// Copyright 2005 Matt Sandstršm/Too Much Too Soon
// This script is freeware, meaning you may copy and
// distribute it free of charge, as long as it's kept intact,
// including this message. Feel free to use the code as
// inspiration for your own scripts, but don't steal.
// Email me at mattias@beauty.se if you have any questions.
// Thank you. Have fun. 

filter "Color Balance 3-way";
group "TMTS Color";

input d0, "Shadows", label, "Shadows"
input rbalance0, "C...R", slider, 0, -100, 100 detent 0;
input gbalance0, "M...G", slider, 0, -100, 100 detent 0;
input bbalance0, "Y...B", slider, 0, -100, 100 detent 0;
input d1, "Midtones", label, "Midtones"
input rbalance1, "C...R", slider, 0, -100, 100 detent 0;
input gbalance1, "M...G", slider, 0, -100, 100 detent 0;
input bbalance1, "Y...B", slider, 0, -100, 100 detent 0;
input d2, "Highlights", label, "Highlights"
input rbalance2, "C...R", slider, 0, -100, 100 detent 0;
input gbalance2, "M...G", slider, 0, -100, 100 detent 0;
input bbalance2, "Y...B", slider, 0, -100, 100 detent 0;

code

float w, h, i, rlut[256], glut[256], blut[256], rr0, gg0, bb0, rr1, gg1, bb1, rr2, gg2, bb2, offset0[3], offset128[3];
dimensionsof(dest, w, h);
image buf[w][h];

offset128[1] = 128;
offset128[2] = 128;

rr0 = rbalance0/2
gg0 = -rbalance0/4
bb0 = -rbalance0/4
rr0 -= gbalance0/4
gg0 += gbalance0/2
bb0 -= gbalance0/4
rr0 -= bbalance0/4
gg0 -= bbalance0/4
bb0 += bbalance0/2
rr1 = rbalance1/2
gg1 = -rbalance1/4
bb1 = -rbalance1/4
rr1 -= gbalance1/4
gg1 += gbalance1/2
bb1 -= gbalance1/4
rr1 -= bbalance1/4
gg1 -= bbalance1/4
bb1 += bbalance1/2
rr2 = rbalance2/2
gg2 = -rbalance2/4
bb2 = -rbalance2/4
rr2 -= gbalance2/4
gg2 += gbalance2/2
bb2 -= gbalance2/4
rr2 -= bbalance2/4
gg2 -= bbalance2/4
bb2 += bbalance2/2

for i = 0 to 127
	rlut[i] = i+(127-i)*rr0/127+i*rr1/127;
	glut[i] = i+(127-i)*gg0/127+i*gg1/127;
	blut[i] = i+(127-i)*bb0/127+i*bb1/127;
	if rlut[i] < 0
		rlut[i] = 0;
	else if rlut[i] > 255
		rlut[i] = 255;
	end if;
	if glut[i] < 0
		glut[i] = 0;
	else if glut[i] > 255
		glut[i] = 255;
	end if;	
	if blut[i] < 0
		blut[i] = 0;
	else if blut[i] > 255
		blut[i] = 255;
	end if;
next;
for i = 128 to 255
	rlut[i] = i+(255-i)*rr1/127+(i-128)*rr2/127;
	glut[i] = i+(255-i)*gg1/127+(i-128)*gg2/127;
	blut[i] = i+(255-i)*bb1/127+(i-128)*bb2/127;
	if rlut[i] < 0
		rlut[i] = 0;
	else if rlut[i] > 255
		rlut[i] = 255;
	end if;
	if glut[i] < 0
		glut[i] = 0;
	else if glut[i] > 255
		glut[i] = 255;
	end if;	
	if blut[i] < 0
		blut[i] = 0;
	else if blut[i] > 255
		blut[i] = 255;
	end if;
next;
rlut /= 255;
glut /= 255;
blut /= 255;

levelmap(src1, dest, linearRamp, rlut, glut, blut);
colorTransform(dest, dest, RGBtoYUV, offset0, offset128);

colorTransform(Src1, buf, RGBtoYUV, offset0, offset128);

channelcopy(buf, dest, knone, kred, knone, knone);
colorTransform(Dest, Dest, YUVtoRGB, offset128, offset0);