Yes that happens to me sometimes when I am looking at a picture of the quilting with high contrast. It looks like the thread is up and the fabric is down - instead of the other way around. It's just an optical illusion. I look away and blink and it usually flips.

Does anyone else have trouble with their quilting vision. Quite often I see quilting in reverse - like seeing it in negative so ups are down and downs are up. I mean on photos on here or books, no problem with with quilts 'in the flesh'. Sometimes if I blink I can get it right