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Image MIME Reference
HEIF

High Efficiency Image File Format

image/heif
VS

JPEG Network Graphics

image/x-jng
JNG

A complete technical comparison of High Efficiency Image File Format and JPEG Network Graphics — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature HEIF JNG
Transparency (Alpha) Yes Yes
Animation Support Yes ✕ No
Progressive Loading ✕ No Yes
HDR Support Yes ✕ No
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
High Efficiency Image File Format
image/heif
Extension
.heif.hif
Container HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression Lossy / Lossless
Algorithm
Codec Agnostic (HEVC, AVC, JPEG, AV1)
Color Depth 8-bit, 10-bit, 12-bit, 16-bit
Developed by Moving Picture Experts Group (MPEG)
Released 2015
Magic Bytes
XX XX XX XX 66 74 79 70 6D 69 66 31
Full HEIF reference →
JPEG Network Graphics
image/x-jng
Extension
.jng
Container PNG-style Chunk Structure (JHDR, JDAT, IDAT, IEND)
Compression Lossy (JPEG/DCT for color) / Lossless (Deflate for alpha mask)
Algorithm
JPEG (Discrete Cosine Transform)Deflate (LZ77)
Color Depth 8-bit, 12-bit, 24-bit (RGB), 32-bit (RGBA)
Developed by MNG Development Group (Glenn Randers-Pehrson et al.)
Released 2001
Magic Bytes
8B 4A 4E 47 0D 0A 1A 0A
Full JNG reference →

Browser Support Comparison

Browser HEIF JNG
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
HEIF

HEIF Strengths

  • Highly flexible container that can store image bursts, animations, focal stacks, and stereo 3D images in one file
  • Natively supports depth maps and alpha channels, making it perfect for computational photography
  • When paired with modern codecs like HEVC or AV1, it provides massive storage savings over legacy formats like JPEG
Limitations
  • Codec agnosticism makes broad software decoding difficult, as the container might hold proprietary or unsupported codecs
  • Zero cross-platform web browser support, requiring conversion for online publishing
  • Often confused with the more specific 'image/heic' and 'image/avif' MIME types
JNG

JNG Strengths

  • Solved a massive technical hurdle in the early 2000s by combining high-compression lossy photographic data with crisp, 8-bit alpha transparency
  • Utilized the highly robust, extensible chunk-based architecture of the PNG format
  • Provided an excellent, bandwidth-saving alternative to massive 32-bit transparent PNGs for web design
Limitations
  • Failed to achieve critical mass; browser vendors largely abandoned the MNG/JNG standard due to implementation complexity
  • Completely obsolete today, having been superseded by natively supported, superior formats like WebP, AVIF, and HEIC
  • Decoding requires a hybrid engine that can parse PNG chunks while simultaneously decoding a JPEG stream and a Deflate stream, complicating software support

When to choose which format

HEIF
Use HEIF when…
  • Digital Photography
  • Camera Capture
  • Image Archiving
  • Multi-image composites
JNG
Use JNG when…
  • Embedded frames in MNG animations
  • Historical web graphics requiring lossy compression with transparency

More comparisons

HEIF vs ACES → JNG vs ACES → HEIF vs APNG → JNG vs APNG → HEIF vs AVCI → JNG vs AVCI → HEIF vs AVCS → JNG vs AVCS → HEIF vs AVIF → JNG vs AVIF → All comparisons →
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