DICOM-RLE

DICOM Run-Length Encoding

image/dicom-rle Released 1993 · by National Electrical Manufacturers Association (NEMA) / ACR

DICOM RLE is a specific transfer syntax within the Digital Imaging and Communications in Medicine (DICOM) standard. It utilizes Run-Length Encoding (RLE) for lossless image compression, commonly used for transmitting and archiving medical imaging data such as ultrasounds, X-rays, and MRIs while perfectly preserving diagnostic quality.

Medical & Scientific Animation ✦ HDR Production Ready

Technical Specifications

MIME Type

image/dicom-rle

Extensions

.dcm.dicom

Container

DICOM (PS3.10)

Compression

Lossless (RLE)

Algorithms

Run-Length Encoding (RLE)

Color Depth

8-bit, 16-bit, 24-bit

Metadata

ICC

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: application/dicom

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

44 49 43 4D (at byte offset 128)

ASCII: DICM

HTTP Headers

Content-Type: image/dicom-rle

HTML Accept Attribute

accept="image/dicom-rle, .dcm"

Browser Support Matrix

Browser	Status	Min Version
Chrome	Not Supported	—
Firefox	Not Supported	—
Safari	Not Supported	—
Edge	Not Supported	—
Internet Explorer	Not Supported	Legacy

Advantages & Limitations

Advantages

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

Developer Code Snippets

import pydicom
# pydicom handles standard .dcm files
ds = pydicom.dcmread('scan.dcm')
if ds.file_meta.TransferSyntaxUID == '1.2.840.10008.1.2.5':
    print('DICOM RLE Lossless')

const dicomParser = require('dicom-parser');
// Requires reading the file into a Uint8Array and parsing the dataset to check the Transfer Syntax UID

// Custom parsing required to skip 128 bytes and read the 'DICM' string.

$mime = mime_content_type('scan.dcm');
echo $mime; // Standard servers usually return 'application/dicom' rather than 'image/dicom-rle'

File Detection Steps

How to programmatically detect a image/dicom-rle file by reading its raw bytes:

1 Skip the first 128 bytes (preamble)
2 Check bytes 128-131 for 'DICM'
3 Parse the DICOM header tags to verify the Transfer Syntax UID is 1.2.840.10008.1.2.5 (RLE Lossless)

Software Support

O

OsiriX

H

Horos

R

RadiAnt DICOM Viewer

3

3D Slicer

ImageMagick

Conversion Tools

Share & Embed

Markdown Badge

[![DICOM-RLE Format](https://freewebptojpg.com/mime/image/dicom-rle/badge.svg)](https://freewebptojpg.com/mime/image/dicom-rle)

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/dicom-rle/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="DICOM-RLE Specs"></iframe>

JSON API

All data on this page is available as a free, open JSON API. Use it in your project, documentation, or tooling.

GET https://freewebptojpg.com/mime/image/dicom-rle.json Open JSON

Free to use

No auth required

CORS enabled

Use from any domain

Cached 24h

Cache-Control headers set

Frequently Asked Questions

What is the magic byte for DICOM files?

All standard DICOM Part 10 files have a 128-byte preamble followed by the 4-byte ASCII signature 'DICM' (hex: 44 49 43 4D) at offset 128.

How is image/dicom-rle different from standard DICOM?

The DICOM standard supports multiple image compression algorithms (Transfer Syntaxes). The image/dicom-rle MIME type specifically denotes a DICOM file where the pixel data is compressed using the lossless Run-Length Encoding (RLE) method (Transfer Syntax UID 1.2.840.10008.1.2.5).

Can web browsers display DICOM images?

No native web browser supports rendering DICOM files directly. Developers must use JavaScript libraries like Cornerstone.js to parse the DICOM metadata and render the RLE-compressed pixel data onto an HTML5 canvas.