Free professional photo apps for a short time: Better pictures on Android and iOS
Nevertheless, HD Camera Pro is worth a look - an incredible number of filters will give your pictures any mood. However, this works only directly when photographing and not subsequently.
iOS users should strike with Camera RX but immediately. From RAW images on a manual selection of the lens with dual camera to the manual flash, many ingenious features are on board. ISO strength, exposure time and color temperature can of course be set arbitrarily. Intuitive operation and display of the battery level directly in the app complete the package.
As already mentioned, Android users will certainly get their money's worth with Open Camera as well. A remote trigger function via a voice command such as "Cheese" is just one of the highlights.