Hi, to generate a resized image try this code:
<?php
if($upload->moveTo($path))
         {
                   $name_of_miniature = "example_name123";
                   $img = new Phalcon\Image\Adapter\Gd($path); 
                   $path_mini = "img/miniatures/".$name_of_miniature.".jpg"; 
                    //117 px width, 90 px height
                    $img->resize(117,90)->crop(117,90);
                    if($img->save($path_mini, 100))
                    {
                      //  ok
                    }
                    else
                    {
                      // bad
                    }
         }