Image MIME Reference
AVCS
AVC Image Sequence (HEIF Container)
image/avcs
VS
Minolta Raw Image
image/x-minolta-mrw
Minolta-MRW
A complete technical comparison of AVC Image Sequence (HEIF Container) and Minolta Raw Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | AVCS | Minolta-MRW |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | Yes | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | Yes |
| ICC Color Profile | Yes | Yes |
AVC Image Sequence (HEIF Container)
image/avcs
Extension
.avcs.heifs
Container
HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression
Lossy / Lossless
Algorithm
AVC (Advanced Video Coding / H.264)
Color Depth
8-bit, 10-bit, 12-bit
Developed by
Moving Picture Experts Group (MPEG) / ISO/IEC JTC 1
Released
2015
Magic Bytes
XX XX XX XX 66 74 79 70 61 76 63 73
Minolta Raw Image
image/x-minolta-mrw
Extension
.mrw
Container
Proprietary MRW Container
Compression
Uncompressed / Proprietary Lossless
Algorithm
NoneProprietary Lossless
Color Depth
12-bit (Per Channel)
Developed by
Minolta (later Konica Minolta)
Released
2001
Magic Bytes
00 4D 52 4D
Browser Support Comparison
| Browser | AVCS | Minolta-MRW |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
AVCS
AVCS Strengths
- Efficiently stores bursts of images or animations utilizing inter-frame compression
- Leverages the highly compatible and widely hardware-accelerated AVC (H.264) codec
- Robust HEIF container supports extensive metadata, alpha channels, and depth maps
Limitations
- Zero native support in web browsers
- Largely superseded in efficiency by newer sequence formats like HEICS (HEVC) or Animated AVIF (AV1)
- Complicated container structure requires specialized parsing libraries
Minolta-MRW
Minolta-MRW Strengths
- Retains full, unadulterated sensor data from early CCD digital cameras, allowing modern demosaicing algorithms to extract far superior image quality than what was possible when the cameras were released
- Possesses a very distinct, unambiguous magic header (\x00MRM), making programmatic identification completely foolproof
Limitations
- Completely obsolete proprietary format that has not seen a new camera release since 2006
- Cannot be natively viewed in web browsers or standard operating system image viewers without specialized decoders
- Relies entirely on open-source reverse engineering (like LibRaw) for continued modern software compatibility
When to choose which format
AVCS
Use AVCS when…
- Burst Photography
- Short Animations
- Camera Capture
- Archival Storage
Minolta-MRW
Use Minolta-MRW when…
- Vintage Digital Photography (Konica Minolta DiMAGE / Maxxum)
- Raw Imaging Archival
- Historical Camera Sensor Research