coyote: CGGMASCL

Description
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.