Black-Box Demos


The Black-Box Toolbox provides functions for computations involving large linear systems. The system is used as a black-box, which means that it is accessed only via matrix-vector products.

In large-scale computations the operator is usually structured in a way that can be exploited in computations involving these operators. The demos below shows how BBTools can be used to manipulate and solve such problems of this kind.

All the demos are playscripts, i.e. if you install BBTools you may run the examples from Matlab and compare the results with you own configuration.

Image deblurring

Deblurring an images is a classical problem in ill-posed problems. The following three demos shows an example where BBTools can cope with a reasonably large image. To show off, we use a circular image, and the blurring kernel is non-seperable. This is usually difficult to handle for other software packages.

Tomographic reconstruction

Tomography is the science that allows e.g. medical scanners at hospitals to look inside people for diagnosis. A CT scanner, for instance, produces images much like x-ray. However, instead of a flat image, it produces a number of slices and allowes the doctor to see an a virtual arbitrary cut of the scanned area.

This toolbox was largely developed to address another kind of scanners: PET and SPECT. These scanners are able to track a molecule which have been made radioactive, and are used to find cancer (tracing sugar-molecules known as FDG) and receptor-systems in the brain.

The following demos demonstrate the technique using two widely used algorithms.

SVD Problems

These provides a short introduction to the SVD capabilities of BBTools. They are not flashy, but demonstrate how to use BBTools and how to make a trade-off between memory and computation. Although these are toy problems, the techniques demonstrated in the demo may be useful if you encounter a large-scale problem.