exif_imagetype

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

exif_imagetype — Determine the type of an image

Descrizione

exif_imagetype(string $filename): int|false

exif_imagetype() reads the first bytes of an image and checks its signature.

exif_imagetype() can be used to avoid calls to other exif functions with unsupported file types or in conjunction with $_SERVER['HTTP_ACCEPT'] to check whether or not the viewer is able to see a specific image in the browser.

Elenco dei parametri

filename: The image being checked.

Valori restituiti

When a correct signature is found, the appropriate constant value will be returned otherwise the return value is false. The return value is the same value that getimagesize() returns in index 2 but exif_imagetype() is much faster.

The following constants are defined, and represent possible exif_imagetype() return values:

**Imagetype Constants**
Value	Constant
1	`IMAGETYPE_GIF`
2	`IMAGETYPE_JPEG`
3	`IMAGETYPE_PNG`
4	`IMAGETYPE_SWF`
5	`IMAGETYPE_PSD`
6	`IMAGETYPE_BMP`
7	`IMAGETYPE_TIFF_II` (intel byte order)
8	`IMAGETYPE_TIFF_MM` (motorola byte order)
9	`IMAGETYPE_JPC`
10	`IMAGETYPE_JP2`
11	`IMAGETYPE_JPX`
12	`IMAGETYPE_JB2`
13	`IMAGETYPE_SWC`
14	`IMAGETYPE_IFF`
15	`IMAGETYPE_WBMP`
16	`IMAGETYPE_XBM`
17	`IMAGETYPE_ICO`
18	`IMAGETYPE_WEBP`
19	`IMAGETYPE_AVIF`

Nota:
exif_imagetype() will emit an E_NOTICE and return false if it is unable to read enough bytes from the file to determine the image type.

Log delle modifiche

Versione	Descrizione
7.1.0	Added WebP support.
8.1.0	Added AVIF support.

Esempi

Example #1 exif_imagetype() example

<?php
if (exif_imagetype('image.gif') != IMAGETYPE_GIF) {
    echo 'The picture is not a gif';
}
?>

Vedere anche:

image_type_to_mime_type() - Get Mime-Type for image-type returned by getimagesize, exif_read_data, exif_thumbnail, exif_imagetype
getimagesize() - Get the size of an image

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User Contributed Notes 4 notes

down

christophe dot tournayre at univ*bpclermont dot Fr ¶

11 years ago

Because I only want to check for jpeg or png from a memory string, this is my 2 functions that are quick and don't have any dependencies :

<?php
  function is_jpeg(&$pict)
  {
    return (bin2hex($pict[0]) == 'ff' && bin2hex($pict[1]) == 'd8');
  }

  function is_png(&$pict)
  {
    return (bin2hex($pict[0]) == '89' && $pict[1] == 'P' && $pict[2] == 'N' && $pict[3] == 'G');
  }
?>

down

Tim ¶

17 years ago

By trial and error, it seems that a file has to be 12 bytes or larger in order to avoid a "Read error!".  Here's a work-around to avoid an error being thrown:

// exif_imagetype throws "Read error!" if file is too small
if (filesize($uploadfile) > 11)
    $mimetype = exif_imagetype($uploadfile);
else
    $mimetype = false;

down

admin at leonard !spam challis dot com ¶

14 years ago

Windows users: If you get the fatal error "Fatal error:  Call to undefined function exif_imagetype()", and you have enabled php_exif.dll, make sure you enable php_mbstring.dll. You must put mbstring before exif in the php.ini, i.e.:

extension=php_mbstring.dll
extension=php_exif.dll

You can check whether this has worked by calling phpinfo() and searching for exif.

down

tom dot ghyselinck at telenet dot be ¶

16 years ago

If the function exif_imagetype() is not available,
you can try the following workaround:

if ( ! function_exists( 'exif_imagetype' ) ) {
    function exif_imagetype ( $filename ) {
        if ( ( list($width, $height, $type, $attr) = getimagesize( $filename ) ) !== false ) {
            return $type;
        }
    return false;
    }
}

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