Image MIME Reference
JPEG-2000
JPEG 2000 Core Image File
image/jp2
VS
RealNetworks RealPix
image/vnd.rn-realpix
RealPix
A complete technical comparison of JPEG 2000 Core Image File and RealNetworks RealPix — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
JPEG-2000 wins on browser support
Feature Support
| Feature | JPEG-2000 | RealPix |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | Yes | Yes |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
JPEG 2000 Core Image File
image/jp2
Extension
.jp2.j2k.jpf.jpx.jpm
Container
JP2 (ISO/IEC 15444-1)
Compression
Lossy / Lossless
Algorithm
Discrete Wavelet Transform (DWT)
Color Depth
8-bit, 16-bit, 32-bit, 38-bit
Developed by
Joint Photographic Experts Group
Released
2000
Magic Bytes
00 00 00 0C 6A 50 20 20 0D 0A 87 0A
RealNetworks RealPix
image/vnd.rn-realpix
Extension
.rp
Container
IMFL (XML Markup)
Compression
Uncompressed (Plain Text Markup)
Algorithm
None (Plain Text)
Color Depth
Dependent on referenced images
Developed by
RealNetworks
Released
1998
Magic Bytes
3C 69 6D 66 6C
Browser Support Comparison
| Browser | JPEG-2000 | RealPix |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✓ 5+
|
✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
JPEG-2000
JPEG-2000 Strengths
- Superior compression efficiency over baseline JPEG without introducing blocking artifacts
- True mathematically lossless compression available in the same format
- Extremely scalable: a single file can be decoded at various resolutions (thumbnails to full size) without loading the entire file
Limitations
- Very poor native web browser support prevents it from being a web standard
- High computational complexity makes encoding and decoding significantly slower than JPEG
- Early patent concerns and complex licensing hindered its initial adoption rate
RealPix
RealPix Strengths
- Allowed for 'Ken Burns'-style animated slideshows at a fraction of the bandwidth required for actual video, crucial for 1990s dial-up connections
- Plain text XML architecture made it easy for developers and hobbyists to hand-code complex multimedia presentations
- Perfectly synchronized with RealAudio streams using SMIL-like timing parameters
Limitations
- Completely obsolete and heavily reliant on the proprietary, defunct RealPlayer browser plugin
- Not a true image format, causing confusion when handled by standard image processing libraries which expect binary pixel data
- Lacks modern CSS or HTML5 canvas equivalents without completely rewriting the presentation logic
When to choose which format
JPEG-2000
Use JPEG-2000 when…
- Digital Cinema (DCP)
- Medical Imaging (DICOM)
- Geospatial Data
- Archival Preservation
RealPix
Use RealPix when…
- Historical Dial-up Streaming Presentations
- RealPlayer Slideshows
- Bandwidth-efficient 'Video' Alternatives (late 1990s)