Filtering Tool

  • Tools -> Filtering

Changes in analytical conditions can cause ‘spikes’ in data, regions of extremely low or high signal resulting from instrument noise. These can be removed by applying a local filter at the position of each spike. The Filtering Tool removes spikes by comparing pixel values to a locally defined threshold, outlying values are then replaced with the local mean or median. A visual example is provided in Application of a rolling median filter..

The parameters of the filters in Available Filters are set using the inputs directly below the filter selection box. To toggle visibility of a filter (for comparison) click the Filter Visible button.

../_images/filtering_image.png

Application of a rolling median filter.

Available Filters

Filters implemented in pew².

Type

Threshold

Rolling Mean

σ

Distance in stddevs from the local mean. Stddev excludes the tested value.

Rolling Median

M

Distance in medians from the local median.

See also

Example: De-noising an image.

Example using the filtering tool.