IMAGETYPE定数と拡張子とmimeTypeの一覧を取得

image_types.php

<?php
// ワンライナーは挫折しました…。
$imageTypes = array_fill_keys(array_filter(array_keys(get_defined_constants()),
    function($name) {
        return (strncmp('IMAGETYPE_', $name, 10) === 0);
    }
), array());

array_walk($imageTypes, function(&$item, $key, $supported) {
    $imageType = constant($key);
    $supported = (0 !== ($supported & $imageType));
    $item['constant' ] = $key;
    $item['imageType'] = $imageType;
    $item['supported'] = $supported;
    $item['extension'] = image_type_to_extension($imageType, false);
    $item['mimeType' ] = image_type_to_mime_type($imageType);
}, imagetypes());

echo '<pre>';
print_r($imageTypes);
echo '</pre>';