diff --git a/imuread.c b/imuread.c
index 68412b2..c55d2ac 100644
--- a/imuread.c
+++ b/imuread.c
@@ -21,8 +21,67 @@ static void glut_display_callback(void)
 	glutSwapBuffers();
 }
 
+extern int invert_q0;
+extern int invert_q1;
+extern int invert_q2;
+extern int invert_q3;
+extern int invert_x;
+extern int invert_y;
+extern int invert_z;
+
+static void print_invert_state(void)
+{
+	printf("Invert: %s %s %s %s  %s %s %s\n",
+		(invert_q0 ? "Q0" : "  "),
+		(invert_q1 ? "Q1" : "  "),
+		(invert_q2 ? "Q2" : "  "),
+		(invert_q3 ? "Q3" : "  "),
+		(invert_x ? "x'" : "  "),
+		(invert_y ? "y'" : "  "),
+		(invert_z ? "z'" : "  ")
+	);
+}
+
+
 static void glut_keystroke_callback(unsigned char ch, int x, int y)
 {
+	if (ch == '0') {
+		invert_q0 ^= 1;
+		print_invert_state();
+		return;
+	}
+	if (ch == '1') {
+		invert_q1 ^= 1;
+		print_invert_state();
+		return;
+	}
+	if (ch == '2') {
+		invert_q2 ^= 1;
+		print_invert_state();
+		return;
+	}
+	if (ch == '3') {
+		invert_q3 ^= 1;
+		print_invert_state();
+		return;
+	}
+	if (ch == 'x') {
+		invert_x ^= 1;
+		print_invert_state();
+		return;
+	}
+	if (ch == 'y') {
+		invert_y ^= 1;
+		print_invert_state();
+		return;
+	}
+	if (ch == 'z') {
+		invert_z ^= 1;
+		print_invert_state();
+		return;
+	}
+
+
 	if (magcal.FitError > 9.0) {
 		printf("Poor Calibration: ");
 		printf("soft iron fit error = %.1f%%\n", magcal.FitError);
diff --git a/visualize.c b/visualize.c
index 1141686..7fc11ab 100644
--- a/visualize.c
+++ b/visualize.c
@@ -46,6 +46,14 @@ static void rotate(const Point_t *in, Point_t *out, const float *rmatrix)
 static GLuint spherelist;
 static GLuint spherelowreslist;
 
+int invert_q0=0;
+int invert_q1=0;
+int invert_q2=0;
+int invert_q3=1;
+int invert_x=0;
+int invert_y=0;
+int invert_z=0;
+
 void display_callback(void)
 {
 	int i;
@@ -76,11 +84,22 @@ void display_callback(void)
 		memcpy(&orientation, &current_orientation, sizeof(orientation));
 		// TODO: this almost but doesn't perfectly seems to get the
 		//  real & screen axes in sync....
-		//orientation.q0 *= -1.0f;
-		//orientation.q1 *= -1.0f;
-		//orientation.q2 *= -1.0f;
-		orientation.q3 *= -1.0f;
+		if (invert_q0) orientation.q0 *= -1.0f;
+		if (invert_q1) orientation.q1 *= -1.0f;
+		if (invert_q2) orientation.q2 *= -1.0f;
+		if (invert_q3) orientation.q3 *= -1.0f;
 		quad_to_rotation(&orientation, rotation);
+
+		//rotation[0] *= -1.0f;
+		//rotation[1] *= -1.0f;
+		//rotation[2] *= -1.0f;
+		//rotation[3] *= -1.0f;
+		//rotation[4] *= -1.0f;
+		//rotation[5] *= -1.0f;
+		//rotation[6] *= -1.0f;
+		//rotation[7] *= -1.0f;
+		//rotation[8] *= -1.0f;
+
 		for (i=0; i < MAGBUFFSIZE; i++) {
 			if (magcal.valid[i]) {
 				apply_calibration(magcal.BpFast[0][i], magcal.BpFast[1][i],
@@ -91,6 +110,9 @@ void display_callback(void)
 				quality_update(&point);
 				rotate(&point, &draw, rotation);
 				glPushMatrix();
+				if (invert_x) draw.x *= -1.0f;
+				if (invert_y) draw.y *= -1.0f;
+				if (invert_z) draw.z *= -1.0f;
 				glTranslatef(
 					draw.x * xscale + xoff,
 					draw.z * yscale + yoff,