Extension:PageImages/ja

PageImages拡張機能は、ページ上で使用されるイメージに関する情報を収集します.

その目的は、記事に関連付けられた単一の最も適切なサムネイルを返すことです.

MediaWiki 1.29以降、PageImageによりウィキに掲載した記事のOpenGraph プロトコルメタデータをFacebookなどサードパーティ向けに抽出して提供します.

API
PageImages拡張機能は、 の APIに を追加することによって画像情報を提供します.

設定
$wgPageImagesBlacklistはイメージブラックリストのソースの配列です. ブラックリストに載っているイメージはページのイメージとして決して選択されません. 例:

複数のソースを同時に使用することができます.

$wgPageImagesBlacklistExpiryは、ブラックリストがキャッシュされる期間を秒単位で指定します. 既定値: 15 * 60 (15分)

$wgPageImagesExpandOpenSearchXmlがtrueに設定されている場合、PageImagesは APIモジュール内のイメージ検出を、より正確な結果で上書きします. 既定値: false

$wgPageImagesNamespacesはPageImagesが有効になる名前空間の配列です. 既定値: NS_MAIN

ブラックリスト自体に、ブラックリスト指定したファイルのウィキリンクを格納すべきで、それ以外の内容は不適切（であり他のページへのリンクを含めることができます）. 例:

注意したいのは、ページに追加した画像から発生したファイルリンクは無効（そういうファイルは理由があってブラックリスト指定されましたよね？）なため、リンクの先頭に半角コロン の入力を忘れないでください.

動作の仕組み
When a page is saved with a local image, the parser runs the hooks  and. The PageImages extension responds to these (and other hooks) and inserts a new property for the page into the table. The property name is  and its value is the name of the image.

The extension only stores the chosen image name. Other features may display the image, such as Page information, Hovercards, and Mobile search while typing.

How can I check which image is associated with a page?
Page images will be listed on the ?action=info page.

どのように画像を選択しているのか?
All images in the page are collected and a score for each image is calculated. The image with the highest score is selected as the page image. If the wiki is configured such that images contain metadata that specifies images are not freely licensed, the image with the best score that is also freely licensed is also stored. If no suitable image is found or all the images score badly (i.e. has a negative score), the page will not have any images.

If $wgPageImagesLeadSectionOnly is true, only images in the lead section will be considered. Currently it is true for only Wikipedia projects, all other projects can pull images from outside the lead.

画像はどのようにスコアリングされるのか?
The best possible page image on Wikimedia wikis is one of the first four images in an article which has a width/height between 400-600px and a height/width which is twice the value of the other dimension.


 * The algorithm is configurable.
 * Scores are calculated by a combination of:
 * Image widths as defined in $wgPageImagesScores['width']
 * In Wikimedia wikis, images smaller than 119 pixels are weighted highly negatively. Images with widths between 400px-600px are favoured, with a preference for the lower bound.
 * Images inside galleries are scored separately using $wgPageImagesScores['galleryImageWidth']
 * In Wikimedia wikis gallery images which are smaller than 100 are disregarded.
 * Position in document is also considered as defined in $wgPageImagesScores['position']
 * On Wikimedia wikis, only the first 4 images that appear in the document are considered.
 * The ratio of the image's width to height is considered $wgPageImagesScores['ratio']
 * On Wikimedia wikis the best possible images are images where the height is half the width or the height is double the width. Any images for which the ratio is less than 0.5 will score negatively and be discarded.

Be more technical please...
Pageimages populates images whenever the LinksUpdate hook runs.

In PageImages this is executed in LinksUpdateHookHandler::doLinksUpdate

Can I exclude certain page images?
Yes! There is a blacklist on every wiki that administrators can edit, at MediaWiki:Pageimages-blacklist (example). Any images that appear here will not be page images for any article.

What about just for one particular article?
Sadly not at the current time. Please use the blacklist or move the image outside the lead section.

How can I see the page image for a page?
Using the  link in the sidebar (or adding  to the URL) you'll be able to see the current image choice.

How can I purge a bad image?
The pageimage only changes when a link in an article changes. For emergencies, please add/remove links from the page, reverting if necessary. Purging will not work. For larger emergencies please file a Phabricator ticket.

Why is my page image a blank box?
This likely relates to video content in your article. If a video file begins with a blank screen, that will become the default thumbnail for the video and if used as the page image, it will become the page image. We are currently working on a fix for this, that will allow you to change the default thumbnail of a video. See: phab:T92457 and phab:T22647 for further information.