- add average color comparison

src/ImageComparator.php

@@ -49,8 +49,11 @@ public function compare(
     ): float {
         $hash1 = $this->hashImage($sourceImage); // this one should never be rotated
         $hash2 = $this->hashImage($comparedImage, $rotation);
+        $color1 = $this->getAverageRGB($sourceImage);
+        $color2 = $this->getAverageRGB($comparedImage);
+        $similarityColor = $this->calculateSimilarity($color1, $color2);
 
-        return $this->compareHashes($hash1, $hash2, $precision);
+        return $this->compareHashes($hash1, $hash2, $precision, $similarityColor);
     }
 
     /**
@@ -281,7 +284,7 @@ private function normalizeAsResource(string|GdImage $image): GdImage
      * @throws MathException
      * @throws NumberFormatException
      */
-    private function compareHashes(array $hash1, array $hash2, int $precision): float
+    private function compareHashes(array $hash1, array $hash2, int $precision, float $colorSimilarity): float
     {
         if (count($hash1) !== count($hash2)) {
             throw new InvalidArgumentException('Hashes must be of the same length.');
@@ -296,10 +299,12 @@ private function compareHashes(array $hash1, array $hash2, int $precision): floa
             }
         }
 
-        $percentage = $similarity->dividedBy($totalBits, $precision, RoundingMode::HALF_UP)
+        $hashSimilarity = $similarity->dividedBy($totalBits, $precision, RoundingMode::HALF_UP)
             ->multipliedBy(BigDecimal::of(100));
+        $hashSimilarity = BigDecimal::of($hashSimilarity)->multipliedBy($colorSimilarity);
+        $hashSimilarity = $hashSimilarity->toScale($precision, RoundingMode::HALF_UP);
 
-        return $percentage->toFloat();
+        return $hashSimilarity->toFloat();
     }
 
     /**
@@ -347,4 +352,62 @@ private function processImagePixels(
 
         return $pixels;
     }
+
+    private function calculateRGBDistance(array $color1, array $color2): float
+    {
+        $r1 = $color1['r'];
+        $g1 = $color1['g'];
+        $b1 = $color1['b'];
+
+        $r2 = $color2['r'];
+        $g2 = $color2['g'];
+        $b2 = $color2['b'];
+
+        return sqrt(pow($r1 - $r2, 2) + pow($g1 - $g2, 2) + pow($b1 - $b2, 2));
+    }
+
+    private function calculateSimilarity(array $color1, array $color2): float
+    {
+        $maxRGBDifference = sqrt(pow(255, 2) + pow(255, 2) + pow(255, 2));
+        $distance = $this->calculateRGBDistance($color1, $color2);
+
+        return 1 - ($distance / $maxRGBDifference);
+    }
+
+    /**
+     * @throws ImageResourceException
+     */
+    private function getAverageRGB(
+        GdImage|string $image,
+        int $size = 8
+    ): array {
+        $image = $this->normalizeAsResource($image);
+        $imageResized = imagescale($image, $size, $size);
+
+        $width = imagesx($imageResized);
+        $height = imagesy($imageResized);
+
+        $totalRed = $totalGreen = $totalBlue = 0;
+        $totalPixels = $width * $height;
+
+        for ($y = 0; $y < $height; $y++) {
+            for ($x = 0; $x < $width; $x++) {
+                $colorIndex = imagecolorat($imageResized, $x, $y);
+
+                $red = ($colorIndex >> 16) & 0xFF;
+                $green = ($colorIndex >> 8) & 0xFF;
+                $blue = $colorIndex & 0xFF;
+
+                $totalRed += $red;
+                $totalGreen += $green;
+                $totalBlue += $blue;
+            }
+        }
+
+        return [
+            'r' => round($totalRed / $totalPixels),
+            'g' => round($totalGreen / $totalPixels),
+            'b' => round($totalBlue / $totalPixels),
+        ];
+    }
 }

tests/Unit/ImageComparatorTest.php

@@ -76,11 +76,11 @@ public function testCompareRotated(): void
 
         $result = $this->imageComparator->compare($image, $imageRotated, ImageRotationAngle::D90);
 
-        $this->assertSame(96.9, $result);
+        $this->assertSame(96.363, $result);
 
         $result = $this->imageComparator->compare($image, $imageRotated, ImageRotationAngle::D90, 10);
 
-        $this->assertSame(96.875, $result);
+        $this->assertSame(96.3377374947, $result);
     }
 
     public function testCompareShouldThrowException(): void
@@ -110,7 +110,7 @@ public function testSquareImage(): void
 
         $result = $this->imageComparator->compare('tests/images/flower2.jpg', $squareImage);
 
-        $this->assertSame(48.4, $result);
+        $this->assertSame(36.973, $result);
     }
 
     public function testHashImage(): void
@@ -259,7 +259,7 @@ public function testCompareWithBrightnessContrastAdjustment(): void
 
         $result = $this->imageComparator->compare($image1, $image2);
 
-        $this->assertGreaterThan(70, $result);
+        $this->assertGreaterThan(55, $result);
     }
 
     public function testCompareBlurredImages(): void
@@ -289,6 +289,16 @@ public static function differentImagesProvider(): array
                 'image1' => 'tests/images/ebay-image2.png',
                 'image2' => 'tests/images/amazon-image2.png',
                 'expectedPercentage' => 60.00
+            ],
+            'Similar image black and white' => [
+                'image1' => 'tests/images/black.png',
+                'image2' => 'tests/images/white.png',
+                'expectedPercentage' => 1.00
+            ],
+            'Similar image red and blue' => [
+                'image1' => 'tests/images/red.png',
+                'image2' => 'tests/images/blue.png',
+                'expectedPercentage' => 20
             ]
         ];
     }