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Image MIME Reference
DjVu

DjVu Document

image/vnd.djvu
VS

Portable Network Graphics (Legacy MIME)

image/x-png
PNG

A complete technical comparison of DjVu Document and Portable Network Graphics (Legacy MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

PNG wins on browser support

Feature Support

Feature DjVu PNG
Transparency (Alpha) Yes Yes
Animation Support ✕ No ✕ No
Progressive Loading Yes Yes
HDR Support ✕ No Yes
EXIF Metadata ✕ No Yes
ICC Color Profile ✕ No Yes
DjVu Document
image/vnd.djvu
Extension
.djvu.djv
Container Interchange File Format (IFF)
Compression JB2 (Bi-tonal Text) / IW44 (Wavelet Background) / BZZ (General Data/Text)
Algorithm
JB2IW44BZZ
Color Depth 1-bit (Foreground Text), 24-bit (Background)
Developed by AT&T Labs (Yann LeCun, Léon Bottou, Patrick Haffner, Paul G. Howard)
Released 1996
Magic Bytes
41 54 26 54 46 4F 52 4D
Full DjVu reference →
Portable Network Graphics (Legacy MIME)
image/x-png
Extension
.png
Container PNG Chunk Structure (IHDR, IDAT, IEND)
Compression Deflate (Lossless)
Algorithm
Deflate (LZ77)
Color Depth 1-bit to 16-bit (Grayscale), 8-bit (Indexed Palette), 24-bit (True Color), 32-bit (True Color with Alpha), 48-bit (High Color), 64-bit (High Color with Alpha)
Developed by PNG Development Group
Released 1996
Magic Bytes
89 50 4E 47 0D 0A 1A 0A
Full PNG reference →

Browser Support Comparison

Browser DjVu PNG
Chrome Chrome
✕
✓ 1
Firefox Firefox
✕
✓ 1
Safari Safari
✕
✓ 1
Edge Edge
✕
✓ 12
IE IE (Legacy)
✕
✓
DjVu

DjVu Strengths

  • Unmatched compression ratios for high-resolution scanned documents (often 5 to 10 times smaller than equivalent JPEG/TIFF-based PDFs)
  • Separates text layers cleanly from backgrounds, allowing for highly legible text even at low file sizes
  • Embedded OCR (Optical Character Recognition) text layers allow for fast searching
Limitations
  • Lacks native support in modern operating systems and web browsers, requiring third-party software
  • Largely superseded by PDF/A and modern PDF compression standards in standard corporate workflows
  • Not suitable for vector graphics or born-digital documents (like Word exports), where standard PDF is far superior
PNG

PNG Strengths

  • The underlying format provides flawless, lossless compression and perfect 8-bit alpha channel transparency
  • Universally supported by every modern operating system, image editor, and web browser
Limitations
  • The 'image/x-png' string is an obsolete vendor quirk that forces backend developers to write redundant normalization logic in file upload scripts
  • If left unnormalized, strict MIME validators or content security policies on modern systems may incorrectly reject valid PNG files

When to choose which format

DjVu
Use DjVu when…
  • Scanned Books and Manuals
  • Digital Libraries (e.g., Internet Archive)
  • Historical Document Archiving
PNG
Use PNG when…
  • Legacy Internet Explorer File Uploads
  • Older ASP/PHP Web Applications
  • Lossless Web Graphics

More comparisons

DjVu vs ACES → PNG vs ACES → DjVu vs APNG → PNG vs APNG → DjVu vs AVCI → PNG vs AVCI → DjVu vs AVCS → PNG vs AVCS → DjVu vs AVIF → PNG vs AVIF → All comparisons →
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