Image effetcs

/*$image = imagecreatefrompng("galapagos.jpg");
imagefilter($image, IMG_FILTER_GRAYSCALE);
imagefilter($image, IMG_FILTER_NEGATE);
header("content-type: image/png");
imagepng($image);
imagedestroy($image);*/

$base_img_dir = "img/";

$img_conv_dir = "./bin/";

echo "filename :".$filename= "galapagos.jpg";
// retrieve image info
$imginfo = getimagesize($filename);

echo "imageinfo:".$imginfo[2];

// handle image according to type
switch ($imginfo[2]) {
case 1: // gif
// convert gif to png using shell command
$command = $img_conv_dir."gif2png $filename";
exec($command);

// remove original gif file and rename converted png
unlink($filename);
rename("$filename.png", $filename);

// check png image by loading and saving the file
// to prevent wrong uploaded files and errors
$img = imagecreatefrompng($filename);
imagepng($img, $filename);
imagedestroy($img);

// set image type to png
$img_type = "PNG";
break;
case 2: // jpeg
// check jpeg image by loading and saving the file
// to prevent wrong uploaded files and errors
$img = imagecreatefromjpeg($filename);
imagejpeg($img, $filename);
imagedestroy($img);

// set image type to jpeg
$img_type = "JPG";
break;

case 3: // png
// check png image by loading and saving the file
// to prevent wrong uploaded files and errors
$img = imagecreatefrompng($filename);
imagepng($img, $filename);
imagedestroy($img);

// set image type to png
$img_type = "PNG";
break;
case 4: // bmp
// rename file to bmp
rename($filename, "$filename.bmp");

// convert bmp to png using shell command
$command = $img_conv_dir."bmptoppm $filename.bmp | ".
$img_conv_dir."pnmtopng > $filename";
exec($command);

// remove original bmp
unlink("$filename.bmp");

// check png image by loading and saving the file
// to prevent wrong uploaded files and errors
$img = imagecreatefrompng($filename);
imagepng($img, $filename);
imagedestroy($img);

// set image type to png
$img_type = "PNG";
break;

default:
break;
}