If for some reason you need to download a copy of an image you've previously uploaded then you can do this as follows.
Select the Gallery which contains the image you wish to download by clicking on that Gallery.
Select the image you wish to download by clicking on its thumbnail. The selected image will have a yellow border:
It will also appear in the display at the top of the page:
From here simple click on the Download button located underneath the image:
Your image download should begin shortly.