How to resize all images?

Question

JPEG

There are many images of different resolutions, horizontal orientation, vertical, completely disproportionate. You need to reduce (not crop) them to a certain resolution and put them in a white square of the same height / width. That is, so that on the sides, on top of the side there was a white fill, and the images in the center.
Is there a program that can do this, or will it have to be done manually?

Answer 1

Any graphics editor or viewer that can batch process. The same XnView.

Answer 2

Adobe Photoshop CC 2015 - via scripts