I was able to fix the image size for Judy.
I won't post the actual logo but let's say it was the red area you see below.

What I did was increase the canvas height using Snagit. Note canvas height rather than image height. That gave me space above and below the image which retained its original size. That space was then filled with the same colour as the heading.
In the skin editor I then replaced the original image with this new one. It needed more width so in the skin editor I changed that in the Header settings.
Previously the image was stretching to fill the height and being constrained by the default width setting. This deeper image did not stretch as it filled the height and the change to the width setting fixed that aspect.