Screenie Qt is very easy to use, after you run screenshots, or simply images/photos are added to one of the three windows, using drag and drop.
After adding images in the Screenie, sliders on the toolbar you can customize the layout (size, angle, position), to set the reflection and the level, background color and transparency. The image is saved in PNG format (on the right crack right-click).
Installation latest version into Linux Mint 13/14/15/16/17/17.1/17.2:
sudo apt-get install screenie-qt