# coyote: CGSDEVSCL

- coyote/Utilities
- coyote/Graphics
- [Source code]

Description

      This is a utility routine to perform standard deviation scaling
      on image arrays. The user defines a multiple of the standard
      deviation and this is used with the standard deviation of the
      pixels in the image to create a threshold for linear scaling.
      Use the EXCLUDE keyword to exclude a particular value from
      the standard deviation calculation.

Categories

      Utilities, Graphics

Params

      image: in, required, type=numeric
         The image array that is to be scaled.

Keywords

      exclude: in, optional, type=numeric
          Set this keyword to a value in the image array that is to be excluded from the
          standard deviation calculation. Normally, this would be the backgroud value of
          the image, if there is a background.
      multiplier: in, optional, type=float, default=2.0
         The standard deviation of the image pixels is computed and then
         multiplied by the multiplier factor to produce upper and lower
         thresholds for the linear scaling of the image by subtracting
         or adding this value to the mean value of the image. The image
         is linearly scaled between these two threshold values.
      negative: in, optional, type=boolean
           Set this keyword to return the "negative" or reverse of the image scaling.
      omax: in, optional, type=byte, default=255
           Normally, the image is scaled into the range of 0 to 255. Setting the
           OMIN and OMAX keywords can change this scaling.
      omin: in, optional, type=byte, default=0
           Normally, the image is scaled into the range of 0 to 255. Setting the
           OMIN and OMAX keywords can change this scaling.
      threshold: out, optional, type=float
           A two-element array that contains the minimum and maximum thresholds, respectively,
           that were calculated for the scaling.

Examples

      To display an image with standard deviation scaling::
         image = cgDemoData(5)
         cgDisplay, 256*3, 256
         !P.Multi = [0,3,1]
         cgImage, image
         cgImage, SDevScl(image)
         cgImage, SDevScl(image, Exclude=0)
         !P.Multi = 0

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, 5 June 2012.
         Renamed cgSDevScl from SDevScl. 27 Mar 2015. DWF.

Copyright

      Copyright (c) 2012, Fanning Software Consulting, Inc.