diff --git a/.todo b/.todo
index e277410..bddca63 100644
--- a/.todo
+++ b/.todo
@@ -4,7 +4,6 @@ FART To-Do List
   High Priority:
     - Add distribution infrastructure
     - Multi-threading
-    - Attenuate color passing through a transparent object by obj. color
 
   Medium Priority:
     - Shape definitions / reusability
diff --git a/main/Scene.cc b/main/Scene.cc
index eef9559..5bd9a50 100644
--- a/main/Scene.cc
+++ b/main/Scene.cc
@@ -263,10 +263,12 @@ Color Scene::computePhong(const refptr<Material> material,
             directionToLight.reflect(surfaceNormal);
 
         Ray surfaceToLight(surfacePoint, directionToLight);
-        double light_contribution =
+        Color light_contribution =
             calculateLightContribution(surfaceToLight.shift(0.0001), *it);
 
-        if (light_contribution > 0.0)
+        if (   light_contribution.r > 0.0
+            || light_contribution.g > 0.0
+            || light_contribution.b > 0.0 )
         {
             /* calculate the diffuse term */
             double diffuse_coef = directionToLight % surfaceNormal;
@@ -301,10 +303,10 @@ Color Scene::computePhong(const refptr<Material> material,
     return result;
 }
 
-double Scene::calculateLightContribution(const Ray & toLight,
+Color Scene::calculateLightContribution(const Ray & toLight,
                                          refptr<Light> light)
 {
-    double contrib = 1.0;
+    Color contrib(1.0, 1.0, 1.0);
     double dist_to_light = toLight.getOrigin().dist_to(light->getPosition());
     double dist_so_far = 0.0;
 
@@ -323,8 +325,11 @@ double Scene::calculateLightContribution(const Ray & toLight,
             break;
 
         contrib *= hit.shape->getMaterial()->getTransparency();
+        contrib *= hit.shape->getMaterial()->getDiffuseColor();
 
-        if ( contrib < SCENE_FACTOR_THRESHOLD )
+        if (    contrib.r < SCENE_FACTOR_THRESHOLD 
+             && contrib.g < SCENE_FACTOR_THRESHOLD
+             && contrib.b < SCENE_FACTOR_THRESHOLD )
             break;
 
         dist_so_far += offset;
diff --git a/main/Scene.h b/main/Scene.h
index 9133a58..9eeeb06 100644
--- a/main/Scene.h
+++ b/main/Scene.h
@@ -42,8 +42,8 @@ class Scene
                            const Ray & viewRay,
                            const Vector & surfacePoint,
                            const Vector & surfaceNormal);
-        double calculateLightContribution(const Ray & toLight,
-                                          refptr<Light> light);
+        Color calculateLightContribution(const Ray & toLight,
+                                         refptr<Light> light);
 
         /* In Scene-load.cc */
         void load(const char * filename);
diff --git a/util/Color.cc b/util/Color.cc
index 1649356..86b8a45 100644
--- a/util/Color.cc
+++ b/util/Color.cc
@@ -79,6 +79,14 @@ Color & Color::operator*=(double scale)
     return *this;
 }
 
+Color & Color::operator*=(const Color & other)
+{
+    r *= other.r;
+    g *= other.g;
+    b *= other.b;
+    return *this;
+}
+
 Color operator+(const Color & c1, const Color & c2)
 {
     return Color(c1.r + c2.r, c1.g + c2.g, c1.b + c2.b);
diff --git a/util/Color.h b/util/Color.h
index 01d19cb..e46b871 100644
--- a/util/Color.h
+++ b/util/Color.h
@@ -22,6 +22,7 @@ class Color
         Color & operator+=(const Color & other);
         Color & operator-=(const Color & other);
         Color & operator*=(double scale);
+        Color & operator*=(const Color & other);
 
         static const Color black;
         static const Color white;