我写了一张表格来上传图像并创建缩略图，它会检查以确保图像是JPG，PNG或GIF。在大多数情况下都可以使用，但是某些JPG文件被称为“无效文件格式”。
我尝试降低分辨率/文件大小，但是没有运气，但是如果将文件转换为.png，效果很好。
这里是指向JPG的链接，但失败； http://yourcomputerassistant.net/IMG0015.JPG
我的代码（为了使问题简短，我删除了缩略图的创建）；
if(isset($_FILES["userimage"]) && $_FILES["userimage"]["error"] == 0){
$allowed = array("jpg" => "image/jpg", "jpeg" => "image/jpeg", "gif" => "image/gif", "png" => "image/png");
$userimage = $_FILES["userimage"]["name"];
$filetype = $_FILES["userimage"]["type"];
$targetDir = "uploads/";
$targetFilePath = $targetDir . $userimage;
$targetThumbFilePath = "uploads/thumbs/";
if(!file_exists("uploads/" . $_FILES["userimage"]["name"])){
// Verify file extension
$ext = pathinfo($userimage, PATHINFO_EXTENSION);
if(array_key_exists($ext, $allowed)) {
if (move_uploaded_file($_FILES["userimage"]["tmp_name"], $targetFilePath)){
$successmsg .= "<div class='alert alert-success'>Image - " . $userimage . " - Uploaded Successfully!</div>";
}
} else {
$error .= "Invalid File Format<br>";
}
} else {
$error .= "The Filename " . $_FILES["userimage"]["name"] . " already exists - please rename your picture before uploading<br>";
}
}