Die Testst für die Standardfarben sind erfolgreich.

src/Transformer/CyanMagentaYellowKeyTransformer.php

@@ -5,6 +5,7 @@ namespace TorstenHettstedt\Colors\Transformer;
 
 
 use TorstenHettstedt\Colors\ColorModels\CyanMagentaYellowKey;
+use TorstenHettstedt\Colors\ColorModels\HueSaturationValue;
 use TorstenHettstedt\Colors\ColorModels\RedGreenBlue;
 
 class CyanMagentaYellowKeyTransformer implements ColorModelTransformInterface
@@ -42,4 +43,10 @@ class CyanMagentaYellowKeyTransformer implements ColorModelTransformInterface
     {
         return clone $this->color;
     }
+
+    public function toHueSaturationValue(): HueSaturationValue
+    {
+        $utility = new Utilities\CyanMagentaYellowKeyToHueSaturationValue($this->color);
+        return $utility->convert();
+    }
 }

src/Transformer/Utilities/CyanMagentaYellowKeyToHueSaturationValue.php

@@ -0,0 +1,131 @@
+<?php
+
+namespace TorstenHettstedt\Colors\Transformer\Utilities;
+
+use TorstenHettstedt\Colors\ColorModels\CyanMagentaYellowKey;
+use TorstenHettstedt\Colors\ColorModels\HueSaturationValue;
+
+class CyanMagentaYellowKeyToHueSaturationValue
+{
+
+    const PROPERTY_CYAN = 'cyan';
+    const PROPERTY_MAGENTA = 'magenta';
+    const PROPERTY_YELLOW = 'yellow';
+    const PROPERTY_KEY = 'key';
+
+    // Daten für CMYK
+    /** @var float : Definition des Cyan-Anteil */
+    protected float $cyan;
+    /** @var float : Definition des Magenta-Anteil */
+    protected float $magenta;
+    /** @var float : Definition des Gelbanteil */
+    protected float $yellow;
+    /** @var float : Definition des Schwarzanteil */
+    protected float $key;
+
+    /** @var float : Der größte CMY-Farbwert */
+    protected float $maxCmyProperty;
+    /** @var float : Der kleinste CMY-Farbwert */
+    protected float $minCmyProperty;
+
+    // Daten für HSV
+    /** @var float : Definition des Farbton als Anteil eines Vollkreises '$Hue * π' */
+    protected float $hue = 0.0;
+    /** @var float : Definition der Sättigung der Farbe */
+    protected float $saturation = 0.0;
+    /** @var float : Definition der Helligkeit der Farbe */
+    protected float $value = 1.0;
+
+    /**
+     * CyanMagentaYellowKeyToHueSaturationValue constructor.
+     * @param CyanMagentaYellowKey $from_color
+     * @noinspection PhpPureAttributeCanBeAddedInspection
+     */
+    public function __construct(CyanMagentaYellowKey $from_color)
+    {
+        $this->cyan = $from_color->getCyan();
+        $this->magenta = $from_color->getMagenta();
+        $this->yellow = $from_color->getYellow();
+        $this->key = $from_color->getKey();
+    }
+
+    protected function processConvert(): void
+    {
+        $this->maxCmyProperty = max($this->cyan, $this->magenta, $this->yellow);
+        $this->minCmyProperty = min($this->cyan, $this->magenta, $this->yellow);
+
+        $this->hue = round($this->buildHueAmount(), 3);
+        $this->hue = $this->buildHueAmount();
+        $this->saturation = $this->buildSaturationAmount();
+        $this->value = 1 - $this->key;
+    }
+
+    public function convert(): HueSaturationValue
+    {
+        $this->processConvert();
+
+        return (new HueSaturationValue())
+            ->setHue($this->hue)
+            ->setSaturation($this->saturation)
+            ->setValue($this->value);
+    }
+
+    protected function buildHueAmount(): float
+    {
+        if ($this->maxCmyProperty === 0) {
+            return 0.0;
+        }
+
+        return match ($this->maxCmyProperty) {
+            $this->cyan => $this->hueAmount(self::PROPERTY_CYAN),
+            $this->magenta => $this->hueAmount(self::PROPERTY_MAGENTA),
+            default => $this->hueAmount(self::PROPERTY_YELLOW),
+        };
+    }
+
+    protected function buildSaturationAmount(): float
+    {
+        if ($this->maxCmyProperty === 0.0) {
+            return 0.0;
+        }
+
+        return ($this->maxCmyProperty - $this->minCmyProperty) / $this->maxCmyProperty;
+    }
+
+    /**
+     * @param string $property  : Name der CMYK-Eigenschaft
+     * @return float
+     */
+    private function hueAmount(string $property): float
+    {
+        if ($this->maxCmyProperty === 0.0) {
+            return 0.0;
+        }
+
+        static $amount_share = 2.0;
+
+        $divisor = $this->maxCmyProperty - $this->minCmyProperty;
+
+        switch ($property) {
+            case self::PROPERTY_YELLOW:
+                $amount = 0; // 0.167
+                $dividend = $this->cyan - $this->magenta;
+                break;
+            case self::PROPERTY_CYAN:
+                $amount = 1; // 0.500
+                $dividend = $this->magenta -$this->yellow;
+                break;
+            case self::PROPERTY_MAGENTA:
+                $amount = 2; // 0.833
+                $dividend = $this->yellow - $this->cyan;
+                break;
+            default:
+                return 0;
+        }
+
+        $start_amount = ($amount * $amount_share) + 1.0;
+        $expansion_amount = $dividend / $divisor;
+        return ($start_amount + $expansion_amount) / 6.0;
+    }
+
+}