Convert_Abstraction_Factory.php

<?php

interface iFactory {
    public function image_convert($img);
}

abstract class Convert_Abstraction_Factory  implements iFactory {
    
    const IMG_PATH  = './img';    
    const TMP_PATH  = './tmp';
    const CONV_PATH = './conv';
	
    protected function __construct() {}

    protected function to_pnm($img) {
        $time = time();
        
        exec('anytopnm ' . self::IMG_PATH . DIRECTORY_SEPARATOR . $img . ' > ' . self::TMP_PATH . DIRECTORY_SEPARATOR . $time .  '.pnm');
        
        return $time;
    }
    
}