It's simple to adjust image's color by swapping Red / Green / Blue channel each other.
This app won't cause any loss of image quality.
How to it works:
1. Click RG \ RB \ GB buttons to select channel to be mixed
2. Drag slider to change swapping volume
3. Save
The Mac version of Swap RGB is also available now.
Compatible update for iOS12
Photo GPS Modifier 
Enhance RGB 