From 30ab6a6c5439de155e5487aaced28f4ef682f39b Mon Sep 17 00:00:00 2001
From: Oliver Vogel <oliver@olivervogel.com>
Date: Sat, 2 Dec 2023 12:07:30 +0100
Subject: [PATCH] Implement HSL color model & fix bugs

---
 src/Colors/Cmyk/Colorspace.php                |   2 +
 src/Colors/Hsl/Channels/Hue.php               |  28 ++++
 src/Colors/Hsl/Channels/Luminance.php         |  28 ++++
 src/Colors/Hsl/Channels/Saturation.php        |  28 ++++
 src/Colors/Hsl/Color.php                      | 148 ++++++++++++++++++
 src/Colors/Hsl/Colorspace.php                 | 109 +++++++++++++
 .../Hsl/Decoders/StringColorDecoder.php       |  40 +++++
 src/Colors/Hsv/Colorspace.php                 |  22 ++-
 src/Colors/Rgb/Colorspace.php                 |  31 ++++
 src/Drivers/Gd/ColorProcessor.php             |   2 +-
 src/Drivers/Gd/InputHandler.php               |   2 +
 src/Drivers/Imagick/InputHandler.php          |   2 +
 tests/Colors/Cmyk/ColorspaceTest.php          |  41 ++++-
 tests/Colors/Hsl/ChannelTest.php              |  74 +++++++++
 tests/Colors/Hsl/ColorTest.php                |  84 ++++++++++
 tests/Colors/Hsl/ColorspaceTest.php           |  70 +++++++++
 .../Hsl/Decoders/StringColorDecoderTest.php   |  35 +++++
 tests/Colors/Hsv/ColorspaceTest.php           |  47 +++++-
 tests/Colors/Rgb/ColorspaceTest.php           |  53 +++++--
 19 files changed, 817 insertions(+), 29 deletions(-)
 create mode 100644 src/Colors/Hsl/Channels/Hue.php
 create mode 100644 src/Colors/Hsl/Channels/Luminance.php
 create mode 100644 src/Colors/Hsl/Channels/Saturation.php
 create mode 100644 src/Colors/Hsl/Color.php
 create mode 100644 src/Colors/Hsl/Colorspace.php
 create mode 100644 src/Colors/Hsl/Decoders/StringColorDecoder.php
 create mode 100644 tests/Colors/Hsl/ChannelTest.php
 create mode 100644 tests/Colors/Hsl/ColorTest.php
 create mode 100644 tests/Colors/Hsl/ColorspaceTest.php
 create mode 100644 tests/Colors/Hsl/Decoders/StringColorDecoderTest.php

diff --git a/src/Colors/Cmyk/Colorspace.php b/src/Colors/Cmyk/Colorspace.php
index 45e1065a..e67072b2 100644
--- a/src/Colors/Cmyk/Colorspace.php
+++ b/src/Colors/Cmyk/Colorspace.php
@@ -5,6 +5,7 @@ namespace Intervention\Image\Colors\Cmyk;
 use Intervention\Image\Colors\Rgb\Color as RgbColor;
 use Intervention\Image\Colors\Cmyk\Color as CmykColor;
 use Intervention\Image\Colors\Hsv\Color as HsvColor;
+use Intervention\Image\Colors\Hsl\Color as HslColor;
 use Intervention\Image\Colors\Rgb\Colorspace as RgbColorspace;
 use Intervention\Image\Interfaces\ColorInterface;
 use Intervention\Image\Interfaces\ColorspaceInterface;
@@ -42,6 +43,7 @@ class Colorspace implements ColorspaceInterface
         return match (get_class($color)) {
             RgbColor::class => $this->importRgbColor($color),
             HsvColor::class => $this->importRgbColor($color->convertTo(RgbColorspace::class)),
+            HslColor::class => $this->importRgbColor($color->convertTo(RgbColorspace::class)),
             default => $color,
         };
     }
diff --git a/src/Colors/Hsl/Channels/Hue.php b/src/Colors/Hsl/Channels/Hue.php
new file mode 100644
index 00000000..e795aebb
--- /dev/null
+++ b/src/Colors/Hsl/Channels/Hue.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace Intervention\Image\Colors\Hsl\Channels;
+
+use Intervention\Image\Colors\AbstractColorChannel;
+
+class Hue extends AbstractColorChannel
+{
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorChannelInterface::min()
+     */
+    public function min(): int
+    {
+        return 0;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorChannelInterface::max()
+     */
+    public function max(): int
+    {
+        return 360;
+    }
+}
diff --git a/src/Colors/Hsl/Channels/Luminance.php b/src/Colors/Hsl/Channels/Luminance.php
new file mode 100644
index 00000000..77aa34cf
--- /dev/null
+++ b/src/Colors/Hsl/Channels/Luminance.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace Intervention\Image\Colors\Hsl\Channels;
+
+use Intervention\Image\Colors\AbstractColorChannel;
+
+class Luminance extends AbstractColorChannel
+{
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorChannelInterface::min()
+     */
+    public function min(): int
+    {
+        return 0;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorChannelInterface::max()
+     */
+    public function max(): int
+    {
+        return 100;
+    }
+}
diff --git a/src/Colors/Hsl/Channels/Saturation.php b/src/Colors/Hsl/Channels/Saturation.php
new file mode 100644
index 00000000..c63d20df
--- /dev/null
+++ b/src/Colors/Hsl/Channels/Saturation.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace Intervention\Image\Colors\Hsl\Channels;
+
+use Intervention\Image\Colors\AbstractColorChannel;
+
+class Saturation extends AbstractColorChannel
+{
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorChannelInterface::min()
+     */
+    public function min(): int
+    {
+        return 0;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorChannelInterface::max()
+     */
+    public function max(): int
+    {
+        return 100;
+    }
+}
diff --git a/src/Colors/Hsl/Color.php b/src/Colors/Hsl/Color.php
new file mode 100644
index 00000000..57858db5
--- /dev/null
+++ b/src/Colors/Hsl/Color.php
@@ -0,0 +1,148 @@
+<?php
+
+namespace Intervention\Image\Colors\Hsl;
+
+use Intervention\Image\Colors\Hsl\Channels\Hue;
+use Intervention\Image\Colors\Hsl\Channels\Luminance;
+use Intervention\Image\Colors\Hsl\Channels\Saturation;
+use Intervention\Image\Colors\Rgb\Colorspace as RgbColorspace;
+use Intervention\Image\Colors\Traits\CanHandleChannels;
+use Intervention\Image\Drivers\AbstractInputHandler;
+use Intervention\Image\Interfaces\ColorChannelInterface;
+use Intervention\Image\Interfaces\ColorInterface;
+use Intervention\Image\Interfaces\ColorspaceInterface;
+
+class Color implements ColorInterface
+{
+    use CanHandleChannels;
+
+    /**
+     * Color channels
+     */
+    protected array $channels;
+
+    public function __construct(int $h, int $s, int $l)
+    {
+        $this->channels = [
+            new Hue($h),
+            new Saturation($s),
+            new Luminance($l),
+        ];
+    }
+
+    public function colorspace(): ColorspaceInterface
+    {
+        return new Colorspace();
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::create()
+     */
+    public static function create(mixed $input): ColorInterface
+    {
+        return (new class ([
+            Decoders\StringColorDecoder::class,
+        ]) extends AbstractInputHandler
+        {
+        })->handle($input);
+    }
+
+    /**
+     * Return the Hue channel
+     *
+     * @return ColorChannelInterface
+     */
+    public function hue(): ColorChannelInterface
+    {
+        return $this->channel(Hue::class);
+    }
+
+    /**
+     * Return the Saturation channel
+     *
+     * @return ColorChannelInterface
+     */
+    public function saturation(): ColorChannelInterface
+    {
+        return $this->channel(Saturation::class);
+    }
+
+    /**
+     * Return the Luminance channel
+     *
+     * @return ColorChannelInterface
+     */
+    public function luminance(): ColorChannelInterface
+    {
+        return $this->channel(Luminance::class);
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::toArray()
+     */
+    public function toArray(): array
+    {
+        return array_map(function (ColorChannelInterface $channel) {
+            return $channel->value();
+        }, $this->channels());
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::convertTo()
+     */
+    public function convertTo(string|ColorspaceInterface $colorspace): ColorInterface
+    {
+        $colorspace = match (true) {
+            is_object($colorspace) => $colorspace,
+            default => new $colorspace(),
+        };
+
+        return $colorspace->importColor($this);
+    }
+
+    public function toHex(string $prefix = ''): string
+    {
+        return $this->convertTo(RgbColorspace::class)->toHex($prefix);
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::toString()
+     */
+    public function toString(): string
+    {
+        return sprintf(
+            'hsl(%d, %d%%, %d%%)',
+            $this->hue()->value(),
+            $this->saturation()->value(),
+            $this->luminance()->value()
+        );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::isGreyscale()
+     */
+    public function isGreyscale(): bool
+    {
+        return $this->saturation()->value() == 0;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::__toString()
+     */
+    public function __toString(): string
+    {
+        return $this->toString();
+    }
+}
diff --git a/src/Colors/Hsl/Colorspace.php b/src/Colors/Hsl/Colorspace.php
new file mode 100644
index 00000000..7a26cfde
--- /dev/null
+++ b/src/Colors/Hsl/Colorspace.php
@@ -0,0 +1,109 @@
+<?php
+
+namespace Intervention\Image\Colors\Hsl;
+
+use Intervention\Image\Colors\Cmyk\Color as CmykColor;
+use Intervention\Image\Colors\Rgb\Color as RgbColor;
+use Intervention\Image\Colors\Hsv\Color as HsvColor;
+use Intervention\Image\Colors\Rgb\Colorspace as RgbColorspace;
+use Intervention\Image\Interfaces\ColorInterface;
+use Intervention\Image\Interfaces\ColorspaceInterface;
+
+class Colorspace implements ColorspaceInterface
+{
+    public static $channels = [
+        Channels\Hue::class,
+        Channels\Saturation::class,
+        Channels\Luminance::class
+    ];
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorspaceInterface::colorFromNormalized()
+     */
+    public function colorFromNormalized(array $normalized): ColorInterface
+    {
+        $values = array_map(function ($classname, $value_normalized) {
+            return (new $classname(normalized: $value_normalized))->value();
+        }, self::$channels, $normalized);
+
+        return new Color(...$values);
+    }
+
+    public function importColor(ColorInterface $color): ColorInterface
+    {
+        return match (get_class($color)) {
+            CmykColor::class => $this->importRgbColor($color->convertTo(RgbColorspace::class)),
+            RgbColor::class => $this->importRgbColor($color),
+            HsvColor::class => $this->importHsvColor($color),
+            default => $color,
+        };
+    }
+
+    protected function importRgbColor(RgbColor $color): ColorInterface
+    {
+        // normalized values of rgb channels
+        $values = array_map(function ($channel) {
+            return $channel->normalize();
+        }, $color->channels());
+
+        // take only RGB
+        $values = array_slice($values, 0, 3);
+
+        // calculate Luminance
+        $min = min(...$values);
+        $max = max(...$values);
+        $luminance = ($max + $min) / 2;
+        $delta = $max - $min;
+
+        // calculate saturation
+        $saturation = match (true) {
+            $delta == 0 => 0,
+            default => $delta / (1 - abs(2 * $luminance - 1)),
+        };
+
+        // calculate hue
+        list($r, $g, $b) = $values;
+        $hue = match (true) {
+            ($delta == 0) => 0,
+            ($max == $r) => 60 * fmod((($g - $b) / $delta), 6),
+            ($max == $g) => 60 * ((($b - $r) / $delta) + 2),
+            ($max == $b) => 60 * ((($r - $g) / $delta) + 4),
+            default => 0,
+        };
+
+        $hue = ($hue + 360) % 360; // normalize hue
+
+        return new Color(
+            intval(round($hue)),
+            intval(round($saturation * 100)),
+            intval(round($luminance * 100)),
+        );
+    }
+
+    protected function importHsvColor(HsvColor $color): ColorInterface
+    {
+        // normalized values of hsv channels
+        list($h, $s, $v) = array_map(function ($channel) {
+            return $channel->normalize();
+        }, $color->channels());
+
+        // calculate Luminance
+        $luminance = (2 - $s) * $v / 2;
+
+        // calculate Saturation
+        $saturation = match (true) {
+            $luminance == 0 => $s,
+            $luminance == 1 => 0,
+            $luminance < .5 => $s * $v / ($luminance * 2),
+            default => $s * $v / (2 - $luminance * 2),
+        };
+
+        return new Color(
+            intval(round($h * 360)),
+            intval(round($saturation * 100)),
+            intval(round($luminance * 100)),
+        );
+    }
+}
diff --git a/src/Colors/Hsl/Decoders/StringColorDecoder.php b/src/Colors/Hsl/Decoders/StringColorDecoder.php
new file mode 100644
index 00000000..21944354
--- /dev/null
+++ b/src/Colors/Hsl/Decoders/StringColorDecoder.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace Intervention\Image\Colors\Hsl\Decoders;
+
+use Intervention\Image\Colors\Hsl\Color;
+use Intervention\Image\Drivers\AbstractDecoder;
+use Intervention\Image\Exceptions\DecoderException;
+use Intervention\Image\Interfaces\ColorInterface;
+use Intervention\Image\Interfaces\DecoderInterface;
+use Intervention\Image\Interfaces\ImageInterface;
+
+class StringColorDecoder extends AbstractDecoder implements DecoderInterface
+{
+    /**
+     * Decode hsl color strings
+     *
+     * @param  mixed $input
+     * @return ImageInterface|ColorInterface
+     */
+    public function decode($input): ImageInterface|ColorInterface
+    {
+        if (! is_string($input)) {
+            throw new DecoderException('Unable to decode input');
+        }
+
+        $pattern = '/^hsl\((?P<h>[0-9\.]+), ?(?P<s>[0-9\.]+%?), ?(?P<l>[0-9\.]+%?)?\)$/i';
+        if (preg_match($pattern, $input, $matches) != 1) {
+            throw new DecoderException('Unable to decode input');
+        }
+
+        $values = array_map(function ($value) {
+            return match (strpos($value, '%')) {
+                false => intval(trim($value)),
+                default => intval(trim(str_replace('%', '', $value))),
+            };
+        }, [$matches['h'], $matches['s'], $matches['l']]);
+
+        return new Color(...$values);
+    }
+}
diff --git a/src/Colors/Hsv/Colorspace.php b/src/Colors/Hsv/Colorspace.php
index 419e1392..229ffaf8 100644
--- a/src/Colors/Hsv/Colorspace.php
+++ b/src/Colors/Hsv/Colorspace.php
@@ -4,6 +4,7 @@ namespace Intervention\Image\Colors\Hsv;
 
 use Intervention\Image\Colors\Cmyk\Color as CmykColor;
 use Intervention\Image\Colors\Rgb\Color as RgbColor;
+use Intervention\Image\Colors\Hsl\Color as HslColor;
 use Intervention\Image\Colors\Rgb\Colorspace as RgbColorspace;
 use Intervention\Image\Interfaces\ColorInterface;
 use Intervention\Image\Interfaces\ColorspaceInterface;
@@ -40,13 +41,14 @@ class Colorspace implements ColorspaceInterface
         return match (get_class($color)) {
             CmykColor::class => $this->importRgbColor($color->convertTo(RgbColorspace::class)),
             RgbColor::class => $this->importRgbColor($color),
+            HslColor::class => $this->importHslColor($color),
             default => $color,
         };
     }
 
     protected function importRgbColor(RgbColor $color): ColorInterface
     {
-        // percentage values of rgb channels
+        // normalized values of rgb channels
         $values = array_map(function ($channel) {
             return $channel->normalize();
         }, $color->channels());
@@ -62,6 +64,11 @@ class Colorspace implements ColorspaceInterface
         // calculate value
         $v = 100 * $max;
 
+        if ($chroma == 0) {
+            // greyscale color
+            return new Color(0, 0, intval(round($v)));
+        }
+
         // calculate saturation
         $s = 100 * ($chroma / $max);
 
@@ -79,4 +86,17 @@ class Colorspace implements ColorspaceInterface
             intval(round($v))
         );
     }
+
+    protected function importHslColor(HslColor $color): ColorInterface
+    {
+        // normalized values of hsl channels
+        list($h, $s, $l) = array_map(function ($channel) {
+            return $channel->normalize();
+        }, $color->channels());
+
+        $v = $l + $s * min($l, 1 - $l);
+        $s = ($v == 0) ? 0 : 2 * (1 - $l / $v);
+
+        return $this->colorFromNormalized([$h, $s, $v]);
+    }
 }
diff --git a/src/Colors/Rgb/Colorspace.php b/src/Colors/Rgb/Colorspace.php
index 83adc479..12487e71 100644
--- a/src/Colors/Rgb/Colorspace.php
+++ b/src/Colors/Rgb/Colorspace.php
@@ -3,6 +3,7 @@
 namespace Intervention\Image\Colors\Rgb;
 
 use Intervention\Image\Colors\Hsv\Color as HsvColor;
+use Intervention\Image\Colors\Hsl\Color as HslColor;
 use Intervention\Image\Colors\Cmyk\Color as CmykColor;
 use Intervention\Image\Interfaces\ColorInterface;
 use Intervention\Image\Interfaces\ColorspaceInterface;
@@ -40,6 +41,7 @@ class Colorspace implements ColorspaceInterface
         return match (get_class($color)) {
             CmykColor::class => $this->importCmykColor($color),
             HsvColor::class => $this->importHsvColor($color),
+            HslColor::class => $this->importHslColor($color),
             default => $color,
         };
     }
@@ -78,4 +80,33 @@ class Colorspace implements ColorspaceInterface
 
         return $this->colorFromNormalized($values);
     }
+
+    protected function importHslColor(HslColor $color): ColorInterface
+    {
+        // normalized values of hsl channels
+        list($h, $s, $l) = array_map(function ($channel) {
+            return $channel->normalize();
+        }, $color->channels());
+
+        $c = (1 - abs(2 * $l - 1)) * $s;
+        $x = $c * (1 - abs(fmod($h * 6, 2) - 1));
+        $m = $l - $c / 2;
+
+        $values = match (true) {
+            $h < 1 / 6 => [$c, $x, 0],
+            $h < 2 / 6 => [$x, $c, 0],
+            $h < 3 / 6 => [0, $c, $x],
+            $h < 4 / 6 => [0, $x, $c],
+            $h < 5 / 6 => [$x, 0, $c],
+            default => [$c, 0, $x],
+        };
+
+        $values = array_map(function ($value) use ($m) {
+            return $value + $m;
+        }, $values);
+
+        array_push($values, 1); // append alpha channel value
+
+        return $this->colorFromNormalized($values);
+    }
 }
diff --git a/src/Drivers/Gd/ColorProcessor.php b/src/Drivers/Gd/ColorProcessor.php
index 795fcabd..caceff21 100644
--- a/src/Drivers/Gd/ColorProcessor.php
+++ b/src/Drivers/Gd/ColorProcessor.php
@@ -21,7 +21,7 @@ class ColorProcessor implements ColorProcessorInterface
 
     public function colorToNative(ColorInterface $color): int
     {
-        // convert color to image colorspace
+        // convert color to colorspace
         $color = $color->convertTo($this->colorspace);
 
         // gd only supports rgb so the channels can be accessed directly
diff --git a/src/Drivers/Gd/InputHandler.php b/src/Drivers/Gd/InputHandler.php
index 96a0e162..50a0e55f 100644
--- a/src/Drivers/Gd/InputHandler.php
+++ b/src/Drivers/Gd/InputHandler.php
@@ -8,6 +8,7 @@ use Intervention\Image\Colors\Rgb\Decoders\HtmlColornameDecoder;
 use Intervention\Image\Colors\Rgb\Decoders\TransparentColorDecoder;
 use Intervention\Image\Colors\Cmyk\Decoders\StringColorDecoder as CmykStringColorDecoder;
 use Intervention\Image\Colors\Hsv\Decoders\StringColorDecoder as HsvStringColorDecoder;
+use Intervention\Image\Colors\Hsl\Decoders\StringColorDecoder as HslStringColorDecoder;
 use Intervention\Image\Drivers\AbstractInputHandler;
 use Intervention\Image\Drivers\Gd\Decoders\ImageObjectDecoder;
 use Intervention\Image\Drivers\Gd\Decoders\ColorObjectDecoder;
@@ -27,6 +28,7 @@ class InputHandler extends AbstractInputHandler
         RgbStringColorDecoder::class,
         CmykStringColorDecoder::class,
         HsvStringColorDecoder::class,
+        HslStringColorDecoder::class,
         TransparentColorDecoder::class,
         HtmlColornameDecoder::class,
         FilePointerImageDecoder::class,
diff --git a/src/Drivers/Imagick/InputHandler.php b/src/Drivers/Imagick/InputHandler.php
index 7afaa2a9..621585a1 100644
--- a/src/Drivers/Imagick/InputHandler.php
+++ b/src/Drivers/Imagick/InputHandler.php
@@ -8,6 +8,7 @@ use Intervention\Image\Colors\Rgb\Decoders\HtmlColornameDecoder;
 use Intervention\Image\Colors\Rgb\Decoders\TransparentColorDecoder;
 use Intervention\Image\Colors\Cmyk\Decoders\StringColorDecoder as CmykStringColorDecoder;
 use Intervention\Image\Colors\Hsv\Decoders\StringColorDecoder as HsvStringColorDecoder;
+use Intervention\Image\Colors\Hsl\Decoders\StringColorDecoder as HslStringColorDecoder;
 use Intervention\Image\Drivers\AbstractInputHandler;
 use Intervention\Image\Drivers\Imagick\Decoders\ImageObjectDecoder;
 use Intervention\Image\Drivers\Imagick\Decoders\ColorObjectDecoder;
@@ -27,6 +28,7 @@ class InputHandler extends AbstractInputHandler
         RgbStringColorDecoder::class,
         CmykStringColorDecoder::class,
         HsvStringColorDecoder::class,
+        HslStringColorDecoder::class,
         TransparentColorDecoder::class,
         HtmlColornameDecoder::class,
         FilePointerImageDecoder::class,
diff --git a/tests/Colors/Cmyk/ColorspaceTest.php b/tests/Colors/Cmyk/ColorspaceTest.php
index 94f78bb9..69fca686 100644
--- a/tests/Colors/Cmyk/ColorspaceTest.php
+++ b/tests/Colors/Cmyk/ColorspaceTest.php
@@ -9,34 +9,61 @@ use Intervention\Image\Colors\Cmyk\Channels\Yellow;
 use Intervention\Image\Colors\Cmyk\Color as CmykColor;
 use Intervention\Image\Colors\Rgb\Color as RgbColor;
 use Intervention\Image\Colors\Hsv\Color as HsvColor;
+use Intervention\Image\Colors\Hsl\Color as HslColor;
 use Intervention\Image\Colors\Cmyk\Colorspace;
 use Intervention\Image\Tests\TestCase;
 
 /**
- * @requires extension gd
  * @covers \Intervention\Image\Colors\Cmyk\Colorspace
  */
 class ColorspaceTest extends TestCase
 {
-    public function testConvertRgbColor(): void
+    public function testImportRgbColor(): void
     {
         $colorspace = new Colorspace();
-        $result = $colorspace->importColor(new RgbColor(0, 0, 255));
+
+        $result = $colorspace->importColor(new RgbColor(255, 0, 255));
         $this->assertInstanceOf(CmykColor::class, $result);
-        $this->assertEquals(100, $result->channel(Cyan::class)->value());
+        $this->assertEquals(0, $result->channel(Cyan::class)->value());
         $this->assertEquals(100, $result->channel(Magenta::class)->value());
         $this->assertEquals(0, $result->channel(Yellow::class)->value());
         $this->assertEquals(0, $result->channel(Key::class)->value());
+
+        $result = $colorspace->importColor(new RgbColor(127, 127, 127));
+        $this->assertInstanceOf(CmykColor::class, $result);
+        $this->assertEquals(0, $result->channel(Cyan::class)->value());
+        $this->assertEquals(0, $result->channel(Magenta::class)->value());
+        $this->assertEquals(0, $result->channel(Yellow::class)->value());
+        $this->assertEquals(50, $result->channel(Key::class)->value());
     }
 
-    public function testConvertHsvColor(): void
+    public function testImportHsvColor(): void
     {
         $colorspace = new Colorspace();
-        $result = $colorspace->importColor(new HsvColor(240, 100, 100));
+        $result = $colorspace->importColor(new HsvColor(0, 0, 50));
         $this->assertInstanceOf(CmykColor::class, $result);
-        $this->assertEquals(100, $result->channel(Cyan::class)->value());
+        $this->assertEquals(0, $result->channel(Cyan::class)->value());
+        $this->assertEquals(0, $result->channel(Magenta::class)->value());
+        $this->assertEquals(0, $result->channel(Yellow::class)->value());
+        $this->assertEquals(50, $result->channel(Key::class)->value());
+    }
+
+    public function testImportHslColor(): void
+    {
+        $colorspace = new Colorspace();
+
+        $result = $colorspace->importColor(new HslColor(300, 100, 50));
+        $this->assertInstanceOf(CmykColor::class, $result);
+        $this->assertEquals(0, $result->channel(Cyan::class)->value());
         $this->assertEquals(100, $result->channel(Magenta::class)->value());
         $this->assertEquals(0, $result->channel(Yellow::class)->value());
         $this->assertEquals(0, $result->channel(Key::class)->value());
+
+        $result = $colorspace->importColor(new HslColor(0, 0, 50));
+        $this->assertInstanceOf(CmykColor::class, $result);
+        $this->assertEquals(0, $result->channel(Cyan::class)->value());
+        $this->assertEquals(0, $result->channel(Magenta::class)->value());
+        $this->assertEquals(0, $result->channel(Yellow::class)->value());
+        $this->assertEquals(50, $result->channel(Key::class)->value());
     }
 }
diff --git a/tests/Colors/Hsl/ChannelTest.php b/tests/Colors/Hsl/ChannelTest.php
new file mode 100644
index 00000000..2c7f9c27
--- /dev/null
+++ b/tests/Colors/Hsl/ChannelTest.php
@@ -0,0 +1,74 @@
+<?php
+
+namespace Intervention\Image\Tests\Colors\Hsl;
+
+use Intervention\Image\Colors\Hsl\Channels\Hue;
+use Intervention\Image\Colors\Hsl\Channels\Saturation;
+use Intervention\Image\Colors\Hsl\Channels\Luminance;
+use Intervention\Image\Exceptions\ColorException;
+use Intervention\Image\Tests\TestCase;
+
+/**
+ * @covers \Intervention\Image\Colors\Hsl\Channels\Hue
+ * @covers \Intervention\Image\Colors\Hsl\Channels\Saturation
+ * @covers \Intervention\Image\Colors\Hsl\Channels\Value
+ */
+class ChannelTest extends TestCase
+{
+    public function testConstructor(): void
+    {
+        $channel = new Hue(0);
+        $this->assertInstanceOf(Hue::class, $channel);
+
+        $channel = new Hue(value: 0);
+        $this->assertInstanceOf(Hue::class, $channel);
+
+        $channel = new Hue(normalized: 0);
+        $this->assertInstanceOf(Hue::class, $channel);
+
+        $this->expectException(ColorException::class);
+        $channel = new Hue();
+
+        $this->expectException(ColorException::class);
+        $channel = new Hue(normalized: 2);
+    }
+
+    public function testValue(): void
+    {
+        $channel = new Hue(10);
+        $this->assertEquals(10, $channel->value());
+    }
+
+    public function testNormalize(): void
+    {
+        $channel = new Hue(360);
+        $this->assertEquals(1, $channel->normalize());
+        $channel = new Hue(180);
+        $this->assertEquals(0.5, $channel->normalize());
+        $channel = new Hue(0);
+        $this->assertEquals(0, $channel->normalize());
+        $channel = new Luminance(90);
+        $this->assertEquals(.9, $channel->normalize());
+    }
+
+    public function testValidate(): void
+    {
+        $this->expectException(ColorException::class);
+        new Hue(361);
+
+        $this->expectException(ColorException::class);
+        new Hue(-1);
+
+        $this->expectException(ColorException::class);
+        new Saturation(101);
+
+        $this->expectException(ColorException::class);
+        new Saturation(-1);
+
+        $this->expectException(ColorException::class);
+        new Luminance(101);
+
+        $this->expectException(ColorException::class);
+        new Luminance(-1);
+    }
+}
diff --git a/tests/Colors/Hsl/ColorTest.php b/tests/Colors/Hsl/ColorTest.php
new file mode 100644
index 00000000..9039309c
--- /dev/null
+++ b/tests/Colors/Hsl/ColorTest.php
@@ -0,0 +1,84 @@
+<?php
+
+namespace Intervention\Image\Tests\Colors\Hsl;
+
+use Intervention\Image\Colors\Hsl\Channels\Hue;
+use Intervention\Image\Colors\Hsl\Channels\Luminance;
+use Intervention\Image\Colors\Hsl\Channels\Saturation;
+use Intervention\Image\Colors\Hsl\Color;
+use Intervention\Image\Colors\Hsl\Colorspace;
+use Intervention\Image\Tests\TestCase;
+
+/**
+ * @covers \Intervention\Image\Colors\Hsl\Color
+ */
+class ColorTest extends TestCase
+{
+    public function testConstructor(): void
+    {
+        $color = new Color(0, 0, 0);
+        $this->assertInstanceOf(Color::class, $color);
+    }
+
+    public function testColorspace(): void
+    {
+        $color = new Color(0, 0, 0);
+        $this->assertInstanceOf(Colorspace::class, $color->colorspace());
+    }
+
+    public function testChannels(): void
+    {
+        $color = new Color(10, 20, 30);
+        $this->assertIsArray($color->channels());
+        $this->assertCount(3, $color->channels());
+    }
+
+    public function testChannel(): void
+    {
+        $color = new Color(10, 20, 30);
+        $channel = $color->channel(Hue::class);
+        $this->assertInstanceOf(Hue::class, $channel);
+        $this->assertEquals(10, $channel->value());
+    }
+
+    public function testHueSaturationLuminanceKey(): void
+    {
+        $color = new Color(10, 20, 30);
+        $this->assertInstanceOf(Hue::class, $color->hue());
+        $this->assertInstanceOf(Saturation::class, $color->saturation());
+        $this->assertInstanceOf(Luminance::class, $color->luminance());
+        $this->assertEquals(10, $color->hue()->value());
+        $this->assertEquals(20, $color->saturation()->value());
+        $this->assertEquals(30, $color->luminance()->value());
+    }
+
+    public function testToArray(): void
+    {
+        $color = new Color(10, 20, 30);
+        $this->assertEquals([10, 20, 30], $color->toArray());
+    }
+
+    public function testNormalize(): void
+    {
+        $color = new Color(180, 50, 25);
+        $this->assertEquals([.5, 0.5, 0.25], $color->normalize());
+    }
+
+    public function testToString(): void
+    {
+        $color = new Color(100, 50, 20, 0);
+        $this->assertEquals('hsl(100, 50%, 20%)', (string) $color);
+    }
+
+    public function testIsGreyscale(): void
+    {
+        $color = new Color(0, 1, 0);
+        $this->assertFalse($color->isGreyscale());
+
+        $color = new Color(1, 0, 0);
+        $this->assertTrue($color->isGreyscale());
+
+        $color = new Color(0, 0, 1);
+        $this->assertTrue($color->isGreyscale());
+    }
+}
diff --git a/tests/Colors/Hsl/ColorspaceTest.php b/tests/Colors/Hsl/ColorspaceTest.php
new file mode 100644
index 00000000..7ab48c50
--- /dev/null
+++ b/tests/Colors/Hsl/ColorspaceTest.php
@@ -0,0 +1,70 @@
+<?php
+
+namespace Intervention\Image\Tests\Colors\Hsl;
+
+use Intervention\Image\Colors\Cmyk\Color as CmykColor;
+use Intervention\Image\Colors\Hsl\Channels\Hue;
+use Intervention\Image\Colors\Hsl\Channels\Luminance;
+use Intervention\Image\Colors\Hsl\Channels\Saturation;
+use Intervention\Image\Colors\Hsl\Color as HslColor;
+use Intervention\Image\Colors\Rgb\Color as RgbColor;
+use Intervention\Image\Colors\Hsv\Color as HsvColor;
+use Intervention\Image\Colors\Hsl\Colorspace;
+use Intervention\Image\Tests\TestCase;
+
+/**
+ * @covers \Intervention\Image\Colors\Hsl\Colorspace
+ */
+class ColorspaceTest extends TestCase
+{
+    public function testImportRgbColor(): void
+    {
+        $colorspace = new Colorspace();
+
+        $result = $colorspace->importColor(new RgbColor(255, 0, 255));
+        $this->assertInstanceOf(HslColor::class, $result);
+        $this->assertEquals(300, $result->channel(Hue::class)->value());
+        $this->assertEquals(100, $result->channel(Saturation::class)->value());
+        $this->assertEquals(50, $result->channel(Luminance::class)->value());
+
+        $result = $colorspace->importColor(new RgbColor(127, 127, 127));
+        $this->assertInstanceOf(HslColor::class, $result);
+        $this->assertEquals(0, $result->channel(Hue::class)->value());
+        $this->assertEquals(0, $result->channel(Saturation::class)->value());
+        $this->assertEquals(50, $result->channel(Luminance::class)->value());
+    }
+
+    public function testImportCmykColor(): void
+    {
+        $colorspace = new Colorspace();
+
+        $result = $colorspace->importColor(new CmykColor(0, 100, 0, 0));
+        $this->assertInstanceOf(HslColor::class, $result);
+        $this->assertEquals(300, $result->channel(Hue::class)->value());
+        $this->assertEquals(100, $result->channel(Saturation::class)->value());
+        $this->assertEquals(50, $result->channel(Luminance::class)->value());
+
+        $result = $colorspace->importColor(new CmykColor(0, 0, 0, 50));
+        $this->assertInstanceOf(HslColor::class, $result);
+        $this->assertEquals(0, $result->channel(Hue::class)->value());
+        $this->assertEquals(0, $result->channel(Saturation::class)->value());
+        $this->assertEquals(50, $result->channel(Luminance::class)->value());
+    }
+
+    public function testImportHsvColor(): void
+    {
+        $colorspace = new Colorspace();
+
+        $result = $colorspace->importColor(new HsvColor(300, 100, 100));
+        $this->assertInstanceOf(HslColor::class, $result);
+        $this->assertEquals(300, $result->channel(Hue::class)->value());
+        $this->assertEquals(100, $result->channel(Saturation::class)->value());
+        $this->assertEquals(50, $result->channel(Luminance::class)->value());
+
+        $result = $colorspace->importColor(new HsvColor(0, 0, 50));
+        $this->assertInstanceOf(HslColor::class, $result);
+        $this->assertEquals(0, $result->channel(Hue::class)->value());
+        $this->assertEquals(0, $result->channel(Saturation::class)->value());
+        $this->assertEquals(50, $result->channel(Luminance::class)->value());
+    }
+}
diff --git a/tests/Colors/Hsl/Decoders/StringColorDecoderTest.php b/tests/Colors/Hsl/Decoders/StringColorDecoderTest.php
new file mode 100644
index 00000000..351ba02d
--- /dev/null
+++ b/tests/Colors/Hsl/Decoders/StringColorDecoderTest.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace Intervention\Image\Tests\Colors\Hsl\Decoders;
+
+use Intervention\Image\Colors\Hsl\Color;
+use Intervention\Image\Colors\Hsl\Decoders\StringColorDecoder;
+use Intervention\Image\Tests\TestCase;
+
+/**
+ * @requires extension gd
+ * @covers \Intervention\Image\Colors\Hsl\Decoders\StringColorDecoder
+ */
+class StringColorDecoderTest extends TestCase
+{
+    public function testDecode(): void
+    {
+        $decoder = new StringColorDecoder();
+
+        $result = $decoder->decode('hsl(0,0,0)');
+        $this->assertInstanceOf(Color::class, $result);
+        $this->assertEquals([0, 0, 0], $result->toArray());
+
+        $result = $decoder->decode('hsl(0, 100, 50)');
+        $this->assertInstanceOf(Color::class, $result);
+        $this->assertEquals([0, 100, 50], $result->toArray());
+
+        $result = $decoder->decode('hsl(360, 100, 50)');
+        $this->assertInstanceOf(Color::class, $result);
+        $this->assertEquals([360, 100, 50], $result->toArray());
+
+        $result = $decoder->decode('hsl(180, 100%, 50%)');
+        $this->assertInstanceOf(Color::class, $result);
+        $this->assertEquals([180, 100, 50], $result->toArray());
+    }
+}
diff --git a/tests/Colors/Hsv/ColorspaceTest.php b/tests/Colors/Hsv/ColorspaceTest.php
index d956bfbd..297b6960 100644
--- a/tests/Colors/Hsv/ColorspaceTest.php
+++ b/tests/Colors/Hsv/ColorspaceTest.php
@@ -8,32 +8,63 @@ use Intervention\Image\Colors\Hsv\Channels\Saturation;
 use Intervention\Image\Colors\Hsv\Channels\Value;
 use Intervention\Image\Colors\Hsv\Color as HsvColor;
 use Intervention\Image\Colors\Rgb\Color as RgbColor;
+use Intervention\Image\Colors\Hsl\Color as HslColor;
 use Intervention\Image\Colors\Hsv\Colorspace;
 use Intervention\Image\Tests\TestCase;
 
 /**
- * @requires extension gd
  * @covers \Intervention\Image\Colors\Hsv\Colorspace
  */
 class ColorspaceTest extends TestCase
 {
-    public function testConvertRgbColor(): void
+    public function testImportRgbColor(): void
     {
         $colorspace = new Colorspace();
-        $result = $colorspace->importColor(new RgbColor(26, 26, 128));
+
+        $result = $colorspace->importColor(new RgbColor(255, 0, 255));
         $this->assertInstanceOf(HsvColor::class, $result);
-        $this->assertEquals(240, $result->channel(Hue::class)->value());
-        $this->assertEquals(80, $result->channel(Saturation::class)->value());
+        $this->assertEquals(300, $result->channel(Hue::class)->value());
+        $this->assertEquals(100, $result->channel(Saturation::class)->value());
+        $this->assertEquals(100, $result->channel(Value::class)->value());
+
+        $result = $colorspace->importColor(new RgbColor(127, 127, 127));
+        $this->assertInstanceOf(HsvColor::class, $result);
+        $this->assertEquals(0, $result->channel(Hue::class)->value());
+        $this->assertEquals(0, $result->channel(Saturation::class)->value());
         $this->assertEquals(50, $result->channel(Value::class)->value());
     }
 
-    public function testConvertCmykColor(): void
+    public function testImportCmykColor(): void
     {
         $colorspace = new Colorspace();
-        $result = $colorspace->importColor(new CmykColor(100, 0, 100, 0));
+
+        $result = $colorspace->importColor(new CmykColor(0, 100, 0, 0));
         $this->assertInstanceOf(HsvColor::class, $result);
-        $this->assertEquals(120, $result->channel(Hue::class)->value());
+        $this->assertEquals(300, $result->channel(Hue::class)->value());
         $this->assertEquals(100, $result->channel(Saturation::class)->value());
         $this->assertEquals(100, $result->channel(Value::class)->value());
+
+        $result = $colorspace->importColor(new CmykColor(0, 0, 0, 50));
+        $this->assertInstanceOf(HsvColor::class, $result);
+        $this->assertEquals(0, $result->channel(Hue::class)->value());
+        $this->assertEquals(0, $result->channel(Saturation::class)->value());
+        $this->assertEquals(50, $result->channel(Value::class)->value());
+    }
+
+    public function testImportHslColor(): void
+    {
+        $colorspace = new Colorspace();
+
+        $result = $colorspace->importColor(new HslColor(300, 100, 50));
+        $this->assertInstanceOf(HsvColor::class, $result);
+        $this->assertEquals(300, $result->channel(Hue::class)->value());
+        $this->assertEquals(100, $result->channel(Saturation::class)->value());
+        $this->assertEquals(100, $result->channel(Value::class)->value());
+
+        $result = $colorspace->importColor(new HslColor(0, 0, 50));
+        $this->assertInstanceOf(HsvColor::class, $result);
+        $this->assertEquals(0, $result->channel(Hue::class)->value());
+        $this->assertEquals(0, $result->channel(Saturation::class)->value());
+        $this->assertEquals(50, $result->channel(Value::class)->value());
     }
 }
diff --git a/tests/Colors/Rgb/ColorspaceTest.php b/tests/Colors/Rgb/ColorspaceTest.php
index 042de1b9..1ea0eb44 100644
--- a/tests/Colors/Rgb/ColorspaceTest.php
+++ b/tests/Colors/Rgb/ColorspaceTest.php
@@ -8,33 +8,62 @@ use Intervention\Image\Colors\Rgb\Channels\Blue;
 use Intervention\Image\Colors\Rgb\Channels\Green;
 use Intervention\Image\Colors\Rgb\Channels\Red;
 use Intervention\Image\Colors\Rgb\Color as RgbColor;
+use Intervention\Image\Colors\Hsl\Color as HslColor;
 use Intervention\Image\Colors\Rgb\Colorspace;
 use Intervention\Image\Tests\TestCase;
 
 /**
- * @requires extension gd
  * @covers \Intervention\Image\Colors\Rgb\Colorspace
  */
 class ColorspaceTest extends TestCase
 {
-    public function testConvertCmykColor(): void
+    public function testImportCmykColor(): void
     {
         $colorspace = new Colorspace();
-        $this->assertInstanceOf(
-            RgbColor::class,
-            $colorspace->importColor(
-                new CmykColor(0, 0, 0, 0)
-            )
-        );
+        $result = $colorspace->importColor(new CmykColor(0, 100, 0, 0));
+        $this->assertInstanceOf(RgbColor::class, $result);
+        $this->assertEquals(255, $result->channel(Red::class)->value());
+        $this->assertEquals(0, $result->channel(Green::class)->value());
+        $this->assertEquals(255, $result->channel(Blue::class)->value());
+
+        $result = $colorspace->importColor(new CmykColor(0, 0, 0, 50));
+        $this->assertInstanceOf(RgbColor::class, $result);
+        $this->assertEquals(127, $result->channel(Red::class)->value());
+        $this->assertEquals(127, $result->channel(Green::class)->value());
+        $this->assertEquals(127, $result->channel(Blue::class)->value());
     }
 
-    public function testConvertHsvColor(): void
+    public function testImportHsvColor(): void
     {
         $colorspace = new Colorspace();
-        $result = $colorspace->importColor(new HsvColor(240, 80, 50));
+
+        $result = $colorspace->importColor(new HsvColor(300, 100, 100));
         $this->assertInstanceOf(RgbColor::class, $result);
-        $this->assertEquals(26, $result->channel(Red::class)->value());
-        $this->assertEquals(26, $result->channel(Green::class)->value());
+        $this->assertEquals(255, $result->channel(Red::class)->value());
+        $this->assertEquals(0, $result->channel(Green::class)->value());
+        $this->assertEquals(255, $result->channel(Blue::class)->value());
+
+        $result = $colorspace->importColor(new HsvColor(0, 0, 50));
+        $this->assertInstanceOf(RgbColor::class, $result);
+        $this->assertEquals(128, $result->channel(Red::class)->value());
+        $this->assertEquals(128, $result->channel(Green::class)->value());
+        $this->assertEquals(128, $result->channel(Blue::class)->value());
+    }
+
+    public function testImportHslColor(): void
+    {
+        $colorspace = new Colorspace();
+
+        $result = $colorspace->importColor(new HslColor(300, 100, 50));
+        $this->assertInstanceOf(RgbColor::class, $result);
+        $this->assertEquals(255, $result->channel(Red::class)->value());
+        $this->assertEquals(0, $result->channel(Green::class)->value());
+        $this->assertEquals(255, $result->channel(Blue::class)->value());
+
+        $result = $colorspace->importColor(new HslColor(0, 0, 50));
+        $this->assertInstanceOf(RgbColor::class, $result);
+        $this->assertEquals(128, $result->channel(Red::class)->value());
+        $this->assertEquals(128, $result->channel(Green::class)->value());
         $this->assertEquals(128, $result->channel(Blue::class)->value());
     }
 }