XGimp Image Editor for Android
XGimp Image Editor for Android is an adaptation for Android of the app GIMP (GNU Image Manipulation). It uses the GIMP app provided by OffiDocs, and it is available in the Google Play Store Store:
MaxiPDF PDF editor & builder for Android
MaxiPDF PDF editor & builder for Android is the best one to work with PDF files. It allows you to create, edit, view and annotate PDF files, and it is available in the Google Play Store Store: