wp_image_editors

Filters the list of image editing library classes. Official documentation: wp_image_editors

Available editors are: ‘WP_Image_Editor_Imagick‘, ‘WP_Image_Editor_GD‘.

Code Example:

Set default WordPress image editor to GD.

function careless_image_editor_default_to_gd( $editors ) {
    $gd_editor = 'WP_Image_Editor_GD';
    $editors = array_diff( $editors, array( $gd_editor ) );
    array_unshift( $editors, $gd_editor );
    return $editors;
}
add_filter( 'wp_image_editors', 'careless_image_editor_default_to_gd' );

All example code goes in the functions.php file of your active theme.