UseReducedData

Declaration: FrmHCA.UseReducedData: boolean;
The property UseReducedData controls whether the clustering algorithm should be sped up for preliminary analyses by using a reduced dataset.

The reduction of the dataset works according to the following idea: in the first step the distances of all spectra (pixels) are calculated and those which are closer to each other than a predefined part are combined into mini clusters which are represented by their average spectra. This way the the number of spectra submitted to the final cluster analysis is reduced to a manageable number (less than 10000). The sensitivity of the creation of the mini clusters can be controlled by the parameter PercMinDist which defines the percentile of all distances which are not regarded significant. A higher value of PercMinDist creates less mini clusters and thus speeds up the calculation.