Matrix-Compression Techniques

The reconstruction can be accelerated by applying matrix compression. To this end, the system matrix S is transformed into a different domain by applying a basis transformation on the rows of the system matrix. In MPIReco.jl, matrix compression can be enabled by specifying sparseTrafo which can be "DCT-IV" or "FFT".

The transformations can be restricted to the drive-field field-of-view by setting useDFFoV = true. The compression factor that controls how many coefficients are dropped after application of the transformation is controlled by the parameter redFactor. For instance a reduction factor of redFactor = 0.01 will drop 99 % of the data.