I don't know how to state this problem nor to google it. I made a pattern on Illustrator, it's a quite complicated pattern, but it's ok on my preview (left) I use my GPU Preview for working default. the right image shows the pattern in CPU Preview. I thought it's still OK, its just my CPU/GPU difference. but after I export it in JPG highest quality, and PDF highest quality, the pattern looks like the middle image. And so I printed those image, the quality of the pattern unchanged.
My goals are to make a seamless pattern, yet the glitch makes it uglier than seamed pattern :(