DJVU ファイルについて
DJVU (DjVu Document · 文書フォーマット)
DjVu Document（.djvu）は、専門的なワークフローやデータ交換・アーカイブで広く利用されているファイル形式です。KaijuConverterで高速に変換できます。
カテゴリ
Documents & Text
拡張子
.djvu
MIMEタイプ
image/vnd.djvu
対応ロール
DJVU が誕生した
背景と歴史。
DjVu — pronounced "déjà vu" — was developed at AT&T Labs in 1996 by Yann LeCun (later the inventor of modern convolutional neural networks), Léon Bottou, Patrick Haffner, and Paul Howard. The goal was extreme compression of scanned documents: take a 300 DPI color page scan that weighed 25 MB as TIFF, separate it into a foreground (text and line art) and background (photos and paper texture) using wavelets, and compress each layer aggressively. A typical scanned page dropped from 25 MB to under 50 KB while staying perfectly readable.
Internet Archive, Project Gutenberg, and library digitization projects adopted DjVu throughout the 2000s for millions of scanned books. Browser support was always via a plugin (the Caminova/LizardTech one), which meant the format struggled as the plugin era ended. Today DjVu’s niche has mostly been filled by PDF/JBIG2, but you still find it anywhere scanned archives are kept — Wikipedia, Archive.org, and most academic library scans default to DjVu for the ratio.
豆知識＆
トリビア。
DjVu was co-invented by Yann LeCun, who later founded Meta AI Research and won the Turing Award for work on convolutional neural networks.
A typical 300 DPI color scan of a book page is 25 MB as TIFF, ~600 KB as PDF, and ~50 KB as DjVu at perceptually equal quality.
Archive.org's Open Library stores millions of scanned books with a DjVu version alongside the PDF.
The trick is layered wavelet compression: text and line art go in a foreground bitplane, photos and paper stain go in a low-res background, both recombine at display time.
Browser plugin support died with NPAPI around 2015 — which is why PDF won the scanned-document war despite being 5-10× larger.
長所と
制限事項。
長所
- Extreme compression for scanned documents — typically 5-10× smaller than PDF.
- Preserves OCR text layer alongside scanned image.
- Mature archival format at Internet Archive, Wikipedia, academic libraries.
- Separate foreground/background layers compress each content type optimally.
制限・弱点
- No native browser support since the NPAPI era (~2015).
- Tooling outside Linux is sparse.
- Encoding requires the proprietary LizardTech/Caminova toolchain or djvulibre.
- PDF/JBIG2 now covers most of DjVu's use cases with wider compatibility.
一般的なファイルサイズ目安
Scanned page (B&W, text-only)
10-30 KB
Scanned page (color, illustrations)
40-150 KB
300-page scanned book
5-30 MB
技術仕様
- MIME type
- image/vnd.djvu
- Extensions
- .djvu, .djv
- Compression
- Wavelet (IW44) + JB2 for line art
- Invented at
- AT&T Labs (1996)
- Reference tool
- djvulibre (open source)
他形式から変換
DJVU
主な活用シーン
Scanned document archives
関連フォーマット
よく見られている比較
DJVU の人気変換ペア
DJVU から変換する際によく選ばれている出力形式です。
DJVU に関するよくある質問
よくある 質問
KaijuConverterにDJVUファイルをアップロードするだけで、ソフトをインストールせずにPDF、JPG、PNGなどの標準形式へ即座に変換できます。
はい、25MBまで完全無料（24時間パスやProプランでは最大1GB）で変換でき、アップロードされたファイルは60分後にサーバーから自動削除されます。
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1回限りの支払いで24時間、最大1GBのファイルおよび最大50ファイルの一括変換が利用可能です。
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