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Image MIME Reference
PJPEG

Progressive JPEG (Legacy IE Alias)

image/pjpeg
VS

Tagged Image File Format (Legacy MIME)

image/x-tiff
TIFF

A complete technical comparison of Progressive JPEG (Legacy IE Alias) and Tagged Image File Format (Legacy MIME) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

PJPEG wins on browser support

Feature Support

Feature PJPEG TIFF
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading Yes ✕ No
HDR Support ✕ No Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
Progressive JPEG (Legacy IE Alias)
image/pjpeg
Extension
.jpeg.jpg.pjpeg.pjp.jfif
Container JPEG (ISO/IEC 10918-1)
Compression Lossy (DCT)
Algorithm
Discrete Cosine Transform (DCT)
Color Depth 8-bit, 12-bit
Developed by Joint Photographic Experts Group / Microsoft (Alias)
Released 1992
Magic Bytes
FF D8 FF E0 (JFIF) / FF D8 FF E1 (Exif)
Full PJPEG reference →
Tagged Image File Format (Legacy MIME)
image/x-tiff
Extension
.tiff.tif
Container IFD (Image File Directory) Tag Structure
Compression Uncompressed / LZW (Lossless) / ZIP / Deflate (Lossless) / PackBits (Lossless RLE) / JPEG (Lossy) / CCITT Group 3/4 (Fax/Document)
Algorithm
NoneLZWDeflatePackBitsJPEGCCITT
Color Depth 1-bit (Monochrome), 8-bit (Grayscale or Indexed), 16-bit (Per Channel), 32-bit (Float Per Channel)
Developed by Aldus Corporation (Later acquired by Adobe Systems)
Released 1986
Magic Bytes
49 49 2A 00 (Little-endian) or 4D 4D 00 2A (Big-endian)
Full TIFF reference →

Browser Support Comparison

Browser PJPEG TIFF
Chrome Chrome
✓ All
 ✕
Firefox Firefox
✓ All
 ✕
Safari Safari
✓ All
 ✕
Edge Edge
✓ All
 ✕
IE IE (Legacy)
✓
 ✕
PJPEG

PJPEG Strengths

  • Progressive JPEGs (which this MIME type attempted to describe) provide excellent perceived loading speeds on slow connections by rendering a low-resolution preview first
  • Files sent with this MIME type are fully backwards compatible with any standard JPEG decoder
Limitations
  • It is a non-standard MIME type that violates IANA specifications
  • Causes strict file upload validation scripts to fail if not explicitly whitelisted or mapped
  • Creates unnecessary confusion, as the official image/jpeg MIME type already fully encompasses progressive encoding
TIFF

TIFF Strengths

  • Universally accepted as the gold standard for high-fidelity archival and professional print workflows
  • Highly adaptable structure supports multiple pages (documents), layers, vast bit depths, and diverse compression algorithms within a single file
  • Unmatched support for rich metadata including EXIF, IPTC, XMP, and custom ICC color profiles
Limitations
  • Produces exceptionally large file sizes compared to modern web formats
  • The 'x-tiff' legacy MIME string forces developers to write extra validation logic to prevent strict security filters from rejecting valid uploads
  • The format's immense complexity means that many lightweight parsers only implement a subset of the specification, sometimes failing to read obscure compressions (like CCITT or old JPEG-in-TIFF)

When to choose which format

PJPEG
Use PJPEG when…
  • Legacy Internet Explorer File Uploads
  • Progressive Image Rendering (Historical context)
TIFF
Use TIFF when…
  • Professional Print and Desktop Publishing
  • High-Resolution Archival Scanning
  • Master Copies of Digital Photography

More comparisons

PJPEG vs ACES → TIFF vs ACES → PJPEG vs APNG → TIFF vs APNG → PJPEG vs AVCI → TIFF vs AVCI → PJPEG vs AVCS → TIFF vs AVCS → PJPEG vs AVIF → TIFF vs AVIF → All comparisons →
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