do it

FileImageConverter.class.php

@@ -38,27 +38,39 @@ class FileImageConverter {
 
 		$new_filename = "result.png";
 
-		$header = "";
+			//some gradient
+		$fancy_header = "";
 		for($i = 0;$i < 255;$i += 5) {
-			$header .= chr($i);
+			$fancy_header .= chr($i);
 		}
-		$header .= chr(0);
-		$header .= $filesize;
-		$header .= chr(0);
-		$header .= $md5;
 
 			//header done, now read the file content
 		$content = file_get_contents($filename);
 
-			//get size for the image
-		$size = strlen($header) + 1 + $filesize;
+			//get final minimum size for the image
+			//(do not mix up strlen of $filesize and the actual $filesize)
+		$size = strlen($fancy_header) + 1 + strlen($filesize) + 1 + strlen($md5) + 1 + $filesize + 1;
 
 			//create and prepare image
 		$this->image = new BoxImage($size);
-		$this->image->fillImage(0,0,0,127);
+		$this->image->fillImage(0,0,0,0);
 
-			//header first
-		$this->addDataToImage($header);
+			//some fancy header
+		$this->addDataToImage($fancy_header);
+
+			//magic pixel
+		$this->image->setCurrentPixel(0,0,0,127);
+		$this->image->movePointer(1);
+
+			//add filesize
+		$this->addDataToImage($filesize);
+
+			//magic pixel
+		$this->image->setCurrentPixel(0,0,0,127);
+		$this->image->movePointer(1);
+
+			//add md5 value of content
+		$this->addDataToImage($md5);
 
 			//magic pixel
 		$this->image->setCurrentPixel(0,0,0,127);
@@ -67,6 +79,10 @@ class FileImageConverter {
 			//content
 		$this->addDataToImage($content);
 
+			//magic pixel
+		$this->image->setCurrentPixel(0,0,0,127);
+		$this->image->movePointer(1);
+
 			//save image
 		$this->image->writeToFile($new_filename, 0);