I have a handful of jpg files that are tall and vary in size. I want the excess length to be trimmed (so aligned top-center and cropped to a square) but I don't want to add any extra systems like thumb.php, ImageMagick, etc. to the page because simplicity and file-size are important for this quick project.

They are all 430 pixels wide and they should all be aligned to the top (rather than cropped to the center or something)

Any advice or help would be greatly appreciated.