I have an app with a 40GB and growing document folder which consists of mostly pdf’s and image files. I can secure pdf’s by file type under Page and Folder Security, but I don’t seem to be able to secure the images by either security group or by folder. I really don’t want to reinvent the wheel by moving all these files to a table (I’m using MySQL), but I can’t have my images exposed to the world. I hope I’m just missing something simple. I can't help but think there has to be a straightforward solution. My folder structure is:

mydomain.com/file_purpose/company_name/file_name.png

I want to secure everything under the “file_purpose” folder. Thanks in advance.