Photo Wall with random picks

Random pick from 3 different photo folders and appear on the block wall with different 3 group blocks (see image [login to view URL]) Need to create 3-5 folders (first create 3 then later we might have to create 5) Folder-sm Folder-med Folder-large Each folder will have about 10-20 images. They will populate randomly on the block wall where there are 3 different block sizes and each size will pull the images from the different folders sizes. So on the small blocks, the images on the Folder-sm will show/pull randomly on just those blocks and so on. It will also have a gradient effect but that can be created in css just for a design perspective. ([login to view URL] example)