Image MIME Reference
Generic-RAW
Digital Camera Raw (Generic Linux MIME)
image/x-dcraw
VS
High Efficiency Image File Format
image/heif
HEIF
A complete technical comparison of Digital Camera Raw (Generic Linux MIME) and High Efficiency Image File Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | Generic-RAW | HEIF |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | Yes |
| ICC Color Profile | Yes | Yes |
Digital Camera Raw (Generic Linux MIME)
image/x-dcraw
Extension
.raw
Container
Varies (Predominantly TIFF/EP)
Compression
Lossless / Uncompressed
Algorithm
Varies (Often Lossless JPEG ITU-T81 or uncompressed)
Color Depth
12-bit, 14-bit, 16-bit
Developed by
freedesktop.org (MIME mapping) / Dave Coffin (dcraw tool)
Released
1997
Magic Bytes
Varies by vendor format
High Efficiency Image File Format
image/heif
Extension
.heif.hif
Container
HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression
Lossy / Lossless
Algorithm
Codec Agnostic (HEVC, AVC, JPEG, AV1)
Color Depth
8-bit, 10-bit, 12-bit, 16-bit
Developed by
Moving Picture Experts Group (MPEG)
Released
2015
Magic Bytes
XX XX XX XX 66 74 79 70 6D 69 66 31
Browser Support Comparison
| Browser | Generic-RAW | HEIF |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
Generic-RAW
Generic-RAW Strengths
- Provides a unified, highly useful catch-all MIME type for application developers who just need to know if a file is a raw image, rather than tracking 50+ individual camera extensions
- Deeply integrated into the Linux desktop ecosystem, ensuring file manager thumbnails work seamlessly via tools like ufraw-thumbnailer
Limitations
- Not an official IANA standard
- Can cause conflicts where standard TIFF files are misidentified as raw camera data by over-aggressive MIME sniffers
- The underlying 'dcraw' tool was abandoned by its creator in 2018 (though its successor, LibRaw, continues to maintain the ecosystem)
HEIF
HEIF Strengths
- Highly flexible container that can store image bursts, animations, focal stacks, and stereo 3D images in one file
- Natively supports depth maps and alpha channels, making it perfect for computational photography
- When paired with modern codecs like HEVC or AV1, it provides massive storage savings over legacy formats like JPEG
Limitations
- Codec agnosticism makes broad software decoding difficult, as the container might hold proprietary or unsupported codecs
- Zero cross-platform web browser support, requiring conversion for online publishing
- Often confused with the more specific 'image/heic' and 'image/avif' MIME types
When to choose which format
Generic-RAW
Use Generic-RAW when…
- Linux Desktop File Associations (GNOME/KDE)
- Thumbnail Generation for Raw Images (UFRaw/LibRaw)
- Server-side Image Processing Fallbacks
HEIF
Use HEIF when…
- Digital Photography
- Camera Capture
- Image Archiving
- Multi-image composites