How to fix iPhone 5S reporting excessive space used for Photo Library?

I have an iPhone 5S running iOS 8.1.3. I have removed all photos from the phone (i.e. the Camera Roll is empty). However, under Settings -> General -> Usage -> Manage Storage, it reports that 1.9 GB is still in use for Photos & Camera. Specifically, underneath that, it reports that 1.9 GB is being used for the Photo Library (which is ostensibly empty). This is a large chunk of the storage on my 16 GB phone!

I have tried doing a factory reset of the phone and restoring from backup, with no effect; it still reports the excessive storage usage. I've checked the following:

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  Photo Stream is not enabled.

  
  


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  iCloud "Photos" is not enabled.

  
  


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  There is no photo sharing of any kind enabled.

  
  

Is there anything else that I should look at to determine why the incorrect amount of usage is being reported?