De La Rue Giori S.a.

Luigi Stringa

A sheet of paper (,) with the image to be checked passes in front of a camera (,) designed to capture three chromatic images and to emit three signals (S,S,S,). These signals are introduced into a device (,) applying a function F which comprises coefficients (K,K,K,K,K,K,) previously recorded in a suitable device (,). The single signal (,) resulting from the function F is delivered to a device (,) for checking the printing quality.

Method for automatically checking the printing quality of a multicolor image

A procedure for producing a reference model for checking the printing quality of an image composed of at least two drawings starts with printed test sheets. The sheets are aligned so that drawings printed in a first printing are in register. The images are recorded, storing the densitometric pixel values which constitute the images in memory. The minimum value obtained is associated with each pixel and a model for the first drawing is obtained. The same procedure is followed for producing a second drawing and another model. The models thus obtained are recombined in order to form the reference model of the image to be checked.

Procedure for producing a reference model intended to be used for

The installation for quality control of printed sheets (1) comprises means (8-13) for transferring said sheets, and cameras (2, 4, 6) for checking the print quality. The transfer means (8-13) are designed to transport the sheets in a plane and to allow the print quality of each of the faces of the sheet to be checked as well as a quality check using transparency to be carried out in succession and in a single pass. The means for checking each face are two cameras (2, 3) located on either side of said plane at two offset locations, the transfer means being designed to leave an open window at the side of each camera. A third camera (6) carries out the check using transparency.

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Trento, Italy

Luigi Stringa