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Image MIME Reference
DICOM-RLE

DICOM Run-Length Encoding

image/dicom-rle
VS

Apple PICT Image

image/x-pict
PICT

A complete technical comparison of DICOM Run-Length Encoding and Apple PICT Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature DICOM-RLE PICT
Transparency (Alpha) ✕ No Yes
Animation Support Yes ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile Yes ✕ No
DICOM Run-Length Encoding
image/dicom-rle
Extension
.dcm.dicom
Container DICOM (PS3.10)
Compression Lossless (RLE)
Algorithm
Run-Length Encoding (RLE)
Color Depth 8-bit, 16-bit, 24-bit
Developed by National Electrical Manufacturers Association (NEMA) / ACR
Released 1993
Magic Bytes
44 49 43 4D (at byte offset 128)
Full DICOM-RLE reference →
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)
Full PICT reference →

Browser Support Comparison

Browser DICOM-RLE PICT
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
DICOM-RLE

DICOM-RLE Strengths

  • Guarantees lossless preservation of critical medical data necessary for diagnostics
  • Extremely robust metadata structure containing patient information, modality, and spatial geometry
  • Faster to encode and decode than complex compression schemes like JPEG 2000
Limitations
  • RLE compression offers very low compression ratios compared to modern codecs like JPEG-LS or JPEG 2000
  • Zero support in web browsers or standard consumer image viewers
  • Strict data privacy regulations (HIPAA/GDPR) make handling DICOM files complex due to embedded PHI
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

DICOM-RLE
Use DICOM-RLE when…
  • Medical Imaging
  • Ultrasound
  • X-Rays / CT / MRI
  • PACS Archives
PICT
Use PICT when…
  • Classic Mac OS Clipboard Data
  • Legacy Macintosh Desktop Publishing (Aldus PageMaker, QuarkXPress)
  • 1980s/1990s Digital Clip Art

More comparisons

DICOM-RLE vs ACES → PICT vs ACES → DICOM-RLE vs APNG → PICT vs APNG → DICOM-RLE vs AVCI → PICT vs AVCI → DICOM-RLE vs AVCS → PICT vs AVCS → DICOM-RLE vs AVIF → PICT vs AVIF → All comparisons →
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