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How to open .DRLE files on Mac

To open .DRLE files on Mac, if the file came from a DICOM workflow, treat .DRLE as DICOM RLE content rather than a standard image.

Step-by-step instructions

  1. If the file came from a DICOM workflow, treat .DRLE as DICOM RLE content rather than a standard image.
  2. Open it using DICOM-capable tooling; if your DICOM viewer does not support this transfer syntax, transcode it within a DICOM toolchain to a supported DICOM transfer syntax and then open the output.

Alternative methods

  • Open .DRLE in a browser-based viewer if desktop apps fail.
  • Try opening .DRLE on Mac with a secondary app to rule out app-specific issues.
  • Convert .DRLE only with trusted tools when direct opening is not possible.

Common issues

The file opens as “unknown format” or won’t preview

Many general image viewers do not support DICOM or the DICOM RLE Lossless transfer syntax, so the OS may not know what app to use.

  1. Open it with DICOM-capable tooling rather than a photo viewer.
  2. If your DICOM viewer does not support RLE transfer syntax, transcode within a DICOM toolchain to another DICOM transfer syntax your viewer supports, then try again.

Confusion about MIME type (image/dicom-rle vs image/dicom+rle)

Different ecosystems may label DICOM RLE differently; some mappings use "image/dicom-rle", while DICOM documentation references a media type parameter using "+rle".

  1. If you are integrating with a loader or pipeline, follow the mapping expected by that software (for example, an explicit mapping of .drle to a DICOM-RLE media type).
  2. When exchanging files, prioritize DICOM transfer syntax compatibility over the filename extension or MIME label.

Viewer opens the file but image looks wrong or fails to decode

This can happen when a tool does not fully implement the RLE encapsulation rules or expects a different transfer syntax.

  1. Verify the content is actually DICOM RLE Lossless (Transfer Syntax UID 1.2.840.10008.1.2.5) in your DICOM toolchain.
  2. Transcode the dataset to a more broadly supported DICOM transfer syntax and retry in the viewer.

Security note

.DRLE should be treated as DICOM-related content; DICOM decoders are complex, so only open files from trusted medical systems or known sources to reduce the risk of parser vulnerabilities.

Back to .DRLE extension page