Canon Kabushiki Kaisha

Paul Joseph Ellis

Ben Yip

Son Thai

Disclosed is a method () of encoding a message () into a target area of an original image by determining a set of data items into which the message can be partitioned, partitioning the message into the data items, encoding () a first mark into the target area at a location determined by applying () a hash function () to a first data item, and encoding () a second mark into the target area at a location dependent upon (a) a hash value determined by applying () the hash function () to the first data item and a second data item, (b) the location of the encoded first mark, and (c) a predetermined constraint (), wherein the first and second marks form at least part of a pattern of marks in the target area of the encoded image, the pattern having a visual characteristic defined by the predetermined constraint.

Two dimensional information symbol

Disclosed are methods () and apparatuses () for determining a location of a graphical object () printed onto a print medium (), said graphical object comprising a plurality of object marks, the method comprising the steps of superposing a two-dimensional reference pattern () having a pre-defined degree of accuracy over the printed graphical object, the two-dimensional reference pattern comprising a plurality of pattern marks (); scanning the superposed printed graphical object and reference pattern to produce a scanned image (); determining a location coordinate () of the graphical object in the scanned image (); and refining the location coordinate dependent upon the scanned reference pattern to determine a reference pattern coordinate (') associated with the location coordinate (). Also disclosed are methods (), apparatuses, and computer program products for determining a head size () of a print head () of a printer () using the aforementioned method.

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Gladesville, Australia

Paul Joseph Ellis