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CGGMASCL

CGGMASCL
  This is a utility routine to perform basic gray-level pixel transformations of images.
  I think of it as BYTSCL on steroids. It is similar to IMADJUST in _Digital Image
  Processing with MATLAB_ by Gonzales, Wood, and Eddins. It performs a log scaling
  of the image array.

Categories


    Image Processing

Returns


    A byte scaled image is returned.

Params


    image: in, required
      The image to be scaled. Written for 2D images, but arrays of any size are treated alike.

Keywords


    gamma: in, optional, type=float, default=1.0
        The exponent in a power-law transformation (image^gamma). A gamma value of 1 results in
        a linear distribution of values between OMIN and OMAX. Gamma values less than 1 map
        darker image values into a wider range of output values, and Gamma values greater than
        1 maps lighter image values into a wider range of output values. The gamma value is
        constrained to be greater than 1.0e-6.
    max: in, optional
          Any value in the input image greater than this value is set to this value
          before scaling.
    min: in, optional
          Any value in the input image less than this value is set to this value
          before scaling.
    negative, in, optional, type=boolean, default=0
          If set, the "negative" of the result is returned.
    omax: in, optional, type=byte, default=255
          The output image is scaled between OMIN and OMAX.
    omin: in, optional, type=byte, default=0
          The output image is scaled between OMIN and OMAX.

Examples


      cgLoadCT, 0 ; Gray-scale colors.
      image = cgDemoData(11) ; Load image.
      TVImage, cgGmaScl(image, Min=30, Max=100) ; Similar to BytScl.
      TVImage, cgGmaScl(image, /Negative) ; Produce negative image.
      power = Shift(ALog(Abs(FFT(image,-1))), 124, 124) ; Create power spectrum.
      TVImage, cgGmaScl(power, Gamma=2.5) ; View power specturm with gamma correction.
      TVImage, cgGmaScl(power, Gamma=2.5, /Negative) ; Reverse power spectrum.

Author


      FANNING SOFTWARE CONSULTING::
          David W. Fanning
          1645 Sheely Drive
          Fort Collins, CO 80526 USA
          Phone: 970-221-0438
          E-mail: david@idlcoyote.com
          Coyote's Guide to IDL Programming: http://www.idlcoyote.com

History


    Change History::
      Written by: David W. Fanning, 17 February 2006.
      Fixed a problem with output scaling. 1 July 2009. DWF (with input from Bo Milvang-Jensen).
      Now setting NAN keyword on all MIN and MAX functions. 2 Dec 2011. DWF.
      Renamed cgGmaScl from GmaScl. 27 March 2015. DWF.

Copyright


    Copyright (c) 2006-2015, Fanning Software Consulting, Inc.



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