This is a simple file converter, PDF to JPG, JPG to PDF, of course, you can also use the camera as a Scanner to take photos and convert to PDF file, the converted files can be shared via email attach compressed ZIP files (password can be set or not).
Features are:

App Output folders:
/storage/emulated/0/Android/data/tw.tn.ted.ttrpdfjpg/files/
subfolders as below:
pdf2jpg
jpg2pdf
scan2pdf
ziptemp (If you want to send to friends,zip file will be auto generated at this temp folder.)

PDF2JPG Tab
1.You can add multi folders and files.

2. The minus button to clear the screen of all added items ,you can also uncheck small box or move item to left or right to remove.

3. You can change the order of items by long press item to move up or move down.

4. Short Click the item to view the file contents.

5. Click on the conversion button,will Convert to JPG or PNG files.

6.When conversion is processing,you can stop current conversion task by pressing back key.

JPG2PDF Tab
Operation is the same above.

SCAN2PDF Tab
Operation is the same above.
Use Camera to take pictures and convert to a PDF file.

set up
Three parts:
1.PDF2JPG can be set: The output image format, magnification, rotation, page numbering, display icon.
2.JPG2PDF SCAN2PDF: PDF size, image size fit with PDF size, PDF portrait or landscape orientation, rotation angle, quick camera resolution.
3.sharing settings: zip converted files(can set password or not) to send.