PHP Work out colour saturation

Question

lets say i have the following RGB values:

R:129 G:98 B:87

Photoshop says the saturation of that colour is 33%

How would i work out that percentage using PHP and the RGB values?

http://stackoverflow.com/questions/1773698/rgb-to-hsv-in-php — oops, Mar 05 '10 at 00:56

score 3 · Accepted Answer · edited May 23 '17 at 12:31

3

See RGB to HSV in PHP

Taking only the saturation bits from that code, and converting into a percentage:

function saturation($R, $G, $B) {  // 0-255
     $Min = min($R, $G, $B);
     $Max = max($R, $G, $B);
     return $Max == 0 ? 0 : (($Max - $Min) / $Max) * 100;
}

Alternately you could use the original code in the link above - the HSV values it returns are between 0.0 and 1.0, so you just need to multiply the saturation value by 100 to get your percentage.

edited May 23 '17 at 12:31

Community

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answered Mar 05 '10 at 00:56

rjh

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Perfect :) Thanks for rewriting it to be much smaller, running this in every iteration of a 600 * 600 loop :P – Ozzy Mar 05 '10 at 01:08
This produces inaccurate results if `255` is not one of the passed values, and errors out if black (`0,0,0`) is passed. Works great if you change the return statement to: `return $Max ? (($Max - $Min) / 255) : 0;` – Stephen M. Harris Jun 24 '14 at 17:39
Thanks, I corrected the division by zero. However, I am not sure why the second `$Max` should be replaced with 255, that's not in any other code I can see? – rjh Jun 24 '14 at 19:44

score 0 · Answer 2 · answered Mar 05 '10 at 01:00

PEAR (PHP Extensions And Application Repository) has a nice package called Image_Color2 which allows you do to quick conversions between different color models:

include "Image/Color2.php";

$color = new Image_Color2(array(129,98,87));
$hsv = $color->convertTo('hsv');
$hsvArray = $hsv->getArray();

echo "Hue is " . $hsvArray[0] . "\n";
echo "Saturation is: " . $hsvArray[1] . "\n";
echo "Brightness is: " . $hsvArray[2];

PHP Work out colour saturation

2 Answers2