How to convert a png file from from 600 x 800 into 600 x 400?

Question

Get info on my source png file.

file  old.png
old.png: PNG image data, 600 x 800, 8-bit colormap, non-interlaced

I want to convert old.png from 600 x 800 into 600 x 400.

convert -resize 600x400  old.png  new.png

Check my output.

file new.png
new.png: PNG image data, 300 x 400, 8-bit/color RGB, non-interlaced

Answer 1

convert -resize 600x400! old.png new.png