The one currently on there is way bigger and since browsers do a poor job in resizing, it looks very jagged on my screen. Also: it is important for consistency that the image is the same across all sites. Is it not safe to assume users will also visit the docker homepage? (for both speed (already cached) and retina displays (they look at the other site as well, you'd say..) ). 

Since I was looking more closely at the image we have on the homepage we can actually improve the quality a bit further, it would be great if we can update the image on all sites in one go. 

My reasoning is that putting something different here does not really help, and since the blog also already just points to the one on docker.io we can update that image and get the benefits everywhere.