Q: Small white dots on screen - Preview

When using preview, I find that when opening different images or PDF's there are a bunch of small white dots that appear on the image. Then, when zooming in, they disappear and reappear in other places. I've wiped my OS twice now, and am using a 2015 MacBook Pro 13inch. I'm currently running Sierra, however it happened before I upgraded to Sierra and I hoped that upgrading to the latest and greatest would fix the issue.

This is a plain purple/black image: (obviously not plain due to dots)