Say I have an one image that is 3000 pixels long and 700 pixels high, and a second that is 700 pixels long and 3000 pixels high, and I would like to export them simultaneously to each be 1500 x 1500 px square with LR adding white where needed to extend the canvass.
Is this possible to dictate in the Export dialog to keep as a prest, or how would you do it?