Sidebar image

Dear all,

I removed the sidebar picture on my web site http://www.adyssmeets.com due to its low quality since a few days. How is this even possible? It was always high quality and now it looks very pixel-y, even though it is still the same picture… How is that possible?

[closed as duplicate of https://wordpress.org/support/topic/poor-image-quality-4?replies=2 ]