4.18 sddsbaseline

• description: sddsbaseline performs baseline removal for SDDS column data. Several methods of determining the baseline are provided.
• examples: Remove baselines from a video image organized with each scan line in a separate column. The baseline is determined by looking at 10 points at either end of each line and averaging the pixel count for these points.

  sddsbaseline image.sdds image1.sdds -columns=VideoLine* -select=endpoints=10 -method=average

• synopsis:

  sddsbaseline [input] [output] [-pipe=[in][,out]] [-columns=listOfNames] -select={endPoints=number | -outsideFWHA=multiplier | -antiOutlier=passes} -method={fit | average} [-nonnegative [-despike=passes=number,widthlimit=value] [-repeats=count]]

• files: input is an SDDS file containing one or more pages of data to be processed. output is an SDDS file in which the result is placed. Columns that are not processed are copied from input to output without change.
• switches:
  • -pipe=[input][,output] — The standard SDDS Toolkit pipe option.
  • -columns=listOfNames — Specifies an optionally-wildcarded list of names of columns from which to remove baselines.
  • -select={endPoints=number | -outsideFWHA=multiplier | -antiOutlier=passes} — Specifies how to select the points from which to determine the baseline. endPoints specifies selecting number values from the start and end of the column. outsideFWHA specifies selecting all values that are outside multiplier times the full-width-at-half-amplitude (FWHA) of the pixel count distribution. antiOutlier specifies selecting all values that are not deemed outliers in the 2-sigma sense in any of passes inspections. These last two options implicitly assume that the statistical distribution of the pixel counts is baseline dominated.
  • -method={fit | average} — Specifies how to compute the baseline from the selected points. fit specifies fitting a line to the values (as a function of index). average specifies taking a simple average of the values.
  • -nonnegative [-despike=passes=number,widthlimit=value] [-repeats=count] — Specifies that the resulting function after baseline removal must be nonnegative. Any negative values are set to 0. In addition, despiking (as in sddssmooth) may be applied after removal of negative values; this can result in the removal of positive noise spikes. Giving -repeats allows applying the baseline removal procedure iteratively to the data.
• see also:
  • sddssmooth
  • sddscliptails
• author: M. Borland, ANL/APS.