This extensions provides evaluation for image alternatives.
Override the eval option for the alternative column inside the sys_file_reference TCA configuration like the following:
use TYPO3\CMS\Core\Utility\ArrayUtility;
ArrayUtility::mergeRecursiveWithOverrule($GLOBALS['TCA']['sys_file_reference'], [
'columns' => [
'alternative' => [
'config' => [
'eval' => \VV\T3imagealternative\Evaluation\ImageAlternative::class
]
]
]
]);