diff --git a/src/config/config.dev.js b/src/config/config.dev.js
index ea01319..8a44bcd 100644
--- a/src/config/config.dev.js
+++ b/src/config/config.dev.js
@@ -18,7 +18,7 @@ module.exports = {
         singleChannel: false // true: only the red color-channel is read
     },
     locate: true,
-    numOfWorkers: 0,
+    numOfWorkers: 1,
     decoder: {
         readers: [
             'code_128_reader'
diff --git a/src/input/frame_grabber.js b/src/input/frame_grabber.js
index 503f52b..92a1cad 100644
--- a/src/input/frame_grabber.js
+++ b/src/input/frame_grabber.js
@@ -4,6 +4,21 @@ import {
     computeGray
 } from '../common/cv_utils';
 
+function adjustCanvasSize(canvas, targetSize) {
+    if (canvas.width !== targetSize.x) {
+        if (ENV.development) {
+            console.log("WARNING: canvas-size needs to be adjusted");
+        }
+        canvas.width = targetSize.x;
+    }
+    if (canvas.height !== targetSize.y) {
+        if (ENV.development) {
+            console.log("WARNING: canvas-size needs to be adjusted");
+        }
+        canvas.height = targetSize.y;
+    }
+}
+
 var FrameGrabber = {};
 
 FrameGrabber.create = function(inputStream, canvas) {
@@ -56,6 +71,7 @@ FrameGrabber.create = function(inputStream, canvas) {
             frame = inputStream.getFrame(),
             ctxData;
         if (frame) {
+            adjustCanvasSize(_canvas, _canvasSize);
             _ctx.drawImage(frame, 0, 0, _canvasSize.x, _canvasSize.y);
             ctxData = _ctx.getImageData(_sx, _sy, _size.x, _size.y).data;
             if (doHalfSample){
diff --git a/src/quagga.js b/src/quagga.js
index b79db56..b565f27 100644
--- a/src/quagga.js
+++ b/src/quagga.js
@@ -8,6 +8,9 @@ import Config from './config/config';
 import {merge, pick, omitBy, isEmpty, omit} from 'lodash';
 
 
+// scanner map
+// Keep record of already created scanners for reuse?!
+
 function fromImage(config, imageSrc, imageConfig) {
     config =
         merge({
@@ -27,7 +30,7 @@ function fromImage(config, imageSrc, imageConfig) {
         {inputStream: imageConfig});
 
     console.log(config);
-    const scanner = createScanner(config);
+    const scanner = createScanner();
     return {
         addEventListener: (eventType, cb) => {
             scanner.decodeSingle(config, cb);
@@ -106,22 +109,27 @@ function createApi(configuration = Config) {
         config(conf) {
             return createApi(merge({}, configuration, conf));
         },
-        start: function() {
+        start() {
             defaultScanner.start();
         },
-        stop: function() {
+        stop() {
             defaultScanner.stop();
         },
-        pause: function() {
+        pause() {
             defaultScanner.pause();
         },
-        registerResultCollector: function(resultCollector) {
+        registerResultCollector(resultCollector) {
             defaultScanner.registerResultCollector(resultCollector);
         },
-        ImageWrapper: ImageWrapper,
-        ImageDebug: ImageDebug,
-        ResultCollector: ResultCollector,
-        canvas: defaultScanner.canvas
+        getCanvas() {
+            return defaultScanner.canvas;
+        },
+        ImageWrapper,
+        ImageDebug,
+        ResultCollector,
+        _worker: {
+            createScanner
+        }
     };
 }
 export default createApi();
diff --git a/src/scanner.js b/src/scanner.js
index b19c364..d7854ca 100644
--- a/src/scanner.js
+++ b/src/scanner.js
@@ -383,7 +383,8 @@ function createScanner() {
                 return;
             }
         }
-        var imageWrapper;
+        var imageWrapper,
+            scanner = Quagga._worker.createScanner();
 
         self.onmessage = function(e) {
             if (e.data.cmd === 'init') {
@@ -393,13 +394,11 @@ function createScanner() {
                     x: e.data.size.x,
                     y: e.data.size.y
                 }, new Uint8Array(e.data.imageData));
-                Quagga.init(config, ready, imageWrapper);
-                Quagga.onProcessed(onProcessed);
+                scanner.init(config, ready, imageWrapper);
+                scanner.onProcessed(onProcessed);
             } else if (e.data.cmd === 'process') {
                 imageWrapper.data = new Uint8Array(e.data.imageData);
-                Quagga.start();
-            } else if (e.data.cmd === 'setReaders') {
-                Quagga.setReaders(e.data.readers);
+                scanner.start();
             }
         };