diff --git a/iOS/Resources/main_ios.js b/iOS/Resources/main_ios.js
index 5c7ca4f74..4104749cf 100644
--- a/iOS/Resources/main_ios.js
+++ b/iOS/Resources/main_ios.js
@@ -34,8 +34,12 @@ class ImageViewer {
 		this.hideLoadingIndicator();
 
 		var canvas = document.createElement("canvas");
-		canvas.width = this.img.naturalWidth * window.devicePixelRatio;
-		canvas.height = this.img.naturalHeight * window.devicePixelRatio;
+		var pixelRatio = window.devicePixelRatio;
+		do {
+			canvas.width = this.img.naturalWidth * pixelRatio;
+			canvas.height = this.img.naturalHeight * pixelRatio;
+			pixelRatio--;
+		} while (pixelRatio > 0 && canvas.width * canvas.height > 16777216)
 		canvas.getContext("2d").drawImage(this.img, 0, 0, canvas.width, canvas.height);
 
 		const rect = this.img.getBoundingClientRect();