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File-opening guide

DICOM unsupported transfer syntax: how to open the images

A transfer-syntax error means the viewer cannot handle the way that DICOM file’s data is encoded; it does not by itself prove the scan is damaged. Keep the original and ask for a supported DICOM encoding, such as an uncompressed export, without changing the image resolution.

By the Ossidex team · How we write and check these pages · Updated

Download on the App StoreFree to download · iPhone & iPad · iOS 17+

Encoding, geometry and file damage are different failures

What you haveWhat it means
Transfer-syntax or pixel-decoding errorThe file may use compression or a pixel layout the viewer cannot decode. Record the exact message and syntax UID if available.
Images open in 2D, but MPR failsMay be a geometry issue rather than a decoder failure. Reconstruction requires a suitable spatial series.
File ends early or archive is incompleteA damaged transfer is a separate possibility. Compare the file with the original before converting anything.

How to open the images

  1. Record the exact failure. Note which viewer and version failed, which series was selected and any displayed transfer-syntax UID. Do not identify the encoding from .dcm alone.
  2. Check the published support scope. Compare the actual file with the compatibility page. Browser and native import limits differ; a scanner brand is not an encoding guarantee.
  3. Ask the sender for a supported export. Request the complete image series as standard uncompressed DICOM at the original resolution and bit depth. Keep the original compressed export as well.
  4. Import and compare. Use Files / ZIP or Folder in the iPhone/iPad app, or Open folder in the browser. Check the resulting study and series before removing the original.

What to check if it still does not open

DICOM defines multiple transfer syntaxes, including different JPEG 2000 encodings. The extension alone does not identify which decoder is required. Unzipping an archive removes archive compression, not necessarily compression inside each DICOM file.

The browser can also report that a format or series geometry is unsupported. This is a broader message than a specific codec diagnosis. If re-exporting still fails, send support the exact message and export settings; do not assume a conversion to JPG preserves the source data.

Viewer options and format limits

On a Mac, open the browser viewer and choose Open folder for the complete DICOM folder or Open files for a ZIP. Browser format and memory limits differ from the iPhone/iPad app; a successful import does not establish that the examination is complete.

See the matching format or export guide and tested samples and compatibility limits. Ossidex is a viewer and planning aid, not a diagnostic device.

Frequently asked questions

Does ZIP compression cause this error?

Not necessarily. ZIP is the outer container; DICOM pixels can be compressed separately inside each file. Extracting the ZIP does not change their transfer syntax.

Can I fix it by changing .dcm to .jpg?

No. That changes only the filename. Request a supported DICOM export or use a viewer documented to decode the original encoding.

Sources

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