Let's take a closer look at some of the effective methods to darken the text in a PDF file and make it more readableAdjust Colors and Background Settings in Adobe Acrobat Reader Is there an easy way to increase the contrast of the document in pdf form? This is a waste of paper and time Add text anywhere in your PDF and select your desired font style from a long list of choices. You can also choose the font attribute for text (i.e., bold, italic, underline, etc.), as well as adjust the font size.