DICOM preview support

[User-3090]

QuickLook currently does not support DICOM files. Adding basic preview support for medical images would be useful for users working with radiology and clinical datasets.

Technical notes:

• DICOM is a container format (ISO 12052) that wraps pixel data plus metadata.

• Common transfer syntaxes / encodings used in practice:

  • Uncompressed: Implicit VR Little Endian, Explicit VR Little Endian
  • JPEG Baseline (lossy, 8-bit)
  • JPEG Extended
  • JPEG Lossless
  • JPEG-LS (lossy and lossless)
  • JPEG 2000 (lossy and lossless)

• Pixel data may be monochrome (MONOCHROME1/2) or RGB.

• Window level (VOI LUT) handling is required for grayscale images to render correctly.

• Multi-frame DICOMs exist; a reasonable first step could be previewing the first frame only.

Implementation approach:

• Use an existing DICOM parsing library (e.g. DCMTK, GDCM, or fo-dicom) to read metadata and extract pixel data.
• Decode JPEG/JPEG 2000 using existing decoders (libjpeg, libjpeg-turbo, OpenJPEG).
• Render a single frame to a bitmap for preview; ignore advanced features initially (overlays, annotations, multi-series).
• No need for full diagnostic accuracy; preview-only rendering is sufficient.

Scope could be limited to:

• Single-image DICOM files
• JPEG / JPEG 2000 / uncompressed transfer syntaxes
• First-frame preview only

[emako]

Is this what you want?

https://github.com/termijn/dicom-viewer

[User-3090]

No, just a preview for the most common format. Not a full viewer.

[emako]

Try latest preview version in https://github.com/QL-Win/QuickLook/releases/tag/latest

And is this the preview you want?

P.S. This is not a permanent support and will be adjusted to the plugin later.

[emako]

Test files from https://github.com/suyashkumar/dicom/tree/main/testdata