Help:Smoothing text in PDF or DjVu scanned books

In some scanned PDF or DjVu books the text is not clear enough to read comfortably: the letters look a bit distorted, sharp and edgy. Here is how to smooth it out. The idea is to extract the pages as images and use ImageMagick convert utility to apply a tiny blur, then assemble the images back into a book format. Also, the free version PDF-XChange Viewer allows to view PDF documents with smoothing the text, without changing the file.

Viewing in PDF X-Change Viewer

To view PDF books in PDF-XChange Viewer with smoothed text, enable the setting Edit -> Preferences... -> Rendering -> Smooth text. The file itself is not modified.

Step 1: Extract the pages as images

See Extract PDF pages as images page.

Step 2: Smooth the text

Use ImageMagick convert to apply a tiny blur.

Step 3: Convert the images back to PDF or DjVu format

See Creating PDF from images page.