1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
|
<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.10 $ -->
<!-- splitted from ./en/functions/image.xml, last change in rev 1.78 -->
<refentry id="function.exif-read-data">
<refnamediv>
<refname>exif_read_data</refname>
<refpurpose>Reads the <acronym>EXIF</acronym> headers from <acronym>JPEG</acronym> or <acronym>TIFF</acronym></refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>array</type><methodname>exif_read_data</methodname>
<methodparam><type>string</type><parameter>filename</parameter></methodparam>
<methodparam choice="opt"><type>string</type><parameter>sections</parameter></methodparam>
<methodparam choice="opt"><type>bool</type><parameter>arrays</parameter></methodparam>
<methodparam choice="opt"><type>bool</type><parameter>thumbnail</parameter></methodparam>
</methodsynopsis>
<para>
<function>exif_read_data</function> reads the
<acronym>EXIF</acronym> headers from a <acronym>JPEG</acronym> or
<acronym>TIFF</acronym> image file. This way you can read meta data
generated by digital cameras.
</para>
<para>
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.
</para>
<para>
<literal>Height</literal> and <literal>Width</literal> are computed the
same way <function>getimagesize</function> does so their values must not be
part of any header returned. Also, <literal>html</literal> is a
height/width text string to be used inside normal <acronym>HTML</acronym>.
</para>
<para>
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 <literal>Copyright.Photographer</literal>
and <literal>Copyright.Editor</literal> 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 <literal>Copyright</literal> which
is either the original copyright string, or a comma separated list of the
photo and editor copyright.
</para>
<para>
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 <literal>UserCommentEncoding</literal> and
<literal>UserComment</literal>. The entry <literal>UserComment</literal>
is available in both cases so it should be used in preference to the value
in IFD0 section.
</para>
<para>
<function>exif_read_data</function> also validates EXIF data tags according
to the EXIF specification (<ulink
url="&url.exifspec;">&url.exifspec;</ulink>, page 20).
</para>
<note>
<para>
Windows ME/XP can both wipe the Exif headers when connecting to a camera.
More information available at <ulink url="&url.winexif;">&url.winexif;</ulink>.
</para>
</note>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>filename</parameter></term>
<listitem>
<para>
The name of the image file being read. This cannot be an
<acronym>URL</acronym>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>sections</parameter></term>
<listitem>
<para>
Is a comma separated list of sections that need to be present in file
to produce a result <type>array</type>. If none of the requested
sections could be found the return value is &false;.
<informaltable>
<tgroup cols="2">
<tbody>
<row>
<entry>FILE</entry>
<entry>FileName, FileSize, FileDateTime, SectionsFound</entry>
</row>
<row>
<entry>COMPUTED</entry>
<entry>
html, Width, Height, IsColor, and more if available. Height and
Width are computed the same way <function>getimagesize</function>
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
<acronym>HTML</acronym>.
</entry>
</row>
<row>
<entry>ANY_TAG</entry>
<entry>Any information that has a Tag e.g. IFD0, EXIF, ...</entry>
</row>
<row>
<entry>IFD0</entry>
<entry>
All tagged data of IFD0. In normal imagefiles this contains
image size and so forth.
</entry>
</row>
<row>
<entry>THUMBNAIL</entry>
<entry>
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.
</entry>
</row>
<row>
<entry>COMMENT</entry>
<entry>Comment headers of JPEG images.</entry>
</row>
<row>
<entry>EXIF</entry>
<entry>
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.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>arrays</parameter></term>
<listitem>
<para>
Specifies whether or not each section becomes an array. The
<parameter>sections</parameter> <literal>COMPUTED</literal>,
<literal>THUMBNAIL</literal>, and <literal>COMMENT</literal>
always become arrays as they may contain values whose names conflict
with other sections.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>thumbnail</parameter></term>
<listitem>
<para>
When set to &true; the thumbnail itself is read. Otherwise, only the
tagged data is read.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
It returns an associative <type>array</type> 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,
<function>exif_read_data</function> will return &false;.
</para>
</refsect1>
<refsect1 role="changelog">
&reftitle.changelog;
<para>
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
<row>
<entry>4.3.0</entry>
<entry>
Can read all embedded <acronym>IFD</acronym> data including arrays
(returned as such). Also the size of an embedded thumbnail is
returned in a <literal>THUMBNAIL</literal> subarray, and can
return thumbnails in <acronym>TIFF</acronym> format. Also, there is
no longer a maximum length for returned values (not until the memory
limit has been reached)
</entry>
</row>
<row>
<entry>4.3.0</entry>
<entry>
If PHP has <link linkend="ref.mbstring">mbstring</link> 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;
</entry>
</row>
<row>
<entry>4.3.0</entry>
<entry>
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.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title><function>exif_read_data</function> example</title>
<programlisting role="php">
<![CDATA[
<?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";
}
}
?>
]]>
</programlisting>
<para>
The first call fails because the image has no header information.
</para>
&example.outputs.similar;
<screen role="php">
<![CDATA[
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
]]>
</screen>
</example>
</para>
</refsect1>
<refsect1>
&reftitle.seealso;
<para>
<simplelist>
<member><function>exif_thumbnail</function></member>
<member><function>getimagesize</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"../../../../manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->
|
