Canon S400 Reference Manual page 169

Check 2
Is Halftoning set for optimum performance?
Check the Halftoning setting in the Quality tab of the printer driver. The Dif-
fusion setting smoothes uneven or streaked colours.
Windows
1
Open the Printer Properties dialogue box.
2
Click the Advanced button in the Main tab.
3
In the Halftoning box under the Quality tab, disable Auto if it is checked on.
4
Click Diffusion on and click the OK button.
Macintosh
1
When using Manual for printing, click the Details button in the Print dia-
logue box.
2
In the Quality panel, set Halftoning to Scatter.
Troubleshooting - Printout is Unsatisfactory
Colours streaked or uneven
169