XXXIII. Exif Functions

IntroducciÃ³n

With the exif extension you are able to work with image meta data. For example, you may use exif functions to read meta data of pictures taken from digital cameras by working with information stored in the headers of the JPEG and TIFF images.

Requisitos

Your PHP must be compiled in with --enable-exif. PHP does not require any additional library for the exif module. Windows users must also have the mbstring extension enabled.

InstalaciÃ³n

To enable exif-support configure PHP with --enable-exif

Windows users must enable both the php_mbstring.dll and php_exif.dll DLL's in php.ini. The php_mbstring.dll DLL must be loaded before the php_exif.dll DLL so adjust your php.ini accordingly.

ConfiguraciÃ³n en tiempo de ejecuciÃ³n

El comportamiento de estas funciones estÃ¡ afectado por los valores definidos en php.ini.

Exif supports automatically conversion for Unicode and JIS character encodings of user comments when module mbstring is available. This is done by first decoding the comment using the specified characterset. The result is then encoded with another characterset which should match your HTTP output.

Tabla 1. Exif configuration options

Name	Default	Changeable	Changelog
exif.encode_unicode	"ISO-8859-15"	PHP_INI_ALL	Available since PHP 4.3.0.
exif.decode_unicode_motorola	"UCS-2BE"	PHP_INI_ALL	Available since PHP 4.3.0.
exif.decode_unicode_intel	"UCS-2LE"	PHP_INI_ALL	Available since PHP 4.3.0.
exif.encode_jis	""	PHP_INI_ALL	Available since PHP 4.3.0.
exif.decode_jis_motorola	"JIS"	PHP_INI_ALL	Available since PHP 4.3.0.
exif.decode_jis_intel	"JIS"	PHP_INI_ALL	Available since PHP 4.3.0.

For further details and definitions of the PHP_INI_* constants, see the ApÃ©ndice G.

A continuaciÃ³n se presenta una corta explicaciÃ³n de las directivas de configuraciÃ³n.

exif.encode_unicode string: exif.encode_unicode defines the characterset UNICODE user comments are handled. This defaults to ISO-8859-15 which should work for most non Asian countries. The setting can be empty or must be an encoding supported by mbstring. If it is empty the current internal encoding of mbstring is used.
exif.decode_unicode_motorola string: exif.decode_unicode_motorola defines the image internal characterset for Unicode encoded user comments if image is in motorola byte order (big-endian). This setting cannot be empty but you can specify a list of encodings supported by mbstring. The default is UCS-2BE.
exif.decode_unicode_intel string: exif.decode_unicode_intel defines the image internal characterset for Unicode encoded user comments if image is in intel byte order (little-endian). This setting cannot be empty but you can specify a list of encodings supported by mbstring. The default is UCS-2LE.
exif.encode_jis string: exif.encode_jis defines the characterset JIS user comments are handled. This defaults to an empty value which forces the functions to use the current internal encoding of mbstring.
exif.decode_jis_motorola string: exif.decode_jis_motorola defines the image internal characterset for JIS encoded user comments if image is in motorola byte order (big-endian). This setting cannot be empty but you can specify a list of encodings supported by mbstring. The default is JIS.
exif.decode_jis_intel string: exif.decode_jis_intel defines the image internal characterset for JIS encoded user comments if image is in intel byte order (little-endian). This setting cannot be empty but you can specify a list of encodings supported by mbstring. The default is JIS.

Tipos de recursos

Esta extensiÃ³n no tiene ningÃºn tipo de recurso definido.

Constantes predefinidas

Estas constantes estÃ¡n definidas por esta extensiÃ³n y estarÃ¡n disponibles solamente cuando la extensiÃ³n ha sido o bien compilada dentro de PHP o grabada dinÃ¡micamente en tiempo de ejecuciÃ³n.

EXIF_USE_MBSTRING (integer)

The exif_imagetype() lists several related built-in constants.

Tabla de contenidos
exif_imagetype -- Determine the type of an image
exif_read_data -- Reads the EXIF headers from JPEG or TIFF
exif_tagname -- Get the header name for an index
exif_thumbnail -- Retrieve the embedded thumbnail of a TIFF or JPEG image
read_exif_data -- Alias of exif_read_data()

add a note User Contributed Notes
Exif Functions

filter_phpmanual at oderwat dot de
03-Sep-2005 07:26


I just found that I had to change the order of modules in php.ini to use the exif extension in php 4.3.11 on my windows system.



If I include the exif module in the order given in php.ini (first exif .. later mbstring) apache fails without any obvious reason.



After placing the exif module after the mbstring module it works.



I thought that info may prevent other people to search hours for errors in their setup too...

23-Dec-2004 02:55


exif.encode_unicode  string



    exif.encode_unicode defines the characterset UNICODE user comments are handled. This defaults to ISO-8859-15 which should work for most non Asian countries. The setting can be empty or must be an encoding supported by mbstring. If it is empty the current internal encoding of mbstring is used. 



How come ISO-8859-15 works for most non-Asian countries? It's only for West European and does NOT work for Russian, Greek, Albanian, Polish, Czech, and so forth. The default should be 'UTF-8'

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