画像サイズを調整するPHPの画像リサイズ関数の詳細説明

if(isset($_FILES['manager_photo']) && !empty($_FILES['manager_photo']['name']))
    {
        $photo_name=$manager_name."-".$_FILES["manager_photo"]["name"];
        $tmpname = $_FILES['manager_photo']['tmp_name'];
        $file_ext= substr($photo_name, strripos($photo_name, '.'));   
        $dir = "./manager_photos/";
        // finally resize
        @img_resize( $tmpname , 90 ,  $dir , $photo_name, 1);
}
function img_resize( $tmpname, $size, $save_dir, $save_name, $maxisheight = 0 )
    {
    $save_dir     .= ( substr($save_dir,-1) != "/") ? "/" : "";
    $gis        = getimagesize($tmpname);
    $type        = $gis[2];
    switch($type)
        {
        case "1": $imorig = imagecreatefromgif($tmpname); break;
        case "2": $imorig = imagecreatefromjpeg($tmpname);break;
        case "3": $imorig = imagecreatefrompng($tmpname); break;
        default:  $imorig = imagecreatefromjpeg($tmpname);
        }
        $x = imagesx($imorig);
        $y = imagesy($imorig);
        $woh = (!$maxisheight)? $gis[0] : $gis[1] ; 
        if($woh <= $size)
        {
        $aw = $x;
        $ah = $y;
        }
            else
        {
            if(!$maxisheight){
                $aw = $size;
                $ah = $size * $y / $x;
            } else {
                $aw = $size * $x / $y;
                $ah = $size;
            }
        }
        $im = imagecreatetruecolor($aw,$ah);
    if (imagecopyresampled($im,$imorig , 0,0,0,0,$aw,$ah,$x,$y))
        if (imagejpeg($im, $save_dir.$save_name))
            return true;
            else
            return false;
}//img_resize

 $image = new Imagick($src);
 $image->resizeImage($width,$height,Imagick::FILTER_LANCZOS,1);
 $image->cropImage($width_2, $height_2, $x, $y);
 $image->setCompression(Imagick::COMPRESSION_JPEG);
 $image->setImageCompressionQuality(82);
 $image->writeImage($dest);
 $image->destroy();

function resize($originalImage){
list($width, $height) = getimagesize($originalImage);
$newName=basename($originalImage);
$imageResized = imagecreatetruecolor(128, 128);
$imageTmp = imagecreatefromjpeg($originalImage);
imagecopyresampled($imageResized, $imageTmp, 0, 0, 0, 0, 128, 128, $width, $height);
imagejpeg($imageResized, "resizedImg/$newName",100);
imageDestroy($imageResized);
}