Image MIME Reference
BMP
Windows Bitmap (Legacy Windows MIME Alias)
image/x-windows-bmp
VS
JPEG-LS
image/jls
JPEG-LS
A complete technical comparison of Windows Bitmap (Legacy Windows MIME Alias) and JPEG-LS — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
BMP wins on browser support
Feature Support
| Feature | BMP | JPEG-LS |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | Yes | ✕ No |
Windows Bitmap (Legacy Windows MIME Alias)
image/x-windows-bmp
Extension
.bmp.dib
Container
DIB (Device-Independent Bitmap)
Compression
Uncompressed / Run-Length Encoding (RLE)
Algorithm
NoneRLE4RLE8
Color Depth
1-bit (Monochrome), 4-bit (16 colors), 8-bit (256 colors), 16-bit (High Color), 24-bit (True Color), 32-bit (True Color with Alpha)
Developed by
Microsoft Corporation
Released
1985
Magic Bytes
42 4D
JPEG-LS
image/jls
Extension
.jls.jl
Container
JPEG Bitstream
Compression
Lossless / Near-Lossless (Predictive Coding)
Algorithm
LOCO-I (Low Complexity Lossless Compression for Images)Golomb-Rice Coding
Color Depth
8-bit, 12-bit, 16-bit (Per Channel)
Developed by
Joint Photographic Experts Group (ISO/ITU-T) & HP Labs
Released
1999
Magic Bytes
FF D8 FF F7
Browser Support Comparison
| Browser | BMP | JPEG-LS |
|---|---|---|
Chrome
|
✓ 1
|
✕ |
Firefox
|
✓ 1
|
✕ |
Safari
|
✓ 1
|
✕ |
Edge
|
✓ 12
|
✕ |
IE (Legacy)
|
✓
|
✕ |
BMP
BMP Strengths
- Universally supported by all major operating systems and modern web browsers
- Maintains perfect, lossless fidelity because pixel data is stored without lossy compression artifacts
Limitations
- Massive file size overhead due to a lack of modern compression algorithms
- Legacy MIME strings like 'image/x-windows-bmp' can trigger validation warnings in strict security or API environments if unhandled
JPEG-LS
JPEG-LS Strengths
- Provides state-of-the-art lossless compression ratios for continuous-tone images, often outperforming Lossless JPEG and JPEG 2000
- Extremely fast and computationally inexpensive to encode/decode, requiring no complex floating-point math or DCTs
- Highly resilient in constrained hardware environments, making it ideal for medical equipment and deep-space probes (e.g., Mars rovers)
Limitations
- Zero native support in web browsers or standard consumer operating systems
- Lacks the advanced resolution scalability and progressive decoding features found in JPEG 2000
- Primarily relegated to niche enterprise sectors (healthcare/DICOM and aerospace) rather than consumer adoption
When to choose which format
BMP
Use BMP when…
- Legacy Windows Desktop Registry Associations
- Older Enterprise Intranet Applications
- Windows Graphics Archival
JPEG-LS
Use JPEG-LS when…
- Medical Imaging (DICOM Encapsulation)
- Space and Planetary Imaging (NASA/ESA)
- Industrial Machine Vision
- Scientific Archival Storage