diff --git a/README.md b/README.md
index d06248c..ca58c49 100644
--- a/README.md
+++ b/README.md
@@ -77,15 +77,15 @@ resemble.outputSettings({
 // resembleControl.repaint();
 ```
 
-It is possible to narrow down the area of comparison, by specifying bounding box:
+It is possible to narrow down the area of comparison, by specifying a bounding box measured in pixels from the top left:
 
 ```javascript
 resemble.outputSettings({
   boundingBox: {
-    x1: 100,  // left
-    y1: 200,  // top
-    x2: 200,  // right
-    y2: 600,  // bottom
+    left: 100,
+    top: 200,
+    right: 200,
+    bottom: 600
   }
 });
 // resembleControl.repaint();
diff --git a/demoassets/main.js b/demoassets/main.js
index 7c2b92c..993b86e 100644
--- a/demoassets/main.js
+++ b/demoassets/main.js
@@ -196,10 +196,10 @@ $(function(){
 		if($this.is('#boundingBox')){
 			resemble.outputSettings({
 				boundingBox: {
-					x1: $("#x1").val(),
-					y1: $("#y1").val(),
-					x2: $("#x2").val(),
-					y2: $("#y2").val(),
+					left: $("#x1").val(),
+					top: $("#y1").val(),
+					right: $("#x2").val(),
+					bottom: $("#y2").val()
 				}
 			});
 			resembleControl.repaint();
diff --git a/index.html b/index.html
index 6c47e67..0443795 100644
--- a/index.html
+++ b/index.html
@@ -133,19 +133,19 @@
 								<div class="btn-group buttons" style="display:none">
 									<div class="row">
 										<div class="span1">
-											<label>X1</label>
+											<label>Left</label>
 											<input type="number" class="input-mini" id="x1" value="100" />
 										</div>
 										<div class="span1">
-											<label>Y1</label>
+											<label>Top</label>
 											<input type="number" class="input-mini" id="y1" value="100" />
 										</div>
 										<div class="span1">
-											<label>X2</label>
+											<label>Right</label>
 											<input type="number" class="input-mini" id="x2" value="400" />
 										</div>
 										<div class="span1">
-											<label>Y2</label>
+											<label>Bottom</label>
 											<input type="number" class="input-mini" id="y2" value="300" />
 										</div>
 										<div class="span2">
diff --git a/resemble.js b/resemble.js
index 938146f..58cefb0 100644
--- a/resemble.js
+++ b/resemble.js
@@ -34,10 +34,10 @@ URL: https://github.com/Huddle/Resemble.js
 			return true;
 		}
 
-        return x > (boundingBox.x1 || 0) &&
-            x < (boundingBox.x2 || width) &&
-            y > (boundingBox.y1 || 0) &&
-            y < (boundingBox.y2 || height);
+        return x > (boundingBox.left || 0) &&
+            x < (boundingBox.right || width) &&
+            y > (boundingBox.top || 0) &&
+            y < (boundingBox.bottom || height);
 	}
 
 	var errorPixelTransform = {