If you create a new image PDF file through scanning, just do as below:
1. Choose Scan on the sidebar and click , there you can take photos or import photos from Gallery;
2. Then click Finish, here you can adjust them, and click Use;
3. Then you can change the filters and edit the photos;
4. After that, click and choose Store as PDF;
5. Or you can click Done, then tap Export as PDF.