;;
; The GIMP -- an image manipulation program
; Copyright (C) 1995 Spencer Kimball and Peter Mattis
;
; Auto Contrast Correction script  for GIMP 2.4
; Original author: Mark Lowry 
;
; Tags: color, photo, exposure
;
; Author statement:
;
; Automatically adjusts contrast of the current
; drawable by duplicating the layer, setting the
; new layer to Value blend mode, then running
; Auto Levels on the Value layer.
;
; --------------------------------------------------------------------
; Distributed by Gimp FX Foundry project
; --------------------------------------------------------------------
;   - Changelog -
; Created 4/5/2006
; Revised 10/26/2007 to fix unbound variables (required for v.2.4.0)
; Revised 10/31/2007 - added option to skip autolevels for later manual adjustment - Alexia Death
; Revised 11/01/2007 - Added Hue correction layer - Alexia Death
;
; --------------------------------------------------------------------
;
; 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.
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;



(define (script-fu-auto-contrast-lowry img drawable merge-flag alskip-flag)
    
    (let* (
            (value-layer 0)
            (hue-layer 0)
          )
        
        
        ; Start an undo group.  Everything between the start and the end
        ; will be carried out if an undo command is issued.
        
        (gimp-image-undo-group-start img)
        
        ;; CREATE THE VALUE LAYER ;;
        
        ; Create a new layer
        
        (set! value-layer (car (gimp-layer-copy drawable 0)))
        (set! hue-layer (car (gimp-layer-copy drawable 0)))
        
        ; Give it a name
        (gimp-drawable-set-name value-layer "Contrast Adjustment Layer")
        (gimp-drawable-set-name hue-layer "Hue Correction Layer")
        
        ; Add the new layer to the image
        (gimp-image-add-layer img value-layer 0)
        (gimp-image-add-layer img hue-layer 0)
        
        ; Set opacity to 100%
        (gimp-layer-set-opacity value-layer 100)
        (gimp-layer-set-opacity hue-layer 100)
        
        ; Set the layer modes to Value and hue
        (gimp-layer-set-mode value-layer LAYER-MODE-HSV-VALUE)
        (gimp-layer-set-mode hue-layer LAYER-MODE-HSV-HUE)
        
        ; Adjust contrast
        (if (equal? alskip-flag FALSE)
            (gimp-drawable-levels-stretch value-layer)
        )
        ; Merge down, if required
        
        (if (equal? merge-flag TRUE)
            (begin
                (gimp-image-merge-down img value-layer 1)
                (gimp-image-merge-down img hue-layer 1)
            )
        )
        
        
        
        ; Complete the undo group
        (gimp-image-undo-group-end img)
        
        ; Flush the display
        (gimp-displays-flush)
        
    )
)


(script-fu-register "script-fu-auto-contrast-lowry"
    "Auto contrast correction"
    "Automatically adjust contrast of drawable. Brightens dull photos. \nfile:lowry-auto-contrast.scm"
    "Mark Lowry"
    "Mark Lowry"
    "2007"
    "RGB*, GRAY*"
    SF-IMAGE "Image" 0
    SF-DRAWABLE "Current Layer" 0
    SF-TOGGLE "Merge Layers"  FALSE
    SF-TOGGLE "Skip auto levels"  FALSE
)

(script-fu-menu-register "script-fu-auto-contrast-lowry" "<Toolbox>/Script-Fu/Photo/Enhancement/")

; end of script