Open PDF File: In order to open the required PDF file in paint, first open the file in the PDF viewer. The detailed tutorial on opening PDF in Paint: 1. credit: Creatas Images/Creatas/Getty Images. There are two ways to convert from Paint to PDF: the first creates an actual-size picture with white space covering the rest of the page, and the second creates a full-page picture. Frequently Asked Questions How do I convert paint to PDF?