Image MIME Reference
Canon-CR2
Canon Raw Version 2
image/x-canon-cr2
VS
Portable Graymap
image/x-portable-graymap
PGM
A complete technical comparison of Canon Raw Version 2 and Portable Graymap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | Canon-CR2 | PGM |
|---|---|---|
| Transparency (Alpha) | ✕ No | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
Canon Raw Version 2
image/x-canon-cr2
Extension
.cr2
Container
TIFF
Compression
Lossless JPEG (ITU-T81)
Algorithm
Lossless JPEG (ITU-T81)
Color Depth
12-bit (Per Channel), 14-bit (Per Channel)
Developed by
Canon Inc.
Released
2004
Magic Bytes
49 49 2A 00 10 00 00 00 43 52 02 00
Portable Graymap
image/x-portable-graymap
Extension
.pgm
Container
Netpbm
Compression
Uncompressed
Algorithm
None
Color Depth
8-bit (Grayscale), 16-bit (Grayscale)
Developed by
Jef Poskanzer (Netpbm Project)
Released
1988
Magic Bytes
50 32 (ASCII) or 50 35 (Binary)
Browser Support Comparison
| Browser | Canon-CR2 | PGM |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
Canon-CR2
Canon-CR2 Strengths
- Retains maximum sensor data, allowing extreme recovery of highlights and shadows that would be permanently lost in a JPEG
- White balance and color profiling are not 'baked in', meaning they can be completely altered in post-production without degrading the image
- Lossless compression ensures perfect pixel accuracy while reducing file size compared to fully uncompressed formats
Limitations
- Proprietary format means it requires constant updates to raw processing engines (like Adobe Camera Raw) every time Canon releases a new camera model
- Produces very large file sizes (often 20MB to 40MB per image depending on sensor resolution)
- Cannot be directly embedded into web pages or used in standard HTML/CSS contexts
PGM
PGM Strengths
- Extremely simple format allows custom parsers to be written from scratch in minimal time
- Supports 16-bit precision, making it highly valuable for scientific, medical, and height-map data where 8-bit precision is insufficient
- ASCII encoding ('P2') allows manual editing and visual inspection of pixel values directly within a text editor
Limitations
- Strictly limited to grayscale; cannot display color
- Lack of compression results in massive file sizes, making it entirely impractical for web delivery or consumer storage
- Does not support alpha transparency or modern metadata structures
When to choose which format
Canon-CR2
Use Canon-CR2 when…
- Professional Digital Photography
- Non-destructive Image Post-Processing
- High Dynamic Range (HDR) Imaging Archival
PGM
Use PGM when…
- Computer Vision and Machine Learning Pre-processing
- Scientific and Medical Image Processing
- Unix/Linux Command-Line Image Pipelines