Disable Image down loading
Some people would like to prevent viewers from downloading their images from their sites.
If you display an image on your site you can't prevent a viewer from copying it.
If someone views it, it is already downloaded their computer (in their cache).
A viewer can use screen capture to copy the image.
What you can do:
Use only low-quality images and offer to sell high-quality ones.
Put a copyright notice on images See this
You can disable right-click on photos (Not really possible in Google Sites) Read This but one person discovered that you can place the images inside a "Table", and to that table, apply the following code: <table oncontextmenu = "return false" onkeydown="return false"></table> See example below.
Put a watermark on your images Read this
Image in a table. Right-click disabled.
<table oncontextmenu = "return false" onkeydown="return false">
<td><img src="https://drive.google.com/uc?export=view&id=0B28Gtf1n8u8DcHlTZW5kNzlkNUk" border="0" alt=""width=200></td>