Há o mesmo problema com uma resolução nesta postagem no fórum, Correção de imagens de navegador borradas no Chrome e no FireFox
You know what the problem was? Apparently my font size in Windows Control Panel under Display settings wast at “Medium 125%” and the browsers suddenly started respecting the Operating System font size and it was enlarging whole pages, images included which made them blurry and pixelated. You can go change that back to 100% easily.
So now I’m thinking that is probably happening to a lot of people and they really don’t notice. So just go check your Control Panel Display settings and make sure it says 100% then go view some webpages after. They may seem smaller at first but they will be so much more clear and laid out how the designer wanted you to see them.