Resize to fit in a box and set background to black on “empty” part

Question

I\'m trying to obtain this result: fixed box size (133x100), the image should be resized but not stretched to fit inside that box, the empt

Answer 1

Looks like I've found the solution by myself with this link: http://www.imagemagick.org/Usage/thumbnails/#fit_summery

And this code solved my issue:

convert from.jpg -thumbnail 133x100 -background black -gravity center -extent 133x100 to.jpg