Instagram already has a number of filters for it’s users, however many 3rd party iOS apps have been designed with new filters – creating a trend for users to further transform photos in other apps before uploading them to Instagram.
My favorite is BeFunky. I took a photo of a Rolls Royce and you can see this neat greyed out effect with thick outline:
If you are looking for a paid app that really can transform your photos into brilliant colors and filters, check out Deluxe FX. For only 99cents this is well worth the money to give your photos a unique look.