$PIC_WIDTH  =  75;
$PIC_HEIGHT =  56;
$img = imagecreatetruecolor ( $PIC_WIDTH*$PIC_ROWS, $PIC_HEIGHT * $all_cols );
imagefill($img, 0, 0, imagecolorallocate($img, 225, 225, 225));

 for ( $y=0; $y < $all_cols; $y++ ) {
  for ( $x = 0; $x < $PIC_ROWS; $x++,$i++ ){
       $file =  $json_a[$i]['src_preview'];
       $imgtmp = imagecreatefromgif($file);
       $imginfo = getimagesize ($file);
       imagecopyresampled ( $img , $imgtmp, $x*$PIC_WIDTH , $y*$PIC_HEIGHT, 0, 0, $PIC_WIDTH, $PIC_HEIGHT, $imginfo[0], $imginfo[1]);
       imagedestroy ($imgtmp);
    }
  }
  imagepng($img, 'img/blatt.png',0);