[sjsdaiuasgdia]

MS Paint, Resize/Skew option. Ctrl-W is the hotkey.

It allows you to resize either in terms of pixel count or percentage. The percentage approach is very nice for just putting 50 in both horizontal and vertical fields and getting an image half as large in both dimensions, but showing the same image (with reduced quality, because fewer pixels) and at the same aspect ratio.

[axelMI]

done! added in the "composition" menu and fully integrated in the workflow

I preferred just having an input with the correct pixels rather than % (to keep UI clean) but you'll get the same result