Image MIME Reference
Canon-CRW
Canon Raw Format
image/x-canon-crw
VS
High Efficiency Image Container
image/heic
HEIC
A complete technical comparison of Canon Raw Format and High Efficiency Image Container — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
HEIC wins on browser support
Feature Support
| Feature | Canon-CRW | HEIC |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | Yes |
| ICC Color Profile | ✕ No | Yes |
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)
High Efficiency Image Container
image/heic
Extension
.heic
Container
HEIF / ISOBMFF
Compression
Lossy / Lossless
Algorithm
HEVC (H.265)
Color Depth
8-bit, 10-bit, 12-bit, 16-bit
Developed by
MPEG (Standard) / Apple (Adoption)
Released
2017
Magic Bytes
XX XX XX XX 66 74 79 70 68 65 69 63
Browser Support Comparison
| Browser | Canon-CRW | HEIC |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ |
✓ 11+
|
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
HEIC
HEIC Strengths
- Exceptional compression efficiency — stores images at roughly half the file size of JPEG with equal or better visual quality
- Natively supports modern photography features like depth maps, 16-bit color, HDR, and alpha channel transparency
- Can store image bursts, focal stacks, and animations (Live Photos) within a single file
Limitations
- Heavily encumbered by software patents, leading to very poor adoption outside the Apple ecosystem
- Not supported by standard web browsers (except Safari), requiring server-side or client-side conversion for web delivery
- Windows requires downloading a separate (often paid) extension from the Microsoft Store to view natively
When to choose which format
Canon-CRW
Use Canon-CRW when…
- Historical Digital Photography (2000-2004)
- Non-destructive Image Post-Processing
- Raw Imaging Archival
HEIC
Use HEIC when…
- iOS / iPhone Photography
- macOS Ecosystem
- High-Quality Image Archiving