; 210_contrast_change-contrast.scm
; last modified/tested by Paul Sherman [gimphelp.org]
; Wednesday, 07/01/2020 on GIMP 2.10.20
;==================================================
;
; Installation:
; This script should be placed in the user or system-wide script folder.
;
;	Windows 7/10
;	C:\Program Files\GIMP 2\share\gimp\2.0\scripts
;	or
;	C:\Users\YOUR-NAME\AppData\Roaming\GIMP\2.10\scripts
;	
;    
;	Linux
;	/home/yourname/.config/GIMP/2.10/scripts  
;	or
;	Linux system-wide
;	/usr/share/gimp/2.0/scripts
;
;==================================================
;
; LICENSE
;
;    This program is free software: you can redistribute it and/or modify
;    it under the terms of the GNU General Public License as published by
;    the Free Software Foundation, either version 3 of the License, or
;    (at your option) any later version.
;
;    This program is distributed in the hope that it will be useful,
;    but WITHOUT ANY WARRANTY; without even the implied warranty of
;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;    GNU General Public License for more details.
;
;    You should have received a copy of the GNU General Public License
;    along with this program.  If not, see <http://www.gnu.org/licenses/>.
;
;==============================================================
; Original information 
;
; Original was "Vivid saturation" script  for GIMP 2.4
; by Dennis Bond with thanks to Jozef Trawinski
; Modified for use in GMP-2.4 by Paul Sherman 
; This is modification 2 made on 11/15/2007
; distributed by gimphelp.org
;==============================================================
;
(define (210-shadows-highlights
		image
		drawable
		shadows
		highlights
		inMerge
	)
	;Start an undo group so the process can be undone with one undo
	(gimp-image-undo-group-start image)
	(if (not (= RGB (car (gimp-image-base-type image))))
			 (gimp-image-convert-rgb image))
	; create a highlights layer
	(let ((highlights-layer (car (gimp-layer-copy drawable 1))))
	(gimp-item-set-name highlights-layer "fix highlights (adjust opacity)")
	(gimp-image-insert-layer image highlights-layer 0 -1)
	;process shadows/highlights layer
	(gimp-desaturate highlights-layer)
	(gimp-invert highlights-layer)
	(gimp-layer-set-mode highlights-layer 5)
	(plug-in-gauss-iir2 1 image highlights-layer 25 25)
	;copy highlights layer to create shadows layer
	(define shadows-layer (car (gimp-layer-copy highlights-layer 1)))
	(gimp-item-set-name shadows-layer "fix shadows (adjust opacity)")
	(gimp-image-insert-layer image shadows-layer 0 -1)
	;process highlights layer
	(plug-in-colortoalpha 1 image highlights-layer '(255 255 255))
	(gimp-layer-set-opacity highlights-layer highlights)
	;process shadows layer
	(plug-in-colortoalpha 1 image shadows-layer '(0 0 0))
	(gimp-layer-set-opacity shadows-layer shadows)
	(if (= inMerge TRUE)(gimp-image-merge-visible-layers image EXPAND-AS-NECESSARY))
	(gimp-image-undo-group-end image)
	(gimp-displays-flush))
)
(script-fu-register "210-shadows-highlights"
	"Change Shadows-Highlights"
	"Removes shadows and highlights from a photograph, makes image feel more saturated"
	"Dennis Bond - thanks to Jozef Trawinski"
	"Dennis Bond - thanks to Jozef Trawinski"
	"October 26, 2006"
	"*"
	SF-IMAGE 		"Image" 							0
	SF-DRAWABLE 	"Drawable" 							0
	SF-ADJUSTMENT 	"Shadows"    						'(50 0  100   1   1   0   0)
	SF-ADJUSTMENT 	"Highlights" 						'(0  0  100   1   1   0   0)
	SF-TOGGLE     	"Merge layers when complete?" 		FALSE
)
(script-fu-menu-register "210-shadows-highlights" "<Image>/Script-Fu/Contrast")