RGB à HSV en PHP

En PHP, ce qui est la façon la plus simple pour convertir RVB, triplet de valeurs HSV?

<?php
function RGB_TO_HSV ($R, $G, $B)  //RGB Values:Number 0-255
{                                 //HSV Results:Number 0-1
$HSL = array();
$var_R = ($R / 255);
$var_G = ($G / 255);
$var_B = ($B / 255);
$var_Min = min($var_R, $var_G, $var_B);
$var_Max = max($var_R, $var_G, $var_B);
$del_Max = $var_Max - $var_Min;
$V = $var_Max;
if ($del_Max == 0)
{
$H = 0;
$S = 0;
}
else
{
$S = $del_Max / $var_Max;
$del_R = ( ( ( $var_Max - $var_R ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
$del_G = ( ( ( $var_Max - $var_G ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
$del_B = ( ( ( $var_Max - $var_B ) / 6 ) + ( $del_Max / 2 ) ) / $del_Max;
if      ($var_R == $var_Max) $H = $del_B - $del_G;
else if ($var_G == $var_Max) $H = ( 1 / 3 ) + $del_R - $del_B;
else if ($var_B == $var_Max) $H = ( 2 / 3 ) + $del_G - $del_R;
if ($H<0) $H++;
if ($H>1) $H--;
}
$HSL['H'] = $H;
$HSL['S'] = $S;
$HSL['V'] = $V;
return $HSL;
}

Ici est une simple méthode qui retourne le HSV valeurs en degrés et en pourcentages, ce qui est le Photoshop du sélecteur de couleurs utilise.

Remarque que les valeurs de retour ne sont pas arrondis, vous pouvez le faire vous-même si nécessaire. Gardez à l'esprit que H(360) == H(0)donc H valeurs de 359.5 et plus grande doit tour à 0

Fortement documenté à des fins d'apprentissage.

/**
* Licensed under the terms of the BSD License.
* (Basically, this means you can do whatever you like with it,
*   but if you just copy and paste my code into your app, you
*   should give me a shout-out/credit :)
*/
<?php
function RGBtoHSV($R, $G, $B)    //RGB values:    0-255, 0-255, 0-255
{                                //HSV values:    0-360, 0-100, 0-100
//Convert the RGB byte-values to percentages
$R = ($R / 255);
$G = ($G / 255);
$B = ($B / 255);
//Calculate a few basic values, the maximum value of R,G,B, the
//  minimum value, and the difference of the two (chroma).
$maxRGB = max($R, $G, $B);
$minRGB = min($R, $G, $B);
$chroma = $maxRGB - $minRGB;
//Value (also called Brightness) is the easiest component to calculate,
//  and is simply the highest value among the R,G,B components.
//We multiply by 100 to turn the decimal into a readable percent value.
$computedV = 100 * $maxRGB;
//Special case if hueless (equal parts RGB make black, white, or grays)
//Note that Hue is technically undefined when chroma is zero, as
//  attempting to calculate it would cause division by zero (see
//  below), so most applications simply substitute a Hue of zero.
//Saturation will always be zero in this case, see below for details.
if ($chroma == 0)
return array(0, 0, $computedV);
//Saturation is also simple to compute, and is simply the chroma
//  over the Value (or Brightness)
//Again, multiplied by 100 to get a percentage.
$computedS = 100 * ($chroma / $maxRGB);
//Calculate Hue component
//Hue is calculated on the "chromacity plane", which is represented
//  as a 2D hexagon, divided into six 60-degree sectors. We calculate
//  the bisecting angle as a value 0 <= x < 6, that represents which
//  portion of which sector the line falls on.
if ($R == $minRGB)
$h = 3 - (($G - $B) / $chroma);
elseif ($B == $minRGB)
$h = 1 - (($R - $G) / $chroma);
else //$G == $minRGB
$h = 5 - (($B - $R) / $chroma);
//After we have the sector position, we multiply it by the size of
//  each sector's arc (60 degrees) to obtain the angle in degrees.
$computedH = 60 * $h;
return array($computedH, $computedS, $computedV);
}
?>

Voici ma rotation sur elle-même, avec une unité de test. Depuis le S et V les valeurs sont des pourcentages, ce code renvoie sous la forme d'entiers (0, 100), par opposition à (0, 1) - Exemple, 75 au lieu de 0.75.

final class MathService
{    
/**
* Converts an RGB point into HSV
*
* @param int $r
* @param int $g
* @param int $b
* @return array
*/
public function rgbToHsv(int $r, int $g, int $b): array
{
$rPrime = $r / 255;
$gPrime = $g / 255;
$bPrime = $b / 255;
$max = max([$rPrime, $gPrime, $bPrime]);
$min = min([$rPrime, $gPrime, $bPrime]);
$delta = $max - $min;
//Calculate H
if ($delta == 0) {
$h = 0;
} else {
if ($max === $rPrime) {
$h = 60 * ((($gPrime - $bPrime) / $delta) % 6);
}
if ($max === $gPrime) {
$h = 60 * ((($bPrime - $rPrime) / $delta) + 2);
}
if ($max === $bPrime) {
$h = 60 * ((($rPrime - $gPrime) / $delta) + 4);
}
}
//Calculate S
if ($max == 0) {
$s = 0;
} else {
$s = $delta / $max;
}
//Calculate V
$v = $max;
return [$h, (int)($s * 100), (int)($v * 100)];
}
}

PHPUnit cas de test avec PHP 7.2

/**
* @test
*/
public function rgbToHsv_ComputesCorrectValues(): void
{
$service = new MathService();
$samples = [
//[R, G, B, H, S, V]
[0, 0, 0, 0, 0, 0],
[255, 255, 255, 0, 0, 100],
[255, 0, 0, 0, 100, 100],
[0, 255, 0, 120, 100, 100],
[0, 0, 255, 240, 100, 100],
[255, 255, 0, 60, 100, 100],
[0, 255, 255, 180, 100, 100],
[255, 0, 255, 300, 100, 100],
[192, 192, 192, 0, 0, 75],
[128, 128, 128, 0, 0, 50],
[128, 0, 0, 0, 100, 50],
[128, 128, 0, 60, 100, 50],
[0, 128, 0, 120, 100, 50],
[128, 0, 128, 300, 100, 50],
[0, 128, 128, 180, 100, 50],
[0, 0, 128, 240, 100, 50],
];
foreach ($samples as $sample) {
list($r, $g, $b) = array_slice($sample, 0, 3);
$expected = array_slice($sample, 3);
$hsv = $service->rgbToHsv($r, $g, $b);
list($h, $s, $v) = $hsv;
self::assertEquals($expected, $hsv, "Error converting ({$r}, ${g}, ${b}). Got ({$h}, {$s}, {$v})");
}
}

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