Can you suggest a minimum size for the page header image? Here’s what I’ve done.
In the page header editor I added a featured image that is 1440 x 420 px, crunched to 87kb. Then in the page header editor I set the re-size option to 1900 x 500. This worked great. It didn’t compromise the quality of the image going from a smaller original image to a bigger re-sized. Is there a point when the original image is too small? What do you recommend as a minimum width for the original image?
There isn’t a minimum. I would say that if you are using full width then you would want to use something around 1920px width should be good as it won’t get zoomed in.
If you are not using full width then the try using the same width as the container width.