Some services or programs can scan your document, use OCR to convert the scanned image to readable text, and save the result as a PDF. However, these services and programs often cost money.

Yet when a document is scanned into PDF format, it can be difficult to edit-unless you first convert the text using a process known as OCR, or optical character recognition.

It's easy to convert images into PDF files -- whether on Windows, Mac, or directly on your mobile phone. We'll show you how it works.