iphone 5s photos deleted but still showing in storage

I have the same issue on an iPhone 4S, with iOS 8.2. I've deleted all photos, cleared the deleted photos folder, but still have 3.1G of storage used by "Photo Library". If I look at the usage in iTunes, it shows 157 photos.

The problem has been around for a while, and is not associated withe the upgrade to 8.2. I tried "Erase All Content and Settings" from the reset menu, but when I restored from my backup, the phantom photos were still chewing up 3.1GB of storage. I am open to any suggestions...

Thanks