The examples in the toolbox are meant to be show how the the features of BBTools can be used in real-world situations. They may be complex, require large amounts of memory, and may need to run a long time.

In time it is intended to put more extensive examples on the web page.


Demos are given in the form of "playscripts", and are generally designed to be runnable for an average user (although, the average user of BBTools is expected to have a modern machine targeted for number crunching).

These are a more appropiate place to start, but does not show the real strength of the toolbox. To start a demo, open the Demos pane in the Help browser and select under Toolboxes. You can also type demo in the MATLAB prompt.


Principal Components Analysis
This example creates the function bbpca, which computes a Principal Component Analysis (PCA) of a data-matrix.


The datasets shipped with BBTools are released under the terms of the GPL. They are intended for used in both examples and demos, and is available for everyone who obeys the license.

The bird image was captured by Germ Wind, and graciously donated to this project. It was shot with a Sigma camera utilizing a Foveon image sensor. This has the important property that all pixels in the image are significant, in contrast to other digital cameras that interpolate.

In order to compress the image shipped with this toolbox, colors were removed by adding the seperate components of the camera. This has the advantage that the intensity remains a count, and can roughly be modelled as Poisson distributed. Pixels were summed in blocks of 4 for additional compression, retaining the discrete distribution.

The image shipped with the toolbox therefore represents raw counts. To display this properly, it is necessary to correct for the non-linearity of the display. Assuming exact display is overkill, this can be done by raising each pixel to the power of 1/2.2 for any sRGB compliant monitor.