; docformat = 'rst' ; ; NAME: ; cgGmaScl ; ; PURPOSE: ; 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. ; ;******************************************************************************************; ; ; ; Copyright (c) 2015, 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. ; ;******************************************************************************************; ; ;+ ; 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. ;- FUNCTION cgGmaScl, image, $ GAMMA=gamma, $ 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 = Double(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.' ; Gamma must be greater than 0. IF N_Elements(gamma) EQ 0 THEN gamma = 1.0D ELSE gamma = 1.0e-6 > Double(gamma) ; Perform initial scaling of the image. output = cgScaleVector(Temporary(output), 0.0D, 1.0D, MinValue=imageMin, MaxValue=imageMax, /NAN, Double=1) ; For gamma, we need positive values. Make sure we have them IF Min(output, /NAN) LT 0.0D THEN output = output + Abs(Min(output, /NAN)) output = cgScaleVector(output^gamma, minOut, maxOut, MinValue=0.0D, MaxValue=1.0D, /NAN, Double=1) ; 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