The app is deprecated. For GoPro Hero 5 and newer models (e.g. Hero 5/6/7/8/9, GoPro Fusion/Max 360°) please use the Bracketing for Heros app (click here for download links).
The HDR Photo for GoPro Hero 4 and 5 cameras app allows you to capture multiple images with different exposure and ISO (bracketing). The images can then be stitched into a single HDR (High Dynamic Range), well-exposed, noise-reduced, image using other applications (such as HDR Photo, Photoshop, ...).
Features include (some features are platform dependent):