What command do you use to preview any image

I'm trying to write a command in sh using 开发者_如何学编程the software ImageMagick. I was trying to find a command that allows me use any image( presumably jpeg) and be able to preview the image but at a 200x200 pixels instead of the original size?

display -size 200x200 filename

See http://www.imagemagick.org/www/display.html

I use xv or xview:

xv -geom 200x200 filename
xview -geometry 200x200 filename