Free webp to jpg
EN
Image MIME Reference
JPX

JPEG 2000 Part 2 (Extended)

image/jpx
VS

Portable Network Graphics (Legacy MIME)

image/x-png
PNG

A complete technical comparison of JPEG 2000 Part 2 (Extended) 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 JPX PNG
Transparency (Alpha) Yes Yes
Animation Support Yes ✕ No
Progressive Loading Yes Yes
HDR Support Yes Yes
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
JPEG 2000 Part 2 (Extended)
image/jpx
Extension
.jpx.jpf
Container ISOBMFF / JPX (ISO/IEC 15444-2)
Compression Lossy / Lossless
Algorithm
Discrete Wavelet Transform (DWT)
Color Depth 8-bit, 16-bit, 32-bit, 38-bit
Developed by Joint Photographic Experts Group (JPEG)
Released 2002
Magic Bytes
00 00 00 0C 6A 50 20 20 0D 0A 87 0A ... 66 74 79 70 6A 70 78 20
Full JPX 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 JPX PNG
Chrome Chrome
✕
✓ 1
Firefox Firefox
✕
✓ 1
Safari Safari
✕
✓ 1
Edge Edge
✕
✓ 12
IE IE (Legacy)
✕
✓
JPX

JPX Strengths

  • Removes the color space limitations of baseline JP2, adding native support for CMYK, CIE Lab, and custom vendor color spaces
  • Supports multiple codestreams in a single file, allowing for rich compositing and animation
  • Enables fragmented files where image data and metadata can reside in separate physical files via data references
Limitations
  • Extremely complex specification makes full software implementation rare, leading to compatibility issues
  • Zero web browser support, rendering it unsuitable for public internet distribution
  • Often overkill for standard imaging tasks where baseline JP2 or modern alternatives like AVIF suffice
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

JPX
Use JPX when…
  • Prepress & Commercial Printing (CMYK)
  • Geospatial Data
  • Archival Preservation
  • Medical Imaging
PNG
Use PNG when…
  • Legacy Internet Explorer File Uploads
  • Older ASP/PHP Web Applications
  • Lossless Web Graphics

More comparisons

JPX vs ACES → PNG vs ACES → JPX vs APNG → PNG vs APNG → JPX vs AVCI → PNG vs AVCI → JPX vs AVCS → PNG vs AVCS → JPX vs AVIF → PNG vs AVIF → All comparisons →
Share this comparison