Image uploading web application using PHP

Need to develop PHP web application which should have Images uploading, adding watermarks,categorizing images and searching functions. Database websites with extensive searching capabilities amount 100,000 photos indexing the key words embedded in the metadata of each image Client have about that many images, and he'd like to have a web server that could bring up the images, such that a stranger could indicate a couple of search terms and then see a display of the images. Client have domains and servers already, please keep in mind that when a search is done, nobody wants to see the images one at a time. The end user should be able to select 4 at a time 9 at a time 16 at a time. Then when the end user clicks on the image, it should go to full screen. Other than the file name, and maybe the key words, nothing else need be displayed besides each image. in selections of 4 or more, only the file name is needed. Client need to be able to put in as many relevant keywords as possible to describe a photo, and the endures puts in whatever he is looking for. The database search then brings up all images that have all or most of the words the end user puts in, like Google.