Image MIME Reference
Canon-CRW
Canon Raw Format
image/x-canon-crw
VS
X Pixmap
image/x-xpixmap
XPM
A complete technical comparison of Canon Raw Format and X Pixmap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | Canon-CRW | XPM |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Canon Raw Format
image/x-canon-crw
Extension
.crw
Container
CIFF (Camera Image File Format)
Compression
Lossless JPEG (ITU-T81)
Algorithm
Lossless JPEG
Color Depth
10-bit (Per Channel), 12-bit (Per Channel)
Developed by
Canon Inc.
Released
1998
Magic Bytes
49 49 1A 00 00 00 (Header) / 48 45 41 50 43 43 44 52 (HEAPCCDR signature near end)
X Pixmap
image/x-xpixmap
Extension
.xpm
Container
C Source Code Header (.c / .h)
Compression
Uncompressed (Source Code)
Algorithm
None
Color Depth
Indexed Color (Custom Palette with RGB and Alpha 'None')
Developed by
Daniel Dardailler and Colas Nahaboo (Bull / X Consortium)
Released
1989
Magic Bytes
2F 2A 20 58 50 4D 20 2A 2F (ASCII '/* XPM */')
Browser Support Comparison
| Browser | Canon-CRW | XPM |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ |
✓
|
Canon-CRW
Canon-CRW Strengths
- Preserves original raw sensor data from foundational early digital SLR cameras, allowing for modern noise reduction and demosaicing algorithms to extract better images than software could in 2003
- Files are remarkably small (often 6-8 MB) compared to modern 40MB+ raw files due to the lower megapixel count of early sensors
Limitations
- Completely obsolete and utilizes the idiosyncratic CIFF structure rather than the modern, standardized TIFF/EP structure
- Cannot be natively viewed in web browsers or standard operating system image viewers without specialized codecs
- Less robust metadata support compared to modern CR2 or CR3 formats
XPM
XPM Strengths
- Can be compiled directly into C or C++ source code without requiring an external asset loading mechanism
- Human-readable palette mapping allows developers to inspect, modify, or hand-craft icons directly within a text editor
- Native support for color palettes and transparency via the 'None' keyword
Limitations
- Extremely inefficient storage structure for large images, resulting in massive file bloat compared to binary formats like PNG
- Completely obsolete and unsupported in modern web browsers
- Parsing overhead requires compiling or interpreting text-based color tables at runtime
When to choose which format
Canon-CRW
Use Canon-CRW when…
- Historical Digital Photography (2000-2004)
- Non-destructive Image Post-Processing
- Raw Imaging Archival
XPM
Use XPM when…
- X Window System (X11) Application Icons and Cursors
- Embedded C/C++ Firmware Color UI Assets
- Early Linux Desktop Environment Themes