﻿Preview the image to estimate quality (use pinch zoom to see details).
Drag the crop rectangle to select the portion of the picture you want to use as PDF page or to extract the text from. 
Tap "Extract Text" on the action bar to start text recognition.
Tap "Add to PDF" to add the image as new page to PDF file.

You can always return to the image tab if you want to select different region.
