Hi DK and ChenX.
I see some circular ripple rings (like when tossing pebble into pond). Ya might need to go to big-view. It sort-of looks like age rings on a crosscut tree stump. Gray-scales vary inconsistently as distance from light-center… increases.
Hey ChenX - what browser and computer are you using? I’m using Firefox 60.7.0 esr on Dell Inspiron Desktop/Windows 7. Maybe we have broken browsers/gfx chips. I hope not.
If each ring… was consistently a bit darker… in steps… as ring diameters increase… then that would be somewhat understandable. There’s 256 shades of gray, so SOME ring-steps would be normal.
BUT… I am seeing inconsistency… lighter, then darker, then lighter again, then darker again… as the ring diameters increase. Interesting.
ChenX, can you possibly create a playground that shows the same problem? If so, THEN we can view it with many browser types and device types… and see if we can locate problem area. (Wingnut washes his Dell desktop to make sure it is ready for further tests.)
ChenX… try to test with multiple browsers and multiple devices… at your house, too. Try. Report what you discover, please. Thx!