I was going to ask you how you were calculating that the values were 'wrong'. However I realised that doing the conversion RGB -> HSL -> RGB gives different RGB color than the starting one.....e.g. the code below outputs:

InputColor: rgb(158, 146, 130)
FinalColor: rgb(158.00, 141.00, 130.00)


This is very likely going to be an issue with the underlying ImageMagick library, which I will need to investigate and report upstream.


$inputColor = "rgb(158, 146, 130)";

$fromRGB = new ImagickPixel($inputColor);
$hsl = $fromRGB->getHSL();

$hslString = sprintf(
	"hsl(%.4f, %.4f, %.4f)", 
	$hsl['hue'] * 255,
	$hsl['saturation'] * 255,
	$hsl['luminosity'] * 255
);

$fromHSL = new ImagickPixel($hslString);
$outputColorArray = $fromHSL->getColor(false);
$finalColor = sprintf(
    "rgb(%.2f, %.2f, %.2f)", 
    $outputColorArray['r'],
    $outputColorArray['g'],
    $outputColorArray['b']
);

echo "hslString is $hslString\n";

echo "InputColor: ".$inputColor."\n";
echo "FinalColor: ".$finalColor."\n";

Reported upstream as: https://github.com/ImageMagick/ImageMagick/issues/64

So, it's not a bug.

The values are all normalized 0 - 1.0. Most HSL converters don't normalize the hue to that range, and instead have 0-360 or 0-3.6. 

To get your expected result you need to multiply by 3.6

Forgot to change the status before.