Prisma is great with my photos.

Prisma

This application was recommended by Adam Christianson of the Maccast podcast and it has quite a good few filters and effects to apply to photos. This is one I applied to a photo I took in Barcelona and gives a very arty farty style of photo. The quality of the images produced are not very high but good enough for sending to Instagram. With Instagram is now possible to do non-square photos, but the application forces you to make your photos square anyway. I suspect that over time the application will be updated and upgraded to higher quality photos and other options to. Since getting the application there have already been some extr filters added.