;+ ; NAME: ; GMASCL ; ; 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. ; ; AUTHOR: ; ; FANNING SOFTWARE CONSULTING ; David Fanning, Ph.D. ; 1645 Sheely Drive ; Fort Collins, CO 80526 USA ; Phone: 970-221-0438 ; E-mail: davidf@dfanning.com ; Coyote's Guide to IDL Programming: http://www.dfanning.com ; ; CATEGORY: ; ; Utilities ; ; CALLING SEQUENCE: ; ; scaledImage = GMASCL(image) ; ; ARGUMENTS: ; ; image: The image to be scaled. Written for 2D images, but arrays ; of any size are treated alike. ; ; KEYWORDS: ; ; GAMMA: 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 compress the ; lower range of values and extend the upper range. Gamma values ; greater than 1 compress the upper range of values and extend the ; lower range. The gamma value is constrained to be greater than 1.0e-6. ; ; 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 = LoadData(11) ; Load image. ; TV, GmaScl(image, Min=30, Max=100) ; Similar to BytScl. ; TV, GmaScl(image, /Negative) ; Produce negative image. ; power = Shift(ALog(Abs(FFT(image,-1))), 124, 124) ; Create power spectrum. ; TV, GmaScl(power, Gamma=2.5) ; View power specturm with gamma correction. ; TV, GmaScl(power, Gamma=2.5, /Negative) ; Reverse power spectrum. ; ; RESTRICTIONS: ; ; Requires SCALE_VECTOR from the Coyote Library: ; ; http://www.dfanning.com/programs/scale_vector.pro ; ; MODIFICATION HISTORY: ; ; Written by: David W. Fanning, 17 February 2006. ;- ;########################################################################### ; ; LICENSE ; ; This software is OSI Certified Open Source Software. ; OSI Certified is a certification mark of the Open Source Initiative. ; ; Copyright © 2006 Fanning Software Consulting ; ; This software is provided "as-is", without any express or ; implied warranty. In no event will the authors be held liable ; for any damages arising from the use of this software. ; ; Permission is granted to anyone to use this software for any ; purpose, including commercial applications, and to alter it and ; redistribute it freely, subject to the following restrictions: ; ; 1. The origin of this software must not be misrepresented; you must ; not claim you wrote the original software. If you use this software ; in a product, an acknowledgment in the product documentation ; would be appreciated, but is not required. ; ; 2. Altered source versions must be plainly marked as such, and must ; not be misrepresented as being the original software. ; ; 3. This notice may not be removed or altered from any source distribution. ; ; For more information on Open Source Software, visit the Open Source ; web site: http://www.opensource.org. ; ;########################################################################### FUNCTION GmaScl, 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 = Error_Message() 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) IF N_Elements(imageMin) EQ 0 THEN imageMin = Min(output) 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 = Scale_Vector(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) LT 0.0D THEN output = output + Abs(Min(output)) output = Scale_Vector(output^gamma, minOut, maxOut, /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