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      Apply an absolute color table to an array of values.


Calling Sequence

      img = act_apply(z)


      z = Input 2-d array of values to color. in

Keyword Parameters


        STR=s Structure with absolute color table.
          s={z:z,h:h,s:s,v:v,rgb:rgb,step_flag:step_flag, $
            z = Array of tiepoint values.
            h = Array of hues at tiepoints.
            s = Array of saturations at tiepoints.
            v = Array of values at tiepoints.
            log = 1 if log, 0 if linear color table.
            rgb = 1: interpolate in rgb, 0: interpolate in hsv.
            abs_flag = 1 if absolute, 0 if not.
              Software can use this value as a suggestion.
            step_flag = 1 if stepped, 0 if smooth.
            step = Step size for stepped color table.
              For log color tables use 1, 2, 5, or 10.
            step_offset = -0.5, 0, or 0.5 to offset step.
              Assumed 0 for log color tables.
            barmin = Data start range in z (def=min(z)).
            barmax = Data end range in z (def=max(z)).
        FILE=file Name of absolute color table file.
          This is a text file in txtdb format with the same items
          as in the structure above. Such a color table is built
          by act_edit. Use either STR or FILE but not both.
          Give the path and file name for the color table, or use
          the keywords /lib_tables, /my_tables to set the path as
          described below. Other flags or values may be given in
          either the structure or the txtdb file and their value
          accessed using val=act_info(tag).
        /LIB_TABLES Assume the given color table file is in the
          same directory (like IDLUSR) as this routine, act_apply.
        /MY_TABLES Assume the given color table file is in the
          same directory as the routine that calls act_apply.
          These two keywords will add the indicated path to file
          only if the given file has no path.
        SLOPE=slope, OFFSET=offset Convert color table units.
          These keywords allow a single color table to be displayed
          in different units by converting the original table units.
          Color tables are defined in terms of colors at certain
          values where the values are in some units.
          Unit conversion: NEW = OLD*slope + offset
          Be careful mixing this conversion with the NEWRANGE keyword.
          Avoid SLOPE and OFFSET with log color tables.
        UNITS=units Instead of giving SLOPE and OFFSET may give
          units for some color tables that have units conversions.
          For example, the color table act_temp_k.txt is an
          absolute color table with the following units.
          Set units to one of these: 'deg C', 'deg F', 'deg K'
          This allows the same color table to be applied to an
          array with values in the corresponding units.
        NEWRANGE=nran The original color table as given by the
          FILE keyword has a data range and a display range,
          may be the same but need not be (the table might
          also color out of range flag values for example).
          The data range covered by the color table may not be
          a good match to the actual data range in the given
          data array. The same color table can be remapped to
          a new data range using the NEWRANGE keyword:
            NEWRANGE=[data_lo, data_hi] which applies the full
          color table display range to data_lo to data_hi. If
          -1 is used for data_lo then min(data) is used. If
          -1 is used for data_hi then max(data) is used.
          To use only part of the original color table the desired
          section may also be given:
            NEWRANGE=[data_lo, data_hi, newmin, newmax]
          which will use the colors between newmin and newmax
          to color data in the range data_lo to data_hi, where
          newmin and newmax refer to the original color table,
          not the remapped color table.
          To use the color table to autoscale the data do
          NEWRANGE=[min(z),max(z)] which makes the color table
          relative. The new scaling is not remembered on next
          call so the original color table is not changed.
          May also do NEWRANGE=[-1,-1] to autoscale (relative).
          NEWRANGE=[0,0] or [0,0,0,0] does nothing.
          NEWRANGE=[0,0,newmin,newmax] only sets newmin and newmax.
        /CLIP clip data to color table range. If /clip is not
          used then the data can use flag values outside the
          range barmin to barmax if the color table extends there.
        /DETAILS displays a more detailed explanation of absolute
          color tables and how the NEWRANGE keyword works.
        TRUE=tr Specify dimension to interleave (1, 2, or 3=def).
        ERROR=err Error flag: 0=ok.
        CFLAG=cflag Returned flag: 0=no, 1=yes (image is constant).
        CONSTANT=const Returned value if image is constant.
        /C24 Return an array of 24-bit colors instead of a color image.


      img = Returned color image. out
        or an array of 24-bit colors if /C24 is used.

Common Blocks



      Notes: The color table is remembered until a new one
        is given.

Modification History

      R. Sterner, 2007 Dec 20
      R. Sterner, 2008 Jan 03 --- Added NEWRANGE keyword.
      R. Sterner, 2008 Jan 07 --- Allowed NEWRANGE to use partial table.
      R. Sterner, 2008 Jan 15 --- Handled constant arrays.
      R. Sterner, 2008 Jan 18 --- Allowed NEWRANGE to be all 0s, ignored.
      R. Sterner, 2008 May 22 --- Upgraded NEWRANGE. Added /CLIP.
      R. Sterner, 2008 Nov 17 --- Modified common.
      R. Sterner, 2008 Nov 25 --- Adjusted step to vary as range varies.
      R. Sterner, 2008 Nov 25 --- Better help text for NEWRANGE.
      R. Sterner, 2008 Dec 12 --- Fixed a comment typo.
      R. Sterner, 2010 Mar 22 --- Kept copy of structure in common.
      R. Sterner, 2010 Apr 08 --- Forced returned image to be type byte.
      R. Sterner, 2010 Apr 12 --- Fixed path & added /lib_tables, /my_tables.
      R. Sterner, 2010 Apr 12 --- Fixed clipping to use barmin, barmax.
      R. Sterner, 2010 Apr 13 --- Fixed the error return when no array given.
      R. Sterner, 2010 May 07 --- Added keyword TRUE=tr (interleave dim).
      R. Sterner, 2010 Jul 06 --- Added SLOPE=slope, OFFSET=offset for units conversion.
      R. Sterner, 2010 Nov 10 --- Added support for log color tables.
      R. Sterner, 2010 Nov 11 --- Made better log color table stepping.
      R. Sterner, 2010 Dec 14 --- Added /DETAILS.
      R. Sterner, 2010 Dec 14 --- Allowed NEWRANGE=[0,0,newmin,newmax].
      R. Sterner, 2010 Dec 31 --- Added UNITS=units keyword.
      R. Sterner, 2011 Jan 07 --- The no units case got broken, fixed.
      R. Sterner, 2011 Dec 07 --- Allowed NEWRANGE=[-1,-1,...]
      R. Sterner, 2012 May 30 --- Added /C24.
  Copyright (C) 2007, Johns Hopkins University/Applied Physics Laboratory
  This software may be used, copied, or redistributed as long as it is not
  sold and this copyright notice is reproduced on each copy made. This
  routine is provided as is without any express or implied warranties
  whatsoever. Other limitations apply as described in the file disclaimer.txt.

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