Brief
We have modified the 'image_functions.php' file for release 3.4.7.
 
Description.
In some cases watermark caused an error and image was not shown.
 
Solution.
We would recommend to download an updated version of the file from here: http://www.viart.com/downloads/image_functions-3.4.7.zip
 
Further, extract the above mentioned file into the 'includes' folder of your shop replacing an existing one. Don't forget to make a backup copy of the current file in case something goes wrong.