One of the applications of printers with white inks is to print on a transparent substrate and cover it
with white, so that the image, printed in mirror image, is seen through the substrate on a white
background. An unmirrored image can be printed on the other side, allowing for an image on both sides
of the substrate. This is referred to as a (three‐layer) sandwich mode.
To reduce translucency, a variation is the five‐layer sandwich mode, in which the middle white layer is
replaced by another sandwich of white, black and white.
Depending on the hardware, in particular the carriage layout, this can be printed in a single job: so this
has to print the first image in mirror image, then cover it with white, optionally a layer of black and
another layer of white, and finally print the second image.
To do this, you need (logical) pens of all fluids needed for the first image at the bottom of your carriage,
which passes over the image first, after that a pen with white ink, and finally another set of pens for the
We describe an approach in which each physical trench (nozzle array) of a given colorant in a given pass
only has to print the data of a single image plane, and mask it with a single mask. It is described how two
image planes and two masks can be encoded in a single one, enabling the three layer mode with a single
trench, and five layer with just two trenches, at the cost of a reduced bit depth of each image.
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INC, HP, "MULTI-LAYER PRINTING MODES", Technical Disclosure Commons, (July 22, 2021)