writing new image data to a file after converting to grayscale php -

im using following code take image, convert grayscale, , save grayscale image:

$imagename = "$imagename"; // path uploaded color jpeg          $im = imagecreatefromjpeg($imagename);      $imgw = imagesx($im);     $imgh = imagesy($im);      ($i=0; $i<$imgw; $i++)     {             ($j=0; $j<$imgh; $j++)             {                      $rgb = imagecolorat($im, $i, $j);                      $rr = ($rgb >> 16) & 0xff;                     $gg = ($rgb >> 8) & 0xff;                     $bb = $rgb & 0xff;                      $g = round(($rr + $gg + $bb) / 3);                      $val = imagecolorallocate($im, $g, $g, $g);                      imagesetpixel ($im, $i, $j, $val);             }     }      $grayimgpath = "step2cache/".$saltname."_gray.jpg"; //$saltname randomly generated image name    $fh = fopen($grayimgpath, 'w') or die("can't open file"); fwrite($fh, $im); fclose($fh); 

the problem is, when access file, blank, 15 bytes.

what missing here?

you trying write file image handle not actual image data. try this:

imagejpeg($im, $grayimgpath);