kolibrios-fun/data/common/media/grafx2/scripts/samples_2.4/picture/RemapImageTo3bitPal.lua

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--SCENE: Remap pic to 3bit, LineEDdith. (Same line simple error-diffusion dither)
--by Richard Fhager
--http://hem.fyristorg.com/dawnbringer/
-- Copyright 2010 Richard Fhager
--
-- 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; version 2
-- of the License. See <http://www.gnu.org/licenses/>
--
-- Just a demonstration.
--
power = 0.6
-- Channel shades (shades = 2 ^ bit-depth)
shades = 2
mult = 255 / (shades-1)
colors = {}
col = 0
for r = 0, shades-1, 1 do
for g = 0, shades-1, 1 do
for b = 0, shades-1, 1 do
col = col + 1
colors[col] = { r*mult, g*mult, b*mult }
end
end
end
for c = 1, #colors, 1 do
setcolor(c-1,colors[c][1],colors[c][2],colors[c][3])
end
for c = #colors, 255, 1 do
setcolor(c,0,0,0)
end
w, h = getpicturesize()
for y = 0, h - 1, 1 do
re = 0
ge = 0
be = 0
for x = (y%2), w - 1, 1 do
r,g,b = getbackupcolor(getbackuppixel(x,y));
rn = re + r
gn = ge + g
bn = be + b
n = matchcolor(rn,gn,bn);
putpicturepixel(x, y, n);
rn,gn,bn = getcolor(getpicturepixel(x,y));
re = (re + (r - rn)) * power
ge = (ge + (g - gn)) * power
be = (be + (b - bn)) * power
end
end