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