J'ai bien compris, mais si je passe les valeurs à "true", je me retrouve avec le problème décrit initialement;
anomalie des valeurs $conf['show_exif'] et $conf['use_exif'], ce qui me fais tourner en rond!

OK, on y vas. J'utilise Notepad++, mais c'est un détail;


<?php
// +-----------------------------------------------------------------------+
// | Piwigo - a PHP based photo gallery                                    |
// +-----------------------------------------------------------------------+
// | Copyright(C) 2008-2011 Piwigo Team                  http://piwigo.org |
// | Copyright(C) 2003-2008 PhpWebGallery Team    http://phpwebgallery.net |
// | Copyright(C) 2002-2003 Pierrick LE GALL   http://le-gall.net/pierrick |
// +-----------------------------------------------------------------------+
// | This program is free software; you can redistribute it and/or modify  |
// | it under the terms of the GNU General Public License as published by  |
// | the Free Software Foundation                                          |
// |                                                                       |
// | This program is distributed in the hope that it will be useful, but   |
// | WITHOUT ANY WARRANTY; without even the implied warranty of            |
// | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU      |
// | General Public License for more details.                              |
// |                                                                       |
// | You should have received a copy of the GNU General Public License     |
// | along with this program; if not, write to the Free Software           |
// | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, |
// | USA.                                                                  |
// +-----------------------------------------------------------------------+

/**
*                           configuration page
*
* Set configuration parameters that are not in the table config. In the
* application, configuration parameters are considered in the same way
* coming from config table or config_default.inc.php.
*
* It is recommended to let config_default.inc.php as provided and to
* overwrite configuration in your local configuration file
* local/config/config.inc.php. See tools/config.inc.php as an example.
*
* Why having some parameters in config table and others in
* config_*.inc.php? Modifying config_*.inc.php is a "hard" task for low
* skilled users, they need a GUI for this : admin/configuration. But only
* parameters that might be modified by low skilled users are in config
* table, other parameters are in config_*.inc.php
*/

// +-----------------------------------------------------------------------+
// |                                 misc                                  |
// +-----------------------------------------------------------------------+

// order_by_custom and order_by_inside_category_custom : for non common pattern
// you can define special ORDER configuration
//
// $conf['order_by_custom'] = ' ORDER BY date_available DESC, file ASC, id ASC';

// order_by_inside_category : inside a category, images can also be ordered
// by rank. A manually defined rank on each image for the category.
//
// $conf['order_by_inside_category_custom'] = $conf['order_by_custom'];

// file_ext : file extensions (case sensitive) authorized
$conf['file_ext'] = array('jpg','JPG','jpeg','JPEG',
                          'png','PNG','gif','GIF','mpg','zip',
                          'avi','mp3','ogg');

// picture_ext : file extensions for picture file, must be a subset of
// file_ext
$conf['picture_ext'] = array('jpg','JPG','jpeg','JPEG',
                             'png','PNG','gif','GIF');

// top_number : number of element to display for "best rated" and "most
// visited" categories
$conf['top_number'] = 15;

// anti-flood_time : number of seconds between 2 comments : 0 to disable
$conf['anti-flood_time'] = 60;

// qualified spam comments are not registered (false will register them
// but they will require admin validation)
$conf['comment_spam_reject'] = true;

// maximum number of links in a comment before it is qualified spam
$conf['comment_spam_max_links'] = 3;

// calendar_datefield : date field of table "images" used for calendar
// catgory
$conf['calendar_datefield'] = 'date_creation';

// calendar_show_any : the calendar shows an aditional 'any' button in the
// year/month/week/day navigation bars
$conf['calendar_show_any'] = true;

// calendar_show_empty : the calendar shows month/weeks/days even if there are
//no elements for these
$conf['calendar_show_empty'] = true;

// calendar_month_cell_width, calendar_month_cell_height : define the
// width and the height of a cell in the monthly calendar when viewing a
// given month. a value of 0 means that the pretty view is not shown.
// a good suggestion would be to have the width and the height equal
// and smaller than upload thumbnails configuration size.
$conf['calendar_month_cell_width'] =80;
$conf['calendar_month_cell_height']=80;

// newcat_default_commentable : at creation, must a category be commentable
// or not ?
$conf['newcat_default_commentable'] = true;

// newcat_default_visible : at creation, must a category be visible or not ?
// Warning : if the parent category is invisible, the category is
// automatically create invisible. (invisible = locked)
$conf['newcat_default_visible'] = true;

// newcat_default_status : at creation, must a category be public or private
// ? Warning : if the parent category is private, the category is
// automatically create private.
$conf['newcat_default_status'] = 'public';

// level_separator : character string used for separating a category level
// to the sub level. Suggestions : ' / ', ' &raquo; ', ' &rarr; ', ' - ',
// ' &gt;'
$conf['level_separator'] = ' / ';

// paginate_pages_around : on paginate navigation bar, how many pages
// display before and after the current page ?
$conf['paginate_pages_around'] = 2;

// show_version : shall the version of Piwigo be displayed at the
// bottom of each page ?
$conf['show_version'] = false;

// meta_ref to reference multiple sets of incorporated pages or elements
// Set it false to avoid referencing in google, and other search engines.
$conf['meta_ref'] = true;

// links : list of external links to add in the menu. An example is the best
// than a long explanation :
//
// Simple use:
//  for each link is associated a label
//  $conf['links'] = array(
//    'http://piwigo.org' => 'PWG website',
//    'http://piwigo.org/forum' => 'PWG forum',
//    );
//
// Advenced use:
//  You can also used special options. Instead to pass a string like parameter value
//  you can pass a array with different optional parameter values
//  $conf['links'] = array(
//    'http://piwigo.org' => array('label' => 'PWG website', 'new_window' => false, 'eval_visible' => 'return true;'),
//    'http://piwigo.org/forum' => array('label' => 'For ADMIN', 'new_window' => true, 'eval_visible' => 'return is_admin();'),
//    'http://piwigo.org/ext' => array('label' => 'For Guest', 'new_window' => true, 'eval_visible' => 'return is_a_guest();'),
//    'http://piwigo.org/downloads' =>
//      array('label' => 'PopUp', 'new_window' => true,
//      'nw_name' => 'PopUp', 'nw_features' => 'width=800,height=450,location=no,status=no,toolbar=no,scrollbars=no,menubar=no'),
//    );
// Parameters:
//  'label':
//    Label to display for the link, must be defined
//  'new_window':
//    If true open link on tab/window
//    [Default value is true if it's not defined]
//  'nw_name':
//    Name use when new_window is true
//    [Default value is '' if it's not defined]
//  'nw_features':
//    features use when new_window is true
//    [Default value is '' if it's not defined]
//  'eval_visible':
//    It's php code witch must return if the link is visible or not
//    [Default value is true if it's not defined]
//
// Equivalence:
//  $conf['links'] = array(
//    'http://piwigo.org' => 'PWG website',
//    );
//  $conf['links'] = array(
//    'http://piwigo.org' => array('label' => 'PWG website', 'new_window' => false, 'visible' => 'return true;'),
//    );
//
// If the array is empty, the "Links" box won't be displayed on the main
// page.
$conf['links'] = array();

// random_index_redirect: list of 'internal' links to use when no section is defined on index.php.
// An example is the best than a long explanation :
//
//  for each link is associated a php condition
//  '' condition is equivalent to 'return true;'
//  $conf['random_index_redirect'] = array(
//    PHPWG_ROOT_PATH.'index.php?/best_rated' => 'return true;',
//    PHPWG_ROOT_PATH.'index.php?/recent_pics' => 'return is_a_guest();',
//    PHPWG_ROOT_PATH.'random.php' => '',
//    PHPWG_ROOT_PATH.'index.php?/categories' => '',
//    );
$conf['random_index_redirect'] = array();

// reverse_home_title: if Piwigo is your home page for a better robot index
// we recommend to set it true (Only index page will reverse its title)
$conf['reverse_home_title'] = false;

// List of notes to display on all header page
// example $conf['header_notes']  = array('Test', 'Hello');
$conf['header_notes']  = array();

// show_thumbnail_caption : on thumbnails page, show thumbnail captions ?
$conf['show_thumbnail_caption'] = true;

// show_picture_name_on_title : on picture presentation page, show picture
// name ?
$conf['show_picture_name_on_title'] = true;

// display_fromto: display the date creation bounds of a
// category.
$conf['display_fromto'] = false;

// allow_random_representative : do you wish Piwigo to search among
// categories elements a new representative at each reload ?
//
// If false, an element is randomly or manually chosen to represent its
// category and remains the representative as long as an admin does not
// change it.
//
// Warning : setting this parameter to true is CPU consuming. Each time you
// change the value of this parameter from false to true, an administrator
// must update categories informations in screen [Admin > General >
// Maintenance].
$conf['allow_random_representative'] = false;

// representative_cache_on_level: if a thumbnail is chosen as representative
// but has higher privacy level than current user, Piwigo randomly selects
// another thumbnail. Should be store this thumbnail in cache to avoid
// another consuming SQL query on next page refresh?
$conf['representative_cache_on_level'] = true;

// representative_cache_on_subcats: if a category (= album) only contains
// sub-categories, Piwigo randomly selects a thumbnail among sub-categories
// representative. Should we store this thumbnail in cache to avoid another
// "slightly" consuming SQL query on next page refresh?
$conf['representative_cache_on_subcats'] = true;

// allow_html_descriptions : authorize administrators to use HTML in
// category and element description.
$conf['allow_html_descriptions'] = true;

// prefix_thumbnail : string before filename. Thumbnail's prefix must only
// contain characters among : a to z (case insensitive), "-" or "_".
$conf['prefix_thumbnail'] = 'TN-';

// dir_thumbnail : directory where thumbnail reside.
$conf['dir_thumbnail'] = 'thumbnail';

// users_page: how many users to display in screen
// Administration>Identification>Users?
$conf['users_page'] = 20;

// image level permissions available in the admin interface
$conf['available_permission_levels'] = array(0,1,2,4,8);

// mail_options: only set it true if you have a send mail warning with
// "options" parameter missing on mail() function execution.
$conf['mail_options'] = false;

// send_bcc_mail_webmaster: send bcc mail to webmaster. Set true for debug
// or test.
$conf['send_bcc_mail_webmaster'] = false;

// default_email_format:
//  Define the default email format use to send email
//  Value could be text/plain  or text/html
$conf['default_email_format'] = 'text/html';

// alternative_email_format:
//  Define the alternative email format use to send email
//  Value could be text/plain  or text/html
$conf['alternative_email_format'] = 'text/plain';

// define the name of sender mail:
// If value is empty, gallery title is used
$conf['mail_sender_name'] = '';

// smtp configuration
// (work if fsockopen function is allowed for smtp port)
// smtp_host: smtp server host
//  if null, regular mail function is used
//   format: hoststring[:port]
//   exemple: smtp.pwg.net:21
// smtp_user/smtp_password: user & password for smtp identication
$conf['smtp_host'] = '';
$conf['smtp_user'] = '';
$conf['smtp_password'] = '';


// check_upgrade_feed: check if there are database upgrade required. Set to
// true, a message will strongly encourage you to upgrade your database if
// needed.
//
// This configuration parameter is set to true in BSF branch and to false
// elsewhere.
$conf['check_upgrade_feed'] = false;

// rate_items: available rates for a picture
$conf['rate_items'] = array(0,1,2,3,4,5);

// Define default method to use ('http' or 'html' in order to do redirect)
$conf['default_redirect_method'] = 'http';

// Define using double password type in admin's users management panel
$conf['double_password_type_in_admin'] = false;

// Define if logins must be case sentitive or not at users registration. ie :
// If set true, the login "user" will equal "User" or "USER" or "user",
// etc. ... And it will be impossible to use such login variation to create a
// new user account.
$conf['insensitive_case_logon'] = false;

// how should we check for unicity when adding a photo. Can be 'md5sum' or
// 'filename'
$conf['uniqueness_mode'] = 'md5sum';

// Library used for image resizing. Value could be 'auto', 'imagick',
// 'ext_imagick' or 'gd'. If value is 'auto', library will be choosen in this
// order. If choosen library is not available, another one will be picked up.
$conf['graphics_library'] = 'auto';

// If library used is external installation of ImageMagick ('ext_imagick'),
// you can define imagemagick directory.
$conf['ext_imagick_dir'] = '';

// +-----------------------------------------------------------------------+
// |                               metadata                                |
// +-----------------------------------------------------------------------+

// show_iptc: Show IPTC metadata on picture.php if asked by user
$conf['show_iptc'] = false;

// show_iptc_mapping : is used for showing IPTC metadata on picture.php
// page. For each key of the array, you need to have the same key in the
// $lang array. For example, if my first key is 'iptc_keywords' (associated
// to '2#025') then you need to have $lang['iptc_keywords'] set in
// language/$user['language']/common.lang.php. If you don't have the lang
// var set, the key will be simply displayed
//
// To know how to associated iptc_field with their meaning, use
// tools/metadata.php
$conf['show_iptc_mapping'] = array(
  'iptc_keywords'        => '2#025',
  'iptc_caption_writer'  => '2#122',
  'iptc_byline_title'    => '2#085',
  'iptc_caption'         => '2#120'
  );

// use_iptc: Use IPTC data during database synchronization with files
// metadata
$conf['use_iptc'] = false;

// use_iptc_mapping : in which IPTC fields will Piwigo find image
// information ? This setting is used during metadata synchronisation. It
// associates a piwigo_images column name to a IPTC key
$conf['use_iptc_mapping'] = array(
  'keywords'        => '2#025',
  'date_creation'   => '2#055',
  'author'          => '2#122',
  'name'            => '2#005',
  'comment'         => '2#120'
  );

// show_exif: Show EXIF metadata on picture.php (table or line presentation
// avalaible)
$conf['show_exif'] = true;

// show_exif_fields : in EXIF fields, you can choose to display fields in
// sub-arrays, for example ['COMPUTED']['ApertureFNumber']. for this, add
// 'COMPUTED;ApertureFNumber' in $conf['show_exif_fields']
//
// The key displayed in picture.php will be $lang['exif_field_Make'] for
// example and if it exists. For compound fields, only take into account the
// last part : for key 'COMPUTED;ApertureFNumber', you need
// $lang['exif_field_ApertureFNumber']
//
// for PHP version newer than 4.1.2 :
// $conf['show_exif_fields'] = array('CameraMake','CameraModel','DateTime');
//
$conf['show_exif_fields'] = array(
  'Make',
  'Model',
  'DateTimeOriginal',
  'COMPUTED;ApertureFNumber'
  );

// use_exif: Use EXIF data during database synchronization with files
// metadata
$conf['use_exif'] = true;

// use_exif_mapping: same behaviour as use_iptc_mapping
$conf['use_exif_mapping'] = array(
  'date_creation' => 'DateTimeOriginal'
  );

// +-----------------------------------------------------------------------+
// |                               sessions                                |
// +-----------------------------------------------------------------------+

// session_use_cookies: specifies to use cookie to store
// the session id on client side
$conf['session_use_cookies'] = true;

// session_use_only_cookies: specifies to only use cookie to store
// the session id on client side
$conf['session_use_only_cookies'] = true;

// session_use_trans_sid: do not use transparent session id support
$conf['session_use_trans_sid'] = false;

// session_name: specifies the name of the session which is used as cookie name
$conf['session_name'] = 'pwg_id';

// session_save_handler: comment the line below
// to use file handler for sessions.
$conf['session_save_handler'] = 'db';

// authorize_remembering : permits user to stay logged for a long time. It
// creates a cookie on client side.
$conf['authorize_remembering'] = true;

// remember_me_name: specifies the name of the cookie used to stay logged
$conf['remember_me_name'] = 'pwg_remember';

// remember_me_length : time of validity for "remember me" cookies, in
// seconds.
$conf['remember_me_length'] = 5184000;

// session_length : time of validity for normal session, in seconds.
$conf['session_length'] = 3600;

// +-----------------------------------------------------------------------+
// |                            debug/performance                          |
// +-----------------------------------------------------------------------+

// show_queries : for debug purpose, show queries and execution times
$conf['show_queries'] = false;

// show_gt : display generation time at the bottom of each page
$conf['show_gt'] = false;

// debug_l10n : display a warning message each time an unset language key is
// accessed
$conf['debug_l10n'] = false;

// activate template debugging - a new window will appear
$conf['debug_template'] = false;

// save copies of sent mails into local data dir
$conf['debug_mail'] = false;

// die_on_sql_error: if an SQL query fails, should everything stop?
$conf['die_on_sql_error'] = false;

// if true, some language strings are replaced during template compilation
// (insted of template output). this results in better performance. however
// any change in the language file will not be propagated until you purge
// the compiled templates from the admin / maintenance menu
$conf['compiled_template_cache_language'] = false;

// This tells Smarty whether to check for recompiling or not. Recompiling
// does not need to happen unless a template is changed. false results in
// better performance.
$conf['template_compile_check'] = true;

// This forces Smarty to (re)compile templates on every invocation. This is
// handy for development and debugging. It should never be used in a
// production environment.
$conf['template_force_compile'] = false;

// activate merging of javascript / css files
$conf['template_combine_files'] = true;

// this permit to show the php errors reporting (see INI 'error_reporting'
// for possible values)
// gives an empty value '' to deactivate
$conf['show_php_errors'] = E_ALL;

// +-----------------------------------------------------------------------+
// |                            authentication                             |
// +-----------------------------------------------------------------------+

// apache_authentication : use Apache authentication as reference instead of
// users table ?
$conf['apache_authentication'] = false;

// users_table: which table is the reference for users? Can be a different
// table than Piwigo table
//
// If you decide to use another table than the default one, you need to
// prepare your database by deleting some datas :
//
// delete from piwigo_user_access;
// delete from piwigo_user_cache;
// delete from piwigo_user_feed;
// delete from piwigo_user_group;
// delete from piwigo_user_infos;
// delete from piwigo_sessions;
// delete from piwigo_rate;
// update piwigo_images set rating_score = null;
// delete from piwigo_caddie;
// delete from piwigo_favorites;
//
// All informations contained in these tables and column are related to
// piwigo_users table.
$conf['users_table'] = $prefixeTable.'users';

// If you decide to use external authentication
// change conf below by $conf['external_authentification'] = true;
$conf['external_authentification'] = false;

// Other tables can be changed, if you define associated constants
// Example:
//   define('USER_INFOS_TABLE', 'pwg_main'.'user_infos');

// user_fields : mapping between generic field names and table specific
// field names. For example, in PWG, the mail address is names
// "mail_address" and in punbb, it's called "email".
$conf['user_fields'] = array(
  'id' => 'id',
  'username' => 'username',
  'password' => 'password',
  'email' => 'mail_address'
  );

// pass_convert : function to crypt or hash the clear user password to store
// it in the database
$conf['pass_convert'] = create_function('$s', 'return md5($s);');

// guest_id : id of the anonymous user
$conf['guest_id'] = 2;
// default_user_id : id of user used for default value
$conf['default_user_id'] = $conf['guest_id'];

// Registering process and guest/generic members get language from the browser
// if language isn't available PHPWG_DEFAULT_LANGUAGE is used as previously
$conf['browser_language'] = true;

// webmaster_id : webmaster'id.
$conf['webmaster_id'] = 1;

// does the guest have access ?
// (not a security feature, set your categories "private" too)
// If false it'll be redirected from index.php to identification.php
$conf['guest_access'] = true;

// +-----------------------------------------------------------------------+
// |                               history                                 |
// +-----------------------------------------------------------------------+

// nb_logs_page :  how many logs to display on a page
$conf['nb_logs_page'] = 300;

// +-----------------------------------------------------------------------+
// |                                 urls                                  |
// +-----------------------------------------------------------------------+

// gallery_url : you can set a specific URL for the home page of your
// gallery. This is for very specific use and you don't need to change this
// setting when move your gallery to a new directory or a new domain name.
$conf['gallery_url'] = null;

// question_mark_in_urls : the generated urls contain a ? sign. This can be
// changed to false only if the server translates PATH_INFO variable
// (depends on the server AcceptPathInfo directive configuration)
$conf['question_mark_in_urls'] = true;

// php_extension_in_urls : if true, the urls generated for picture and
// category will not contain the .php extension. This will work only if
// .htaccess defines Options +MultiViews parameter or url rewriting rules
// are active.
$conf['php_extension_in_urls'] = true;

// category_url_style : one of 'id' (default) or 'id-name'. 'id-name'
// means that an simplified ascii represntation of the category name will
// appear in the url
$conf['category_url_style'] = 'id';

// picture_url_style : one of 'id' (default), 'id-file' or 'file'. 'id-file'
// or 'file' mean that the file name (without extension will appear in the
// url). Note that one aditionnal sql query will occur if 'file' is choosen.
// Note that you might experience navigation issues if you choose 'file'
// and your file names are not unique
$conf['picture_url_style'] = 'id';

// tag_url_style : one of 'id-tag' (default), 'id' or 'tag'.
// Note that if you choose 'tag' and the url (ascii) representation of your
// tags is not unique, all tags with the same url representation will be shown
$conf['tag_url_style'] = 'id-tag';

// +-----------------------------------------------------------------------+
// |                                 tags                                  |
// +-----------------------------------------------------------------------+

// full_tag_cloud_items_number: number of tags to show in the full tag
// cloud. Only the most represented tags will be shown
$conf['full_tag_cloud_items_number'] = 200;

// menubar_tag_cloud_items_number: number of tags to show in the tag
// cloud in the menubar. Only the most represented tags will be shown
$conf['menubar_tag_cloud_items_number'] = 20;

// content_tag_cloud_items_number: number of related tags to show in the tag
// cloud on the content page, when the current section is not a set of
// tags. Only the most represented tags will be shown
$conf['content_tag_cloud_items_number'] = 12;

// tags_levels: number of levels to use for display. Each level is bind to a
// CSS class tagLevelX.
$conf['tags_levels'] = 5;

// tags_default_display_mode: group tags by letter or display a tag cloud by
// default? 'letters' or 'cloud'.
$conf['tags_default_display_mode'] = 'cloud';

// tag_letters_column_number: how many columns to display tags by letter
$conf['tag_letters_column_number'] = 4;

// +-----------------------------------------------------------------------+
// | Notification by mail                                                  |
// +-----------------------------------------------------------------------+

// Default Value for nbm user
$conf['nbm_default_value_user_enabled'] = false;

// Search list user to send quickly (List all without to check news)
// More quickly but less fun to use
$conf['nbm_list_all_enabled_users_to_send'] = false;

// Max time used on one pass in order to send mails.
// Timeout delay ratio.
$conf['nbm_max_treatment_timeout_percent'] = 0.8;

// If timeout cannot be compite with nbm_max_treatment_timeout_percent,
// nbm_treatment_timeout_default is used by default
$conf['nbm_treatment_timeout_default'] = 20;

// Parameters used in get_recent_post_dates for the 2 kind of notification
$conf['recent_post_dates'] = array(
  'RSS' => array('max_dates' => 5, 'max_elements' => 6, 'max_cats' => 6),
  'NBM' => array('max_dates' => 7, 'max_elements' => 3, 'max_cats' => 9)
  );

// the author shown in the RSS feed <author> element
$conf['rss_feed_author'] = 'Piwigo notifier';

// +-----------------------------------------------------------------------+
// | Set admin layout                                                      |
// +-----------------------------------------------------------------------+

$conf['admin_theme'] = 'roma';

// should we load the active plugins ? true=Yes, false=No
$conf['enable_plugins']=true;

// Web services are allowed (true) or completely forbidden (false)
$conf['allow_web_services'] = true;

// enable log for web services
$conf['ws_enable_log'] = false;

// web services log file path
$conf['ws_log_filepath'] = '/tmp/piwigo_ws.log';

// Maximum number of images to be returned foreach call to the web service
$conf['ws_max_images_per_page'] = 500;

// Display a link to subscribe to Piwigo Announcements Newsletter
$conf['show_newsletter_subscription'] = true;

// +-----------------------------------------------------------------------+
// | Filter                                                                |
// +-----------------------------------------------------------------------+
// $conf['filter_pages'] contains configuration for each pages
//   o If values are not defined for a specific page, default value are used
//   o Array is composed by the basename of each page without extention
//   o List of value names:
//     - used: filter function are used
//       (if false nothing is done [start, cancel, stop, ...]
//     - cancel: cancel current started filter
//     - add_notes: add notes about current started filter on the header
//   o Empty configuration in order to disable completely filter functions
//     No filter, No icon,...
//     $conf['filter_pages'] = array();
$conf['filter_pages'] = array
  (
    // Default page
    'default' => array(
      'used' => true, 'cancel' => false, 'add_notes' => false),
    // Real pages
    'index' => array('add_notes' => true),
    'tags' => array('add_notes' => true),
    'search' => array('add_notes' => true),
    'comments' => array('add_notes' => true),
    'admin' => array('used' => false),
    'feed' => array('used' => false),
    'notification' => array('used' => false),
    'nbm' => array('used' => false),
    'popuphelp' => array('used' => false),
    'profile' => array('used' => false),
    'ws' => array('used' => false),
    'identification' => array('cancel' => true),
    'install' => array('cancel' => true),
    'password' => array('cancel' => true),
    'register' => array('cancel' => true),
  );

// +-----------------------------------------------------------------------+
// | Slideshow                                                             |
// +-----------------------------------------------------------------------+
// slideshow_period : waiting time in seconds before loading a new page
// during automated slideshow
// slideshow_period_min, slideshow_period_max are bounds of slideshow_period
// slideshow_period_step is the step of navigation between min and max
$conf['slideshow_period_min'] = 1;
$conf['slideshow_period_max'] = 10;
$conf['slideshow_period_step'] = 1;
$conf['slideshow_period'] = 4;

// slideshow_repeat : slideshow loops on pictures
$conf['slideshow_repeat'] = true;

// $conf['light_slideshow'] indicates to use slideshow.tpl in state of
// picture.tpl for slideshow
// Take care to have slideshow.tpl in all available templates
// Or set it false.
// Check if Picture's plugins are compliant with it
// Every plugin from 1.7 would be design to manage light_slideshow case.
$conf['light_slideshow'] = true;

// the local data directory is used to store data such as compiled templates
// or other plugin variables etc
$conf['local_data_dir'] = dirname(dirname(__FILE__)).'/_data';

// where should the API/UploadForm add photos? This path must be relative to
// the Piwigo installation directory (but can be outside, as long as it's
// reachable from your webserver).
$conf['upload_dir'] = './upload';

// where should the user be guided when there is no photo in his gallery yet?
$conf['no_photo_yet_url'] = 'admin.php?page=photos_add';

// directory with themes inside
$conf['themes_dir'] = PHPWG_ROOT_PATH.'themes';

// pLoader direct download url for windows
$conf['ploader_download_windows'] = 'http://piwigo.org/ext/download.php?eid=270';

// pLoader direct download url for mac
$conf['ploader_download_mac'] = 'http://piwigo.org/ext/download.php?eid=353';

// pLoader direct download url for linux
$conf['ploader_download_linux'] = 'http://piwigo.org/ext/download.php?eid=269';

// enable the synchronization method for adding photos
$conf['enable_synchronization'] = true;

// PEM url
$conf['alternative_pem_url'] = '';

// based on the EXIF "orientation" tag, should we rotate photos added in the
// upload form or through pwg.images.addSimple web API method?
$conf['upload_form_automatic_rotation'] = true;
?>

Bonne lecture, à +

Bonsoir,
Le seul fichier installé du nom de config.inc.php se trouve dans Piwigo/tools. En voici le contenu;

<?php
// this file is provided as an example. It does not modify the configuration
// as long as it remains in "tools" directory. Move it to "include"
// directory if you want to modify default configuration.

$conf['prefix_thumbnail'] = 'thumb_';
$conf['show_gt'] = true;
?>

Alors j'ai en effet modifié les valeurs IPTC à "true" dans le fichier config_default.inc.php, le seul dont je dispose (j'ai fais une recherche sur tout mon disque dur).
Résultat des courses, ça fonctionne bien. J'ai pu récupérer tous mes tags et autres infos. Je ne dispose pas des données Exif en contre partie mais ça ne me gène pas.

Je peux donc considérer mon principal problème solutionné. Merci beaucoup, et bravo pour la réactivité du support et la qualité du logiciel.

Longue vie à Piwigo!

Ok, bien compris. J'ai voulu faire le malin... et voila ce qui arrive. De toute façon, il n'y a aucun souci, si j'ai installé le logiciel en local, c'était pour le tester et me faire la main. Me voila prévenu. Je vais utiliser le plugin, et éditer le bon fichier cette fois.
D'autre nouvelles demain. Merci en attendant et bonne soirée!

Bonsoir à tous,
Tous mes soucis ont trouvé solution.
J'ai remis toutes les valeurs par défault du fichier "config_default.inc.php", opéré les modifications du fichier "..\EasyPHP\apache\php.ini" comme indiqué sur le wiki, activé le plugin LocalFiles Editor qui m'a bien généré un fichier "config.inc.php" dans le réportoire Piwigo]/local/config/ et modidié ce dit fichier en mettant toutes les valeurs IPTC et EXIF à "true".
Tous fonctionne. Qu'est-ce qui me reste à dire?
Ah oui, MERCI.