Add filter or option to Import Image Stack to pad images to a certain Width/Height

This could be automated so the filter gets the largest dimensions of width and height by looking at all the images first, then padding the images to that maximum width/height, then finally doing the import.
This would require the preflight to examine each image in the series for its width/height which might slow down the preflight significantly for large image series. This slow down needs to be weighed by the benefits of adding the options. Maybe as a checkbox option and with some caching of the images the first preflight might take some time but after that it should be fast as long as the files are not changed.

Locate the Import Image Stack filter and its preflight path. Review how image dimensions are obtained across an image series, then assess an opt-in padding option and caching for the preflight and import flow. Done means the series can be padded to the requested or maximum width and height without unnecessary repeated work.

Written by the indexing model from the issue text.