RGB Color Darkener…

[nchipping]

I am in need of making this color class work well – I am trying to have it so that if I give it a color, it will take that color, make it 20% darker, and return it to me. Any pointers on what I’m doing wrong here?

/**

* COLOR

* For use with changing colors from HSV to RGB & the other way around

*/

class Color

{

private $color;

public function HSVtoRGB($tmp)

{

$tmp = explode(",",$tmp);

$H = $tmp[0] / 360;

$S = $tmp[1] / 100;

$V = $tmp[2] / 100;



if ($S == 0) {

$R = $V * 255;

$G = $V * 255;

$B = $V * 255;

} else {

$var_h = $H * 6;

$var_i = floor($var_h);

$var_1 = $V * (1 - $S);

$var_2 = $V * (1 - $S * ($var_h - $var_i));

$var_3 = $V * (1 - $S * (1 - ($var_h - $var_i)));



if ($var_i == 0) {$var_r = $V; $var_g = $var_3; $var_b = $var_1;

} else if ($var_i == 1) {$var_r =$var_2;$var_g = $V;$var_b =$var_1;

} else if ($var_i == 2) {$var_r =$var_1;$var_g = $V;$var_b =$var_3;

} else if ($var_i == 3) {$var_r =$var_1;$var_g =$var_2;$var_b = $V;

} else if ($var_i == 4) {$var_r =$var_3;$var_g =$var_1;$var_b = $V;

} else {$var_r = $V;$var_g =$var_1;$var_b =$var_2;

}

$R = $var_r * 255;

$G = $var_g * 255;

$B = $var_b * 255;

}

$color = round($R) . "," . round($G) . "," . round($B);

return $color;

}



public function RGBtoHSV($tmp)

{

$tmp = explode(",",$tmp);

$R = $tmp[0] / 255.0;

$G = $tmp[1] / 255.0;

$B = $tmp[2] / 255.0;

$H = 0;

$S = 0;

$V = 0;



$min = min(min($R, $G),$B);

$max = max(max($d, $G),$B);

$delta = $max - $min;



$V = $max;

if($delta == 0) {

$H = 0;

$S = 0;

} else {

$S = $delta / $max;

$dR = ((($max - $R) / 6) + ($delta / 2)) / $delta;

$dG = ((($max - $G) / 6) + ($delta / 2)) / $delta;

$dB = ((($max - $B) / 6) + ($delta / 2)) / $delta;



if ($R == $max) {

$H = $dB - $dG;

} else if($G == $max) {

$H = (1/3) + $dR - $dB;

} else {

$H = (2/3) + $dG - $dR;

}

if ($H < 0) { $H += 1; }

if ($H > 1) { $H -= 1; }

}

$color = round($H*360) . ',' . round($S*100) . ',' . round($V*100);

return $color;

}



public function RGBtoDark($tmp)

{

$HSV = $this->RGBtoHSV($tmp);

$HSV = explode(",",$HSV);

$HSV[2] = $HSV[2] - 20;

$HSV = $HSV[0] . "," . $HSV[1] . "," . $HSV[2];

$RGB = $this->HSVtoRGB($HSV);

return $RGB;

}

}

?>

By the way – the only reason I’m converting to HSV, and then back to RGB is that I saw that Photoshop can take HSV values in percentages and I tried to follow that. Thanks.

[nchipping]

Does anyone have any ideas on this one? I really don’t know much about color conversion, and any help of getting a more accurate conversion would be very, very helpful.

[Historical Forums User]

Howdy, I can’t really help aside from point to some work that has already been done. Perhaps this guy’s work, and tutorial, will help you figure this out…

http://serennu.com/colour/rgbtohsl.php

[nchipping]

That worked – thank you!!

[Author]

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