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8 Oversampling

In SEARCH mode PSS evaluates a significance map which by default is on a grid corresponding to the pixel centres of the input dataset. By using the SAMPLE parameter keyword, it is possible to specify that the grid should be either coarser or finer that of the dataset.

For example, SAMPLE=2 means oversample by a factor of two, ie. the significance map will have a pixel size half that of the input dataset. Undersampling is specified by making SAMPLE negative. A value of -2 makes the significance map pixel size twice that of the dataset.p. Oversampling should be used with caution as it slows PSS down by at least a factor of SAMPLE**2 - for the same reason undersampling may be a useful technique for speeding up the program when source confusion is known not to be a problem.

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