diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 3795ec8..d16e137 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -5,6 +5,7 @@ set(AIGO_SRCS
 	quickcam.cpp
 	settings.cpp
 	state.cpp
+	image.cpp
 	)
 
 #find SDL and its related libraries
diff --git a/lib/image.cpp b/lib/image.cpp
new file mode 100644
index 0000000..620794a
--- /dev/null
+++ b/lib/image.cpp
@@ -0,0 +1,19 @@
+#include "image.h"
+
+namespace Image
+{
+	void threshold(SDL_Surface *image, int lowerBound, int upperBound)
+	{
+		int x, y;
+		for (int i = 0; i < image->w * image->h; ++i)
+		{
+			int gray = GRAY(((uint32_t*)image->pixels)[i]);
+			if (gray > lowerBound && gray < upperBound)
+				((uint32_t*)image->pixels)[i] = 0xffffffff;
+			else
+				((uint32_t*)image->pixels)[i] = 0xff000000;
+				//gray | (gray << 8) | (gray << 16);
+
+		}
+	}
+}
diff --git a/lib/image.h b/lib/image.h
new file mode 100644
index 0000000..ef8713c
--- /dev/null
+++ b/lib/image.h
@@ -0,0 +1,28 @@
+#ifndef _IMAGE_H_
+#define _IMAGE_H_
+
+#include <SDL/SDL.h>
+
+// get pixel/something in array p of size w*h 
+#define PX_(p, x, y, w, h) ((p)[(x)+(y)*(w)])
+// get pixel in SDL_Surface i
+#define PX(i,x,y) (PX_((uint32_t*)(i)->pixels, (x), (y), (i)->w, (i)->h))
+// get color components of pixel value. should probably be done in a nicer way
+#define PXR(px) ((px) & 0xff)
+#define PXG(px) (((px) & 0xff00) >> 8)
+#define PXB(px) (((px) & 0xff0000) >> 16)
+
+//get the grayscale value of the pixel
+#define GRAY(px) ((PXR(px) + PXG(px) + PXB(px)) / 3)
+
+// iterate over SDL_Surface s with variables x, y
+#define iter_pixels(s,x,y) for (x = 0; x < s->w; x++) for (y = 0; y < s->h; y++)
+
+namespace Image
+{
+
+	void threshold(SDL_Surface *image, int lowerBound, int upperBound);
+
+}
+
+#endif /* ifndef _IMAGE_H_ */
diff --git a/lib/state.h b/lib/state.h
index 00a66d8..8c94fd9 100644
--- a/lib/state.h
+++ b/lib/state.h
@@ -4,17 +4,7 @@
 #include "settings.h"
 #include <SDL/SDL.h>
 #include <stdint.h>
-
-// get pixel/something in array p of size w*h 
-#define PX_(p, x, y, w, h) ((p)[(x)+(y)*(w)])
-// get pixel in SDL_Surface i
-#define PX(i,x,y) (PX_((uint32_t*)(i)->pixels, (x), (y), (i)->w, (i)->h))
-// get color components of pixel value. should probably be done in a nicer way
-#define PXR(px) ((px) & 0xff)
-#define PXG(px) (((px) & 0xff00) >> 8)
-#define PXB(px) (((px) & 0xff0000) >> 16)
-// iterate over SDL_Surface s with variables x, y
-#define iter_pixels(s,x,y) for (x = 0; x < s->w; x++) for (y = 0; y < s->h; y++)
+#include "image.h"
 
 
 /**
diff --git a/qt/aigoqt.cpp b/qt/aigoqt.cpp
index b3b51f6..922539b 100644
--- a/qt/aigoqt.cpp
+++ b/qt/aigoqt.cpp
@@ -1,6 +1,7 @@
 #include "aigoqt.h"
 #include <QtDebug>
 #include <state.h>
+#include "image.h"
 
 AigoQt::AigoQt(QWidget *parent)
 	: QMainWindow(parent)
@@ -9,8 +10,8 @@ AigoQt::AigoQt(QWidget *parent)
 	cam = new Quickcam("/dev/video0");
 
 	timer = new QTimer(this);
-	connect(timer, SIGNAL(timeout()), this, SLOT(on_buttonDrawPoints_clicked()));
-	timer->start(200);
+	connect(timer, SIGNAL(timeout()), this, SLOT(updateImage()));
+	timer->start(10);
 
 }
 
@@ -23,6 +24,7 @@ void AigoQt::updateImage( void )
 {
 	cam->update();
 	SDL_Surface *s = cam->getSurface();
+	Image::threshold(s, sliderBlack->value(), sliderWhite->value());
 	image->setPixmap(QPixmap::fromImage(QImage((uchar*)s->pixels, s->w, s->h, QImage::Format_RGB32)));
 	on_buttonGenerateState_clicked();
 }