> why do you keep a portion of image to be discarded? I can't speak to the context of the feature in JXL, but this is very very common in mobile image editor m

> why do you keep a portion of image to be discarded? I can't speak to the context of the feature in JXL, but this is very very common in mobile image editor metadata formats, so that users can later "undo" a crop they did, because no data is actually lost. Both iOS and Android support this for all images cropped on device.