Initial project commit.

Author: vajiralasantha

.gitignore

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+/.idea/

composer.json

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+{
+    "name": "vajiral/php-image-compare",
+    "description": "A light weight PHP class that can compare two (jpg/png) images to find if they are similar.",
+    "keywords": ["image", "lightweight", "PHP library", "image compare", "jpg", "png"],
+    "type": "library",
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Vajira Lasantha",
+            "email": "[email protected]"
+        }
+    ],
+    "minimum-stability": "dev",
+    "require": {
+        "php": "^5.5.9 || ^7.0",
+        "ext-gd": "*"
+    },
+    "autoload": {
+        "psr-4": {
+            "BigV\\": "src/"
+        }
+    }
+}

demo/demo.php

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+<?php
+
+use BigV\ImageCompare;
+
+require __DIR__ . "/../vendor/autoload.php";
+
+/**
+ * These two images are almost the same so the hammered distance will be less than 10
+ * Try it with images like below:
+ * 1. Two slightly different images
+ * 2. Two completely different images
+ * 3. Two same images (returned value 0)
+ * 4. Two same image but with different size/aspect ratio (returned value ~0)
+ */
+
+$image = new ImageCompare();
+echo $image->compare(__DIR__ . '/image2-resize.jpg',__DIR__ . '/image2.jpg');
+
+?>

demo/image1-bw.jpg

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+<?php
+namespace BigV;
+
+class ImageCompare {
+
+    /**
+     * Main function. Returns the hammering distance of two images' bit value.
+     *
+     * @param string $pathOne Path to image 1
+     * @param string $pathTwo Path to image 2
+     *
+     * @return bool|int Hammering value on success. False on error.
+     */
+    public function compare($pathOne, $pathTwo) {
+        $i1 = $this->createImage($pathOne);
+        $i2 = $this->createImage($pathTwo);
+
+        if (!$i1 || !$i2) {
+            return false;
+        }
+
+        $i1 = $this->resizeImage($pathOne);
+        $i2 = $this->resizeImage($pathTwo);
+
+        imagefilter($i1, IMG_FILTER_GRAYSCALE);
+        imagefilter($i2, IMG_FILTER_GRAYSCALE);
+
+        $colorMeanOne = $this->colorMeanValue($i1);
+        $colorMeanTwo = $this->colorMeanValue($i2);
+
+        $bits1 = $this->bits($colorMeanOne);
+        $bits2 = $this->bits($colorMeanTwo);
+
+        $hammeringDistance = 0;
+
+        for ($x = 0; $x < 64; $x++) {
+            if ($bits1[$x] != $bits2[$x]) {
+                $hammeringDistance++;
+            }
+        }
+
+        return $hammeringDistance;
+    }
+
+    /**
+     * Returns array with mime type and if its jpg or png. Returns false if it isn't jpg or png.
+     *
+     * @param string $path Path to image.
+     *
+     * @return array|bool
+     */
+	private function mimeType($path) {
+		$mime = getimagesize($path);
+		$return = array($mime[0],$mime[1]);
+      
+		switch ($mime['mime']) {
+			case 'image/jpeg':
+				$return[] = 'jpg';
+				return $return;
+			case 'image/png':
+				$return[] = 'png';
+				return $return;
+			default:
+				return false;
+		}
+    }
+
+    /**
+     * Returns image resource or false if it's not jpg or png
+     *
+     * @param string $path Path to image
+     *
+     * @return bool|resource
+     */
+	private function createImage($path) {
+		$mime = $this->mimeType($path);
+      
+		if ($mime[2] == 'jpg') {
+			return imagecreatefromjpeg ($path);
+		} else if ($mime[2] == 'png') {
+			return imagecreatefrompng ($path);
+		} else {
+			return false; 
+		} 
+    }
+
+    /**
+     * Resize the image to a 8x8 square and returns as image resource.
+     *
+     * @param string $path Path to image
+     *
+     * @return resource Image resource identifier
+     */
+	private function resizeImage($path) {
+		$mime = $this->mimeType($path);
+
+		$t = imagecreatetruecolor(8, 8);
+		
+		$source = $this->createImage($path);
+		
+		imagecopyresized($t, $source, 0, 0, 0, 0, 8, 8, $mime[0], $mime[1]);
+		
+		return $t;
+	}
+
+    /**
+     * Returns the mean value of the colors and the list of all pixel's colors.
+     *
+     * @param resource $resource Image resource identifier
+     *
+     * @return array
+     */
+    private function colorMeanValue($resource) {
+		$colorList = array();
+		$colorSum = 0;
+		for ($a = 0; $a<8; $a++) {
+			for ($b = 0; $b<8; $b++) {
+				$rgb = imagecolorat($resource, $a, $b);
+				$colorList[] = $rgb & 0xFF;
+				$colorSum += $rgb & 0xFF;
+			}
+		}
+		
+		return array($colorSum/64,$colorList);
+	}
+
+    /**
+     * Returns an array with 1 and zeros. If a color is bigger than the mean value of colors it is 1
+     *
+     * @param array $colorMean Color Mean details.
+     *
+     * @return array
+     */
+    private function bits($colorMean) {
+		$bits = array();
+		foreach ($colorMean[1] as $color) {
+		    $bits[] = ($color >= $colorMean[0]) ? 1 : 0;
+		}
+
+		return $bits;
+
+	}
+}
+  
+?>