Solutions
When printing on plain paper, disable the bidirectional setting.
During bidirectional (or high speed) printing, the print head prints while moving in both directions, and vertical lines may be misaligned. Disabling this setting may slow down printing speed but improve print quality.
Windows
Clear Bidirectional Printing on the printer driver’s More Options tab.
Mac OS
Select System Preferences from the Apple menu > Printers & Scanners (or Print & Scan, Print & Fax), and then select the printer. Click Options & Supplies > Options (or Driver). Select Off as the High Speed Printing setting.
Solutions
When printing on photo paper, print using a higher quality setting.
Control panel
In the print settings, select the Advanced Settings tab if there is an Advanced Settings tab, and then select High as the Quality.
Windows
Select High from Quality on the printer driver's Main tab.
Mac OS
Select Fine as Print Quality from the print dialog's Print Settings menu.