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Image MIME Reference
JPEG-XS-(HEIF)

JPEG XS Image (HEIF Container)

image/jxsi
VS

MacPaint Image

image/x-macpaint
MacPaint

A complete technical comparison of JPEG XS Image (HEIF Container) and MacPaint Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature JPEG-XS-(HEIF) MacPaint
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
JPEG XS Image (HEIF Container)
image/jxsi
Extension
.jxsi.jxs.hif
Container HEIF / ISOBMFF (ISO/IEC 23008-12)
Compression Lossy (Visually Lossless) / Mathematically Lossless
Algorithm
JPEG XS (ISO/IEC 21122-1)
Color Depth 8-bit, 10-bit, 12-bit, 14-bit, 16-bit
Developed by Joint Photographic Experts Group (JPEG)
Released 2019
Magic Bytes
XX XX XX XX 66 74 79 70 6A 78 73 69
Full JPEG-XS-(HEIF) reference →
MacPaint Image
image/x-macpaint
Extension
.mac.pntg.pnt.macp
Container Raw pixel payload with a 512-byte pattern header
Compression PackBits (Run-Length Encoding)
Algorithm
PackBits (Apple RLE)
Color Depth 1-bit (Monochrome)
Developed by Apple Computer, Inc. (Bill Atkinson)
Released 1984
Magic Bytes
None (Relies on classic Mac OS 'PNTG' OSType)
Full MacPaint reference →

Browser Support Comparison

Browser JPEG-XS-(HEIF) MacPaint
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
JPEG-XS-(HEIF)

JPEG-XS-(HEIF) Strengths

  • Provides sub-millisecond encoding and decoding latency while retaining visually lossless quality
  • Brings the extensive metadata, EXIF, XMP, and color-profiling capabilities of the HEIF container to JPEG XS
  • Allows grouping of multiple high-quality JPEG XS frames into a single collection file
Limitations
  • Zero web browser compatibility, limiting it entirely to professional and industrial hardware workflows
  • Extremely niche adoption compared to standard HEVC-based HEIC or raw JPEG XS codestreams
  • Requires custom parsing logic to extract the JPEG XS codestream from the HEIF boxes
MacPaint

MacPaint Strengths

  • Profoundly historically significant as the format that introduced millions to the concept of bitmap digital painting
  • Extremely simple PackBits compression makes it easy for emulator developers or archivists to write parsers from scratch in under an hour
Limitations
  • Severely limited: strictly black and white, and hard-locked to exactly 576 x 720 pixels
  • Lack of standard magic bytes makes programmatic file sniffing unreliable on modern filesystems without relying on the file extension
  • Completely obsolete and unsupported by modern web browsers or consumer image viewers

When to choose which format

JPEG-XS-(HEIF)
Use JPEG-XS-(HEIF) when…
  • Live Broadcast Infrastructure
  • Medical Imaging & Archival
  • Video over IP Networks
  • Automotive & Drone Systems
MacPaint
Use MacPaint when…
  • Historical Apple Macintosh Archival
  • Early 1980s Digital Art Preservation
  • Retro UI/UX Academic Research

More comparisons

JPEG-XS-(HEIF) vs ACES → MacPaint vs ACES → JPEG-XS-(HEIF) vs APNG → MacPaint vs APNG → JPEG-XS-(HEIF) vs AVCI → MacPaint vs AVCI → JPEG-XS-(HEIF) vs AVCS → MacPaint vs AVCS → JPEG-XS-(HEIF) vs AVIF → MacPaint vs AVIF → All comparisons →
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