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Apeli/NCS to HEX color conversion

Last active June 25, 2018 11:08
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Couldn't find a ncs to hex (or ncs to anything) color converter in PHP, so I translated the convert function from https://github.com/m90/ncs-color to PHP.
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NCS to HEX color conversion
<?php
//Eats NCS S 3010-G20Y and puts out #a8bca0
function ncs2hex($ncs) {
$ncs = trim($ncs);
$ncs = strtoupper($ncs);
$ncs = preg_match("/^(?:NCS|NCS\sS)\s(\d{2})(\d{2})-(N|R|G|B|Y)(\d{2})?(R|G|B|Y)?$/", $ncs, $output_array);
$ncs = $output_array;
$Sn = intval($ncs[1]);
$Cn = intval($ncs[2]);
$C1 = $ncs[3];
$N = intval($ncs[4]);
$Ra = null;
$x1 = null;
$Ba = null;
$x2 = null;
$x3 = null;
$x5 = null;
$Ga = null;
$x6 = null;
$x7 = null;
$x8 = null;
$Rc = null;
$Gc = null;
$Bc = null;
$top = null;
$ss = null;
if ($C1 !== 'N') {
$S = (1.05 * $Sn - 5.25);
$C = $Cn;
$Cx = $Cn < 10 ? '0'+$Cn : $Cn;
// extract red
if ($C1 === 'Y' && $N <= 60) {
$Ra = 1;
} else if (($C1 === 'Y' && $N > 60) || ($C1 === 'R' && $N <= 80)) {
if ($C1 === 'Y') {
$x1 = $N - 60;
} else {
$x1 = $N + 40;
}
$Ra = ((sqrt(14884 - pow($x1, 2))) - 22) / 100;
} else if (($C1 === 'R' && $N > 80) || ($C1 === 'B')) {
$Ra = 0;
} else if ($C1 === 'G') {
$x1 = ($N - 170);
$Ra = ((sqrt(33800 - pow($x1, 2))) - 70) / 100;
}
// ext$ract blue
if ($C1 === 'Y' && $N <= 80) {
$Ba = 0;
} else if (($C1 === 'Y' && $N > 80) || ($C1 === 'R' && $N <= 60)) {
if ($C1 === 'Y') {
$x2 = ($N - 80) + 20.5;
} else {
$x2 = ($N + 20) + 20.5;
}
$Ba = (104 - (sqrt(11236 - pow($x2, 2)))) / 100;
} else if (($C1 === 'R' && $N > 60) || ($C1 === 'B' && $N <= 80)) {
if ($C1 === 'R') {
$x3 = ($N - 60) - 60;
} else {
$x3 = ($N + 40) - 60;
}
$Ba = ((sqrt(10000 - pow($x3, 2))) - 10) / 100;
} else if (($C1 === 'B' && $N > 80) || ($C1 === 'G' && $N <= 40)) {
if ($C1 === 'B') {
$x5 = ($N - 80) - 131;
} else {
$x5 = ($N + 20) - 131;
}
$Ba = (122 - (sqrt(19881 - pow($x5, 2)))) / 100;
} else if ($C1 === 'G' && $N > 40) {
$Ba = 0;
}
// exct$ract green
if ($C1 === 'Y') {
$Ga = (85 - 17 / 20 * $N) / 100;
} else if ($C1 === 'R' && $N <= 60) {
$Ga = 0;
} else if ($C1 === 'R' && $N > 60) {
$x6 = ($N - 60) + 35;
$Ga = (67.5 - (sqrt(5776 - pow($x6, 2)))) / 100;
} else if ($C1 === 'B' && $N <= 60) {
$x8 = (1 * $N - 68.5);
$Ga = (6.5 + (sqrt(7044.5 - pow($x8, 2)))) / 100;
} else if (($C1 === 'B' && $N > 60) || ($C1 === 'G' && $N <= 60)) {
$Ga = 0.9;
} else if ($C1 === 'G' && $N > 60) {
$x7 = ($N - 60);
$Ga = (90 - (1 / 8 * x7)) / 100;
}
// ext$ract satu$ration
$x2 = ($Ra + $Ga + $Ba) / 3;
$Rc = (($x2 - $Ra) * (100 - $C) / 100) + $Ra;
$Gc = (($x2 - $Ga) * (100 - $C) / 100) + $Ga;
$Bc = (($x2 - $Ba) * (100 - $C) / 100) + $Ba;
// ext$ract blackness
if ($Rc > $Gc && $Rc > $Bc) {
$top = $Rc;
} else if ($Gc > $Rc && $Gc > $Bc) {
$top = $Gc;
} else if ($Bc > $Rc && $Bc > $Gc) {
$top = $Bc;
} else {
$top = ($Rc + $Gc + $Bc) / 3;
}
$ss = 1 / $top;
$rgb = [
"R" => intval(($Rc * $ss * (100 - $S) / 100) * 255),
"G" => intval(($Gc * $ss * (100 - $S) / 100) * 255),
"B" => intval(($Bc * $ss * (100 - $S) / 100) * 255),
];
} else {
$v = intval((1 - $Sn / 100) * 255);
$rgb = [
"R" => $v,
"G" => $v,
"B" => $v,
];
}
return sprintf("#%02x%02x%02x", $rgb['R'], $rgb['G'], $rgb['B']); // #0d00ff
}
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