ISIS Documentation

reduce

Reduce the pixel dimensions of an image

This program reduces a cube to a given proportion of the original or to specific pixel dimensions.

The reduction method options include either averaging the pixels (AVERAGE) or selecting the closest pixel at the window center (NEAREST) when generating a sub-sampled cube. More information is included under the Parameter Group headings.

For Level1:

  • All keywords in the input file label are propagated to the output file
  • An AlphaCube group with the original size is created in the output cube labels
  • Coordinates returned in qview are accurate if SPICE kernels are present in the labels

For Level2 or Mosaic:

  • The Scale and PixelResolution are recomputed if SSCALE and LSCALE are equal
  • The Mapping Group is removed if SSCALE and LSCALE are not equal
  • Coordinates are returned in qview only if the Mapping group was propagated
  • Use the same value for SSCALE and LSCALE if the reduced cubes will be mosaicked together

Use the ONS and ONL parameters with caution because the scaling factor for the samples and lines may be different in the output cube. Within this application, special pixels are considered invalid and will be replaced depending on the settings for VALIDPER and VPER_REPLACE parameters.

Categories

History

Jeff Anderson1995-11-06 Original version
Tracie Sucharski2002-10-12 Ported to Isis 3.0, Separated magcube into reduce and enlarge.
Tracie Sucharski2003-05-13 Read in ons/onl as integers not doubles.
Stuart Sides2003-05-16 Modified schema location from astrogeology... to isis.astrogeology..."
Stuart Sides2003-07-29 Modified filename parameters to be cube parameters where necessary
Jeff Anderson2004-07-14 Fixed propagation bug
Tracie Sucharski2004-07-15 Forget to change ons/onl minimum inclusive values from 1.0 to 1 during the 2003-5-13 change.
Drew Davidson2005-08-17 Added example
Tracie Sucharski2006-04-03 Fixed bug in average algorithm, forgot to divide Vper by 100.
Jeff Anderson2006-09-19 Fixed problems when program ran in batchlist
Sean Crosby2007-02-28 Program now updates output file's mapping keywords
Steven Koechle2008-01-23 Changed so if it failed VPER the output cube would get null values. Now processes cube bands from user input correctly
Steven Lambright2008-05-13 Removed references to CubeInfo
Steven Koechle2008-05-15 Added radio button for VPER options to allow original functionality.
Steven Lambright2008-12-22 The "Scale" keyword in the Projection group in the labels is now being updated if this program is run on a projected cube.
Mackenzie Boyd2009-09-03 Added keyword REDUCTION_TYPE to allow for clear switching between ons, onl and sscale, lscale. Fixed problem involving cube remaining open after an exception.
Janet Barrett2009-10-22 Now uses the SubArea class to produce output cube labels with corrected Mapping, Instrument, and AlphaCube groups.
Travis Addair2009-11-12 Improved documentation, changed parameter names, and updated examples.
Travis Addair2009-12-09 Updated documentation and changed parameters STOTAL and LTOTAL back to ONS and ONL, respectively.
Sharmila Prasad2011-04-26 Ported the reduce by near and average functionality from the app to base/objs/Reduce class
Sharmila Prasad2011-10-07 Fixed bug #0000463 regarding memory leak
Sharmila Prasad2012-02-01 Fixed bug #0000681 - reduce in ISIS 3.3.0 is ignoring the +N band identifier
Tracie Sucharski2013-01-16 Fixed an intermittent bug which caused a round off error which resulted in the output bands beyond band 1 being all NULL. Fixes #1385.
Ella Mae Lee2013-11-06 Updated the documentation and fixed incorrect information. Fixes #1691.