Convert ICO to DJVU
Max file size 100mb.
ICO vs DJVU Format Comparison
| Aspect | ICO (Source Format) | DJVU (Target Format) |
|---|---|---|
| Format Overview |
ICO
Windows Icon
Microsoft's icon file format for application icons, favicons, and system UI elements. ICO files are multi-resolution containers storing multiple sizes (16x16 to 256x256) in a single file, supporting both BMP and PNG compression. Lossless Legacy |
DJVU
DjVu Document Format
A document-centric format developed by AT&T Labs in 1996, specifically designed for scanned documents, digital books, and high-resolution images. DJVU uses separate compression layers for text (JB2), images (IW44 wavelet), and background, achieving file sizes 3-10x smaller than PDF for scanned content. Lossy Standard |
| Technical Specifications | Color Depth: 1-bit to 32-bit (RGBA with alpha) Compression: Uncompressed BMP or PNG per size Transparency: 1-bit mask or 8-bit alpha Animation: Not supported Extensions: .ico |
Color Depth: 8-bit per channel (24-bit RGB)
Compression: IW44 wavelet (images) + JB2 (text/line art) Transparency: Mask layer supported Animation: Not supported (multi-page document) Extensions: .djvu, .djv |
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| Processing & Tools | ICO icon extraction: # Extract largest resolution from ICO magick input.ico[0] output.png # List sizes in ICO container identify input.ico |
DJVU creation with layer separation: # Convert image to DJVU c44 input.ppm output.djvu -dpi 300 # Merge pages into multi-page DJVU djvm -c document.djvu page1.djvu page2.djvu |
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| Version History | Introduced: 1985 (Windows 1.0) Current Version: ICO with PNG (Vista+) Status: Active, essential Windows format Evolution: 16-color → 256-color → 32-bit RGBA → PNG compression |
Introduced: 1996 (AT&T Labs)
Current Version: DjVu specification (open format) Status: Stable, widely used in digital libraries Evolution: AT&T Labs (1996) → LizardTech (2000) → DjVuLibre (2002) |
| Software Support | Image Editors: GIMP, IcoFX, Greenfish Icon Editor Web Browsers: All (favicon support) OS Preview: Windows native Mobile: Not commonly used CLI Tools: ImageMagick, Pillow, icotool |
Image Editors: Limited (viewing format)
Web Browsers: djvu.js plugin OS Preview: WinDjView, MacDjView, Evince Mobile: EBookDroid, DjVu Reader CLI Tools: DjVuLibre (c44, cjb2, djvm) |
Why Convert ICO to DJVU?
Converting ICO to DJVU is useful for documenting and archiving icon collections in a compact, browsable format. UI designers and brand managers can compile entire icon libraries into a single DJVU document where each page displays an icon at its largest resolution.
DJVU excels at compressing icon content — simple graphics with solid colors and sharp edges compress extremely well with DJVU's JB2 and IW44 algorithms, producing smaller files than the original multi-resolution ICO containers.
For software documentation and UI specification, converting ICO icons to DJVU pages creates reference materials for technical documentation. Design system catalogs and icon usage guides benefit from having all icons in a single viewable document.
Note that ICO files contain multiple resolutions — conversion extracts the largest available size. The multi-resolution nature is not preserved in DJVU.
Key Benefits of Converting ICO to DJVU:
- Icon Library Archival: Compile icon collections into single DJVU documents
- Excellent Compression: Flat-color icons compress exceptionally well
- Documentation Ready: Create icon reference sheets for design systems
- Cross-Platform: View catalogs on any OS with DJVU viewers
- Sharp Edges: DJVU maintains crisp pixel boundaries
- Compact Storage: More efficient than individual ICO files
- Cataloging: Multi-page DJVU for organized icon browsing
Practical Examples
Example 1: Design System Icon Catalog
Scenario: A UI designer creates a reference document of all 120 application icons for team review.
Source: settings_icon.ico (15 KB, multi-res: 16/32/48/256px) Conversion: ICO → DJVU (batch, 120 icons) Result: icon_catalog_v3.djvu (180 KB total, 120 pages) ✓ 1.5 KB average per page — extremely compact ✓ Easy to share with stakeholders for approval ✓ Printable icon reference sheets
Example 2: Favicon Registry
Scenario: A web agency manages favicons for 50+ client websites and needs a master reference document.
Source: client_favicon.ico (4 KB, 16x16 and 32x32) Conversion: ICO → DJVU (50 favicons) Result: favicon_registry.djvu (45 KB, 50 pages) ✓ Visual index of all client favicons ✓ Quick reference during maintenance ✓ Tiny file size for entire library
Example 3: Application Icon Archive
Scenario: A software company archives icon versions across releases for historical reference.
Source: app_icon_v5.ico (45 KB, up to 256x256) Conversion: ICO → DJVU (200 icons across versions) Result: icon_history.djvu (850 KB, 200 pages) ✓ Complete visual history in single document ✓ Compliance-ready for software audits ✓ Cross-platform viewable by all teams
Frequently Asked Questions (FAQ)
Q: Which resolution from the ICO is used?
A: The largest available — typically 256x256 PNG-compressed. Multi-resolution structure is not preserved.
Q: Can I make one multi-page DJVU from many ICO files?
A: Yes — each ICO becomes one page, creating a browsable icon catalog.
Q: Is ICO transparency preserved?
A: Icons are composited against a solid background since DJVU does not support transparency.
Q: How well does DJVU compress icon graphics?
A: Extremely well — simple icons compress to 1-3 KB per DJVU page thanks to JB2 compression for sharp edges and uniform colors.
Q: Is DJVU better than PDF for icon catalogs?
A: DJVU produces 3-5x smaller files for icon content. PDF offers broader compatibility.
Q: Can I add labels to icons in the DJVU?
A: Yes — DJVU supports annotation layers for text notes and descriptions.
Q: Can I extract icons back from DJVU?
A: You can extract page images but not multi-resolution ICO containers. Keep originals as sources.
Q: What file sizes to expect?
A: Very compact — 100 icons typically produce a DJVU under 200 KB.