Change image size according to proportion_PHP tutorial

/**
Change the image size according to the proportion (not generating thumbnails)
@param string $img image path
@param int $max_w Maximum zoom width
@param int $max_h Maximum zoom height
*/
function chImageSize ($img,$max_w,$max_h)
{
$size = @getimagesize($img);
          $w = $size[0];
         $h                                                                                                              //Calculate scaling ratio
@$w_ratio = $max_w / $w;
@$h_ratio = $max_h / $h;
//Determine the width and height of the processed image
If( ($w <= $max_w) && ($h <= $max_h) )
{
          $tn['w'] = $w;
          $tn['h'] = $h;
}  
else if(($w_ratio * $h) < $max_h)
{
          $tn['h'] = ceil($w_ratio * $h);
          $tn['w'] = $max_w;
}  
else
{
          $tn['w'] = ceil($h_ratio * $w);
          $tn['h'] = $max_h;
}  
$tn['rc_w'] = $w;
$tn['rc_h'] = $h;
Return $tn ;
}
?>

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