Unidirectional+Printing

=Does Unidirectional printing provide better quality than Bidirectional? How do I select it?=

According to the folks at ColorHQ, Unidirectional printing produces higher quality in deep shadow areas, which may show banding with Bidirectional printing. They strongly advise selecting Unidirectional printing. Others have found little difference. According to Canon Tech Support, the main difference is that there will be a different "angle" or "lean" to the droplets depending which was the head was moving, and that in some cases the reflectivity may vary enough from this to be perceived as banding.

According to Steven Katzman in his IPF5000 Field Test for Rangefinder magazine, "A bidirectional mode decreases printing times but can compromise the integrity of the color since the inks aren’t being sprayed in their proper sequence." He uses unidirectional printing.

To select Unidirectional printing in the Photoshop plugin, select the Main tab, then click on the Set button under the Media Type dropdown box. There is a checkbox in the lower left corner of the dialog box where you can select Unidirectional printing. For optimal color accuracy when making custom profiles, it is probably best to select Unidirectional when printing out the target, since these subtle changes have been reported to affect colors on other printers.