Manual:$wgLogos

Details
An array with factors and their associated relative paths or URL paths to the different versions of the wiki logo. (i.e. the image displayed in the upper-left corner of the page in most MediaWiki installations).

Supported variants

 * The 1.x version should be a square and should maximally have 135x135 pixels.
 * The 1.5x version should be a square and should maximally have 202x202 pixels.
 * The 2x version should be a square and should maximally have 270x270 pixels.
 * The svg version should be a square.
 * The wordmark should be a landscape logo, with maximum set width or height, as these are specified under the  and   keys.

All values (except  and  ) can either be a fully-qualified URL or a relative path from DOCUMENT_ROOT. If it's a relative path, it has to start with a slash (a file in DOCUMENT_ROOT is /file.png, not file.png). Note that if you use a bigger image, MediaWiki will not resize this image! Instead, the image will be cut off so that only part of it (the upper left-hand corner to be precise) will be visible. If this corner is completely white, it might look like the image would not display although in fact it does.