Allowed original image scale to be preserved.

SDWebImageDecoder.m

@@ -116,7 +116,7 @@ static SDWebImageDecoder *sharedInstance;
     CGImageRef decompressedImageRef = CGBitmapContextCreateImage(context);
     CGContextRelease(context);
 
-    UIImage *decompressedImage = [[UIImage alloc] initWithCGImage:decompressedImageRef];
+    UIImage *decompressedImage = [[UIImage alloc] initWithCGImage:decompressedImageRef scale:image.scale orientation:UIImageOrientationUp];
     CGImageRelease(decompressedImageRef);
     return SDWIReturnAutoreleased(decompressedImage);
 }