How do I exclude stuff in a Mac search?

I am trying to search my desktop Mac for all images that I have created, such as tiff, png, jpeg, gif - whatever. My images, pictures, photos are disorganized so I am trying to find them all. I have different photo apps/libraries, imports from other computers, imports from devices, grabs and scans, you name it, there is every kind of file or folder. Problem is, the search finds Application icons and stuff in the thousands that I don't want. I'm pulling up Apple icons and printer lcons, junk! I cannot organize Finder based on location nor can I find a way to exclude location. I tried using Spotlight Preferences, starting with excluding Application and Library, but that won't work because

1. Spotlight in general will skip that when I DO want to search those, thus the SavedSearch in the Smart Folder becomes useless when I change the Spotlight Preference back to a normal full search

2. the Spotlight preference list doesn't really find the root folders at the top of the tree of locations I want to exclude, so Mac is still picking up unwanted thousands

3. i don't want to exclude 'library' as that can be a folder name in a Photo application

I don't understand why search criteria is so hard to create. I don't want EVERYTHING, I need to exclude about 9 /10s of what the Mac is finding. How does that help me? I am very frustrated. Can somebody help?

thanks a bunch, Tina