HTML Display an Resized Image maintaning Ratio

I want to show an image from a URL and I want that image to have a given size but I want to maintain the ratio between height and width.

From stackoverflow

• CSS:

  IMG { width: 30%; height: auto; }

  Something like this?

• <img src="http://..." height="100" />
  

  No magic here, although client-side resizing usually looks crappy.

• you can use css to style an image

  i believe if you use px for example, and specify only one dimension

  img {width:100px}
  

  the ratio is usually maintained

  You can use

  img {width:100px;height:auto;}
  

  which may help

  if you use

  img {width:100px}
  

  the ratio is maintained in IE 7 at least