说明
string 
image_type_to_mime_type ( int imagetype )
    image_type_to_mime_type() 函数可以判断一个 IMAGETYPE
    常量的 MIME 类型。
    
| 例子 1. image_type_to_mime_type (file) | 
<?phpheader("Content-type: " . image_type_to_mime_type(IMAGETYPE_PNG));
 ?>
 | 
 | 
   
    返回值如下:
    
表格 1. 返回值常量
| 图像类型(imagetype) | 返回值 | 
|---|
| IMAGETYPE_GIF | image/gif | 
| IMAGETYPE_JPEG | image/jpeg | 
| IMAGETYPE_PNG | image/png | 
| IMAGETYPE_SWF | application/x-shockwave-flash | 
| IMAGETYPE_PSD | image/psd | 
| IMAGETYPE_BMP | image/bmp | 
| IMAGETYPE_TIFF_II (intel byte order) | image/tiff | 
| IMAGETYPE_TIFF_MM (motorola byte order) | image/tiff | 
| IMAGETYPE_JPC | application/octet-stream | 
| IMAGETYPE_JP2 | image/jp2 | 
| IMAGETYPE_JPX | application/octet-stream | 
| IMAGETYPE_JB2 | application/octet-stream | 
| IMAGETYPE_SWC | application/x-shockwave-flash | 
| IMAGETYPE_IFF | image/iff | 
| IMAGETYPE_WBMP | image/vnd.wap.wbmp | 
| IMAGETYPE_XBM | image/xbm | 
    
   
    参见 getimagesize(),exif_imagetype(),exif_read_data()
    和 exif_thumbnail()。