FTP to Images/Files?

Anyone know if it's possible to ftp to the Design Studio > Images and Files directory?  I have a number of images to optimize and replace and they're separated out into folders.  When I upload an image to the root Images and Files directory, it takes it out of that organized folder structure and puts it in the root.  Hoping I can just FTP in and update the images in that directory without using the Marketo GUI interface.