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G3 to DJVU Converter

Convert G3 files to DJVU — instant online tool

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Server-Side Engine

All processing happens in the cloud. Your computer stays free while G3 converts to DJVU on our servers.

Fax Preservation

Preserve fax content by converting G3 to widely supported DJVU — future-proof your document archive.

Safe Conversion

Your G3 file is removed right after processing. The DJVU download is auto-deleted within 24 hours.

How to convert G3 to DJVU

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose djvu or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your djvu file right afterwards

About formats

G3 is a monochrome image format based on the ITU-T Group 3 facsimile coding standard (Recommendation T.4), ratified by the CCITT in 1980 as the universal compression method for fax transmission over telephone networks. G3 files contain 1-bit (black and white) image data encoded using Modified Huffman (MH) one-dimensional coding, where each scanline is independently compressed by replacing runs of consecutive white or black pixels with variable-length codewords from a predefined Huffman table optimized for typical document content. The standard also defines an optional two-dimensional coding mode (Modified READ) that encodes each line as differences from the previous line, achieving better compression for pages with vertical redundancy. Standard G3 resolution is 204 pixels per inch horizontally and either 98 (standard) or 196 (fine) pixels per inch vertically, producing the characteristic slightly-stretched appearance of received fax documents. The encoding was carefully optimized for the real-time transmission constraints of 1980s modems operating at 2400 to 14400 bps, where encoding and decoding speed had to match the communication channel rate. One advantage is universal telecommunications compatibility: Group 3 encoding remains the mandatory baseline codec for every fax machine manufactured, ensuring that G3 image data can be transmitted to or received from any fax device worldwide. The format's efficiency for document content is another strength — the Huffman tables were statistically tuned to the run-length distributions found in business documents, and typical pages compress to under 30 KB. G3 files are supported by LibreOffice, ImageMagick, and fax server software.
Developer: ITU-T (CCITT)
Initial release: 1980
DjVu (pronounced "deja vu") is a document format developed at AT&T Labs by Yann LeCun, Leon Bottou, Patrick Haffner, and Paul Howard, first released in 1996. The format was specifically designed for storing scanned documents and images at very high compression ratios while maintaining visual quality suitable for on-screen reading. DjVu achieves this through a layered approach: the document image is separated into a foreground layer (text and line art at full resolution), a background layer (photographs and textures at reduced resolution), and a mask layer that determines which layer is visible at each pixel. This separation, combined with purpose-built compression algorithms for each layer type, typically produces files 5-10 times smaller than equivalent JPEG or PDF scans. One advantage is exceptional compression on scanned pages — a 300 DPI color scan that might occupy 25 MB as TIFF or 500 KB as JPEG typically compresses to 40-80 KB in DjVu while preserving legible text. The progressive rendering model is another strength: DjVu files stream efficiently over networks, displaying a readable low-resolution version almost immediately while progressively refining to full quality. The format supports multi-page documents, embedded text layers for searchability, hyperlinks, annotations, and a shared dictionary mechanism that further compresses collections of similar pages. DjVu is widely used by libraries and archives for digitized historical documents and manuscripts.
Developer: AT&T Labs
Initial release: 1996

Frequently Asked Questions

Why convert G3 to DJVU?

DJVU provides universal readability for fax content — ideal for archiving, sharing, or processing scanned fax documents.

Which apps open DJVU files?

Open DJVU files using DjVu Viewer, WinDjView, Sumatra PDF, or Evince.

Is the converted DJVU file high quality?

Document content stays crisp and readable. The converter maintains G3 image fidelity in the DJVU result.

Do I need to pay for this conversion?

No cost for standard G3 to DJVU conversions. Premium plans add faster processing and increased file limits.

Does this tool handle multiple files?

Yes — batch upload is supported. Drop multiple G3 files and each one converts to DJVU for separate download.

Can I use this converter on a Mac?

Yes — the converter runs in any browser on macOS, Windows, Linux, Android, and iOS. Fully cross-platform.