如果文件大小超过50kb，则调整图像大小

使用filesize()。

$sess=66666;
$images = $_FILES["photoimg"]["tmp_name"];
$new_images = "$sess.gif";
$maxsize = 50 * 1024; // 50Kb
if( filesize($images) > $maxsize) {
    $width=200; 
    //*** Fix Width & Heigh (Autu caculate) ***//
    $size=getimagesize($images);
    $height=round($width*$size[1]/$size[0]);
    if($size[2] == 1) {
        $images_orig = imagecreatefromgif($images);
    } else if($size[2] == 2) {
        $images_orig = imagecreatefromjpeg($images);
    }else if($size[2] == 3) {
        $images_orig = imagecreatefrompng($images); 
    }
    $photoX = imagesx($images_orig);
    $photoY = imagesy($images_orig);
    $images_fin = imagecreatetruecolor($width, $height);
    imagecopyresampled($images_fin, $images_orig, 0, 0, 0, 0, $width+1, $height+1,         $photoX, $photoY);
    imagejpeg($images_fin,"images/".$new_images);
    imagedestroy($images_orig);
    imagedestroy($images_fin);
} else {
    imagejpeg($images,"images/".$new_images);
}

测试文件大小如下：

$maxSize = 50 * 1024;
$sess=66666;
$images = $_FILES["photoimg"]["tmp_name"];
if(filesize($images) > $maxSize){
    $sess=66666;
    $images = $_FILES["photoimg"]["tmp_name"];
    $new_images = "$sess.gif";
    $width=200; 
    //*** Fix Width & Heigh (Autu caculate) ***//
    $size=GetimageSize($images);
    $height=round($width*$size[1]/$size[0]);
    if($size[2] == 1) {
        $images_orig = imagecreatefromgif($images);
    } else if($size[2] == 2) {
        $images_orig = imagecreatefromjpeg($images);
    }else if($size[2] == 3) {
        $images_orig = imagecreatefrompng($images); 
    }
    $photoX = ImagesX($images_orig);
    $photoY = ImagesY($images_orig);
    $images_fin = ImageCreateTrueColor($width, $height);
    ImageCopyResampled($images_fin, $images_orig, 0, 0, 0, 0, $width+1, $height+1, $photoX, $photoY);
    Imagejpeg($images_fin,"images/".$new_images);
    ImageDestroy($images_orig);
    ImageDestroy($images_fin);
}