diff --git a/main.cpp b/main.cpp
index c20ed74..6c8f830 100644
--- a/main.cpp
+++ b/main.cpp
@@ -87,9 +87,7 @@ int main(int argc, char * argv[])
 
       // Compute viewing ray
       Ray ray;
-      /* NOTE I flipped the vertical axis of the pixels, because in computer graphics we assume the bottom left pixel
-       * is (0,0), while traditional jpg assumes (0,0) to be the upper left pixel. */
-      viewing_ray(camera,height - i,j,width,height,ray);
+      viewing_ray(camera,i,j,width,height,ray);
 
       // Find first visible object hit by ray and its surface normal n
       double t;
diff --git a/src/viewing_ray.cpp b/src/viewing_ray.cpp
index 4a7218a..a643a9c 100644
--- a/src/viewing_ray.cpp
+++ b/src/viewing_ray.cpp
@@ -18,5 +18,7 @@ void viewing_ray(
     double v = 0 - camera.height / 2 + camera.height * (i + 0.5) / height;
 
     ray.origin = camera.e;
-    ray.direction = (0 - camera.d) * camera.w + u * camera.u + v * camera.v;
+    /* NOTE I flipped the vertical axis of the pixels, because in computer graphics we assume the bottom left pixel
+     * is (0,0), while traditional jpg assumes (0,0) to be the upper left pixel. */
+    ray.direction = (0 - camera.d) * camera.w + u * camera.u - v * camera.v;
 }