Initial data commit

Task/Bitmap-Histogram/PHP/bitmap-histogram.php

@@ -0,0 +1,54 @@
+define('src_name', 'input.jpg');	// source image
+define('dest_name', 'output.jpg');	// destination image
+
+$img = imagecreatefromjpeg(src_name);	// read image
+
+if(empty($img)){
+	echo 'Image could not be loaded!';
+	exit;
+}
+
+$black = imagecolorallocate($img, 0, 0, 0);
+$white = imagecolorallocate($img, 255, 255, 255);
+$width = imagesx($img);
+$height = imagesy($img);
+
+$array_lum = array(); 	// for storage of luminosity of each pixel
+$sum_lum = 0;		// total sum of luminosity
+$average_lum = 0;	// average luminosity of whole image
+
+for($x = 0; $x < $width; $x++){	
+	for($y = 0; $y < $height; $y++){
+		// read pixel value
+		$color = imagecolorat($img, $x, $y);
+		$r = ($color >> 16) & 0xFF;
+		$g = ($color >> 8) & 0xFF;
+		$b = $color & 0xFF;
+		// save pixel luminosity in temporary array
+		$array_lum[$x][$y] = ($r + $g + $b);
+		// add pixel luminosity to sum
+		$sum_lum += $array_lum[$x][$y];
+	}
+}
+
+// calculate average luminosity
+$average_lum = $sum_lum / ($width * $height);
+
+for($x = 0; $x < $width; $x++){	
+	for($y = 0; $y < $height; $y++){
+		// pixel is brighter than average -> set white
+		// else -> set black
+		if($array_lum[$x][$y] > $average_lum){
+			imagesetpixel($img, $x, $y, $white);
+		}
+		else{
+			imagesetpixel($img, $x, $y, $black);
+		}
+	}
+}
+// save black and white image to dest_name
+imagejpeg($img, dest_name);
+
+if(!file_exists(dest_name)){
+	echo 'Image not saved! Check permission!';
+}