>>1784463Downscaling images with reasonable original aspect ratios is trivially easy. MSpaint probably can't do that nicely but anything else (photoshop, GIMP,
paint.net) will do that with ease. Problems arise when the image is something like 800x1200 so you have to fill in the gaps to make it usable.
If you don't need anything spectacular done, I'd suggest getting
paint.net. It's very similar to MSpaint but it actually has features for a tad more advanced editing.
If you have to extend and crop a 800x1200 image to 16:9 ratio, you'll need something with more oomph like Photoshop or GIMP, although I've never tried the latter. Photoshop has some pretty simple-to-use and powerful content-aware tools which can automatically do a lot of stuff which would take ages when done by hand.
