#!/usr/bin/env python
#
# ================================================================================
#                   ColourNegativeInverter.py - (c) Berthold Hinz 2009
# ================================================================================
#
# COLOUR NEGATIVE INVERTER FOR THE GIMP V.3
#
# ================================================================================
#
# INSTRUCTIONS:
#
# Script needs the colour of unexposed film as reference. Either the scanned image 
# includes a small border or edge of unexpoded film or you have to set the Gimp
# foereground colour to the colour of unexposed film.
# 
# Change step-value to influence processing speed and performance. Step value of
# 1 means that each single pixel is taken into account. The higher the step-value
# the more pixels will be skiped. The script will work faster, but the probability
# to ignore important parts of the image will gain too.
#
# ================================================================================
#
# This program is free software; you can redistribute it and/or modify it.
# 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.
#
# ================================================================================
from gimpfu import *
import pygtk
pygtk.require("2.0")
import gtk

def CNI(img, drw, incl, contr_enh, step, merge_layers):
    pdb.gimp_image_undo_group_start(img)
    if incl==True:
        LightMax=0
        pdb.gimp_message("Processing ..." +"\n")
        for i in range (1, img.width-2,step):
            for j in range (1, img.height-2,step):
                val = getpixel(drw, i, j)
                lightness = getV(val[0],val[1],val[2])
                if lightness > LightMax:
                    LightMax=lightness
                    LMax_R=val[0]
                    LMax_G=val[1]
                    LMax_B=val[2]
        gimp.set_foreground(LMax_R,LMax_G,LMax_B)
    else:
        fgc = gimp.get_foreground()
        LMax_R=fgc[0]
        LMax_G=fgc[1]
        LMax_B=fgc[2]
    layer_copy = drw.copy(True)
    layer_copy.mode = NORMAL_MODE
    layer_copy.name = "bias removed"
    img.add_layer(layer_copy,0)
    drw=img.layers[0]
    pdb.gimp_curves_spline(drw, 1, 4,[0, 0, LMax_R, 255])
    pdb.gimp_curves_spline(drw, 2, 4,[0, 0, LMax_G, 255])
    pdb.gimp_curves_spline(drw, 3, 4,[0, 0, LMax_B, 255])
    if contr_enh==True:
        pdb.gimp_levels_stretch(drw)
    pdb.gimp_message("Done!")
    layer_copy = drw.copy(True)
    layer_copy.mode = NORMAL_MODE
    layer_copy.name = "inverted"
    img.add_layer(layer_copy,0)
    drw=img.layers[0]
    pdb.gimp_invert(drw)
    if merge_layers==True:
        pdb.gimp_image_merge_down(img,drw,0)
        pdb.gimp_image_merge_down(img,img.layers[0],0)
    pdb.gimp_image_undo_group_end(img)

def getpixel(drw, x, y):
    """ gets colour values """
    tile = drw.get_tile2(False, x, y)
    x_offset = x % 64
    y_offset = y % 64
    pixel = tile[x_offset, y_offset]
    values = []
    for i in range(len(pixel)):
        values.append(ord(pixel[i]))
    return values

def getV(R, G, B):
    mi=min(R,G,B)*1.0
    ma=max(R,G,B)*1.0
    v = round(ma/255*100)
    return v

register(
    "colour_negative_inverter",
    "Removes orange bias from scanned colour negatives and inverts result"+"\n\n"+"(if you don't use auto-mode, set Gimp foreground colour to colour"+"\n" +"of unexposed film before you run the script)",
    "",
    "Berthold Hinz>",
    "GPL",
    "2009",
    "<Image>/Filters/Photo/Colour Negative Inverter",
    "RGB*",
    [(PF_TOGGLE,"incl","Auto-mode (best if image includes parts of unexposed film):", True),
    (PF_TOGGLE,"contr_enh","Contrast enhancement:", True),
    (PF_SLIDER,"step","Speed (only relevant for auto-mode):",10,(1,100,10)),
    (PF_TOGGLE,"merge_layers","Merge layers:", False),
    ],
    [],
    CNI)
main()