Coraline header image fuzzy (reduced) for 2 col layout

Hi, just noting that the Coraline theme forces the Coraline header image from 990 to 770 wide in 2-col layout.

If you view the header image on this page:https://studiowabisabi.com/painter/ in firefox [right click, “view image info”], note at the bottom it says:
“Dimensions: 990px × 180px (scaled to 770px × 140px)”

This scaling distortion isn’t noticeable with Coraline’s default photo image, however, when I upload other images, the anti-aliassing is obviously off, jaggy, blurry, particularly with previously vector objects like text. So this becomes a more significant obstacle when trying to use a logo in that area.

It would be good if the theme were modified to be able to crop per selected layout preference, rather than forcing it to 990 at the upload, and then squeezing the display for the smaller layout. I have no idea how to do this myself.

I’d love to hear about any resolution. I think this is a spectacular, very useful theme with a lot of great qualities, and I want to use it on a number of upcoming projects.