Displaying full size image may effect your Blogger Layout. So, you are also suggested to display compressed form of a Full Size Picture. Compressed form will display a HQ image with actual resolution and will fit the image in your post body. For Example: If you upload 1024x760 pixels wallpaper, This full size wallpaper may effect your blogger layout. So, its important to display a compressed version of the image. You can choose any compression size that fits for your blog post body. Suppose you choose 600px compression width size. All images will be displayed in 600px width and height will be set automatically. Whenever some one will Right Click and Save the picture, they will get the image in Original Resolution. For More Visit.>! http://www.newfacebookchat.com/2011/07/how-to-compress-full-size-image-into.html