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PHP : Function Reference : Exif Functions : exif_read_data

exif_read_data

Reads the EXIF headers from JPEG or TIFF (PHP 4 >= 4.2.0, PHP 5)
array exif_read_data ( string filename [, string sections [, bool arrays [, bool thumbnail]]] )

exif_read_data() reads the EXIF headers from a JPEG or TIFF image file. This way you can read meta data generated by digital cameras.

Exif headers tend to be present in JPEG/TIFF images generated by digital cameras, but unfortunately each digital camera maker has a different idea of how to actually tag their images, so you can't always rely on a specific Exif header being present.

Height and Width are computed the same way getimagesize() does so their values must not be part of any header returned. Also, html is a height/width text string to be used inside normal HTML.

When an Exif header contains a Copyright note, this itself can contain two values. As the solution is inconsistent in the Exif 2.10 standard, the COMPUTED section will return both entries Copyright.Photographer and Copyright.Editor while the IFD0 sections contains the byte array with the NULL character that splits both entries. Or just the first entry if the datatype was wrong (normal behaviour of Exif). The COMPUTED will also contain the entry Copyright which is either the original copyright string, or a comma separated list of the photo and editor copyright.

The tag UserComment has the same problem as the Copyright tag. It can store two values. First the encoding used, and second the value itself. If so the IFD section only contains the encoding or a byte array. The COMPUTED section will store both in the entries UserCommentEncoding and UserComment. The entry UserComment is available in both cases so it should be used in preference to the value in IFD0 section.

exif_read_data() also validates EXIF data tags according to the EXIF specification (» http://exif.org/Exif2-2.PDF, page 20).

Note:

Windows ME/XP can both wipe the Exif headers when connecting to a camera. More information available at » http://www.canon.co.jp/imaging/notice/011214-e.php.

Parameters

filename

The name of the image file being read. This cannot be an URL.

sections

Is a comma separated list of sections that need to be present in file to produce a result array. If none of the requested sections could be found the return value is FALSE.

FILE FileName, FileSize, FileDateTime, SectionsFound
COMPUTED html, Width, Height, IsColor, and more if available. Height and Width are computed the same way getimagesize() does so their values must not be part of any header returned. Also, html is a height/width text string to be used inside normal HTML.
ANY_TAG Any information that has a Tag e.g. IFD0, EXIF, ...
IFD0 All tagged data of IFD0. In normal imagefiles this contains image size and so forth.
THUMBNAIL A file is supposed to contain a thumbnail if it has a second IFD. All tagged information about the embedded thumbnail is stored in this section.
COMMENT Comment headers of JPEG images.
EXIF The EXIF section is a sub section of IFD0. It contains more detailed information about an image. Most of these entries are digital camera related.
arrays

Specifies whether or not each section becomes an array. The sections COMPUTED, THUMBNAIL, and COMMENT always become arrays as they may contain values whose names conflict with other sections.

thumbnail

When set to TRUE the thumbnail itself is read. Otherwise, only the tagged data is read.

Return Values

It returns an associative array where the array indexes are the header names and the array values are the values associated with those headers. If no data can be returned, exif_read_data() will return FALSE.

ChangeLog

Version Description
4.3.0 Can read all embedded IFD data including arrays (returned as such). Also the size of an embedded thumbnail is returned in a THUMBNAIL subarray, and can return thumbnails in TIFF format. Also, there is no longer a maximum length for returned values (not until the memory limit has been reached)
4.3.0 If PHP has mbstring support, the user comment can automatically change encoding. Also, if the user comment uses Unicode or JIS encoding this encoding will automatically be changed according to the exif ini settings in php.ini
4.3.0 If the image contains any IFD0 data then COMPUTED contains the entry ByteOrderMotorola which is 0 for little-endian (intel) and 1 for big-endian (motorola) byte order. Also, COMPUTED and UserComment no longer only contain the first copyright entry if the datatype was wrong.

Examples

Example 600. exif_read_data() example

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<?php
echo "test1.jpg:<br />\n";
$exif = exif_read_data('tests/test1.jpg', 'IFD0');
echo $exif===false ? "No header data found.<br />\n" : "Image contains headers<br />\n";

$exif = exif_read_data('tests/test2.jpg', 0, true);
echo "test2.jpg:<br />\n";
foreach ($exif as $key => $section) {
   foreach ($section as $name => $val) {
       echo "$key.$name: $val<br />\n";
   }
}
?>

The first call fails because the image has no header information.

The above example will output something similar to:

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test1.jpg:
No header data found.
test2.jpg:
FILE.FileName: test2.jpg
FILE.FileDateTime: 1017666176
FILE.FileSize: 1240
FILE.FileType: 2
FILE.SectionsFound: ANY_TAG, IFD0, THUMBNAIL, COMMENT
COMPUTED.html: width="1" height="1"
COMPUTED.Height: 1
COMPUTED.Width: 1
COMPUTED.IsColor: 1
COMPUTED.ByteOrderMotorola: 1
COMPUTED.UserComment: Exif test image.
COMPUTED.UserCommentEncoding: ASCII
COMPUTED.Copyright: Photo (c) M.Boerger, Edited by M.Boerger.
COMPUTED.Copyright.Photographer: Photo (c) M.Boerger
COMPUTED.Copyright.Editor: Edited by M.Boerger.
IFD0.Copyright: Photo (c) M.Boerger
IFD0.UserComment: ASCII
THUMBNAIL.JPEGInterchangeFormat: 134
THUMBNAIL.JPEGInterchangeFormatLength: 523
COMMENT.0: Comment #1.
COMMENT.1: Comment #2.
COMMENT.2: Comment #3end
THUMBNAIL.JPEGInterchangeFormat: 134
THUMBNAIL.Thumbnail.Height: 1
THUMBNAIL.Thumbnail.Height: 1 ?>


See Also
exif_thumbnail()
getimagesize()

Code Examples / Notes » exif_read_data

05-mar-2007 07:50
When reading EXIF information from the 'WINXP' group, you may need to change used encoding from the default "ISO-8859-15" to "UTF-8". This can be done in php.ini or in your code:
<?php
   ini_set('exif.encode_unicode', 'UTF-8');
   $exif = exif_read_data('TEST.JPG', 0, true);
   echo $exif['WINXP']['Title'];
?>
Useful documentation about EXIF:
http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/EXIF.html
See also comments next to XPTitle and XPAuthor.

wdierkes
Using the exif methods to read WINXP data returns unexpected results unless both exif and mbstring are compiled statically.  Please reference the following bug reports:
Bug #31980
Bug #23105

Specifically, the last comment on #23105:
"[8 Apr 2003 4:26pm UTC] edink@php.net
This cannot be fixed due to the fact that mbstring has been removed from PHP core (it has been 'unbundled') and the rest of core files and other extensions cannot use mbstring functionality when it is compiled as a shared library (dll).
"
If exif is compiled statically (--enable-exif) and mbstring compiled as a DSO module (--enable-mbstring=shared) then exif_read_data may only return a single character rather than the entire string.
Compiling both exif and mbstring statically (--enable-exif --enable-mbstring) resolves the issue.

mafo
some cameras (most higher models) have position senzor (gyroskope?) and taking-position is wrote in EXIF, here is simple script for automatic rotating images
<?php
$exif = exif_read_data($filename);
$ort = $exif['IFD0']['Orientation'];
switch($ort)
{
case 1: // nothing
break;
case 2: // horizontal flip
$image->flipImage($public,1);
break;

case 3: // 180 rotate left
$image->rotateImage($public,180);
break;

case 4: // vertical flip
$image->flipImage($public,2);
break;

case 5: // vertical flip + 90 rotate right
$image->flipImage($public, 2);
       $image->rotateImage($public, -90);
break;

case 6: // 90 rotate right
$image->rotateImage($public, -90);
break;

case 7: // horizontal flip + 90 rotate right
$image->flipImage($public,1);
$image->rotateImage($public, -90);
break;

case 8: // 90 rotate left
$image->rotateImage($public, 90);
break;
}
?>
$image->rotateImage() is inspired by example of http://php.net/manual/en/function.imagerotate.php
$image->flipImage() is inspired by http://php.net/manual/en/function.imagecopy.php#42803 (thank you)

gimpster
I've written a library in pure PHP5 for editing EXIF tags. It deals with both reading and writing EXIF tags, and can be downloaded from http://pel.sourceforge.net/

09-aug-2004 06:11
I've just released the "PHP JPEG Metadata Toolkit" which allows reading, writing and displaying of EXIF information, and does not need the --enable-exif option in PHP4.
It has been tested on 466 different models of digital cameras!
It can decode the following EXIF makernotes:
Agfa, Canon, Casio, Contax, Epson, Fujifilm, Konica, Minolta, Kyocera, Nikon, Olympus, Panasonic, Pentax (Asahi), Ricoh and Sony
Additionaly it can decode IPTC, XMP, Photoshop IRB and many other types of JPEG metadata
Try it out, and download it at:
http://www.ozhiker.com/electronics/pjmt/index.html

pekka
For reading EXIF from XMP data embedded by Adobe Photoshop CS, see  http://www.photography-on-the.net/ee/beta/cs_xmp_to_exif.php

noway
Exif is very unstable under php4.1.2
If you have some problem, (the function didnt return anything, like a blocking call) try this:
$file = './image.jpg';
getimagesize ( $file , $info);
$exif = array();
if (isset($info)) {
foreach($info as $key => $val) {
if ($key != 'APP1') { $exif = read_exif_data($file); break; }
}
}
-- Sharp

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