Blogger Header Issues

Is anyone else having problems with their headers on Blogger?  I'm having issues with my images and words appearing pixelated, like Blogger had to really enlarge my pictures to get them to fit.  I'm especially noticing it on Tess and Maggie's blog and on Belle's Bulletins.  No matter what I do, I can't seem to fix the problem.

I even tried uploading headers from the past that I know were clear and beautiful, and they appeared pixelated as well.

This is so frustrating!  It's terrible having a header that feels shoddy, when I know I can do better.  Have any of you had the same issue?  If so, what did you do to fix it?  Help!!!!!