exif_read_data
(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
exif_read_data — Reads the EXIF headers from an image file
Опис
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).
Параметри
file-
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.
required_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.
as_arrays-
Specifies whether or not each section becomes an array. The
required_sections COMPUTED,
THUMBNAIL, and COMMENT
always become arrays as they may contain values whose names conflict
with other sections.
read_thumbnail-
When set to true the thumbnail itself is read. Otherwise, only the
tagged data is read.
Значення, що повертаються
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.
Помилки/виключення
Errors of level E_WARNING and/or E_NOTICE
may be raised for unsupported tags or other potential error conditions, but the
function still tries to read all comprehensible information.
Приклади
Приклад #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.
Поданий вище приклад виведе щось
схоже на:
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
Приклад #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);
}
?>
Поданий вище приклад виведе щось
схоже на:
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
Примітки
Зауваження:
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().
Зауваження:
If the file is 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.
