; man.scm version 1.2.11
; 06 July 2006
; A Script-Fu script to compensate for underwater colour loss
; at greater than 5m

; 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 2 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, write to the Free Software
; Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

; Only tested on v2.2.11


(define (script-fu-man img photo)

	(gimp-undo-push-group-start img)

	; first copy of photo for eventual merge
	(set! uw-layer (car (gimp-layer-copy photo 1)))
	(gimp-image-add-layer img uw-layer -1)
	(gimp-layer-set-name uw-layer "red enhance 1")

	; second copy of photo, set foreground to grey, fill with grey, leave mode at normal
	(set! uw1-layer (car (gimp-layer-copy photo 1)))
	(gimp-image-add-layer img uw1-layer -1)
	(gimp-layer-set-name uw1-layer "red enhance 1a")
	(gimp-context-set-foreground '(128 128 128))
	(gimp-edit-fill uw1-layer 0)

	; third copy of photo, fill with grey and set mode to value
	(set! uw2-layer (car (gimp-layer-copy photo 1)))
	(gimp-image-add-layer img uw2-layer -1)
	(gimp-layer-set-name uw2-layer "red enhance 1b")
	(gimp-edit-fill uw2-layer 0)
	(gimp-layer-set-mode uw2-layer VALUE)

	; merge down value to grey (clip-to-image)
	(set! uw-layer1 (car (gimp-image-merge-down img uw2-layer 1)))

	; fourth copy of photo, set foreground to grey, fill with grey, leave mode at normal
	(set! uw3-layer (car (gimp-layer-copy photo 1)))
	(gimp-image-add-layer img uw3-layer -1)
	(gimp-layer-set-name uw3-layer "red enhance 1c")
	(gimp-context-set-foreground '(128 128 128))
	(gimp-edit-fill uw3-layer 0)

	; fifth copy of photo, fill with grey and set mode to value
	(set! uw4-layer (car (gimp-layer-copy photo 1)))
	(gimp-image-add-layer img uw4-layer -1)
	(gimp-layer-set-name uw4-layer "red enhance 1d")
	(gimp-edit-fill uw4-layer 0)
	(gimp-layer-set-mode uw4-layer VALUE)

	; merge down value to grey (clip-to-image)
	(set! uw3-layer (car (gimp-image-merge-down img uw4-layer 1)))

	; set background to red fill uw3, set mode to multiply
	(gimp-context-set-background '(255 0 0))
	(gimp-drawable-fill uw3-layer 1)
	(gimp-layer-set-mode uw3-layer MULTIPLY)

	; merge down red to grey (clip-to-image) and set mode to screen
	(set! uw1-layer (car (gimp-image-merge-down img uw3-layer 1)))
	(gimp-layer-set-mode uw1-layer SCREEN)

	; merge down screen to uw (clip-to-image) and set opacity to 50%, tweak up for deep (very green images) or down for shallow
	(set! uw-layer (car (gimp-image-merge-down img uw1-layer 1)))
	(gimp-layer-set-opacity uw-layer 50)

	; clean
	(gimp-undo-push-group-end img)
	(gimp-displays-flush)
)


(script-fu-register "script-fu-man"
		_"<Image>/Script-F_u/_Underwater Photos/Red Enhance _1"
		"Based on the mandrake method for Photoshop. See www.scubaboard.com for the original articles."
		"www.tankedup-imaging.com"
		"Tanked Up Underwater Imaging"
		"06 July 2006"
		""
		SF-IMAGE "Image" 0
		SF-DRAWABLE "Drawable" 0
)