Scan settings, Image quality, Scan settings -4 – Canon L90 User Manual
Page 125: Image quality -4, See “scan settings,” on p

Copying
5-4
Scan Settings
Before pressing [Start] to begin copying, you can adjust the settings to better suit the
document to be scanned. These settings return to the default values if the machine
remains idle for a certain period of time or if you press [Stop/Reset].
Image Quality
The default setting is
1
Press [COPY].