GD缩略图无法在较大的文件大小上运行

Question

我正在使用GD缩略图来创建和存储上传图像的缩略图。现在，当使用小图像尺寸时，一切正常，但是当文件开始变大时，比如大约3MB，则不会创建缩略图。

我的文件上传限制为4MB，实际图片本身已上传，只是没有创建缩略图。

我对脚本不是很熟悉，所以我不确定为什么它不起作用。也许值得注意的是缩略图（当它们被创建时）正在上传到两个不同的目录，但这可能是我一直错过的东西。

非常感谢任何想法。

<?php 
$imagefolder='images';
$thumbsfolder='thumbs';
$pics=directory($imagefolder,"jpg,JPG,JPEG,jpeg,png,PNG");
$pics=ditchtn($pics,"tn_");
if ($pics[0]!="")
{
    foreach ($pics as $p)
    {
        createthumb($p,"tn_".$p,182,182);
    }
}

/*
    Function ditchtn($arr,$thumbname)
    filters out thumbnails
*/
function ditchtn($arr,$thumbname)
{
    foreach ($arr as $item)
    {
        if (!preg_match("/^".$thumbname."/",$item)){$tmparr[]=$item;}
    }
    return $tmparr;
}

/*
    Function createthumb($name,$filename,$new_w,$new_h)
    creates a resized image
    variables:
    $name       Original filename
    $filename   Filename of the resized image
    $new_w      width of resized image
    $new_h      height of resized image
*/  
function createthumb($name,$filename,$new_w,$new_h)
{
    $system=explode(".",$name);
    if (preg_match("/jpg|jpeg/",$system[1])){$src_img=imagecreatefromjpeg($name);}
    if (preg_match("/png/",$system[1])){$src_img=imagecreatefrompng($name);}
    $old_x=imageSX($src_img);
    $old_y=imageSY($src_img);
    if ($old_x > $old_y) 
    {
        $thumb_w=$new_w;
        $thumb_h=$old_y*($new_h/$old_x);
    }
    if ($old_x < $old_y) 
    {
        $thumb_w=$old_x*($new_w/$old_y);
        $thumb_h=$new_h;
    }
    if ($old_x == $old_y) 
    {
        $thumb_w=$new_w;
        $thumb_h=$new_h;
    }
    $dst_img=ImageCreateTrueColor($thumb_w,$thumb_h);
    imagecopyresampled($dst_img,$src_img,0,0,0,0,$thumb_w,$thumb_h,$old_x,$old_y); 
    if (preg_match("/png/",$system[1]))
    {
        imagepng($dst_img,$filename); 
    } else {
        imagejpeg($dst_img,$filename); 
    }
    imagedestroy($dst_img); 
    imagedestroy($src_img); 
}

/*
        Function directory($directory,$filters)
        reads the content of $directory, takes the files that apply to $filter 
        and returns an array of the filenames.
        You can specify which files to read, for example
        $files = directory(".","jpg,gif");
                gets all jpg and gif files in this directory.
        $files = directory(".","all");
                gets all files.
*/
function directory($dir,$filters)
{
    $handle=opendir($dir);
    $files=array();
    if ($filters == "all"){while(($file = readdir($handle))!==false){$files[] = $file;}}
    if ($filters != "all")
    {
        $filters=explode(",",$filters);
        while (($file = readdir($handle))!==false)
        {
            for ($f=0;$f<sizeof($filters);$f++):
                $system=explode(".",$file);
                if ($system[1] == $filters[$f]){$files[] = $file;}
            endfor;
        }
    }
    closedir($handle);
    return $files;
}
?>