(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
exif_thumbnail — 取得嵌入在 TIFF 或 JPEG 图像中的缩略图
$filename,&$width = ?,&$height = ?,&$imagetype = ?
    exif_thumbnail() 读取 TIFF 或 JPEG
    图像中的嵌入缩略图。如果图像不包含缩略图则返回 false。
If you want to deliver thumbnails through this function, you should send the mimetype information using the header() function.
   It is possible that exif_thumbnail() cannot create an 
   image but can determine its size. In this case, the return value is 
   false but width and height 
   are set.
  
filenameThe name of the image file being read. This image contains an embedded thumbnail.
widthThe return width of the returned thumbnail.
heightThe returned height of the returned thumbnail.
imagetypeThe returned image type of the returned thumbnail. This is either TIFF or JPEG.
   Returns the embedded thumbnail, or false if the image contains no 
   thumbnail.
  
| 版本 | 说明 | 
|---|---|
| 4.3.0 | The optional parameters width,height, andimagetypeall became available. | 
| 4.3.0 | May return thumbnails in the TIFF format. | 
示例 #1 exif_thumbnail() 例子
<?php
if (array_key_exists('file',$_REQUEST)) {
    $image = exif_thumbnail($_REQUEST['file'], $width, $height, $type);
} else {
    $image = false;
}
if ($image!==false) {
    header("Content-type: ".image_type_to_mime_type($type));
    echo $image;
    exit;
} else {
    // no thumbnail available, handle the error here
    echo "No thumbnail available";
}
?>