PhotoTune
Uses Apple's Core Image framework for photo proccessing. Supports iOS 11+. Instruments: Brightness, Contrast, Saturation, Sharpness, Vignette, Rotation.
Main features:
Dark Theme
Required iOS 13+.
Autoenhance
Click one button and your photo will be automatically improved.
Resizing image for best perfomance.
It doesn't matter what size of the imported image. But you can choose Full resolution when exporting.
Localization
Supporting languages: English, Russian, Japanesse.
Various Image Sources
You can use Camera, Photolibrary, or Unsplash (internet connection required) as image source.