Well you could describe the thing a little better; integrate software to where? ftp server? client? In any case, it's physically rather difficult to see an image from a remote server without downloading it - even if you wanted to see a thumbnail, you would first have to fetch (download) it, before being able to see it. You could make it so that the image (or thumbnail) is downloaded to a temporary directory for viewing, and deleted from there after the connection is cut off, for example.
Just as when you view an image in a web page, that image is downloaded before it's displayed. You just don't "see" that happen, because it's downloaded to a temporary/cache directory.