Canon LBP7780CX User Manual page 598

[Continue
[Reduce Quality] Printing], [Stop
Printing]
displaying the following error message when the memory required for
the process runs out.
If [Continue Printing] is specified, the printer prints with the image
quality level being lowered automatically without displaying a
message.
If [Stop Printing] is specified, the printer stops printing, displaying
a message. In this case, the printer resumes printing with the
image quality of the data being lowered by pressing [
Online).
] ( :