You can get them from a number of places – if you have a digital camera, you can shoot textures yourself, you can shoot buildings, people, etc, then manipulate them in Photoshop and drop them into After Effects. You can also purchase stock photography from sites such as fotolia.com, shutterstock.com, etc. There are free reseources to. Use google and make sure the images you put into a project can be used commercially (a paid project).
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