Technology
How Ossidex reads and renders DICOM on iPhone and iPad
Ossidex parses DICOM and NIfTI files, decodes compressed pixel data (JPEG 2000, HTJ2K, JPEG Lossless, JPEG-LS, RLE) and rebuilds each series into a calibrated volume on the device. Slices, MPR planes, the dental panorama and 3D are rendered on the GPU with Apple’s Metal. Nothing is sent to a server.
rtAttenPenn · Zenodo 3873446 · CC BY 4.0Import: finding studies in anything
Real-world scans arrive in messy containers: disc folders with a Windows viewer, archives inside archives, files without extensions, DICOMDIR indexes that point to the wrong place. Ossidex walks the whole tree, recognises DICOM by content rather than by file name, groups images into studies and series by their DICOM identifiers, and skips the viewer programs and helper files that come with the disc.
- Archives: ZIP, RAR (including RAR5 and multi-volume), 7z, TAR/GZ, ISO/IMG; password prompts only for genuinely encrypted archives
- DICOMDIR is used when valid; when it is incomplete the folder is scanned directly
- Files without the standard DICOM preamble and without UIDs are still recovered where possible
- Cloud links are resolved to the actual file or folder before download
Decoding pixel data
| Transfer syntax / codec | Supported |
|---|---|
| Uncompressed (implicit/explicit VR) | Yes |
| JPEG Baseline and Extended | Yes |
| JPEG Lossless | Yes |
| JPEG-LS | Yes |
| JPEG 2000 (lossless and lossy) | Yes |
| HTJ2K (High-Throughput JPEG 2000) | Yes |
| RLE Lossless | Yes |
Rescale slope/intercept are applied so CT values are true Hounsfield units, and Enhanced multi-frame objects keep their per-frame geometry and calibration.
Building volumes
For MPR and 3D the slices of a series are sorted by their position in patient space and assembled into a volume with correct spacing and orientation. Built volumes are cached on the device so reopening a large CBCT does not repeat the decoding.
Rendering with Metal
2D slices, oblique MPR planes with slab MIP, the curved panoramic reconstruction along a dental arch and direct volume rendering in 3D are drawn on the GPU. On current iPhones and iPads the panorama follows your finger while you edit the arch.
Measurements and accuracy
Measurements are geometric distances computed from DICOM pixel spacing; their accuracy depends on the scan. We do not publish accuracy figures we have not measured.
Frequently asked questions
Does Ossidex need an internet connection?
Only to download from a cloud link or PACS. Once a study is imported, viewing works offline.
How large a study can it open?
Full-head CBCT and multi-series CT/MRI studies open on current iPhones and iPads. Very large studies depend on the device memory; iPads with more RAM handle them best.
Related pages
Supported formats: DICOM, NIfTI, images, models and archives
Ossidex formats on iPhone and iPad: DICOM CT, MRI, CBCT and ultrasound, NIfTI-1/2, images, PDF, STL/PLY/OBJ models and ZIP, RAR, 7z, ISO archives.
Ossidex features: a full DICOM viewer on iPhone and iPad
Everything Ossidex does: 2D viewing, MPR, 3D rendering, a dental panoramic arch, measurements and PDF reports, cloud-link and PACS import, on-device privacy.
Offline, on-device DICOM viewer: your scans never leave the device
Ossidex opens and renders scans on your iPhone or iPad. No account, no upload of images to our servers, offline viewing, anonymized export when you share.
What’s new in Ossidex
Ossidex release notes: 2.0 brain MRI demo, faster MRI 3D and new implant tools, 1.12 implant planning and AI canal segmentation, import fixes.