Canon Pixma MP520 series Quick Start Manual page 62

(4) Check the printed patterns and use the [ or ]
button to input the number of the pattern in
columns L and M that has the least noticeable
horizontal streaks, then press the OK button.
Note
If it is difficult to pick the best pattern, pick the setting that produces the least noticeable horizontal
white streaks.
(C)
(C) Less noticeable horizontal white streaks
(D) More noticeable horizontal white streaks
58 Routine Maintenance
(D)