We recently placed REXiG HDR within our Top 10 of iOS HDR apps – see here. Well now it’s going free, so there’s even more reason to pick it up. In general, the HDR composite will require multiple Photos. In this application REXiG can represent a high dynamic range by restoring information from the darker and bright portions. When information in a dark part and a bright part is completely lost this in turn will not get good result. Also, Since the noise tends to brighten the dark areas, noise reduction will be very useful.