Using WordPress ‘getimagesize_mimes_to_exts’ PHP filter

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The getimagesize_mimes_to_exts WordPress PHP filter allows you to modify the list of image mime types and their respective extensions.

Usage

add_filter('getimagesize_mimes_to_exts', 'your_custom_function');
function your_custom_function($mime_to_ext) {
    // your custom code here
    return $mime_to_ext;
}

Parameters

  • $mime_to_ext (array): An array containing the image mime types and their matching extensions.

More information

See WordPress Developer Resources: getimagesize_mimes_to_exts

Examples

Add a new mime type and extension

Add the WebP format to the list of supported image formats:

add_filter('getimagesize_mimes_to_exts', 'add_webp_mime_type');
function add_webp_mime_type($mime_to_ext) {
    $mime_to_ext['image/webp'] = 'webp';
    return $mime_to_ext;
}

Remove a mime type and extension

Remove support for GIF images:

add_filter('getimagesize_mimes_to_exts', 'remove_gif_mime_type');
function remove_gif_mime_type($mime_to_ext) {
    unset($mime_to_ext['image/gif']);
    return $mime_to_ext;
}

Change the extension for a mime type

Change the extension for JPEG images to ‘.jpeg’ instead of ‘.jpg’:

add_filter('getimagesize_mimes_to_exts', 'change_jpeg_extension');
function change_jpeg_extension($mime_to_ext) {
    $mime_to_ext['image/jpeg'] = 'jpeg';
    return $mime_to_ext;
}

Add multiple mime types and extensions

Add support for both AVIF and WebP image formats:

add_filter('getimagesize_mimes_to_exts', 'add_avif_webp_mime_types');
function add_avif_webp_mime_types($mime_to_ext) {
    $mime_to_ext['image/avif'] = 'avif';
    $mime_to_ext['image/webp'] = 'webp';
    return $mime_to_ext;
}

Modify the entire mime type and extension list

Replace the default mime types and extensions list with a custom list:

add_filter('getimagesize_mimes_to_exts', 'custom_mime_types_and_extensions');
function custom_mime_types_and_extensions($mime_to_ext) {
    $mime_to_ext = array(
        'image/jpeg' => 'jpg',
        'image/png' => 'png',
        'image/webp' => 'webp'
    );
    return $mime_to_ext;
}