Preserve transparent color info for png files in output.
Try to implement inking in the app. What is Windows 10 all about - innovation, bee dare to implement all new features.
Share target is a good way to share data between app in Windows 10, especially Windows 10 Mobile.
Include option to preserve EXIF info in output images.
As the optional output of process generates html5 picture element in the .txt file. Maybe as some kind of template for later adjustment with server name and etc..
Add the opportunity to individually position the images during the crop. An interface resembling the Preview on the page of the template would do very well the case by offering pan & zoom.
In future version take attention on this segment, index prints are very useful!
Create new Image-Watermark type, especially for .png images with transparency!