Exif 函数
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exif_read_data

(PHP 4 >= 4.2.0, PHP 5)

exif_read_data — 从 JPEG 或 TIFF 文件中读取 EXIF 头信息

说明

array exif_read_data ( string $filename [, string $sections [, bool $arrays [, bool $thumbnail ]]] )

exif_read_data() 函数从 JPEG 或 TIFF 图像文件中读取 EXIF 头信息。这样就可以读取数码相机产生的元数据。

Exif 头信息往往存在于数码相机生成的 JPEG/TIFF 图像中，但不幸的是每个数码相机制造商的标记都不同，因此（编写代码时）不能依赖于某个特定的 Exif 头信息。

Height 和 Width 是用和 getimagesize() 一样的方法计算的，因此它们的值不能是任何返回的头信息的部分。此外 html 是一个 height/width 的文本字符串可以用于普通的 HTML 中。

当一个 Exif 头信息包含有一个 Copyright 时注意它本身可以包含两个值。解决方案和 Exif 2.10 标准不一致，COMPUTED 区段会同时返回 Copyright.Photographer 和 Copyright.Editor，但是 IFD0 区段则包含有一个字节数组用 NULL 字符分隔开两个项目。或者只有第一项如果数据类型错误的话（Exif 的正常行为）。COMPUTED 也会包含 Copyright，要么是原始的版权字符串，要么是逗号分隔的摄像与编辑的版权信息。

UserComment 标记和 Copyright 有同样的问题。它也可以存储两个值，第一个是使用的编码方式，第二个是其值本身。如果这样则 IFD0 区段仅包含编码方式或者一个字节数组。COMPUTED 区段将存储两个值到 UserCommentEncoding 和 UserComment。UserComment 在两种情况下都可用因此应该优先使用它而不是 IFD0 区段中的该值。

exif_read_data() 还会根据 EXIF 规范（» http://exif.org/Exif2-2.PDF，第 20 页）来验证 EXIF 数据。

Note:

Windows ME/XP 在连接到数码相机时能清除掉 Exif 头信息。

参数

filename

被读取的图像文件名。不能是 URL。

sections

是需要存在于文件中的逗号分隔的区段列表用来产生结果数组。如果未找到所请求的区段则返回值为 FALSE。

FILE FileName, FileSize, FileDateTime, SectionsFound
COMPUTED html，Width，Height，IsColor，可能有更多其它的。Height 和 Width 是用和 getimagesize() 一样的方法计算的，因此它们的值不能是任何返回的头信息的部分。此外 html 是一个 height/width 的文本字符串可以用于普通的 HTML 中。
ANY_TAG 任何包含有标记的信息，例如 IFD0，EXIF，...
IFD0 所有 IFD0 的标记数据。在标准的图像文件中这包含了图像大小及其它。
THUMBNAIL 如果有第二个 IFD，文件应该包含有缩略图。所有有关嵌入缩略图的标记信息都存储在本区。
COMMENT JPEG 图像的注释头信息。
EXIF EXIF 区段是 IFDO 的子区，包含有图像的更多详细信息。大多数内容都是数码相机相关的。

arrays

指定了是否每个区段都成为一个数组。sections COMPUTED，THUMBNAIL 和COMMENT 区段总是成为数组，因为它们里面包含的名字和其它区段冲突。

thumbnail

当设定为 TRUE 时，读取缩略图本身。否则只读取标记数据。

返回值

返回一个关联数组，键名是头信息名，值为与其相应的值。如果没有可供返回的数据，exif_read_data() 将返回 FALSE。

更新日志

版本 说明
4.3.0 可以读取所有嵌入的 IFD 数据，包括数组（也返回数组）。此外嵌入的缩略图的大小包括在 THUMBNAIL 子数组中并且 exif_read_data() 可以将缩略图按照 TIFF 格式返回。最后，不再有返回值最大长度的限制了（直到达到内存限定）。
4.3.0 如果 PHP 有 mbstring 支持，则用户注释可以自动改变编码。此外，如果用户注释使用 Unicode 或 JIS 编码，将会根据 EXIF 在 php.ini 中的 设置被自动改变。
4.3.0 如果图像包含任何 IFD0 数据，则 COMPUTED 会包含有一项 ByteOrderMotorola，对于 little-endian (intel) 字节顺序，其值为 0，对于 big-endian (motorola) 字节顺序，其值为 1。此外，COMPUTED 和 UserComment 在数据类型出错时也不再仅包含第一个版权条目。

范例

Example #1 exif_read_data() 例子

<?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";
    }
}
?>

第一个调用失败了，因为图像没有头信息。

以上例程的输出类似于：

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

参见

Exif 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 从 JPEG 或 TIFF 文件中读取 EXIF 头信息

用户评论:

drpain at webster dot org dot za (13-Mar-2012 07:40)

Please note that when resizing images with GD and most image processing scripts or applications you will loose the EXIF information. What I did as a workaround is book this information into MySQL before I re-size images.

<?php

// This function is used to determine the camera details for a specific image. It returns an array with the parameters.
function cameraUsed($imagePath) {

    // Check if the variable is set and if the file itself exists before continuing
    if ((isset($imagePath)) and (file_exists($imagePath))) {
   
      // There are 2 arrays which contains the information we are after, so it's easier to state them both
      $exif_ifd0 = read_exif_data($imagePath ,'IFD0' ,0);      
      $exif_exif = read_exif_data($imagePath ,'EXIF' ,0);
     
      //error control
      $notFound = "Unavailable";
     
      // Make
      if (@array_key_exists('Make', $exif_ifd0)) {
        $camMake = $exif_ifd0['Make'];
      } else { $camMake = $notFound; }
     
      // Model
      if (@array_key_exists('Model', $exif_ifd0)) {
        $camModel = $exif_ifd0['Model'];
      } else { $camModel = $notFound; }
     
      // Exposure
      if (@array_key_exists('ExposureTime', $exif_ifd0)) {
        $camExposure = $exif_ifd0['ExposureTime'];
      } else { $camExposure = $notFound; }

      // Aperture
      if (@array_key_exists('ApertureFNumber', $exif_ifd0['COMPUTED'])) {
        $camAperture = $exif_ifd0['COMPUTED']['ApertureFNumber'];
      } else { $camAperture = $notFound; }
     
      // Date
      if (@array_key_exists('DateTime', $exif_ifd0)) {
        $camDate = $exif_ifd0['DateTime'];
      } else { $camDate = $notFound; }
     
      // ISO
      if (@array_key_exists('ISOSpeedRatings',$exif_exif)) {
        $camIso = $exif_exif['ISOSpeedRatings'];
      } else { $camIso = $notFound; }
     
      $return = array();
      $return['make'] = $camMake;
      $return['model'] = $camModel;
      $return['exposure'] = $camExposure;
      $return['aperture'] = $camAperture;
      $return['date'] = $camDate;
      $return['iso'] = $camIso;
      return $return;
   
    } else {
      return false;
    }
}

?>

An example of it's use follows:

<?php

$camera = cameraUsed("/img/myphoto.jpg");
echo "Camera Used: " . $camera['make'] . " " . $camera['model'] . "<br />";
echo "Exposure Time: " . $camera['exposure'] . "<br />";
echo "Aperture: " . $camera['aperture'] . "<br />";
echo "ISO: " . $camera['iso'] . "<br />";
echo "Date Taken: " . $camera['date'] . "<br />";

?>

Will display the following, depending on the data:

Camera Used: SONY DSC-S930
Exposure Time: 1/400
Aperture: f/4.3
ISO: 100
Date Taken: 2010:12:10 18:18:45

If the image has been re-sized and the information is no longer available then you should receive the following when echoing the same:

Camera Used: Unavailable
Exposure Time: Unavailable
Aperture: Unavailable
ISO: Unavailable
Date Taken: Unavailable

Some cameras do not capture all the information, for instance Blackberry phones do not record an aperture, or iso and you will get Unavailable for those fields. 

I hope you find this helpful.

michael [at[ thisiswilson [dot[ com (21-Nov-2008 05:01)

From - darkain at darkain dot com 's example.

If all the data is from the same image - simply

<?php
        $exif_data = exif_read_data ( $_FILES['photo']

        $emake =$exif_data['Make'];
        $emodel = $exif_data['Model'];
        $eexposuretime = $exif_data['ExposureTime'];
        $efnumber = $exif_data['FNumber'];
        $eiso = $exif_data['ISOSpeedRatings'];
        $edate = $exif_data['DateTime'];
?>

will work, I tried using the PEL library, and while pretty cool, I can't for the life understand how to call some things, this is simpler if your system is pretty basic or if you're in a rush.  If you have time, try playing with PEL.  It's not maintained at the moment though..

http://pel.sourceforge.net/

lincolnzsilva at gmail dot com (27-Sep-2008 12:57)

Get some EXIFs fields (easy way):

<?php
        $exif_make = exif_read_data ( $_FILES['photo']['tmp_name'] ,'IFD0' ,0 );
        $emake = $exif_make['Make'];
       
        $exif_model = exif_read_data ( $_FILES['photo']['tmp_name'] ,'IFD0' ,0 );
        $emodel = $exif_model['Model'];
       
        $exif_exposuretime = exif_read_data ( $_FILES['photo']['tmp_name'] ,'EXIF' ,0 );
        $eexposuretime = $exif_exposuretime['ExposureTime'];
       
        $exif_fnumber = exif_read_data ( $_FILES['photo']['tmp_name'] ,'EXIF' ,0 );
        $efnumber = $exif_fnumber['FNumber'];

        $exif_iso = exif_read_data ( $_FILES['photo']['tmp_name'] ,'EXIF' ,0 );
        $eiso = $exif_iso['ISOSpeedRatings'];
               
        $exif_date = exif_read_data ( $_FILES['photo']['tmp_name'] ,'IFD0' ,0 );
        $edate = $exif_date['DateTime'];
?>

darkain at darkain dot com (29-Jul-2008 07:33)

I wanted some quick and easy functions for computing the shutter speed and f-stop.  I couldn't find any anywhere, so I made some.  It took some research :

<?php
function exif_get_float($value) {
  $pos = strpos($value, '/');
  if ($pos === false) return (float) $value;
  $a = (float) substr($value, 0, $pos);
  $b = (float) substr($value, $pos+1);
  return ($b == 0) ? ($a) : ($a / $b);
}

function exif_get_shutter(&$exif) {
  if (!isset($exif['ShutterSpeedValue'])) return false;
  $apex    = exif_get_float($exif['ShutterSpeedValue']);
  $shutter = pow(2, -$apex);
  if ($shutter == 0) return false;
  if ($shutter >= 1) return round($shutter) . 's';
  return '1/' . round(1 / $shutter) . 's';
}

function exif_get_fstop(&$exif) {
  if (!isset($exif['ApertureValue'])) return false;
  $apex  = exif_get_float($exif['ApertureValue']);
  $fstop = pow(2, $apex/2);
  if ($fstop == 0) return false;
  return 'f/' . round($fstop,1);
}
?>

wdierkes at 5dollarwhitebox dot org (05-Sep-2007 02:20)

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 at mafo removethis dot sk (08-Aug-2007 09:57)

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)

(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.

(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

gimpster at gimpster dot com (18-May-2004 12:24)

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/

noway at nowaysoft dot com (24-Feb-2004 04:44)

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

pekka at photography-on-the dot net (20-Nov-2003 01:50)

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