Extension:VipsScaler

MediaWiki extensions manual

VipsScaler Release status: stable
Implementation	Media
Description	Allows to scale PNG and JPEG images using VIPS
Author(s)	Bryan Tong Minh (Bryantalk)
MediaWiki	1.19+
Database changes	No
License	GNU General Public License 2.0 or later
Download	Download extension Git [?]: Download Git master browse repository (GitHub) commit history repository contributors (GitHub) code review README
Parameters $wgVipsCommand $wgVipsOptions $wgVipsTestExpiry $wgVipsExposeTestPage $wgVipsThumbnailerHost
Hooks used BitmapHandlerCheckImageArea BitmapHandlerTransform
Quarterly downloads	19 (Ranked 146th)
Public wikis using	1,811 (Ranked 203rd)
Translate the VipsScaler extension if it is available at translatewiki.net
Issues	Open tasks · Report a bug

The VipsScaler extension is a wrapper around VIPS, a free image processing software. VIPS is a set of image manipulation tools specially designed for speed and low memory usage. This is useful for resizing large PNGs, and it improves the appearance of shrunken JPEGs.

The extension shells out to the vips binary. It can be configured to scale only certain files (for example: big PNGs) by configuring $wgVipsOptions.

VIPS installation

Install VIPS

Install VIPS. It can be downloaded from https://libvips.github.io/libvips or your OS repository (see below).

Debian / Ubuntu

$ apt-get install libvips-tools

If you want to build from source have a look at upstream documentation: https://libvips.github.io/libvips/install.html

(Wikimedia has packaged and uses a more recent version for Ubuntu 12.04 at apt.wikimedia.org)

Mac OS X

homebrew

brew install homebrew/science/vips

binary symlink is /usr/local/bin/vips

Install VipsScaler extension

• Install VIPS (see above)
• Download and move the extracted VipsScaler folder to your extensions/ directory.
  Developers and code contributors should install the extension from Git instead, using:cd extensions/
git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/VipsScaler
• Add the following code at the bottom of your LocalSettings.php file:

  wfLoadExtension( 'VipsScaler' );
  

• Navigate to Special:VipsTest to verify it is working and see the difference in output quality.
•  Done – Navigate to Special:Version on your wiki to verify that the extension is successfully installed.

Configuration

$wgVipsCommand

path to the vips command (default: vips).

$wgVipsOptions

Options and conditions for images to be scaled with this scaler. Set to an array of arrays. The inner array contains a condition array, which contains a list of conditions that the image should pass for it to be scaled with vips. Conditions are mimeType, minArea, maxArea, minShrinkFactor, maxShrinkFactor. The other items in the array are options. Options available are:

• sharpen - Set to an array with keys 'radius' and 'sigma', which are parameters to gaussian sharpen matrix.
• preconvert - Convert the file to a .v file first, which costs some space, but saves memory on the actual downsize
• bilinear - Use im_resize_linear instead of im_shrink
• convolution - Apply specified convolution matrix
• setcomment - Add an exif comment specifying the source of the file. Requires $wgExiv2Command to be set properly.

$wgVipsOptions = [
  // Sharpen jpeg files which are shrunk more than 1.2
  [
    'conditions' => [
      'mimeType' => 'image/jpeg',
      'minShrinkFactor' => 1.2,
    ],
    'sharpen' => [ 'radius' => 0, 'sigma' => 0.8 ],
  ],
  // Other jpeg files
  [
    'conditions' =>[
      'mimeType' => 'image/jpeg',
    ],
    'sharpen' => false,
    'bilinear' => true,
  ],
  // Do a simple shrink for PNGs
  [
    'conditions' => [
      'mimeType' => 'image/png',
    ],
  ],
];