here is what i was recently working on:
If you build some towers you will notice that the walls gets blurry at the middle and outor zoom (scaled layout by 0.7).
In the same time the towers stay clear and sharp.
There is no much difference between those sprites and still one are blurry, others not.
Btw i noticed that problem dont exist when played on Internet Explorer, but on Mozilla nd Chrom the problem exist.
If anyone can help I'll appreciate it.