CompareArgs.h"
+#include "RGBAImage.h"
+#include <stdio.h>
+
+static const char* copyright = 
+"PerceptualDiff version 1.0, Copyright (C) 2006 Yangli Hector Yee\n\
+PerceptualDiff comes with ABSOLUTELY NO WARRANTY;\n\
+This is free software, and you are welcome\n\
+to redistribute it under certain conditions;\n\
+See the GPL page for details: http://www.gnu.org/copyleft/gpl.html\n\n";
+
+static const char *usage =
+"PeceptualDiff image1.tif image2.tif\n\n\
+   Compares image1.tif and image2.tif using a perceptually based image metric\n\
+   Options:\n\
+\t-verbose       : Turns on verbose mode\n\
+\t-fov deg       : Field of view in degrees (0.1 to 89.9)\n\
+\t-threshold p	 : #pixels p below which differences are ignored\n\
+\t-gamma g       : Value to convert rgb into linear space (default 2.2)\n\
+\t-luminance l   : White luminance (default 100.0 cdm^-2)\n\
+\t-output o.ppm  : Write difference to the file o.ppm\n\
+\n\
+\n Note: Input files can also be in the PNG format\
+\n";
+
+CompareArgs::CompareArgs()
+{
+	ImgA = NULL;
+	ImgB = NULL;
+	ImgDiff = NULL;
+	Verbose = false;
+	FieldOfView = 45.0f;
+	Gamma = 2.2f;
+	ThresholdPixels = 100;
+	Luminance = 100.0f;
+}
+
+CompareArgs::~CompareArgs()
+{
+	if (ImgA) delete ImgA;
+	if (ImgB) delete ImgB;
+	if (ImgDiff) delete ImgDiff;
+}
+
+bool CompareArgs::Parse_Args(int argc, char **argv)
+{
+	if (argc < 3) {
+		ErrorStr = copyright;
+		ErrorStr += usage;
+		return false;
+	}
+	for (int i = 0; i < argc; i++) {
+		if (i == 1) {
+			ImgA = RGBAImage::ReadTiff(argv[1]);
+			if (!ImgA) {
+				ImgA = RGBAImage::ReadPNG(argv[1]);
+				if (!ImgA)
+				{
+					ErrorStr = "FAIL: Cannot open ";
+					ErrorStr += argv[1];
+					ErrorStr += "\n";
+					return false;
+				}
+			}
+		} else if (i == 2) {			
+			ImgB = RGBAImage::ReadTiff(argv[2]);
+			if (!ImgB) {
+				ImgB = RGBAImage::ReadPNG(argv[2]);
+				if (!ImgB)
+				{
+					ErrorStr = "FAIL: Cannot open ";
+					ErrorStr += argv[2];
+					ErrorStr += "\n";
+					return false;
+				}
+			}
+		} else {
+			if (strstr(argv[i], "-fov")) {
+				if (i + 1 < argc) {
+					FieldOfView = (float) atof(argv[i + 1]);
+				}
+			} else if (strstr(argv[i], "-verbose")) {
+				Verbose = true;
+			} else 	if (strstr(argv[i], "-threshold")) {
+				if (i + 1 < argc) {
+					ThresholdPixels = atoi(argv[i + 1]);
+				}
+			} else 	if (strstr(argv[i], "-gamma")) {
+				if (i + 1 < argc) {
+					Gamma = (float) atof(argv[i + 1]);
+				}
+			}else 	if (strstr(argv[i], "-luminance")) {
+				if (i + 1 < argc) {
+					Luminance = (float) atof(argv[i + 1]);
+				}
+			}else 	if (strstr(argv[i], "-output")) {
+				if (i + 1 < argc) {
+					ImgDiff = new RGBAImage(ImgA->Get_Width(), ImgA->Get_Height(), argv[i+1]);
+				}
+			}
+		}
+	} // i
+	return true;
+}
+
+void CompareArgs::Print_Args()
+{
+	printf("Field of view is %f degrees\n", FieldOfView);
+	printf("Threshold pixels is %d pixels\n", ThresholdPixels);
+	printf("The Gamma is %f\n", Gamma);
+	printf("The Display's luminance is %f candela per meter squared\n", Luminance);
+}
diff --git a/test/pdiff/CompareArgs.h b/test/pdiff/CompareArgs.h
new file mode 100644
index 000000000..29265c34f
--- /dev/null
+++ b/test/pdiff/CompareArgs.h
@@ -0,0 +1,44 @@
+/*
+Comapre Args
+Copyright (C) 2006 Yangli Hector Yee
+
+This program is free software; you can redistribute it and/or modify it under the terms of the
+GNU General Public License as published by the Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with this program;
+if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#ifndef _COMPAREARGS_H
+#define _COMPAREARGS_H
+
+#include <string>
+
+class RGBAImage;
+
+// Args to pass into the comparison function
+class CompareArgs
+{
+public:
+	CompareArgs();
+	~CompareArgs();
+	bool Parse_Args(int argc, char **argv);	
+	void Print_Args();
+	
+	RGBAImage		*ImgA;				// Image A
+	RGBAImage		*ImgB;				// Image B
+	RGBAImage		*ImgDiff;			// Diff image
+	bool			Verbose;			// Print lots of text or not
+	float			FieldOfView;		// Field of view in degrees
+	float			Gamma;				// The gamma to convert to linear color space
+	float			Luminance;			// the display's luminance
+	unsigned int	ThresholdPixels;	// How many pixels different to ignore
+	std::string		ErrorStr;			// Error string
+};
+
+#endif
\ No newline at end of file
diff --git a/test/pdiff/LPyramid.cpp b/test/pdiff/LPyramid.cpp
new file mode 100644
index 000000000..6871c1557
--- /dev/null
+++ b/test/pdiff/LPyramid.cpp
@@ -0,0 +1,88 @@
+/*

+Laplacian Pyramid

+Copyright (C) 2006 Yangli Hector Yee

+

+This program is free software; you can redistribute it and/or modify it under the terms of the

+GNU General Public License as published by the Free Software Foundation; either version 2 of the License,

+or (at your option) any later version.

+

+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;

+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

+See the GNU General Public License for more details.

+

+You should have received a copy of the GNU General Public License along with this program;

+if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

+*/

+

+#include "LPyramid.h"

+

+

+//////////////////////////////////////////////////////////////////////

+// Construction/Destruction

+//////////////////////////////////////////////////////////////////////

+

+LPyramid::LPyramid(float *image, int width, int height) :

+	Width(width),

+	Height(height)

+{

+	// Make the Laplacian pyramid by successively

+	// copying the earlier levels and blurring them

+	for (int i=0; i<MAX_PYR_LEVELS; i++) {

+		if (i == 0) {

+			Levels[i] = Copy(image);

+		} else {

+			Levels[i] = new float[Width * Height];

+			Convolve(Levels[i], Levels[i - 1]);

+		}

+	}

+}

+

+LPyramid::~LPyramid()

+{

+	for (int i=0; i<MAX_PYR_LEVELS; i++) {

+		if (Levels[i]) delete Levels[i];

+	}

+}

+

+float *LPyramid::Copy(float *img)

+{

+	int max = Width * Height;

+	float *out = new float[max];

+	for (int i = 0; i < max; i++) out[i] = img[i];

+	

+	return out;

+}

+

+void LPyramid::Convolve(float *a, float *b)

+// convolves image b with the filter kernel and stores it in a

+{

+	int y,x,i,j,nx,ny;

+	const float Kernel[] = {0.05f, 0.25f, 0.4f, 0.25f, 0.05f};

+

+	for (y=0; y<Height; y++) {

+		for (x=0; x<Width; x++) {

+			int index = y * Width + x;

+			a[index] = 0.0f;

+			for (i=-2; i<=2; i++) {

+				for (j=-2; j<=2; j++) {

+					nx=x+i;

+					ny=y+j;

+					if (nx<0) nx=-nx;

+					if (ny<0) ny=-ny;

+					if (nx>=Width) nx=2*(Width-1)-nx;

+					if (ny>=Height) ny=2*(Height-1)-ny;

+					a[index] += Kernel[i+2] * Kernel[j+2] * b[ny * Width + nx];

+				} 

+			}

+		}

+	}

+}

+

+float LPyramid::Get_Value(int x, int y, int level)

+{

+	int index = x + y * Width;

+	int l = level;

+	if (l > MAX_PYR_LEVELS) l = MAX_PYR_LEVELS;

+	return Levels[level][index];

+}

+

diff --git a/test/pdiff/LPyramid.h b/test/pdiff/LPyramid.h
new file mode 100644
index 000000000..5f98a426c
--- /dev/null
+++ b/test/pdiff/LPyramid.h
@@ -0,0 +1,38 @@
+/*

+Laplacian Pyramid

+Copyright (C) 2006 Yangli Hector Yee

+

+This program is free software; you can redistribute it and/or modify it under the terms of the

+GNU General Public License as published by the Free Software Foundation; either version 2 of the License,

+or (at your option) any later version.

+

+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;

+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

+See the GNU General Public License for more details.

+

+You should have received a copy of the GNU General Public License along with this program;

+if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

+*/

+#ifndef _LPYRAMID_H

+#define _LPYRAMID_H

+

+#define MAX_PYR_LEVELS 8

+

+class LPyramid

+{

+public:	

+	LPyramid(float *image, int width, int height);

+	virtual ~LPyramid();

+	float Get_Value(int x, int y, int level);

+protected:

+	float *Copy(float *img);

+	void Convolve(float *a, float *b);

+	

+	// Succesively blurred versions of the original image

+	float *Levels[MAX_PYR_LEVELS];

+

+	int Width;

+	int Height;

+};

+

+#endif // _LPYRAMID_H
\ No newline at end of file
diff --git a/test/pdiff/Metric.cpp b/test/pdiff/Metric.cpp
new file mode 100644
index 000000000..bcfb8ae49
--- /dev/null
+++ b/test/pdiff/Metric.cpp
@@ -0,0 +1,316 @@
+/*
+Metric
+Copyright (C) 2006 Yangli Hector Yee
+
+This program is free software; you can redistribute it and/or modify it under the terms of the
+GNU General Public License as published by the Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with this program;
+if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include "Metric.h"
+#include "CompareArgs.h"
+#include "RGBAImage.h"
+#include "LPyramid.h"
+#include <math.h>
+
+#ifndef M_PI
+#define M_PI 3.14159265f
+#endif
+
+/*
+* Given the adaptation luminance, this function returns the
+* threshold of visibility in cd per m^2
+* TVI means Threshold vs Intensity function
+* This version comes from Ward Larson Siggraph 1997
+*/ 
+
+float tvi(float adaptation_luminance)
+{
+      // returns the threshold luminance given the adaptation luminance
+      // units are candelas per meter squared
+
+      float log_a, r, result; 
+      log_a = log10f(adaptation_luminance);
+
+      if (log_a < -3.94f) {
+            r = -2.86f;
+      } else if (log_a < -1.44f) {
+            r = powf(0.405f * log_a + 1.6f , 2.18f) - 2.86f;
+      } else if (log_a < -0.0184f) {
+            r = log_a - 0.395f;
+      } else if (log_a < 1.9f) {
+            r = powf(0.249f * log_a + 0.65f, 2.7f) - 0.72f;
+      } else {
+            r = log_a - 1.255f;
+      }
+
+      result = powf(10.0f , r); 
+
+      return result;
+
+} 
+
+// computes the contrast sensitivity function (Barten SPIE 1989)
+// given the cycles per degree (cpd) and luminance (lum)
+float csf(float cpd, float lum)
+{
+	float a, b, result; 
+	
+	a = 440.0f * powf((1.0f + 0.7f / lum), -0.2f);
+	b = 0.3f * powf((1.0f + 100.0f / lum), 0.15f);
+		
+	result = a * cpd * expf(-b * cpd) * sqrtf(1.0f + 0.06f * expf(b * cpd)); 
+	
+	return result;	
+}
+
+/*
+* Visual Masking Function
+* from Daly 1993
+*/
+float mask(float contrast)
+{
+      float a, b, result;
+      a = powf(392.498f * contrast,  0.7f);
+      b = powf(0.0153f * a, 4.0f);
+      result = powf(1.0f + b, 0.25f); 
+
+      return result;
+} 
+
+// convert Adobe RGB (1998) with reference white D65 to XYZ
+void AdobeRGBToXYZ(float r, float g, float b, float &x, float &y, float &z)
+{
+	// matrix is from http://www.brucelindbloom.com/
+	x = r * 0.576700f + g * 0.185556f + b * 0.188212f;
+	y = r * 0.297361f + g * 0.627355f + b * 0.0752847f;
+	z = r * 0.0270328f + g * 0.0706879f + b * 0.991248f;
+}
+
+void XYZToLAB(float x, float y, float z, float &L, float &A, float &B)
+{
+	static float xw = -1;
+	static float yw;
+	static float zw;
+	// reference white
+	if (xw < 0) {
+		AdobeRGBToXYZ(1, 1, 1, xw, yw, zw);
+	}
+	const float epsilon  = 216.0f / 24389.0f;
+	const float kappa = 24389.0f / 27.0f;
+	float f[3];
+	float r[3];
+	r[0] = x / xw;
+	r[1] = y / yw;
+	r[2] = z / zw;
+	for (int i = 0; i < 3; i++) {
+		if (r[i] > epsilon) {
+			f[i] = powf(r[i], 1.0f / 3.0f);
+		} else {
+			f[i] = (kappa * r[i] + 16.0f) / 116.0f;
+		}
+	}
+	L = 116.0f * f[1] - 16.0f;
+	A = 500.0f * (f[0] - f[1]);
+	B = 200.0f * (f[1] - f[2]);
+}
+
+bool Yee_Compare(CompareArgs &args)
+{
+	if ((args.ImgA->Get_Width() != args.ImgB->Get_Width()) ||
+		(args.ImgA->Get_Height() != args.ImgB->Get_Height())) {
+		args.ErrorStr = "Image dimensions do not match\n";
+		return false;
+	}
+	
+	unsigned int i, dim;
+	dim = args.ImgA->Get_Width() * args.ImgA->Get_Height();
+	bool identical = true;
+	for (i = 0; i < dim; i++) {
+		if (args.ImgA->Get(i) != args.ImgB->Get(i)) {
+		  identical = false;
+		  break;
+		}
+	}
+	if (identical) {
+		args.ErrorStr = "Images are binary identical\n";
+		return true;
+	}
+	
+	// assuming colorspaces are in Adobe RGB (1998) convert to XYZ
+	float *aX = new float[dim];
+	float *aY = new float[dim];
+	float *aZ = new float[dim];
+	float *bX = new float[dim];
+	float *bY = new float[dim];
+	float *bZ = new float[dim];
+	float *aLum = new float[dim];
+	float *bLum = new float[dim];
+	
+	float *aA = new float[dim];
+	float *bA = new float[dim];
+	float *aB = new float[dim];
+	float *bB = new float[dim];
+
+	if (args.Verbose) printf("Converting RGB to XYZ\n");
+	
+	unsigned int x, y, w, h;
+	w = args.ImgA->Get_Width();
+	h = args.ImgA->Get_Height();
+	for (y = 0; y < h; y++) {
+		for (x = 0; x < w; x++) {
+			float r, g, b, l;
+			i = x + y * w;
+			r = powf(args.ImgA->Get_Red(i) / 255.0f, args.Gamma);
+			g = powf(args.ImgA->Get_Green(i) / 255.0f, args.Gamma);
+			b = powf(args.ImgA->Get_Blue(i) / 255.0f, args.Gamma);						
+			AdobeRGBToXYZ(r,g,b,aX[i],aY[i],aZ[i]);			
+			XYZToLAB(aX[i], aY[i], aZ[i], l, aA[i], aB[i]);
+			r = powf(args.ImgB->Get_Red(i) / 255.0f, args.Gamma);
+			g = powf(args.ImgB->Get_Green(i) / 255.0f, args.Gamma);
+			b = powf(args.ImgB->Get_Blue(i) / 255.0f, args.Gamma);						
+			AdobeRGBToXYZ(r,g,b,bX[i],bY[i],bZ[i]);
+			XYZToLAB(bX[i], bY[i], bZ[i], l, bA[i], bB[i]);
+			aLum[i] = aY[i] * args.Luminance;
+			bLum[i] = bY[i] * args.Luminance;
+		}
+	}
+	
+	if (args.Verbose) printf("Constructing Laplacian Pyramids\n");
+	
+	LPyramid *la = new LPyramid(aLum, w, h);
+	LPyramid *lb = new LPyramid(bLum, w, h);
+	
+	float num_one_degree_pixels = (float) (2 * tan( args.FieldOfView * 0.5 * M_PI / 180) * 180 / M_PI);
+	float pixels_per_degree = w / num_one_degree_pixels;
+	
+	if (args.Verbose) printf("Performing test\n");
+	
+	float num_pixels = 1;
+	unsigned int adaptation_level = 0;
+	for (i = 0; i < MAX_PYR_LEVELS; i++) {
+		adaptation_level = i;
+		if (num_pixels > num_one_degree_pixels) break;
+		num_pixels *= 2;
+	}
+	
+	float cpd[MAX_PYR_LEVELS];
+	cpd[0] = 0.5f * pixels_per_degree;
+	for (i = 1; i < MAX_PYR_LEVELS; i++) cpd[i] = 0.5f * cpd[i - 1];
+	float csf_max = csf(3.248f, 100.0f);
+	
+	float F_freq[MAX_PYR_LEVELS - 2];
+	for (i = 0; i < MAX_PYR_LEVELS - 2; i++) F_freq[i] = csf_max / csf( cpd[i], 100.0f);
+	
+	unsigned int pixels_failed = 0;
+	for (y = 0; y < h; y++) {
+	  for (x = 0; x < w; x++) {
+		int index = x + y * w;
+		float contrast[MAX_PYR_LEVELS - 2];
+		float sum_contrast = 0;
+		for (i = 0; i < MAX_PYR_LEVELS - 2; i++) {
+			float n1 = fabsf(la->Get_Value(x,y,i) - la->Get_Value(x,y,i + 1));
+			float n2 = fabsf(lb->Get_Value(x,y,i) - lb->Get_Value(x,y,i + 1));
+			float numerator = (n1 > n2) ? n1 : n2;
+			float d1 = fabsf(la->Get_Value(x,y,i+2));
+			float d2 = fabsf(lb->Get_Value(x,y,i+2));
+			float denominator = (d1 > d2) ? d1 : d2;
+			if (denominator < 1e-5f) denominator = 1e-5f;
+			contrast[i] = numerator / denominator;
+			sum_contrast += contrast[i];
+		}
+		if (sum_contrast < 1e-5) sum_contrast = 1e-5f;
+		float F_mask[MAX_PYR_LEVELS - 2];
+		float adapt = la->Get_Value(x,y,adaptation_level) + lb->Get_Value(x,y,adaptation_level);
+		adapt *= 0.5f;
+		if (adapt < 1e-5) adapt = 1e-5f;
+		for (i = 0; i < MAX_PYR_LEVELS - 2; i++) {
+			F_mask[i] = mask(contrast[i] * csf(cpd[i], adapt)); 
+		}
+		float factor = 0;
+		for (i = 0; i < MAX_PYR_LEVELS - 2; i++) {
+			factor += contrast[i] * F_freq[i] * F_mask[i] / sum_contrast;
+		}
+		if (factor < 1) factor = 1;
+		if (factor > 10) factor = 10;
+		float delta = fabsf(la->Get_Value(x,y,0) - lb->Get_Value(x,y,0));
+		bool pass = true;
+		// pure luminance test
+		if (delta > factor * tvi(adapt)) {
+			pass = false;
+		} else {
+			// CIE delta E test with modifications
+			float color_scale = 1.0f;
+			// ramp down the color test in scotopic regions
+			if (adapt < 10.0f) {
+				color_scale = 1.0f - (10.0f - color_scale) / 10.0f;
+				color_scale = color_scale * color_scale;
+			}
+			float da = aA[index] - bA[index];
+			float db = aB[index] - bB[index];
+			da = da * da;
+			db = db * db;
+			float delta_e = (da + db) * color_scale;
+			if (delta_e > factor) {
+				pass = false;
+			}
+		}
+		if (!pass) {
+			pixels_failed++;
+			if (args.ImgDiff) {
+				args.ImgDiff->Set(255, 0, 0, 255, index);
+			}
+		} else {
+			if (args.ImgDiff) {
+				args.ImgDiff->Set(0, 0, 0, 255, index);
+			}
+		}
+	  }
+	}
+	
+	if (aX) delete[] aX;
+	if (aY) delete[] aY;
+	if (aZ) delete[] aZ;
+	if (bX) delete[] bX;
+	if (bY) delete[] bY;
+	if (bZ) delete[] bZ;
+	if (aLum) delete[] aLum;
+	if (bLum) delete[] bLum;
+	if (la) delete la;
+	if (lb) delete lb;
+	if (aA) delete aA;
+	if (bA) delete bA;
+	if (aB) delete aB;
+	if (bB) delete bB;
+	
+	if (pixels_failed < args.ThresholdPixels) {
+		args.ErrorStr = "Images are perceptually indistinguishable\n";
+		return true;
+	}
+	
+	char different[100];
+	sprintf(different, "%d pixels are different\n", pixels_failed);
+
+	args.ErrorStr = "Images are visibly different\n";
+	args.ErrorStr += different;
+	
+	if (args.ImgDiff) {
+		if (args.ImgDiff->WritePPM()) {
+			args.ErrorStr += "Wrote difference image to ";
+			args.ErrorStr+= args.ImgDiff->Get_Name();
+			args.ErrorStr += "\n";
+		} else {
+			args.ErrorStr += "Could not write difference image to ";
+			args.ErrorStr+= args.ImgDiff->Get_Name();
+			args.ErrorStr += "\n";
+		}
+	}
+	return false;
+}
\ No newline at end of file
diff --git a/test/pdiff/Metric.h b/test/pdiff/Metric.h
new file mode 100644
index 000000000..86540de06
--- /dev/null
+++ b/test/pdiff/Metric.h
@@ -0,0 +1,26 @@
+/*
+Metric
+Copyright (C) 2006 Yangli Hector Yee
+
+This program is free software; you can redistribute it and/or modify it under the terms of the
+GNU General Public License as published by the Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with this program;
+if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#ifndef _METRIC_H
+#define _METRIC_H
+
+class CompareArgs;
+
+// Image comparison metric using Yee's method
+// References: A Perceptual Metric for Production Testing, Hector Yee, Journal of Graphics Tools 2004
+bool Yee_Compare(CompareArgs &args);
+
+#endif
\ No newline at end of file
diff --git a/test/pdiff/PerceptualDiff.cpp b/test/pdiff/PerceptualDiff.cpp
new file mode 100644
index 000000000..ee796665a
--- /dev/null
+++ b/test/pdiff/PerceptualDiff.cpp
@@ -0,0 +1,45 @@
+/*
+PerceptualDiff - a program that compares two images using a perceptual metric
+based on the paper :
+A perceptual metric for production testing. Journal of graphics tools, 9(4):33-40, 2004, Hector Yee
+Copyright (C) 2006 Yangli Hector Yee
+
+This program is free software; you can redistribute it and/or modify it under the terms of the
+GNU General Public License as published by the Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with this program;
+if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+#include <string>
+#include "LPyramid.h"
+#include "RGBAImage.h"
+#include "CompareArgs.h"
+#include "Metric.h"
+
+int main(int argc, char **argv)
+{
+	CompareArgs args;
+	
+	if (!args.Parse_Args(argc, argv)) {
+		printf("%s", args.ErrorStr.c_str());
+		return -1;
+	} else {
+		if (args.Verbose) args.Print_Args();
+	}
+	int result = Yee_Compare(args) == true;
+	if (result) {
+		printf("PASS: %s\n", args.ErrorStr.c_str());
+	} else {
+		printf("FAIL: %s\n", args.ErrorStr.c_str());
+	}
+	return result;
+}
diff --git a/test/pdiff/README.txt b/test/pdiff/README.txt
new file mode 100644
index 000000000..a873f3c00
--- /dev/null
+++ b/test/pdiff/README.txt
@@ -0,0 +1,45 @@
+pdiff - a program that compares two images using
+a perceptually based image metric.
+Copyright (C) 2006 Yangli Hector Yee
+yeehector@users.sourceforge.net
+http://pdiff.sourceforge.net/
+
+This program is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.
+See the GNU General Public License for more details in the file gpl.txt.
+
+Build Instructions
+1. Download cross platform make from http://www.cmake.org
+2. Download libtiff from http://www.libtiff.org. Download libpng from http://www.libpng.org
+3. Edit CMakeLists.txt to tell it where to find your tiff library
+4. Type cmake .
+5. Type make . (or on Windows systems cmake makes a Visual Studio
+Project file)
+6. To specify the install directory, use make install DESTDIR="/home/me/mydist"
+
+Usage
+
+pdiff image1.(tif | png) image2.(tif | png) [options]
+-verbose : Turns on verbose mode
+-fov deg: field of view, deg, in degrees. Usually between 10.0 to 85.0. 
+This controls how much of the screen the oberserver is seeing. Front row of 
+a theatre has a field of view of around 25 degrees. Back row has a field of
+ view of around 60 degrees.
+-threshold p : Sets the number of pixels, p, to reject. For example if p is
+ 100, then the test fails if 100 or more pixels are perceptably different.
+-gamma g : The gamma to use to convert to RGB linear space. Default is 2.2
+-luminance l: The luminance of the display the observer is seeing. Default
+ is 100 candela per meter squared
+-output foo.ppm : Saves the difference image to foo.ppm
+
+Credits
+
+Hector Yee, project administrator and originator - hectorgon.blogspot.com
+Scott Corley, for png file IO code
+Mick Weiss, Linux build and release & QA
\ No newline at end of file
diff --git a/test/pdiff/RGBAImage.cpp b/test/pdiff/RGBAImage.cpp
new file mode 100644
index 000000000..267b46069
--- /dev/null
+++ b/test/pdiff/RGBAImage.cpp
@@ -0,0 +1,141 @@
+/*
+RGBAImage.cpp
+Copyright (C) 2006 Yangli Hector Yee
+
+This program is free software; you can redistribute it and/or modify it under the terms of the
+GNU General Public License as published by the Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with this program;
+if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include "RGBAImage.h"
+#include "png.h"
+#include "tiff.h"
+#include "tiffio.h"
+
+// Reads Tiff Images
+RGBAImage* RGBAImage::ReadTiff(char *filename)
+{
+	RGBAImage *fimg = 0;
+	
+    TIFF* tif = TIFFOpen(filename, "r");
+	char emsg[1024];
+	emsg[0] = 0;
+    if (tif) {
+		TIFFRGBAImage img;
+		
+		if (TIFFRGBAImageBegin(&img, tif, 0, emsg)) {
+			size_t npixels;
+			uint32* raster;
+
+			npixels = img.width * img.height;
+			raster = (uint32*) _TIFFmalloc(npixels * sizeof (uint32));
+			if (raster != NULL) {
+				if (TIFFRGBAImageGet(&img, raster, img.width, img.height)) {
+					// result is in ABGR
+					fimg = new RGBAImage(img.width, img.height);
+					for (int y = img.height - 1; y >= 0; y--) {
+						for (int x = 0; x < (int) img.width; x++) {
+						   fimg->Set(x,img.height - (y+1), raster[x + y * img.width]);
+						}
+					}
+				}
+			_TIFFfree(raster);
+			}
+	    }
+	    TIFFRGBAImageEnd(&img);
+	}
+	return fimg;
+}
+
+// This portion was written by Scott Corley
+RGBAImage* RGBAImage::ReadPNG(char *filename)
+{
+	RGBAImage *fimg = 0;
+	FILE *fp=fopen(filename, "rb");
+	if (!fp)
+	{
+		return NULL;
+	}
+	png_byte header[8];
+
+	fread(header, 1, 8, fp);
+	bool is_png = !png_sig_cmp(header, 0, 8);
+	if (!is_png)
+	{
+		return NULL;
+	}
+
+    png_structp png_ptr = png_create_read_struct
+       (PNG_LIBPNG_VER_STRING, (png_voidp)NULL,
+        NULL, NULL);
+    if (!png_ptr)
+        return (NULL);
+
+    png_infop info_ptr = png_create_info_struct(png_ptr);
+    if (!info_ptr)
+    {
+        png_destroy_read_struct(&png_ptr,
+           (png_infopp)NULL, (png_infopp)NULL);
+        return (NULL);
+    }
+
+    png_infop end_info = png_create_info_struct(png_ptr);
+    if (!end_info)
+    {
+        png_destroy_read_struct(&png_ptr, &info_ptr,
+          (png_infopp)NULL);
+        return (NULL);
+    }
+
+	png_init_io(png_ptr, fp);
+	png_set_sig_bytes(png_ptr, 8);
+
+	png_read_png(png_ptr, info_ptr, 0, NULL);
+
+	png_bytep *row_pointers;
+	row_pointers = png_get_rows(png_ptr, info_ptr);
+
+	fimg = new RGBAImage(png_ptr->width, png_ptr->height);
+	for (int y = 0; y < (int) png_ptr->height; y++) {
+		for (int x = 0; x < (int) png_ptr->width; x++) {
+			uint32 value = 0;
+			if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+				value = ((uint32)row_pointers[y][x*4]) | (((uint32)row_pointers[y][x*4+1])<<8) | (((uint32)row_pointers[y][x*4+2])<<16) |(((uint32)row_pointers[y][x*4+3])<<24);
+			else if (png_ptr->color_type == PNG_COLOR_TYPE_RGB)
+				value = ((uint32)row_pointers[y][x*3] /*B*/) | (((uint32)row_pointers[y][x*3+1] /*G*/)<<8) | (((uint32)row_pointers[y][x*3+2]/*R*/)<<16) | (0xFFUL << 24);
+		   fimg->Set(x,y, value);
+		}
+	}
+
+	png_read_destroy(png_ptr, info_ptr, end_info);
+	return fimg;
+}
+		   
+bool RGBAImage::WritePPM()
+{	
+	if (Width <= 0) return false;
+	if (Height <=0 ) return false;
+	FILE *out = fopen(Name.c_str(), "wb");
+	if (!out) return false;
+	fprintf(out, "P6\n%d %d 255\n", Width, Height);
+	for (int y = 0; y < Height; y++) {
+		for (int x = 0; x < Width; x++) {
+			int i = x + y * Width;
+			unsigned char r = Get_Red(i);
+			unsigned char g = Get_Green(i);
+			unsigned char b = Get_Blue(i);
+			fwrite(&r, 1, 1, out);
+			fwrite(&g, 1, 1, out);
+			fwrite(&b, 1, 1, out);
+		}
+	}
+	fclose(out);
+	return true;
+}
diff --git a/test/pdiff/RGBAImage.h b/test/pdiff/RGBAImage.h
new file mode 100644
index 000000000..473a59fbc
--- /dev/null
+++ b/test/pdiff/RGBAImage.h
@@ -0,0 +1,57 @@
+/*
+RGBAImage.h
+Copyright (C) 2006 Yangli Hector Yee
+
+This program is free software; you can redistribute it and/or modify it under the terms of the
+GNU General Public License as published by the Free Software Foundation; either version 2 of the License,
+or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with this program;
+if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#ifndef _RGAIMAGE_H
+#define _RGBAIMAGE_H
+
+#include<string>
+
+// assumes data is in the ABGR format
+class RGBAImage
+{
+public:
+	RGBAImage(int w, int h, const char *name = 0)
+	{
+		Width = w;
+		Height = h;
+		if (name) Name = name;
+		Data = new unsigned int[w * h];
+	};
+	~RGBAImage() { if (Data) delete[] Data; }
+	unsigned char Get_Red(unsigned int i) { return (Data[i] & 0xFF); }
+	unsigned char Get_Green(unsigned int i) { return ((Data[i]>>8) & 0xFF); }
+	unsigned char Get_Blue(unsigned int i) { return ((Data[i]>>16) & 0xFF); }
+	unsigned char Get_Alpha(unsigned int i) { return ((Data[i]>>24) & 0xFF); }
+	void Set(unsigned char r, unsigned char g, unsigned char b, unsigned char a, unsigned int i)
+	{ Data[i] = r | (g << 8) | (b << 16) | (a << 24); }
+	int Get_Width(void) const { return Width; }
+	int Get_Height(void) const { return Height; }
+	void Set(int x, int y, unsigned int d) { Data[x + y * Width] = d; }
+	unsigned int Get(int x, int y) const { return Data[x + y * Width]; }
+	unsigned int Get(int i) const { return Data[i]; }
+	const std::string &Get_Name(void) const { return Name; }
+	
+	bool WritePPM();
+	static RGBAImage* ReadTiff(char *filename);
+	static RGBAImage* ReadPNG(char *filename);
+protected:
+	int Width;
+	int Height;
+	std::string Name;
+	unsigned int *Data;
+};
+
+#endif
\ No newline at end of file
diff --git a/test/pdiff/gpl.txt b/test/pdiff/gpl.txt
new file mode 100644
index 000000000..f90922eea
--- /dev/null
+++ b/test/pdiff/gpl.txt
@@ -0,0 +1,340 @@
+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+ 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+			    Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+  Finally, any free program is threatened constantly by software
+patents.  We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary.  To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+		    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The "Program", below,
+refers to any such program or work, and a "work based on the Program"
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+  1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+  2. You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+    a) You must cause the modified files to carry prominent notices
+    stating that you changed the files and the date of any change.
+
+    b) You must cause any work that you distribute or publish, that in
+    whole or in part contains or is derived from the Program or any
+    part thereof, to be licensed as a whole at no charge to all third
+    parties under the terms of this License.
+
+    c) If the modified program normally reads commands interactively
+    when run, you must cause it, when started running for such
+    interactive use in the most ordinary way, to print or display an
+    announcement including an appropriate copyright notice and a
+    notice that there is no warranty (or else, saying that you provide
+    a warranty) and that users may redistribute the program under
+    these conditions, and telling the user how to view a copy of this
+    License.  (Exception: if the Program itself is interactive but
+    does not normally print such an announcement, your work based on
+    the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+    a) Accompany it with the complete corresponding machine-readable
+    source code, which must be distributed under the terms of Sections
+    1 and 2 above on a medium customarily used for software interchange; or,
+
+    b) Accompany it with a written offer, valid for at least three
+    years, to give any third party, for a charge no more than your
+    cost of physically performing source distribution, a complete
+    machine-readable copy of the corresponding source code, to be
+    distributed under the terms of Sections 1 and 2 above on a medium
+    customarily used for software interchange; or,
+
+    c) Accompany it with the information you received as to the offer
+    to distribute corresponding source code.  (This alternative is
+    allowed only for noncommercial distribution and only if you
+    received the program in object code or executable form with such
+    an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+  5. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+			    NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+		     END OF TERMS AND CONDITIONS
+
+	    How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.