What are some alternatives?
When comparing Dark Room and Priime, you can also consider the following products
Snapseed - Snapseed is a photo enhancement and sharing app with a powerful suite of imaging filters and tools...
VSCO Cam - VSCO Cam is an iPhone, iPod Touch, & Android camera app w/ elegant, minimal processing options.
Manual Camera for iPhone - Custom exposure for your iPhone camera
Darktable - darktable is an open source photography workflow application and raw developer.
Ultralight - Fast, light HTML UI solution for C++ apps
Adobe Photoshop Lightroom CC - Adobe Photoshop Lightroom CC is a commercial photo processor and image organizer.