Epson's inkjet printers use proprietary technology such as PrecisionCore to achieve high dot placement accuracy and make stunning prints possible.
However, some types of paper can cockle, sag, or slip during feeding, causing dot misalignment (i.e., inaccurate placement of drops of ink). This invites banding-unevenness, with light or dark areas in the printout, or lines that appear in the direction of printing in stitch areas between adjacent print swathes.
To obscure or eliminate banding, Epson developed MicroWeave, a technology that we provide on all our printers.
Read on to learn more about the role that MicroWeave plays in maintaining print quality.
MicroWeave is an Epson original technology that obscures or eliminates shading unevenness and banding even if dots become misaligned between passes of the printhead.
Interlaced scanning is used to achieve high image quality with serial scanning printers. In interlaced scanning, the printhead passes over the same area multiple times in the print direction as the paper is incrementally fed in amounts that are no more than a fraction of the length of the printhead's nozzle array to prevent visible banding between print swathes. In general, printing speed is sacrificed to obtain greater image quality by making banding at the stitch areas between print swathes less noticeable, but with MicroWeave, Epson minimizes any loss of speed by ejecting ink droplets in the best pass and from the best nozzles for the dot arrangement determined by halftoning.
In other words, MicroWeave works by performing processing of the stitch area between print swathes. Error tolerance is improved by using a dither mask used in halftoning when the placement of dots in the stitch area between print swathes is determined, and, furthermore, the dots are placed in gradations and printed in multiple passes to disperse misaligned dots and make banding caused by errors less noticeable.
Simplified diagram of overlap printing
Here, we explain in more detail what kind of processing is involved in MicroWeave and why this technology can prevent banding.
Inkjet prints are created by converting the amount of ink obtained in a color management flow process into a number of dots by halftoning processing and then performing MicroWeave processing. The technology determines the distance the paper needs to be advanced and in what pass and from which nozzles ink needs to be ejected to achieve the dot placement determined by half toning.
Normally, images produced by serially scanning printers are gradually completed by scanning the printhead over the same area multiple times. The direction perpendicular to the
paper feed direction is called the main scanning direction, and the direction that the paper is fed is called the sub-scanning direction. In addition, a row of dots arranged in
the main scanning direction is called a raster line.
Banding is caused by differences in density in the spaces between raster lines. These differences are caused by various factors, such as dot misalignment due to slippage during paper feeding.Therefore, Epson has been developing ways to minimize banding and make it less visible by using MicroWeave processing to disperse the density differences in each raster line.
Overlap printing, where processing takes place in the area where scanned regions meet, is one way to minimize banding. It is achieved by masking some dots and printing them complementarily in a subsequent scan. This disperses the misaligned dots by configuring the raster line with multiple nozzles.Furthermore, optimizing the placement of dots in the overlapping area through gradated placement, for example, makes banding caused by dot misalignment due to paper advance errors less noticeable. When determining the optimum dot placement, an error-tolerant dither mask used in halftoning is also used to further increase the dot misalignment tolerance. In this way, stable and consist printing is achieved at high speed and with high image quality.