How do I fix the capacity issue on my iPhone 6?

My iPhone 6 continually gives me the capacity warning. I have deleted all of my photos and music and now use the google apps for them, but when I connect my phone to iTunes is still shows a significant amount of space allocated to photos (3.56gb). And there is also a movie on my phone that I cannot for the life of me figure out how to remove and keep solely in iTunes. Please help! tia