Printing on a recording medium by lateral scans of a print head in accordance with print data. Content of print data is determined. Then, the print data is printed either with a first lateral scan process using a critical zone at edges in a lateral scan of the print head for printing, or with a second lateral scan process that does not use the critical zone for printing. The first or second lateral scan process is selected based on the print data. Preferably, the critical zone is sized in correspondence with ramp up non-uniformities of a print carriage on which the print head is mounted, so as to accommodate a distance between a point where print degradation due to speed non-uniformities are noticeable to a point where print degradation due to speed non-uniformities are no longer noticeable. The second lateral scan process preferably is a process in which a predetermined margin is inserted into the first lateral scan process. The second lateral scan process is used if print data for a current scan and print data for a previous scan, in at least the critical zone, are continuous print data, thereby alleviating ripple effects for the continuous data. In a case where the print data for the current scan and the print data for the previous scan are not continuous print data, the print data preferably is printed using the first lateral scan process.