Hewlett-packard Development Company, L.P.

Hp Indigo B.v.

Moshe Haim

Tsafrir Yedid Am

Rivay Mor

Iliya Shahamov

Eli Kaminsky

In an example, a method includes printing a set of images by transferring print agent between a roller of a print agent source and an electrophotographic surface in a plurality of transfer operations, wherein the roller is controlled to have a first voltage profile during each of the transfer operations. A variation in optical density which is consistent across the set of printed images may be detected, and a second voltage profile correction may be determined based on the variation in optical density. The method may further comprise printing a subsequent image by transferring print agent between the print agent source roller and the electrophotographic surface in a subsequent transfer operation, wherein the roller is controlled to have the second voltage profile during the subsequent transfer operation.

Controlling voltage profiles

In an example, two images of a printed calibration image are acquired using two measurement devices. The measurement devices are offset along an axis so that the two images correspond to two portions of the printed calibration image overlapping along the axis. The printed calibration image comprises a pattern extending across the printed calibration image in the direction of the axis, the pattern defining a shape so that in each image, a portion of the pattern appears as different from a straight line parallel to the axis. The two images are aligned using the two portions of pattern.

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Nes Ziona, Israel

Moshe Haim