fixes #247 fixes #1275

Author: Lauren McCarthy

src/core/p5.Renderer2D.js

@@ -150,7 +150,11 @@ p5.Renderer2D.prototype.blend = function() {
   );
 
   this.drawingContext.globalCompositeOperation = blendMode;
-  this._pInst.copy.apply(this._pInst, copyArgs);
+  if (this._pInst) {
+    this._pInst.copy.apply(this._pInst, copyArgs);
+  } else {
+    this.copy.apply(this, copyArgs);
+  }
   this.drawingContext.globalCompositeOperation = currBlend;
 };
 

src/image/p5.Image.js

@@ -535,7 +535,52 @@ p5.Image.prototype.filter = function(operation, value) {
  *
  *
  * http://blogs.adobe.com/webplatform/2013/01/28/blending-features-in-canvas/
+ * @example
+ * <div><code>
+ * var mountains;
+ * var bricks;
+ *
+ * function preload() {
+ *   mountains = loadImage("assets/rockies.jpg");
+ *   bricks = loadImage("assets/bricks_third.jpg");
+ * }
+ *
+ * function setup() {
+ *   mountains.blend(bricks, 0, 0, 33, 100, 67, 0, 33, 100, ADD);
+ *   image(mountains, 0, 0);
+ *   image(bricks, 0, 0);
+ * }
+ * </code></div>
+ * <div><code>
+ * var mountains;
+ * var bricks;
  *
+ * function preload() {
+ *   mountains = loadImage("assets/rockies.jpg");
+ *   bricks = loadImage("assets/bricks_third.jpg");
+ * }
+ *
+ * function setup() {
+ *   mountains.blend(bricks, 0, 0, 33, 100, 67, 0, 33, 100, DARKEST);
+ *   image(mountains, 0, 0);
+ *   image(bricks, 0, 0);
+ * }
+ * </code></div>
+ * <div><code>
+ * var mountains;
+ * var bricks;
+ *
+ * function preload() {
+ *   mountains = loadImage("assets/rockies.jpg");
+ *   bricks = loadImage("assets/bricks_third.jpg");
+ * }
+ *
+ * function setup() {
+ *   mountains.blend(bricks, 0, 0, 33, 100, 67, 0, 33, 100, LIGHTEST);
+ *   image(mountains, 0, 0);
+ *   image(bricks, 0, 0);
+ * }
+ * </code></div>
  */
 p5.Image.prototype.blend = function() {
   p5.prototype.blend.apply(this, arguments);

src/image/pixels.js

@@ -145,7 +145,11 @@ p5.prototype.pixels = [];
  * </code></div>
  */
 p5.prototype.blend = function() {
-  this._renderer.blend.apply(this._renderer, arguments);
+  if (this._renderer) {
+    this._renderer.blend.apply(this._renderer, arguments);
+  } else {
+    p5.Renderer2D.prototype.blend.apply(this, arguments);
+  }
 };
 
 /**