This is a release candidate for version 2.0. Due to this, the MATLAB toolbox-file is omitted and will be included in the final 2.0 release. However, pre-built binaries/library-files are included. There are separate packages for Linux and Windows and for Python, MATLAB and Octave. See the included readme for the optimal folder to extract the files, though any folder on path should suffice. Note that you can still manually build all the files as before. Despite being a pre-release, this version already has all the planned features except for additional SPECT projector. The current version includes only the rotation-based projector for SPECT, but the final release will also include a ray-based projector. For a complete list of changes, see release notes. Below are some highlights for this release: Added (limited) support for Python Only a subset of features are implemented All core components have been implemented though Supports only implementation 2 and the class object Custom algorithms can be computed fully in the GPU by using ArrayFire arrays (OpenCL), PyTorch tensors (CUDA) or CuPy arrays (CUDA) The OMEGA forward and/or backward projection operators thus accept ArrayFire arrays, PyTorch tensors or CuPy arrays (CB)CT reconstructions are much more efficient now than before as long as GPU computing is used Support for raw data format dropped Added two new projectors for CT data Projector type 4 is an interpolation-based GPU-only projector Projector type 5 is the branchless distance-driven projector (GPU only) Only supported by implementations 2 and 5 Added support for SPECT reconstruction Supports also GATE projection data Supports parallel hole collimators Built-in support for hexagonal and circular holes for the detector-response function Forward/backward projection class object is CPU (implementation 4) only in MATLAB/Octave, OpenCL and CUDA only in Python Supported only by implementations 2 and 4 Rotation-based projector Added support for hybrid projectors New algorithms/priors and preconditioners Almost complete code overhaul Complete rework of the example-files Changed coordinate system to be centered on origin