Luminance is a very professional photo processing app, which had been rated as the Apple’s best App of the Week in multiple regions. Currently it ushered free for limited again after 2013, but in the three-year period, Luminance did not receive any updates, its version is still stuck in 2013.
Likes other similar apps, Luminance built a lot of default effects, its various adjustment parameters are divided into two categories: Effects and Adjustments Adjustments included such as white balance, exposure, brightness, contrast, hue, saturation, and a series of common tuning parameters, and six colors can be individually adjusted, not only that it also has a High-end adjustment ‘Tone Curve’ which very similar to ‘Curve’ feature in PhotoShop; The Effects contains a variety of photo effects, which even includes Split Toning, also a high-level feature belonged PhotoShop.
In addition, Luminance also supports ‘batch’ and ‘history’ capabilities. If you are looking for a free alternative of Photoshop on iPhone, then Luminance fully meet your needs.