Not sure you are actually using 5.2.10 with bunlded GD, but it does work fine here. I would suggest to do not use Debian's package for php or at least not for gd.

Not a PHP bug.

Hi,

Actually it's a compiled version of php, using the embed gd :
Configure line : 

./configure  --prefix=/usr/local/php-5.2.10 --with-apxs2=/usr/local/apache2/bin/apxs --with-config-file-path=/etc/php5/apache --disable-debug --with-regex=php --disable-rpath --disable-static --with-pic --with-layout=GNU --with-pear=/usr/share/php --enable-calendar --enable-sysvsem --enable-sysvshm --enable-sysvmsg --enable-bcmath --with-bz2 --enable-ctype --with-db4 --with-iconv --enable-exif --enable-ftp --with-gettext --enable-mbstring --enable-shmop --enable-sockets --with-xmlrpc --with-zlib --without-pgsql --with-openssl=/usr --enable-zip=/usr --with-mime-magic=/usr/share/file/magic.mime --with-curl=shared,/usr --with-zlib-dir=/usr --with-gd --enable-gd-native-ttf --with-jpeg-dir=shared,/usr --with-xpm-dir=shared,/usr/X11R6 --with-png-dir=shared,/usr --with-imap=shared,/usr --with-imap-ssl --with-mhash=shared,/usr --with-mysql=shared,/usr/local/mysql --with-xsl=shared --with-ttf=shared,/usr --with-t1lib=shared,/usr --with-kerberos --with-mcrypt --with-mysqli=shared,/usr/local/mysql/bin/mysql_config --enable-soap --with-pear --with-freetype-dir=/usr/include/freetype2

php -i output : 

phpinfo()
PHP Version => 5.2.10

System => Linux transformer1.doctissimo.fr 2.6.18-5-amd64 #1 SMP Tue Dec 18 21:39:26 UTC 2007 x86_64
Build Date => Jul 23 2009 15:38:45
Configure Command =>  './configure'  '--prefix=/usr/local/php-5.2.10' '--with-apxs2=/usr/local/apache2/bin/apxs' '--with-config-file-path=/etc/php5/apache' '--disable-debug' '--with-regex=php' '--disable-rpa
th' '--disable-static' '--with-pic' '--with-layout=GNU' '--with-pear=/usr/share/php' '--enable-calendar' '--enable-sysvsem' '--enable-sysvshm' '--enable-sysvmsg' '--enable-bcmath' '--with-bz2' '--enable-ctyp
e' '--with-db4' '--with-iconv' '--enable-exif' '--enable-ftp' '--with-gettext' '--enable-mbstring' '--enable-shmop' '--enable-sockets' '--with-xmlrpc' '--with-zlib' '--without-pgsql' '--with-openssl=/usr' '-
-enable-zip=/usr' '--with-mime-magic=/usr/share/file/magic.mime' '--with-curl=shared,/usr' '--with-zlib-dir=/usr' '--with-gd' '--enable-gd-native-ttf' '--with-jpeg-dir=shared,/usr' '--with-xpm-dir=shared,/us
r/X11R6' '--with-png-dir=shared,/usr' '--with-imap=shared,/usr' '--with-imap-ssl' '--with-mhash=shared,/usr' '--with-mysql=shared,/usr/local/mysql' '--with-xsl=shared' '--with-ttf=shared,/usr' '--with-t1lib=
shared,/usr' '--with-kerberos' '--with-mcrypt' '--with-mysqli=shared,/usr/local/mysql/bin/mysql_config' '--enable-soap' '--with-pear' '--with-freetype-dir=/usr/include/freetype2'
Server API => Command Line Interface
Virtual Directory Support => disabled
Configuration File (php.ini) Path => /etc/php5/apache
Loaded Configuration File => /etc/php5/apache/php.ini
Scan this dir for additional .ini files => (none)
additional .ini files parsed => (none)
PHP API => 20041225
PHP Extension => 20060613
Zend Extension => 220060519
Debug Build => no
Thread Safety => disabled
Zend Memory Manager => enabled
IPv6 Support => enabled
Registered PHP Streams => https, ftps, compress.zlib, compress.bzip2, php, file, data, http, ftp, zip
Registered Stream Socket Transports => tcp, udp, unix, udg, ssl, sslv3, sslv2, tls
Registered Stream Filters => zlib.*, bzip2.*, convert.iconv.*, string.rot13, string.toupper, string.tolower, string.strip_tags, convert.*, consumed


This program makes use of the Zend Scripting Language Engine:
Zend Engine v2.2.0, Copyright (c) 1998-2009 Zend Technologies
    with eAccelerator v0.9.5.3, Copyright (c) 2004-2006 eAccelerator, by eAccelerator


[...]

gd

GD Support => enabled
GD Version => bundled (2.0.34 compatible)
FreeType Support => enabled
FreeType Linkage => with freetype
FreeType Version => 2.2.1
T1Lib Support => enabled
GIF Read Support => enabled
GIF Create Support => enabled
JPG Support => enabled
PNG Support => enabled
WBMP Support => enabled
XPM Support => enabled
XBM Support => enabled

Regards,
  Jocelyn Fournier)

Ok, wrong test with the bundled gd, it indeed works fine, it's just the debian one which is not working correctly.

Thanks and regards,
  Jocelyn Fournier)