iTunes says I have photos on iPhone but there are non there!

I have an iPhone 5, a Mac and iTunes.

My iTunes says I have 1.63GB of photos on my iPhone.

My iPhone (Settings>General>Usage>Manage Storage>Photos & Camera) says I have 1.6GB of photos. Clicking further, it says Photo Library has 1.6GB and Synced from iTunes Library 0.7KB photos.

However, I'm confused (and concerned) because:

- I have no photos at all on my iPhone. Non on the Camera Roll or the Recently Deleted. I have no videos.

- In iPhone>Settings>Photos & Camera, iCloud Photo Library, My Photo Stream, iCloud Photo Sharing are all turned off.

How can I get rid of these phantom 1.63GB of photos please? How do I empty the "Photo Library" on my iPhone?

Many thanks for clear and step wise help for computer/phone dummy.