Manual:$wgShowEXIF

Details
Show EXIF data, on by default if available. Requires PHP's EXIF extension.

Default value
The default value is to enable the showing of EXIF data if the system supports it. This is worked out by checking whether the  function exists:

function_exists( 'exif_read_data' );

Do not manually set this value to 'true', as errors may occur if this function is not defined. You may however set it manually to 'false' if you wish to disable this functionality.