Full color 16-gradation test print can mainly check gray balance, gradation performance of each color (YMCBk) and foggy image.
(1) Gray balance
Check to see if the output comes with even density of each color at gray scale area.
(2) Gradation performance
Check gradation performance and density difference of each color (YMCBk)
(3) Foggy image
If there is foggy image at the white area, it may be caused by fault of developing system or photosensitive drum, or correction fault of laser scanning system.