gaussscl.pro
6.25 KB
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;+
; NAME:
; GAUSSSCL
;
; PURPOSE:
;
; This is a utility routine to perform a gaussian gray-level pixel
; transformation stretch on a image.
;
; AUTHOR:
;
; FANNING SOFTWARE CONSULTING
; David Fanning, Ph.D.
; 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
;
; CATEGORY:
;
; Utilities
;
; CALLING SEQUENCE:
;
; scaledImage = GAUSSSCL(image)
;
; ARGUMENTS:
;
; image: The image to be scaled. Written for 2D images, but arrays
; of any size are treated alike.
;
; KEYWORDS:
;
; SIGMA: The sigma value or width of the Gaussian
; function. Set to 1 by default.
;
;
; MAX: Any value in the input image greater than this value is
; set to this value before scaling.
;
; MIN: Any value in the input image less than this value is
; set to this value before scaling.
;
; NEGATIVE: If set, the "negative" of the result is returned.
;
; OMAX: The output image is scaled between OMIN and OMAX. The
; default value is 255.
;
; OMIN: The output image is scaled between OMIN and OMAX. The
; default value is 0.
; RETURN VALUE:
;
; scaledImage: The output, scaled into the range OMIN to OMAX. A byte array.
;
; COMMON BLOCKS:
; None.
;
; EXAMPLES:
;
; LoadCT, 0 ; Gray-scale colors.
; image = cgDemoData(11) ; Load image.
; TV, GaussScl(image)
;
; RESTRICTIONS:
;
; Requires cgScaleVector from the Coyote Library:
;
; http://www.idlcoyote.com/programs/cgScaleVector.pro
;
; MODIFICATION HISTORY:
;
; Written by: David W. Fanning, 5 September 2007.
; Now setting NAN keyword on all MIN and MAX functions. 2 Dec 2011. DWF.
;-
;******************************************************************************************;
; Copyright (c) 2008, by Fanning Software Consulting, Inc. ;
; All rights reserved. ;
; ;
; Redistribution and use in source and binary forms, with or without ;
; modification, are permitted provided that the following conditions are met: ;
; ;
; * Redistributions of source code must retain the above copyright ;
; notice, this list of conditions and the following disclaimer. ;
; * Redistributions in binary form must reproduce the above copyright ;
; notice, this list of conditions and the following disclaimer in the ;
; documentation and/or other materials provided with the distribution. ;
; * Neither the name of Fanning Software Consulting, Inc. nor the names of its ;
; contributors may be used to endorse or promote products derived from this ;
; software without specific prior written permission. ;
; ;
; THIS SOFTWARE IS PROVIDED BY FANNING SOFTWARE CONSULTING, INC. ''AS IS'' AND ANY ;
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ;
; OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT ;
; SHALL FANNING SOFTWARE CONSULTING, INC. BE LIABLE FOR ANY DIRECT, INDIRECT, ;
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED ;
; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ;
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ;
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ;
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;
;******************************************************************************************;
FUNCTION GaussScl, image, $
SIGMA=sigma, $
MAX=imageMax, $
MIN=imageMin, $
NEGATIVE=negative, $
OMAX=maxOut, $
OMIN=minOut
; Return to caller on error.
;On_Error, 2
Catch, theError
IF theError NE 0 THEN BEGIN
Catch, /Cancel
void = cgErrorMsg()
RETURN, vector
ENDIF
; Check arguments.
IF N_Elements(image) EQ 0 THEN Message, 'Must pass IMAGE argument.'
; Check for underflow of values near 0. Yuck!
curExcept = !Except
!Except = 0
i = Where(image GT -1e-35 AND image LT 1e-35, count)
IF count GT 0 THEN image[i] = 0.0
void = Check_Math()
!Except = curExcept
output = image
; Check keywords.
IF N_Elements(imageMax) EQ 0 THEN imageMax = Max(output, /NAN)
IF N_Elements(imageMin) EQ 0 THEN imageMin = Min(output, /NAN)
IF N_Elements(maxOut) EQ 0 THEN maxOut = 255B ELSE maxout = 0 > Byte(maxOut) < 255
IF N_Elements(minOut) EQ 0 THEN minOut = 0B ELSE minOut = 0 > Byte(minOut) < 255
IF minOut GE maxout THEN Message, 'OMIN must be less than OMAX.'
IF N_Elements(sigma) EQ 0 THEN sigma = 1 ELSE sigma = sigma > 0.25
; Perform initial scaling of the image.
output = cgScaleVector(Temporary(output), 0.0D, 1.0D, MinValue=imageMin, MaxValue=imageMax, /NAN, Double=1)
; Perform Gaussian scaling.
output = cgScaleVector(Temporary(output), -!pi, !pi)
f = (1/(sigma*sqrt(2*!dpi)))*Exp(-(Temporary(output)^2/(2*sigma^2)))
output = cgScaleVector(Temporary(f), minOut, maxOut)
; Does the user want the negative result?
IF Keyword_Set(negative) THEN RETURN, BYTE(0B > (maxout - Round(output) + minOut) < 255B) $
ELSE RETURN, BYTE(0B > Round(output) < 255B)
END