Manual:Image administration

(Redirected from Manual:Image Administration)

This article describes how MediaWiki handles and stores files, and gives some information on configuring.

This applies to images as well as to any other type of file that can be uploaded. All files are stored with a corresponding article in the "File:" namespace. Prior to MediaWiki 1.14, the "Image:" namespace was used instead. "Image:" is still retained as an alias for backward compatibility.

Upload and usage of images

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See Help:Images

Enable upload of images

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To upload files, these conditions have to be met:

  1. MediaWiki must have uploads enabled. Set $wgEnableUploads to true.
  2. The file type must be allowed. More information: $wgFileExtensions .
  3. The user must be in a group with the "upload" right. By default this is given to all logged-in users.

Uploads are done using Special:Upload.

See Manual:Configuring file uploads , Manual:MIME type detection and Manual:Adding support for new filetypes

Relevant parameters for file handling

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These parameters are relevant:

Image thumbnailing

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MediaWiki's image syntax allows dynamic resizing and thumbnailing of images (see Manual:Configuring file uploads for general help on file uploads).

Image thumbnailing requires either ImageMagick or GD library – neither are part of the default MediaWiki installation.

PHP comes with GD graphics library enabled by default. GD will not require any configuration or modification to be used.

It is recommended to use GD on Windows systems.

GD can be downloaded from https://libgd.github.io/. In recent PHP versions this is not required.

ImageMagick

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In MediaWiki, enable ImageMagick in LocalSettings.php by setting $wgUseImageMagick to true.

ImageMagick can be downloaded from https://imagemagick.org/.

Once ImageMagick is installed, you must enable ImageMagick and point MediaWiki to the convert or convert.exe program on your computer in LocalSettings.php like this:

$wgUseImageMagick = true;
#$wgImageMagickConvertCommand = 'C:/ImageMagick/convert.exe'; # for Windows
$wgImageMagickConvertCommand = '/usr/bin/convert'; # for Linux

If you use ImageMagick, set $wgUseImageMagick to true in LocalSettings.php. Make sure that the command is executable by the web server process. For example, Windows users will want to change the default to "C:\ImageMagick\convert.exe" (or similar).

To re-create old thumbnail files before you used ImageMagick you can use $wgThumbnailEpoch .

If rendering fails silently, check and increase $wgMaxShellMemory .

See the help page on Image Thumbnails not working for troubleshooting.

GraphicsMagick can also be used as an alternative to ImageMagick. You will need to set $wgCustomConvertCommand to the following. E.g.:

$wgUseImageMagick = false;
$wgCustomConvertCommand = "gm convert %s -resize %wx%h %d";

Image formats

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For thumbnailing GIF-Animations under windows, you need to install ImageMagick as described above.

 
Wikimania 2016 presentation on Dynamic SVG

MediaWiki supports SVG image rendering: if enabled, SVG images can be used like other image files — they will automatically be rendered as a PNG file and thumbnailed as needed on the fly. If you're on a shared host and no SVG renderer is pre-installed, you should probably ask your provider to install it for you.

To enable SVG support:

  1. Allow upload of SVG files in the LocalSettings.php file: $wgFileExtensions [] = 'svg'; Note that MediaWiki will refuse SVG files containing JavaScript, for security reasons.
    If you get an error saying the file is corrupt, make sure MIME type detection is working properly.
  2. Add $wgSVGConverter to LocalSettings.php and set the renderer you want to use.
    Available options are ImageMagick, ImagickExt, sodipodi, inkscape, batik, rsvg, and imgserv.
    For example: $wgSVGConverter = 'ImageMagick';
    • If the converter program is not in the system path, you have to specify the directory that contains the program using $wgSVGConverterPath ..
    • librsvg is fast but not very accurate. It depends on a large number of libraries. To automatically install all these libraries, you may want to use a package manager. The Wikimedia projects use rsvg.
    • Batik is the most accurate SVG renderer available, although its anti-aliasing is sometimes suboptimal. Its SVG parsing is more strict, causing it to reject "almost valid" SVG files that other renderers accept (e.g. commons:File:UbuntuCoF.svg). Batik relies on Java, and is much slower than rsvg, though this may not be a huge issue unless you're constantly adding SVG files. See SVG benchmarks . Requires a lot of work to get running, if not included in your distribution.
    • Inkscape also does an accurate job of SVGs, half the speed of rsvg, but was designed for interactive graphical use; however, it comes with inkview which is a viewer/converter program – it requires a writable home directory for the user it's run as. Since it will be running as user www or something similar, it will try to create .inkscape/ and .gnome2/ directories in the corresponding home directory, and will fail silently, crash or hang indefinitely if it is not able to. Inkscape is preferable to rsvg (a) on Windows (it comes as a standalone package) or (b) if you have important SVGs drawn in Inkscape that do not render correctly in rsvg. Inkscape has as complicated a dependency chain as librsvg — use only if it's in your distribution or available as a complete standalone package.
    • Sodipodi is the program Inkscape was forked from. The same considerations apply. Sodipod is no longer under active development.
    • Since version 6.x.x ImageMagick renders SVGs, but imperfectly. This is the default, but avoid it if possible. However, it does work. On Windows, $wgConvertPath must be set to avoid a conflict with Windows' own convert.exe. One simple alternative in this scenario is to add to LocalSettings.php the line $wgSVGConverters['ImageMagick'] = '"' . $wgImageMagickConvertCommand . '" -background white -thumbnail $widthx$height^! $input PNG:$output';, which also allows for spaces in the path.
      • To prevent thumbnail creation errors with ImageMagick, if it's ≥ 7.0.9-25, then Inkscape must also be ≥ 1.x.x. Likewise, if ImageMagick is < 7.0.9-25, then Inkscape must also be < 1.x.x. See ImageMagick issue.
    • The PHP Imagick extension supports SVG rendering, however the same considerations as for the regular ImageMagick apply.
    • The GD library is not capable of converting SVG images to the PNG format, at least according to Joen Asmussen's June 2008 NoScope blog.
    • Over 98% of web browsers have at least basic support for displaying SVG files directly, but MediaWiki does not use that by default.[notes 1] Without the NativeSvgHandler extension, MediaWiki only supports client-side rendering in MediaWiki 1.41 (released December 2023) and newer, by setting $wgSVGNativeRendering = true.

Set $wgSVGConverter = false if SVG rendering is not needed and you wish to make your users download the svg file in order to view it.

Troubleshooting

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If you see a blank square instead of SVG (Chrome) or no image at all (Firefox) and all PNG links lead to 404 error and you don't see any other error message anywhere please check $wgGenerateThumbnailOnParse variable. Setting it to false may make SVG transformation deferred always. Make sure that proc_open and symlink PHP methods are enabled (they may be disabled in php.ini for security or performance reasons).

JPEG (using GD)

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Simply adding the following line to LocalSettings.php will cause auto fall back to the GD library:

$wgUseImageMagick = false;

For errors with JPEG thumbnails, see JPEG (using GD).

TIFF

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Generating thumbnails of TIFF files requires MediaWiki 1.15.0 or newer.

  1. Allow upload of TIFF files in the LocalSettings.php file: $wgFileExtensions [] = 'tif';
  2. Add $wgTiffThumbnailType to LocalSettings.php and set to either jpg or png to specify which type of thumbnail you wish to have generated.
  3. Making thumbnails of TIFF files may require system resources beyond those needed for thumbnailing JPEG, GIF, or PNG files. Consider appropriate settings for $wgMaxImageArea and $wgMaxShellMemory

DjVu

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Deletion of images

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Files, like wiki pages, can only be deleted by users with the Delete pages (delete)" permission (administrators by default). Deletion of files is done by deleting the associated description page (or by clicking the delete all link in the File history" table).

Deletion of individual revisions

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If a file has been altered, there is a revision history of the files which is displayed on the file article page. Each revision has a delete link. If this is clicked, the revision and the file are deleted.

The versions of files are separate from the page history of the file description page.

Information about old revisions of files are stored in the oldimage table while information on old revisions of the pages are stored in the revision table.

Undeleting files

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Files can be undeleted in exactly the same way as normal wiki pages. The directory in which deleted files are stored is defined by Manual:$wgDeletedDirectory . Information about deleted images are stored in the filearchive table.

Deletion of Archived Files

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Since MediaWiki version 1.11, deleted images are still stored on the server by default. If you want to delete selected archived images, you can do so using the eraseArchivedFile.php maintenance script. If you want to delete all of them completely, you can do that with the deleteArchivedFiles.php script. If you delete archived files, you can not undelete those files anymore.

Reasons for Deleting a File

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When choosing to delete a file, as described above, users will be asked to provide a reason for deletion. The available reasons can be edited on the MediaWiki:Filedelete-reason-dropdown of your wiki.

Data storage

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Whenever an image is uploaded, several things are created:

  1. An article in the file namespace with the name of the file, e.g. File:MyPicture.png. This page is stored and can be edited like any other page.
  2. The file itself is stored in a folder on the file system with whitespaces merged and replaced with _.
  3. If necessary and thumbnailing is available, thumbnailed versions of the file will be created when necessary (such as for the usage on the file description page). These are stored in the thumb directory of the image directory, in a separate directory for each main file.

If $wgHashedUploadDirectory is enabled (by default), MediaWiki creates several subdirectories in the images directory.

The directory names are from the first two characters of the md5 hash of the final filename.

Folders

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All image files are stored in a folder determined by $wgUploadPath (images/, by default).

Description of named image subfolders:

archive
This is the storage place for files that have been replaced by newer versions.
temp
Used for temporary storage of files during image uploading. (Due to task T11018, these files may not always be automatically deleted).
thumb
Thumbnails (automatically generated) for the files. If these are deleted, they are automatically regenerated when needed.

Depending on the configuration, there may be additional image subfolders:

math
Folder to store your rendered TeX input, see also Extension:Math or Manual:Math.
x/xy
If $wgHashedUploadDirectory is set to true (which is the default), images will be stored in subfolders of the images, thus making file paths look like images/a/ab/filename.jpg. See Manual:$wgHashedUploadDirectory for more details on why this might be desired and how this system works.

Database tables

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  • The file description page is stored as any page in the page, text, revision etc. tables
  • image - Holds some metadata such as the size of the file and the upload date.
  • oldimage - This stores information for files that have been replaced with newer versions.
  • filearchive - Holds the information on the deleted files.
  • imagelinks - Records what pages use a file.

Space usage

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Files need considerably more space than articles. The following calculations assume a block size of 4KB with Linux/Unix servers.

The default setting is $wgHashedUploadDirectory = true.

Space requirements for all directories:

  • image directories: 0-f/x0-f: max. 16*16 = 256 directories = 256*4 KB = 1024 KB
  • archive directories: 0-f/x0-f: max. 16*16 = 256 directories = 256*4 KB = 1024 KB
  • thumb directories: 0-f/x0-f: max. 16*16 = 256 directories = 256*4 KB = 1024 KB
  • temp directories: 0-f/x0-f: max. 16*16 = 256 directories = 256*4 KB = 1024 KB

Therefore, the basic amount of space needed without any images uploaded is 4 MB in theory (although the directories are created only when needed).

For each file we need:

  • size of the original image file + 2 KB average overhead

For files that need to be thumbnailed:

  • size of the created thumbnail(s) + 2 KB average overhead (each)
  • directory for thumbnail (4KB) (each image has its own thumbnail directory)

Examples:

  • image 20778 Byte png (small size, no thumb): 24 KB for the image: Total 24 KB
  • image 123.000 Byte jpeg (big size, auto thumb): 124 KB for the image, 4 KB for the thumb directory, 64KB for the thumb: Total: 192 KB

File Access

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Uploaded files are generally served directly by the web server, not through MediaWiki. While there may be a minimal level of security through obscurity with path encryption (e.g. /c/c4/...) if $wgHashedUploadDirectory is set, the path can be calculated easily from the file name and does not provide true protection.

For limiting access to authorized users, see Manual:Image authorization .

Upload form

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See the documentation on configuring the upload form.

Licensing

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MediaWiki allows licenses to be added to files uploaded from the Special:Upload page. The list of licenses that appear in the license selection dropdown can be edited on the MediaWiki:Licenses page by a sysop.

The page should be a bulleted list of items, and can have sub-items. Each item can have one or more parameters, with the parameter separated by the pipe character (|).

To make headers/categories, use only one parameter in a list item. The text will be what appears in the dropdown list, and will appear greyed-out and unclickable.

To add license options, two or more parameters are required. The first parameter will be the template name to use, without the double square brackets. The last parameter will be what appears in the dropdown list for that license. Any additional parameters between the first and last parameters will be passed as arguments to the template. When a license is selected, a preview of what it would look like on the final page is shown in the upload wizard.

Below is a simple example (not using real templates) of how MediaWiki:Licenses should be formatted:

* no-lic|No license.
* Made by me:
** self-lic|And it can only be used on this wiki.
** self-lic|free=yes|And I allow it to be used anywhere.
* Made by someone else:
** pd-lic|It's in the public domain.
** copyright-lic|It's copyrighted.
** cc-lic|It uses some CreativeCommons license.
** cc-lic|by-sa|It uses the CC-BY-SA license.

The above assumes each template ending in "-lic" exists, where some of those templates take positional arguments such as "by-sa" and others take named arguments such as "free=yes". Selecting the "And I allow it to be used anywhere" option, for example, would add the following text to the page of the new file:

{{self-lic|free=yes}}

Sites like Wikipedia and WikiMedia Commons will also use the subst: tag, such as WikiMedia Common's usage of it below:

** subst:Template 2|flickrreview|subst:uwl|Image from Flickr and I do not know the license

"Template 2" is an actual template that will take two parameters (being template names) and surround them with double curly brackets so they get transcluded on the page of the new image. "uwl" is a template, whose documentation requires using it with the "subst:" tag instead of directly. The above will result in the following being added to the uploaded file's page:

{{flickrreview}}{{subst:uwl}}

On Wikipedia, substitution is used in other ways, such as adding a timestamp with the license at the time of upload.

For detailed real world example, see Wikipedia:MediaWiki:Licenses or Commons:MediaWiki:Licenses.

Foreign Repositories

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It is possible to access files stored in foreign repositories, without needing to upload them to the wiki, by setting the $wgForeignFileRepos array. This feature offers several possibilities:

  • ForeignAPIRepo accesses files from a remote MediaWiki installation, such as Wikimedia Commons, through its API
  • ForeignDBRepo accesses files through a database, and is useful for creating wiki families
  • FSRepo accesses files from a local folder

In all cases, one would be able to embed files into a page using ordinary image syntax and specifying the name of the file in the foreign repository. Note that some of the above implementations are still experimental, and might not be suitable for production sites.

Notes

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  1. Wikimedia sites also do not rely on client-side rendering, despite a request to do so, task T5593.