Cause
“Fish eye”, usually nut-shaped white spots surrounding a small coloured spot are caused by hard particles of dried ink, dryer skin, dirt, plaster or other foreign material in the ink. The particle is preventing the closest part of the rubber blanket to transfer the ink and a white area around the particle can be seen.
White spots in solids that are not nut-shaped can be caused by paper dust or particles picked up from the paper.