[Black Snow]

You can do it with BBCode if you are not bothered about the image height or width being adjusted accordingly.

Enter this as your replacement:

<img src="{param}" width="{option}" />{param}:</a>

Then further down, select yes on: Use {option}

Then when you use your BBCode, enter something like:

[imgW=100]http://4.bp.blogspot.com/-JOqxgp-ZWe0/U3BtyEQlEiI/AAAAAAAAOfg/Doq6Q2MwIKA/s1600/google-logo-874x288.png[/imgW]

This will then keep your image 100px wide, and auto adjust the height to match.