diff --git a/externs/oli.js b/externs/oli.js
index 659148c77c..d8d4b86cb1 100644
--- a/externs/oli.js
+++ b/externs/oli.js
@@ -266,6 +266,18 @@ oli.source.ImageEvent = function() {};
 oli.source.ImageEvent.prototype.image;
 
 
+/**
+ * @interface
+ */
+oli.source.RasterEvent = function() {};
+
+
+/**
+ * @type {number}
+ */
+oli.source.RasterEvent.prototype.resolution;
+
+
 /**
  * @interface
  */
diff --git a/src/ol/source/rastersource.js b/src/ol/source/rastersource.js
index 8acfdbf9fd..861fe86605 100644
--- a/src/ol/source/rastersource.js
+++ b/src/ol/source/rastersource.js
@@ -1,6 +1,9 @@
 goog.provide('ol.source.Raster');
+goog.provide('ol.source.RasterEvent');
+goog.provide('ol.source.RasterEventType');
 
 goog.require('goog.asserts');
+goog.require('goog.events.Event');
 goog.require('goog.functions');
 goog.require('goog.vec.Mat4');
 goog.require('ol.ImageCanvas');
@@ -182,6 +185,11 @@ ol.source.Raster.prototype.composeFrame_ = function(frameState) {
   var targetImageData = context.getImageData(0, 0, canvas.width, canvas.height);
   var target = targetImageData.data;
 
+
+  var resolution = frameState.viewState.resolution / frameState.pixelRatio;
+  this.dispatchEvent(new ol.source.RasterEvent(
+      ol.source.RasterEventType.BEFOREOPERATIONS, resolution));
+
   var source, pixel;
   for (var j = 0, jj = target.length; j < jj; j += 4) {
     for (var k = 0; k < len; ++k) {
@@ -192,13 +200,17 @@ ol.source.Raster.prototype.composeFrame_ = function(frameState) {
       pixel[2] = source[j + 2];
       pixel[3] = source[j + 3];
     }
-    this.transformPixels_(pixels);
+    this.runOperations_(pixels);
     pixel = pixels[0];
     target[j] = pixel[0];
     target[j + 1] = pixel[1];
     target[j + 2] = pixel[2];
     target[j + 3] = pixel[3];
   }
+
+  this.dispatchEvent(new ol.source.RasterEvent(
+      ol.source.RasterEventType.AFTEROPERATIONS, resolution));
+
   context.putImageData(targetImageData, 0, 0);
 
   frameState.tileQueue.loadMoreTiles(16, 16);
@@ -211,7 +223,7 @@ ol.source.Raster.prototype.composeFrame_ = function(frameState) {
  * @return {Array.<ol.raster.Pixel>} The modified pixels.
  * @private
  */
-ol.source.Raster.prototype.transformPixels_ = function(pixels) {
+ol.source.Raster.prototype.runOperations_ = function(pixels) {
   for (var i = 0, ii = this.operations_.length; i < ii; ++i) {
     pixels = this.operations_[i](pixels);
   }
@@ -314,3 +326,49 @@ ol.source.Raster.createTileRenderer_ = function(source) {
   var layer = new ol.layer.Tile({source: source});
   return new ol.renderer.canvas.TileLayer(layer);
 };
+
+
+
+/**
+ * @classdesc
+ * Events emitted by {@link ol.source.Raster} instances are instances of this
+ * type.
+ *
+ * @constructor
+ * @extends {goog.events.Event}
+ * @implements {oli.source.RasterEvent}
+ * @param {string} type Type.
+ * @param {number} resolution Map units per pixel.
+ */
+ol.source.RasterEvent = function(type, resolution) {
+  goog.base(this, type);
+
+  /**
+   * Map units per pixel.
+   * @type {number}
+   * @api
+   */
+  this.resolution = resolution;
+
+};
+goog.inherits(ol.source.RasterEvent, goog.events.Event);
+
+
+/**
+ * @enum {string}
+ */
+ol.source.RasterEventType = {
+  /**
+   * Triggered before operations are run.
+   * @event ol.source.RasterEvent#beforeoperations
+   * @api
+   */
+  BEFOREOPERATIONS: 'beforeoperations',
+
+  /**
+   * Triggered after operations are run.
+   * @event ol.source.RasterEvent#afteroperations
+   * @api
+   */
+  AFTEROPERATIONS: 'afteroperations'
+};