Onis Free Edition

Onis Free Edition 2.5

Onis is a neat DICOM file viewer that comes with handy features
3.6  (5 votes) (See all)

DICOM stands for Digital Imaging and Communications in Medicine and represents the digital standard for storing, distributing and viewing any kind of medical image regardless of its origin. As a result, it's also a popular image format for medical-related photography like radiographies, tomographies, and so on.

Onis is a neat DICOM file viewer that comes with handy features such as the support for multi-frame images or for using annotations on the displayed pictures. It can read and display DICOM files from various sources, including directly from a DICOM server, CD or a folder without downloading them into the local database first. Advanced features such as a single oblique MPR (Multi Planar Reconstruction) function or the MIP-based 3D Volume rendering (Maximum Intensity Projection), as well as comprehensive measurement utilities are also supported. Anyway, though it's pretty powerful and handy on its own, the free edition of Onis also comes with quite a few limitations, such as the fact that it doesn't support plugins or multiple monitors, or that it limits its database to a number of 15 patients. Upgrading to the non-free Professional editions will remove most of these restrictions.

I also like about the free edition of Onis the fact that it can export DICOM images to raster formats like JPEG or BMP, and that it supports image filtering of multiple types (linear, bicubic interpolation).

To sum it all up, Onis is a great tool for anyone in need of viewing, annotating, and converting DICOM images.

Margie Smeer
Editor rating:

Review summary


  • Free
  • Easy-to-use interface
  • Supports annotations
  • Supports exporting to raster image formats


  • The database is limited to 15 patients
  • Multiple monitors are not supported
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