[Typo3] Templa Voila Image Fields????

[Chris Van Pelt]

I was messing with an image field in a template of mine.  I told it to
be fixed W + H, and only applied a height parameter in the image tag. 
Templa voila seems to be cropping and resizing the image.  It is also
converting my jpeg into a gif.  How can I control this?  Ideally the
image would be resized to a specific height, keeping the aspect ratio.
 Any idea's??

Thanks