diff --git a/src/drawer.js b/src/drawer.js
index d3867806..a9174d2c 100644
--- a/src/drawer.js
+++ b/src/drawer.js
@@ -369,8 +369,8 @@ $.Drawer.prototype = /** @lends OpenSeadragon.Drawer.prototype */{
      * @param {Float} opacity The opacity of the blending.
      * @param {Float} [scale=1] The scale at which tiles were drawn on the sketch. Default is 1.
      *   Use scale to draw at a lower scale and then enlarge onto the main canvas.
-     * @param OpenSeadragon.Point} [translate] A translation vector that was used to draw the tiles
-     * @param {String} [options.compositeOperation='source-over'] - How the image is composited onto other images; see compositeOperation in {@link OpenSeadragon.Options} for possible values.
+     * @param {OpenSeadragon.Point} [translate] A translation vector that was used to draw the tiles
+     * @param {String} [compositeOperation] - How the image is composited onto other images; see compositeOperation in {@link OpenSeadragon.Options} for possible values.
      * @returns {undefined}
      */
     blendSketch: function(opacity, scale, translate, compositeOperation) {
diff --git a/src/openseadragon.js b/src/openseadragon.js
index 16587057..a129f083 100644
--- a/src/openseadragon.js
+++ b/src/openseadragon.js
@@ -206,8 +206,8 @@
   * @property {Number} [opacity=1]
   *     Default opacity of the tiled images (1=opaque, 0=transparent)
   *
-  * @property {String} [compositeOperation='source-over']
-  *     Valid values are 'source-atop', 'source-in', 'source-out',
+  * @property {String} [compositeOperation=null]
+  *     Valid values are 'source-over', 'source-atop', 'source-in', 'source-out',
   *     'destination-over', 'destination-atop', 'destination-in',
   *     'destination-out', 'lighter', 'copy' or 'xor'
   *
@@ -1072,7 +1072,7 @@ if (typeof define === 'function' && define.amd) {
 
             // APPEARANCE
             opacity:                    1,
-            compositeOperation:         'source-over',
+            compositeOperation:         null,
             placeholderFillStyle:       null,
 
             //REFERENCE STRIP SETTINGS
diff --git a/src/tiledimage.js b/src/tiledimage.js
index 7caa17c9..aa3b56be 100644
--- a/src/tiledimage.js
+++ b/src/tiledimage.js
@@ -66,7 +66,7 @@
  * @param {Number} [options.minPixelRatio] - See {@link OpenSeadragon.Options}.
  * @param {Number} [options.smoothTileEdgesMinZoom] - See {@link OpenSeadragon.Options}.
  * @param {Number} [options.opacity=1] - Opacity the tiled image should be drawn at.
- * @param {String} [options.compositeOperation='source-over'] - How the image is composited onto other images; see compositeOperation in {@link OpenSeadragon.Options} for possible values.
+ * @param {String} [options.compositeOperation] - How the image is composited onto other images; see compositeOperation in {@link OpenSeadragon.Options} for possible values.
  * @param {Boolean} [options.debugMode] - See {@link OpenSeadragon.Options}.
  * @param {String|CanvasGradient|CanvasPattern|Function} [options.placeholderFillStyle] - See {@link OpenSeadragon.Options}.
  * @param {String|Boolean} [options.crossOriginPolicy] - See {@link OpenSeadragon.Options}.