Threshold factors may be computed and applied automatically. This option is primarily meant for use within interactive tools that are designed to help determine what threshold factors will give the best results for later batch processing. To use this option, when asked to “Select method of determining threshold factors”, choose the option to “Compute thresholds based on a percentage of data to attenuate.” This choice will activate the PERCENTILE_THRESHOLD parameter set. To use this option, define a threshold type using the THRESHOLD_TYPE parameter (see section 1.6.2) and specify a percentage of data to attenuate using the PERCENTILE parameter. All frequency bands within all windows within a gather will be ordered by their normalized median or median deviation. The specified percentage of frequency bands with the largest (or smallest) factors will be attenuated. This percentage is applied across an entire gather. A window that contains noisy data may have more frequency bands attenuated than a window that has relatively good data. However, across the entire gather the requested percentage of frequency bands will be attenuated. The computed threshold factors for each window may be stored in the multi-valued trace header literal, TR.THRESH_MULT_VAL. The threshold factors are constant within a gather but will change between gathers.