diff --git a/src/display/api.js b/src/display/api.js
index cce2704b0..ce3713afa 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -2028,7 +2028,7 @@ var WorkerTransport = (function WorkerTransportClosure() {
             var height = img.height;
             var size = width * height;
             var rgbaLength = size * 4;
-            var buf = new Uint8Array(size * components);
+            var buf = new Uint8ClampedArray(size * components);
             var tmpCanvas = document.createElement('canvas');
             tmpCanvas.width = width;
             tmpCanvas.height = height;