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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

Descrizione

exif_read_data(
    resource|string $file,
    ?string $required_sections = null,
    bool $as_arrays = false,
    bool $read_thumbnail = false
): array|false

exif_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).

Elenco dei parametri

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.
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.

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.

Valori restituiti

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.

Errori/Eccezioni

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.

Log delle modifiche

Versione Descrizione
8.0.0 required_sections is nullable now.
7.2.0 The file parameter now supports both local files and stream resources.
7.2.0

Support for the following EXIF formats were added:

  • Samsung
  • DJI
  • Panasonic
  • Sony
  • Pentax
  • Minolta
  • Sigma/Foveon
  • AGFA
  • Kyocera
  • Ricoh
  • Epson

Esempi

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.

Il precedente esempio visualizzerà qualcosa simile a:

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);
}
?>

Il precedente esempio visualizzerà qualcosa simile a:

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

Note

Nota: 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().

Nota: 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.

Vedere anche: