In the past I've used the custom image header option and they have always come out in excellent quality. However at the moment I'm finding that the headers lose quality when they are loaded onto the blog, even when they are exactly the right size for the theme. They are in perfect quality when I go to crop them (which I don't bother with as I make sure that they are the right size when I make them)but then when I am directed back to the main custom header page they have lost a bit of quality.
This is very irritating as it ruins the look of an otherwise great-looking Day Dream theme.
Also I've had a bit of problems with banner disappearing and reverting to a previous banner. I know that the latter problem is known about, but is the former going to be sorted anytime soon?