PDF to DjVu: how to shrink scanned documents

PDF is the default format for finished documents, but it is not always the smallest. A scanned book saved as a PDF can be hundreds of megabytes. DjVu was designed for exactly that problem: scanned pages, compact storage, and fast browsing in a dedicated viewer.

PDF to DjVu is therefore an archiving conversion, not a general-purpose sharing conversion. It is useful when storage size matters and the document is mostly text or line art.

What DjVu does well

DjVu separates a page into layers. It can store a background layer for paper texture and a foreground layer for text and line work, then compress each layer with a method suited to its content. For scanned books, that combination can be much smaller than a PDF that treats every page as one large image.

DjVu is common in digital libraries, academic archives, and collections of old manuals. It is not a good choice for documents that need to be edited, and it is not as widely supported as PDF on phones and tablets.

When to convert PDF to DjVu

Convert when you need to:

• Store a large collection of scanned pages with limited disk space.
• Publish an archive that will be read in a DjVu viewer.
• Reduce a text-heavy scan without turning it into a lossy JPEG.
• Keep a compact master while sharing a separate PDF copy.

Do not convert a colour photo book or a portfolio if colour accuracy matters. The pipeline is tuned for scanned documents, not for photographic colour.

What changes

The page order and page dimensions should remain the same. What can change is image fidelity:

• Fine colour detail may be reduced.
• Highly compressed scans may show new artifacts.
• A text layer may or may not be preserved, depending on the source.
• PDF bookmarks, forms, and annotations are not part of the DjVu page model.

Open several pages after conversion, especially a page with small print and a page with a diagram. If the document is going to an archive, keep the original PDF until you have checked the DjVu copy.

How to convert

Open the PDF to DjVu tool, upload one PDF, and choose DjVu as the output. The server processes the file locally and returns a temporary download link.

If the PDF is mostly text and was exported from an office application, a PDF may already be small enough. DjVu is most valuable for scans, not for born-digital documents.

DjVu or PDF for long-term storage?

Use PDF when compatibility is the priority. Use DjVu when size is the priority and the document is a scan. Keeping both is a reasonable archive strategy: the PDF for access and the DjVu for compact storage.

You can also read the reverse guide, DjVu to PDF, or open the PDF to DjVu converter to try one file.