Calibration apparatus

A non-transitory storage medium including instructions that, when executed by a processor, cause the processor to:

• control a printing mechanism of a printing device to print only a first pattern of first elements on a print medium;
• actuate a media control mechanism of the printing device to advance the print medium;
• control the printing mechanism of the printing device to print only a second pattern of second elements on the print medium that are spaced apart and interleaved with the first elements of the first pattern;
• determine a centroid of at least one of the first elements of the first pattern;
• separately determine the centroid of at least one of the second elements of the second pattern;
• and
• determine a print medium advance error based on the at least one determined centroid of the first elements and the at least one separately determined centroid of the interleaved second elements of the respective first pattern and second pattern, wherein the print media advance error is determined for each line of first pattern of first elements and second pattern of spaced apart and interleaved second elements printed on the print media.

A calibration method for use in a printing device, the method executed by a processor coupled to a non-transitory storage medium having instructions that when read and executed by the processor cause the processor to perform the steps, comprising:

• printing only a first pattern of first elements on a print medium;
• advancing the print medium;
• subsequently printing only a second pattern of second elements on the print medium that are spaced apart and interleaved with the first elements of the first pattern;
• determining a centroid of at least one the first elements of the first pattern;
• separately determining the centroid of at least one of the second elements of the second pattern;
• and
• determining a print medium advance error based on the at least one determined centroid of the first elements and the at least one separately determined centroid of the interleaved second elements of the respective first pattern and second pattern, wherein the print media advance error is determined for each line of the first pattern of first elements and the second pattern of spaced apart and interleaved second elements printed on the print media.