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exif_read_data
(PHP 4 >= 4.2.0, PHP 5, PHP 7)
exif_read_data — Reads the EXIF headers from an image file
Description
$stream
[, string $sections = NULL
[, bool $arrays = FALSE
[, bool $thumbnail = FALSE
]]] ) : arrayexif_read_data() reads the EXIF headers from an 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.
Parameters
-
stream -
The location of the image file. This can either be a path to the file (stream wrappers are also supported as usual) or a stream resource.
-
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
sectionsCOMPUTED, THUMBNAIL, and COMMENT always become arrays as they may contain values whose names conflict with other sections. -
thumbnail -
When set to
TRUEthe 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 |
|---|---|
| 7.2.0 |
The filename parameter was renamed to
stream and now supports both local files
or stream resources.
|
| 7.2.0 |
Support for the following EXIF formats were added:
|
Examples
Example #1 exif_read_data() example
<?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:
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
Example #2 exif_read_data() with streams available as of PHP 7.2.0
<?php
// Open a the file, this should be in binary mode
$fp = fopen('/path/to/image.jpg', 'rb');
if (!$fp) {
echo 'Error: Unable to open image for reading';
exit;
}
// Attempt to read the exif headers
$headers = exif_read_data($fp);
if (!$headers) {
echo 'Error: Unable to read exif headers';
exit;
}
// Print the 'COMPUTED' headers
echo 'EXIF Headers:' . PHP_EOL;
foreach ($headers['COMPUTED'] as $header => $value) {
printf(' %s => %s%s', $header, $value, PHP_EOL);
}
?>
The above example will output something similar to:
EXIF Headers: Height => 576 Width => 1024 IsColor => 1 ByteOrderMotorola => 0 ApertureFNumber => f/5.6 UserComment => UserCommentEncoding => UNDEFINED Copyright => Denis Thumbnail.FileType => 2 Thumbnail.MimeType => image/jpeg
Notes
Note:
If mbstring is enabled, exif will attempt to process the unicode and pick a charset as specified by exif.decode_unicode_motorola and exif.decode_unicode_intel. The exif extension will not attempt to figure out the encoding on its own, and it is up to the user to properly specify the encoding for which to use for decoding by setting one of these two ini directives prior to calling exif_read_data().
Note:
If the
streamis used to pass a stream to this function, then the stream must be seekable. Note that the file pointer position is not changed after this function returns.
See Also
- exif_thumbnail() - Retrieve the embedded thumbnail of an image
- getimagesize() - Get the size of an image
- Supported Protocols and Wrappers
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Document heeft de 30/01/2003 gemaakt, de laatste keer de 26/10/2018 gewijzigd
Bron van het afgedrukte document:https://www.gaudry.be/nl/php-rf-function.exif-read-data.html
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