What are some alternatives?
When comparing Formulas and Hueless, you can also consider the following products
TinType by Hipstamatic - Create vintage self portraits w/ Hipstamatic's new photo app
Lenka - A black & white camera app for iOS and Android
Ezimba - Different filters and effects for your photos, including animated and deep dream.
Deep Art Effects - Deep Art Effects transforms your photos and videos into works of neural art using artistic style transfer of famous artists.
Carbon - Create and share beautiful images of your source code.
White Wall - Turns your digital photos into wall art