Image MIME Reference
HEIF-Sequence
High Efficiency Image File Format Sequence
image/heif-sequence
VS
Apple PICT Image
image/x-pict
PICT
A complete technical comparison of High Efficiency Image File Format Sequence and Apple PICT Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | HEIF-Sequence | PICT |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | Yes | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
High Efficiency Image File Format Sequence
image/heif-sequence
Extension
.heifs.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 73 66 31
Apple PICT Image
image/x-pict
Extension
.pict.pct.pic
Container
QuickDraw Metafile
Compression
Uncompressed / Run-Length Encoding (RLE) / QuickTime Compressors (JPEG, SMC)
Algorithm
Apple PackBits (RLE)QuickTime Image Compression Manager (ICM)
Color Depth
1-bit, 2-bit, 4-bit, 8-bit (Indexed), 16-bit (High Color), 24-bit (True Color), 32-bit (RGBA)
Developed by
Apple Computer, Inc.
Released
1984
Magic Bytes
None (Requires offset parsing, e.g., 00 11 02 FF at byte 522)
Browser Support Comparison
| Browser | HEIF-Sequence | PICT |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
HEIF-Sequence
HEIF-Sequence Strengths
- Codec-agnostic container allows for extreme flexibility when storing multi-frame photographic data
- Maintains the space-saving benefits of ISOBMFF shared frame data blocks
- Excellent for archiving computational photography workloads like exposure brackets or focal stacks
Limitations
- Codec ambiguity means a decoder might be able to parse the container but fail to decode the underlying pixels
- Zero native web browser support
- Complex container structure requires specialized parsing libraries to extract individual frames
PICT
PICT Strengths
- Incredibly versatile for its time, allowing a single file to cleanly scale text and vector shapes while simultaneously housing raster photos
- Served as the flawless universal clipboard format for the classic Mac OS, enabling seamless copy/pasting between wildly different applications
Limitations
- Deeply tied to Apple's legacy QuickDraw graphics architecture, making it exceptionally difficult to write accurate third-party parsers on modern operating systems
- Lack of a standard magic header makes file detection unreliable without seeking 522 bytes deep into the file
- Completely unsupported in modern web environments and discontinued by Apple itself
When to choose which format
HEIF-Sequence
Use HEIF-Sequence when…
- Burst Photography
- Focal Stacking
- Exposure Bracketing
- Time-Lapse Data
PICT
Use PICT when…
- Classic Mac OS Clipboard Data
- Legacy Macintosh Desktop Publishing (Aldus PageMaker, QuarkXPress)
- 1980s/1990s Digital Clip Art