For those posting follow ups - if you find a solution didn't work for you please post a link to your shop. It's possible the issue you're seeing is in the image itself, or even in other parts of the code. Being able to see what you are goes a long way for members to troubleshoot.
I am also having an issue with this. My original logo is quite sharp and large. I tried resizing the original logo to 250 px using Paint and it did not work. I also tried modifying the header liquid to
data-widths="[1080, 1296, 1512, 1728, 2048]"
and it did not make it clearer. Here is the original logo:
www.printmylabel.ca password camishop
I would really appreciate any help.