It should always be 200px high on a Desktop system.

Do not blow up an image that is less than 200px high or less wide than the action bar - instead, just vertically and horizontally center it. For images larger than the area available for the preview, please fit them inside the preview without changing their proportions: if an image is wider than high, ensure it fits it has the width of the preview area; likewise, if an image is higher than wide, ensure its height is 200px.