Screenshot of a custom editor in Unreal, implementing a simple importer for a set of a few dozen textures, all of which are being packed into a single atlas. Developers who know what to look for may notice there's also a placeholder structure for the accompanying UV data, but it's not filled out yet.
https://cdn.masto.host/mastodongamedevplace/media_attachments/files/117/083/094/707/257/702/original/543e3f23d147a61f.jpg