Forces you to use their camera cannot load from album
This app like many others of its type forces you to only use their camera to capture the source images for creating the final HDR.
If you prefer to use a separate more dedicated camera app with better functionality to capture your source images or have an existing library of bracketed images you would like to process, then this app is no use whatsoever.
Zugzig about
vividHDR, v3.1