diff --git a/openseadragon.sublime-project b/openseadragon.sublime-project
index 1d6484e7..4feb36d8 100644
--- a/openseadragon.sublime-project
+++ b/openseadragon.sublime-project
@@ -8,7 +8,8 @@
                 "*.sublime-workspace"
             ],
             "folder_exclude_patterns": [
-                "node_modules"
+                "node_modules",
+                "coverage"
             ]
         }
     ],
@@ -17,5 +18,5 @@
         "tab_size": 4,
         "translate_tabs_to_spaces": true,
         "trim_trailing_white_space_on_save": true
-    }   
+    }
 }
diff --git a/src/drawer.js b/src/drawer.js
index 804f0693..3a02dad4 100644
--- a/src/drawer.js
+++ b/src/drawer.js
@@ -116,27 +116,6 @@ $.Drawer = function( options ) {
     // explicit left-align
     this.container.style.textAlign = "left";
     this.container.appendChild( this.canvas );
-
-    // We need a callback to give image manipulation a chance to happen
-    this._drawingHandler = function(args) {
-        if (_this.viewer) {
-          /**
-           * This event is fired just before the tile is drawn giving the application a chance to alter the image.
-           *
-           * NOTE: This event is only fired when the drawer is using a <canvas>.
-           *
-           * @event tile-drawing
-           * @memberof OpenSeadragon.Viewer
-           * @type {object}
-           * @property {OpenSeadragon.Viewer} eventSource - A reference to the Viewer which raised the event.
-           * @property {OpenSeadragon.Tile} tile - The Tile being drawn.
-           * @property {OpenSeadragon.Tile} context - The HTML canvas context being drawn into.
-           * @property {OpenSeadragon.Tile} rendered - The HTML canvas context containing the tile imagery.
-           * @property {?Object} userData - Arbitrary subscriber-defined object.
-           */
-            _this.viewer.raiseEvent('tile-drawing', args);
-        }
-    };
 };
 
 $.Drawer.prototype = /** @lends OpenSeadragon.Drawer.prototype */{
@@ -249,17 +228,23 @@ $.Drawer.prototype = /** @lends OpenSeadragon.Drawer.prototype */{
     /**
      * Draws the given tile.
      * @param {OpenSeadragon.Tile} tile - The tile to draw.
+     * @param {Function} drawingHandler - Method for firing the drawing event if using canvas.
+     * drawingHandler({context, tile, rendered})
+     * where <code>rendered</code> is the context with the pre-drawn image.
      */
-    drawTile: function( tile ) {
+    drawTile: function( tile, drawingHandler ) {
+        $.console.assert(tile, '[Drawer.drawTile] tile is required');
+        $.console.assert(drawingHandler, '[Drawer.drawTile] drawingHandler is required');
+
         if ( this.useCanvas ) {
             // TODO do this in a more performant way
             // specifically, don't save,rotate,restore every time we draw a tile
             if( this.viewport.degrees !== 0 ) {
                 this._offsetForRotation( tile, this.viewport.degrees );
-                tile.drawCanvas( this.context, this._drawingHandler );
+                tile.drawCanvas( this.context, drawingHandler );
                 this._restoreRotationChanges( tile );
             } else {
-                tile.drawCanvas( this.context, this._drawingHandler );
+                tile.drawCanvas( this.context, drawingHandler );
             }
         } else {
             tile.drawHTML( this.canvas );
diff --git a/src/openseadragon.js b/src/openseadragon.js
index 5a40c560..07abcd42 100644
--- a/src/openseadragon.js
+++ b/src/openseadragon.js
@@ -544,11 +544,11 @@
   *     If collectionMode is true, specifies whether to arrange vertically or horizontally.
   *
   * @property {Number} [collectionTileSize=800]
-  *     If collectionMode is true, specifies the size, in world coordinates, for each TiledImage to fit into.
+  *     If collectionMode is true, specifies the size, in viewport coordinates, for each TiledImage to fit into.
   *     The TiledImage will be centered within a square of the specified size.
   *
   * @property {Number} [collectionTileMargin=80]
-  *     If collectionMode is true, specifies the margin, in world coordinates, between each TiledImage.
+  *     If collectionMode is true, specifies the margin, in viewport coordinates, between each TiledImage.
   *
   * @property {String|Boolean} [crossOriginPolicy=false]
   *      Valid values are 'Anonymous', 'use-credentials', and false. If false, canvas requests will
diff --git a/src/tile.js b/src/tile.js
index b54e9b32..30082315 100644
--- a/src/tile.js
+++ b/src/tile.js
@@ -231,7 +231,8 @@ $.Tile.prototype = /** @lends OpenSeadragon.Tile.prototype */{
      * Renders the tile in a canvas-based context.
      * @function
      * @param {Canvas} context
-     * @param {Function} method for firing the drawing event. drawingHandler({context, tile, rendered})
+     * @param {Function} drawingHandler - Method for firing the drawing event.
+     * drawingHandler({context, tile, rendered})
      * where <code>rendered</code> is the context with the pre-drawn image.
      */
     drawCanvas: function( context, drawingHandler ) {
diff --git a/src/tiledimage.js b/src/tiledimage.js
index 40726dbd..bb74abb4 100644
--- a/src/tiledimage.js
+++ b/src/tiledimage.js
@@ -48,10 +48,10 @@
  * @param {OpenSeadragon.TileCache} options.tileCache - The TileCache for this TiledImage to use.
  * @param {OpenSeadragon.Drawer} options.drawer - The Drawer for this TiledImage to draw onto.
  * @param {OpenSeadragon.ImageLoader} options.imageLoader - The ImageLoader for this TiledImage to use.
- * @param {Number} [options.x=0] - Left position, in world coordinates.
- * @param {Number} [options.y=0] - Top position, in world coordinates.
- * @param {Number} [options.width=1] - Width, in world coordinates.
- * @param {Number} [options.height] - Height, in world coordinates.
+ * @param {Number} [options.x=0] - Left position, in viewport coordinates.
+ * @param {Number} [options.y=0] - Top position, in viewport coordinates.
+ * @param {Number} [options.width=1] - Width, in viewport coordinates.
+ * @param {Number} [options.height] - Height, in viewport coordinates.
  * @param {Number} [options.minZoomImageRatio] - See {@link OpenSeadragon.Options}.
  * @param {Boolean} [options.wrapHorizontal] - See {@link OpenSeadragon.Options}.
  * @param {Boolean} [options.wrapVertical] - See {@link OpenSeadragon.Options}.
@@ -63,6 +63,8 @@
  * @param {String|Boolean} [options.crossOriginPolicy] - See {@link OpenSeadragon.Options}.
  */
 $.TiledImage = function( options ) {
+    var _this = this;
+
     $.console.assert( options.tileCache, "[TiledImage] options.tileCache is required" );
     $.console.assert( options.drawer, "[TiledImage] options.drawer is required" );
     $.console.assert( options.viewer, "[TiledImage] options.viewer is required" );
@@ -87,6 +89,7 @@ $.TiledImage = function( options ) {
 
     // Ratio of zoomable image height to width.
     this.normHeight = options.source.dimensions.y / options.source.dimensions.x;
+    this.contentAspectX = options.source.dimensions.x / options.source.dimensions.y;
 
     if ( options.width ) {
         this._setScale(options.width);
@@ -126,6 +129,28 @@ $.TiledImage = function( options ) {
         crossOriginPolicy:  $.DEFAULT_SETTINGS.crossOriginPolicy
 
     }, options );
+
+    // We need a callback to give image manipulation a chance to happen
+    this._drawingHandler = function(args) {
+      /**
+       * This event is fired just before the tile is drawn giving the application a chance to alter the image.
+       *
+       * NOTE: This event is only fired when the drawer is using a <canvas>.
+       *
+       * @event tile-drawing
+       * @memberof OpenSeadragon.Viewer
+       * @type {object}
+       * @property {OpenSeadragon.Viewer} eventSource - A reference to the Viewer which raised the event.
+       * @property {OpenSeadragon.Tile} tile - The Tile being drawn.
+       * @property {OpenSeadragon.TiledImage} tiledImage - Which TiledImage is being drawn.
+       * @property {OpenSeadragon.Tile} context - The HTML canvas context being drawn into.
+       * @property {OpenSeadragon.Tile} rendered - The HTML canvas context containing the tile imagery.
+       * @property {?Object} userData - Arbitrary subscriber-defined object.
+       */
+        _this.viewer.raiseEvent('tile-drawing', $.extend({
+            tiledImage: _this
+        }, args));
+    };
 };
 
 $.extend($.TiledImage.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.TiledImage.prototype */{
@@ -164,7 +189,7 @@ $.extend($.TiledImage.prototype, $.EventSource.prototype, /** @lends OpenSeadrag
     },
 
     /**
-     * @returns {OpenSeadragon.Rect} This TiledImage's bounds in world coordinates.
+     * @returns {OpenSeadragon.Rect} This TiledImage's bounds in viewport coordinates.
      */
     getBounds: function() {
         return new $.Rect( this._worldX, this._worldY, this._worldWidth, this._worldHeight );
@@ -183,9 +208,136 @@ $.extend($.TiledImage.prototype, $.EventSource.prototype, /** @lends OpenSeadrag
         return new $.Point(this.source.dimensions.x, this.source.dimensions.y);
     },
 
+    // private
+    _viewportToImageDelta: function( viewerX, viewerY ) {
+        return new $.Point(viewerX * (this.source.dimensions.x / this._scale),
+            viewerY * ((this.source.dimensions.y * this.contentAspectX) / this._scale));
+    },
+
+    /**
+     * Translates from OpenSeadragon viewer coordinate system to image coordinate system.
+     * This method can be called either by passing X,Y coordinates or an
+     * OpenSeadragon.Point
+     * @function
+     * @param {OpenSeadragon.Point} viewerX the point in viewport coordinate system.
+     * @param {Number} viewerX X coordinate in viewport coordinate system.
+     * @param {Number} viewerY Y coordinate in viewport coordinate system.
+     * @return {OpenSeadragon.Point} a point representing the coordinates in the image.
+     */
+    viewportToImageCoordinates: function( viewerX, viewerY ) {
+        if ( arguments.length == 1 ) {
+            //they passed a point instead of individual components
+            return this.viewportToImageCoordinates( viewerX.x, viewerX.y );
+        }
+
+        return this._viewportToImageDelta(viewerX - this._worldX, viewerY - this._worldY);
+    },
+
+    // private
+    _imageToViewportDelta: function( imageX, imageY ) {
+        return new $.Point((imageX / this.source.dimensions.x) * this._scale,
+            (imageY / this.source.dimensions.y / this.contentAspectX) * this._scale);
+    },
+
+    /**
+     * Translates from image coordinate system to OpenSeadragon viewer coordinate system
+     * This method can be called either by passing X,Y coordinates or an
+     * OpenSeadragon.Point
+     * @function
+     * @param {OpenSeadragon.Point} imageX the point in image coordinate system.
+     * @param {Number} imageX X coordinate in image coordinate system.
+     * @param {Number} imageY Y coordinate in image coordinate system.
+     * @return {OpenSeadragon.Point} a point representing the coordinates in the viewport.
+     */
+    imageToViewportCoordinates: function( imageX, imageY ) {
+        if ( arguments.length == 1 ) {
+            //they passed a point instead of individual components
+            return this.imageToViewportCoordinates( imageX.x, imageX.y );
+        }
+
+        var point = this._imageToViewportDelta(imageX, imageY);
+        point.x += this._worldX;
+        point.y += this._worldY;
+        return point;
+    },
+
+    /**
+     * Translates from a rectangle which describes a portion of the image in
+     * pixel coordinates to OpenSeadragon viewport rectangle coordinates.
+     * This method can be called either by passing X,Y,width,height or an
+     * OpenSeadragon.Rect
+     * @function
+     * @param {OpenSeadragon.Rect} imageX the rectangle in image coordinate system.
+     * @param {Number} imageX the X coordinate of the top left corner of the rectangle
+     * in image coordinate system.
+     * @param {Number} imageY the Y coordinate of the top left corner of the rectangle
+     * in image coordinate system.
+     * @param {Number} pixelWidth the width in pixel of the rectangle.
+     * @param {Number} pixelHeight the height in pixel of the rectangle.
+     */
+    imageToViewportRectangle: function( imageX, imageY, pixelWidth, pixelHeight ) {
+        var coordA,
+            coordB,
+            rect;
+        if( arguments.length == 1 ) {
+            //they passed a rectangle instead of individual components
+            rect = imageX;
+            return this.imageToViewportRectangle(
+                rect.x, rect.y, rect.width, rect.height
+            );
+        }
+        coordA = this.imageToViewportCoordinates(
+            imageX, imageY
+        );
+        coordB = this._imageToViewportDelta(
+            pixelWidth, pixelHeight
+        );
+        return new $.Rect(
+            coordA.x,
+            coordA.y,
+            coordB.x,
+            coordB.y
+        );
+    },
+
+    /**
+     * Translates from a rectangle which describes a portion of
+     * the viewport in point coordinates to image rectangle coordinates.
+     * This method can be called either by passing X,Y,width,height or an
+     * OpenSeadragon.Rect
+     * @function
+     * @param {OpenSeadragon.Rect} viewerX the rectangle in viewport coordinate system.
+     * @param {Number} viewerX the X coordinate of the top left corner of the rectangle
+     * in viewport coordinate system.
+     * @param {Number} imageY the Y coordinate of the top left corner of the rectangle
+     * in viewport coordinate system.
+     * @param {Number} pointWidth the width of the rectangle in viewport coordinate system.
+     * @param {Number} pointHeight the height of the rectangle in viewport coordinate system.
+     */
+    viewportToImageRectangle: function( viewerX, viewerY, pointWidth, pointHeight ) {
+        var coordA,
+            coordB,
+            rect;
+        if ( arguments.length == 1 ) {
+            //they passed a rectangle instead of individual components
+            rect = viewerX;
+            return this.viewportToImageRectangle(
+                rect.x, rect.y, rect.width, rect.height
+            );
+        }
+        coordA = this.viewportToImageCoordinates( viewerX, viewerY );
+        coordB = this._viewportToImageDelta(pointWidth, pointHeight);
+        return new $.Rect(
+            coordA.x,
+            coordA.y,
+            coordB.x,
+            coordB.y
+        );
+    },
+
     /**
      * Sets the TiledImage's position in the world.
-     * @param {OpenSeadragon.Point} position - The new position, in world coordinates.
+     * @param {OpenSeadragon.Point} position - The new position, in viewport coordinates.
      * @fires OpenSeadragon.TiledImage.event:bounds-change
      */
     setPosition: function(position) {
@@ -201,7 +353,7 @@ $.extend($.TiledImage.prototype, $.EventSource.prototype, /** @lends OpenSeadrag
 
     /**
      * Sets the TiledImage's width in the world, adjusting the height to match based on aspect ratio.
-     * @param {Number} width - The new width, in world coordinates.
+     * @param {Number} width - The new width, in viewport coordinates.
      * @fires OpenSeadragon.TiledImage.event:bounds-change
      */
     setWidth: function(width) {
@@ -216,7 +368,7 @@ $.extend($.TiledImage.prototype, $.EventSource.prototype, /** @lends OpenSeadrag
 
     /**
      * Sets the TiledImage's height in the world, adjusting the width to match based on aspect ratio.
-     * @param {Number} height - The new height, in world coordinates.
+     * @param {Number} height - The new height, in viewport coordinates.
      * @fires OpenSeadragon.TiledImage.event:bounds-change
      */
     setHeight: function(height) {
@@ -874,7 +1026,7 @@ function drawTiles( tiledImage, lastDrawn ){
 
     for ( i = lastDrawn.length - 1; i >= 0; i-- ) {
         tile = lastDrawn[ i ];
-        tiledImage._drawer.drawTile( tile );
+        tiledImage._drawer.drawTile( tile, tiledImage._drawingHandler );
         tile.beingDrawn = true;
 
         if( tiledImage.debugMode ){
diff --git a/src/viewer.js b/src/viewer.js
index 2f1684de..e05bbba8 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -608,6 +608,7 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
                 if (successes) {
                     if (_this._firstOpen || !_this.preserveViewport) {
                         _this.viewport.goHome( true );
+                        _this.viewport.update();
                     }
 
                     _this._firstOpen = false;
@@ -1249,10 +1250,10 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
      *      named 'getTileUrl', it is treated as a custom TileSource.
      * @param {Number} [options.index] The index of the item. Added on top of
      * all other items if not specified.
-     * @param {Number} [options.x=0] The X position for the image in world coordinates.
-     * @param {Number} [options.y=0] The Y position for the image in world coordinates.
-     * @param {Number} [options.width=1] The width for the image in world coordinates.
-     * @param {Number} [options.height] The height for the image in world coordinates.
+     * @param {Number} [options.x=0] The X position for the image in viewport coordinates.
+     * @param {Number} [options.y=0] The Y position for the image in viewport coordinates.
+     * @param {Number} [options.width=1] The width for the image in viewport coordinates.
+     * @param {Number} [options.height] The height for the image in viewport coordinates.
      * @param {Function} [options.success] A function that gets called when the image is
      * successfully added. It's passed the event object which contains a single property:
      * "item", the resulting TiledImage.
diff --git a/src/viewport.js b/src/viewport.js
index 1f07ebbe..77893189 100644
--- a/src/viewport.js
+++ b/src/viewport.js
@@ -163,8 +163,8 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
     /**
      * Updates the viewport's home bounds and constraints.
      * @function
-     * @param {OpenSeadragon.Rect} bounds - the new bounds in world coordinates
-     * @param {Number} contentFactor - how many content units per world unit
+     * @param {OpenSeadragon.Rect} bounds - the new bounds in viewport coordinates
+     * @param {Number} contentFactor - how many content units per viewport unit
      * @fires OpenSeadragon.Viewer.event:reset-size
      */
     setHomeBounds: function(bounds, contentFactor) {
@@ -303,7 +303,7 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
     /**
      * @function
      * @param {Boolean} current - Pass true for the current location; defaults to false (target location).
-     * @returns {OpenSeadragon.Rect} The location you are zoomed/panned to, in world coordinates.
+     * @returns {OpenSeadragon.Rect} The location you are zoomed/panned to, in viewport coordinates.
      */
     getBounds: function( current ) {
         var center = this.getCenter( current ),
@@ -322,7 +322,7 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
      * @function
      * @param {Boolean} current - Pass true for the current location; defaults to false (target location).
      * @returns {OpenSeadragon.Rect} The location you are zoomed/panned to,
-     * including the space taken by margins, in world coordinates.
+     * including the space taken by margins, in viewport coordinates.
      */
     getBoundsWithMargins: function( current ) {
         var bounds = this.getBounds(current);
@@ -938,10 +938,18 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
         );
     },
 
+    // private
+    _viewportToImageDelta: function( viewerX, viewerY ) {
+        var scale = this.homeBounds.width;
+        return new $.Point(viewerX * (this.contentSize.x / scale),
+            viewerY * ((this.contentSize.y * this.contentAspectX) / scale));
+    },
+
     /**
      * Translates from OpenSeadragon viewer coordinate system to image coordinate system.
      * This method can be called either by passing X,Y coordinates or an
      * OpenSeadragon.Point
+     * Note: not accurate with multi-image; use TiledImage.viewportToImageCoordinates instead.
      * @function
      * @param {OpenSeadragon.Point} viewerX the point in viewport coordinate system.
      * @param {Number} viewerX X coordinate in viewport coordinate system.
@@ -953,13 +961,26 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
             //they passed a point instead of individual components
             return this.viewportToImageCoordinates( viewerX.x, viewerX.y );
         }
-        return new $.Point( viewerX * this.contentSize.x, viewerY * this.contentSize.y * this.contentAspectX );
+
+        if (this.viewer && this.viewer.world.getItemCount() > 1) {
+            $.console.error('[Viewport.viewportToImageCoordinates] is not accurate with multi-image; use TiledImage.viewportToImageCoordinates instead.');
+        }
+
+        return this._viewportToImageDelta(viewerX - this.homeBounds.x, viewerY - this.homeBounds.y);
+    },
+
+    // private
+    _imageToViewportDelta: function( imageX, imageY ) {
+        var scale = this.homeBounds.width;
+        return new $.Point((imageX / this.contentSize.x) * scale,
+            (imageY / this.contentSize.y / this.contentAspectX) * scale);
     },
 
     /**
      * Translates from image coordinate system to OpenSeadragon viewer coordinate system
      * This method can be called either by passing X,Y coordinates or an
      * OpenSeadragon.Point
+     * Note: not accurate with multi-image; use TiledImage.imageToViewportCoordinates instead.
      * @function
      * @param {OpenSeadragon.Point} imageX the point in image coordinate system.
      * @param {Number} imageX X coordinate in image coordinate system.
@@ -971,7 +992,15 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
             //they passed a point instead of individual components
             return this.imageToViewportCoordinates( imageX.x, imageX.y );
         }
-        return new $.Point( imageX / this.contentSize.x, imageY / this.contentSize.y / this.contentAspectX );
+
+        if (this.viewer && this.viewer.world.getItemCount() > 1) {
+            $.console.error('[Viewport.imageToViewportCoordinates] is not accurate with multi-image; use TiledImage.imageToViewportCoordinates instead.');
+        }
+
+        var point = this._imageToViewportDelta(imageX, imageY);
+        point.x += this.homeBounds.x;
+        point.y += this.homeBounds.y;
+        return point;
     },
 
     /**
@@ -979,6 +1008,7 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
      * pixel coordinates to OpenSeadragon viewport rectangle coordinates.
      * This method can be called either by passing X,Y,width,height or an
      * OpenSeadragon.Rect
+     * Note: not accurate with multi-image; use TiledImage.imageToViewportRectangle instead.
      * @function
      * @param {OpenSeadragon.Rect} imageX the rectangle in image coordinate system.
      * @param {Number} imageX the X coordinate of the top left corner of the rectangle
@@ -999,10 +1029,11 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
                 rect.x, rect.y, rect.width, rect.height
             );
         }
+
         coordA = this.imageToViewportCoordinates(
             imageX, imageY
         );
-        coordB = this.imageToViewportCoordinates(
+        coordB = this._imageToViewportDelta(
             pixelWidth, pixelHeight
         );
         return new $.Rect(
@@ -1018,6 +1049,7 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
      * the viewport in point coordinates to image rectangle coordinates.
      * This method can be called either by passing X,Y,width,height or an
      * OpenSeadragon.Rect
+     * Note: not accurate with multi-image; use TiledImage.viewportToImageRectangle instead.
      * @function
      * @param {OpenSeadragon.Rect} viewerX the rectangle in viewport coordinate system.
      * @param {Number} viewerX the X coordinate of the top left corner of the rectangle
@@ -1038,8 +1070,9 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
                 rect.x, rect.y, rect.width, rect.height
             );
         }
+
         coordA = this.viewportToImageCoordinates( viewerX, viewerY );
-        coordB = this.viewportToImageCoordinates( pointWidth, pointHeight );
+        coordB = this._viewportToImageDelta(pointWidth, pointHeight);
         return new $.Rect(
             coordA.x,
             coordA.y,
@@ -1051,6 +1084,7 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
     /**
      * Convert pixel coordinates relative to the viewer element to image
      * coordinates.
+     * Note: not accurate with multi-image.
      * @param {OpenSeadragon.Point} pixel
      * @returns {OpenSeadragon.Point}
      */
@@ -1062,6 +1096,7 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
     /**
      * Convert pixel coordinates relative to the image to
      * viewer element coordinates.
+     * Note: not accurate with multi-image.
      * @param {OpenSeadragon.Point} pixel
      * @returns {OpenSeadragon.Point}
      */
@@ -1072,6 +1107,7 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
 
     /**
      * Convert pixel coordinates relative to the window to image coordinates.
+     * Note: not accurate with multi-image.
      * @param {OpenSeadragon.Point} pixel
      * @returns {OpenSeadragon.Point}
      */
@@ -1083,6 +1119,7 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
 
     /**
      * Convert image coordinates to pixel coordinates relative to the window.
+     * Note: not accurate with multi-image.
      * @param {OpenSeadragon.Point} pixel
      * @returns {OpenSeadragon.Point}
      */
@@ -1140,15 +1177,21 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
      * 1 means original image size, 0.5 half size...
      * Viewport zoom: ratio of the displayed image's width to viewport's width.
      * 1 means identical width, 2 means image's width is twice the viewport's width...
+     * Note: not accurate with multi-image.
      * @function
      * @param {Number} viewportZoom The viewport zoom
      * target zoom.
      * @returns {Number} imageZoom The image zoom
      */
     viewportToImageZoom: function( viewportZoom ) {
-        var imageWidth = this.viewer.source.dimensions.x;
+        if (this.viewer && this.viewer.world.getItemCount() > 1) {
+            $.console.error('[Viewport.viewportToImageZoom] is not accurate with multi-image.');
+        }
+
+        var imageWidth = this.contentSize.x;
         var containerWidth = this._containerInnerSize.x;
-        var viewportToImageZoomRatio = containerWidth / imageWidth;
+        var scale = this.homeBounds.width;
+        var viewportToImageZoomRatio = (containerWidth / imageWidth) * scale;
         return viewportZoom * viewportToImageZoomRatio;
     },
 
@@ -1158,15 +1201,21 @@ $.Viewport.prototype = /** @lends OpenSeadragon.Viewport.prototype */{
      * 1 means original image size, 0.5 half size...
      * Viewport zoom: ratio of the displayed image's width to viewport's width.
      * 1 means identical width, 2 means image's width is twice the viewport's width...
+     * Note: not accurate with multi-image.
      * @function
      * @param {Number} imageZoom The image zoom
      * target zoom.
      * @returns {Number} viewportZoom The viewport zoom
      */
     imageToViewportZoom: function( imageZoom ) {
-        var imageWidth = this.viewer.source.dimensions.x;
+        if (this.viewer && this.viewer.world.getItemCount() > 1) {
+            $.console.error('[Viewport.imageToViewportZoom] is not accurate with multi-image.');
+        }
+
+        var imageWidth = this.contentSize.x;
         var containerWidth = this._containerInnerSize.x;
-        var viewportToImageZoomRatio = imageWidth / containerWidth;
+        var scale = this.homeBounds.width;
+        var viewportToImageZoomRatio = (imageWidth / containerWidth) / scale;
         return imageZoom * viewportToImageZoomRatio;
     }
 };
diff --git a/src/world.js b/src/world.js
index 2c7a3f7f..9591183b 100644
--- a/src/world.js
+++ b/src/world.js
@@ -245,7 +245,7 @@ $.extend( $.World.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.W
     },
 
     /**
-     * @returns {OpenSeadragon.Rect} The smallest rectangle that encloses all items, in world coordinates.
+     * @returns {OpenSeadragon.Rect} The smallest rectangle that encloses all items, in viewport coordinates.
      */
     getHomeBounds: function() {
         return this._homeBounds.clone();
@@ -253,9 +253,9 @@ $.extend( $.World.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.W
 
     /**
      * To facilitate zoom constraints, we keep track of the pixel density of the
-     * densest item in the World (i.e. the item whose content size to world size
+     * densest item in the World (i.e. the item whose content size to viewport size
      * ratio is the highest) and save it as this "content factor".
-     * @returns {Number} the number of content units per world unit.
+     * @returns {Number} the number of content units per viewport unit.
      */
     getContentFactor: function() {
         return this._contentFactor;
diff --git a/test/demo/collections/main.js b/test/demo/collections/main.js
index 669d4fdb..b2c7eeb8 100644
--- a/test/demo/collections/main.js
+++ b/test/demo/collections/main.js
@@ -7,7 +7,7 @@
             var self = this;
 
             var testInitialOpen = true;
-            var testOverlays = true;
+            var testOverlays = false;
             var testMargins = false;
             var testNavigator = false;
             var margins;
@@ -34,6 +34,12 @@
 
             if (testInitialOpen) {
                 config.tileSources = [
+                    {
+                        tileSource: "../../data/testpattern.dzi",
+                        x: 4,
+                        y: 2,
+                        width: 2
+                    },
                     {
                         tileSource: "../../data/tall.dzi",
                         x: 1.5,
diff --git a/test/modules/drawer.js b/test/modules/drawer.js
index e024c72e..80f9fa7f 100644
--- a/test/modules/drawer.js
+++ b/test/modules/drawer.js
@@ -39,22 +39,6 @@
         start();
     });
 
-    // ----------
-    asyncTest('tile-drawing event', function() {
-        createViewer({
-            tileSources: '/test/data/testpattern.dzi'
-        });
-
-        viewer.addHandler('tile-drawing', function handler(event) {
-            viewer.removeHandler('tile-drawing', handler);
-            equal(event.eventSource, viewer, 'sender of tile-drawing event was viewer');
-            ok(event.tile, 'tile-drawing event includes a tile');
-            ok(event.context, 'tile-drawing event includes a context');
-            ok(event.rendered, 'tile-drawing event includes a rendered');
-            start();
-        });
-    });
-
     // ----------
     asyncTest('rotation', function() {
         createViewer({
diff --git a/test/modules/tiledimage.js b/test/modules/tiledimage.js
index 186d6686..703cc72a 100644
--- a/test/modules/tiledimage.js
+++ b/test/modules/tiledimage.js
@@ -1,4 +1,4 @@
-/* global module, asyncTest, $, ok, equal, notEqual, start, test, Util, testLog */
+/* global module, asyncTest, $, ok, equal, notEqual, start, test, Util, testLog, propEqual */
 
 (function() {
     var viewer;
@@ -45,6 +45,20 @@
 
             checkBounds(image, new OpenSeadragon.Rect(5, 6, 10, 40), 'initial bounds');
 
+            var scale = image.getContentSize().x / image.getBounds().width;
+            var viewportPoint = new OpenSeadragon.Point(10, 11);
+            var imagePoint = viewportPoint.minus(image.getBounds().getTopLeft()).times(scale);
+
+            propEqual(image.viewportToImageCoordinates(viewportPoint), imagePoint, 'viewportToImageCoordinates');
+            propEqual(image.imageToViewportCoordinates(imagePoint), viewportPoint, 'imageToViewportCoordinates');
+
+            var viewportRect = new OpenSeadragon.Rect(viewportPoint.x, viewportPoint.y, 6, 7);
+            var imageRect = new OpenSeadragon.Rect(imagePoint.x, imagePoint.y,
+                viewportRect.width * scale, viewportRect.height * scale);
+
+            propEqual(image.viewportToImageRectangle(viewportRect), imageRect, 'viewportToImageRectangle');
+            propEqual(image.imageToViewportRectangle(imageRect), viewportRect, 'imageToViewportRectangle');
+
             image.addHandler('bounds-change', function boundsChangeHandler(event) {
                 image.removeHandler('bounds-change', boundsChangeHandler);
                 handlerCount++;
@@ -102,6 +116,16 @@
                 ok(event.tile, 'update-tile event includes tile');
             });
 
+            viewer.addHandler('tile-drawing', function tileDrawingHandler(event) {
+                viewer.removeHandler('tile-drawing', tileDrawingHandler);
+                handlerCount++;
+                equal(event.eventSource, viewer, 'sender of tile-drawing event was viewer');
+                equal(event.tiledImage, image, 'tiledImage of update-level event is correct');
+                ok(event.tile, 'tile-drawing event includes a tile');
+                ok(event.context, 'tile-drawing event includes a context');
+                ok(event.rendered, 'tile-drawing event includes a rendered');
+            });
+
             viewer.addHandler('tile-drawn', function tileDrawnHandler(event) {
                 viewer.removeHandler('tile-drawn', tileDrawnHandler);
                 handlerCount++;
@@ -109,7 +133,7 @@
                 equal(event.tiledImage, image, 'tiledImage of update-level event is correct');
                 ok(event.tile, 'tile-drawn event includes tile');
 
-                equal(handlerCount, 3, 'correct number of handlers called');
+                equal(handlerCount, 4, 'correct number of handlers called');
                 start();
             });