Today, on my friends phone, a different brand, I think it was an Iphone 6, I saw her going through her photo gallery. There was a little "love heart button" on each photo that she could highlight if she liked the photo. I asked her what this was and she showed me these photos were automatically saved in an album called favourites.
I think this feature would be so quick and handy to sort out the photos you want to keep and have immediate access to, instead of scrolling through many photos trying to find a specific one.
Can you develop a feature like this?