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US 6,665,424 B1Granted
Automatic inspection of print quality using an elastic model
AssigneeDe La Rue Giori S.A.
InventorLuigi Stringa
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AssigneeDe La Rue Giori S.A.
InventorLuigi Stringa
Estimating the term…
The invention relates to a process for producing by electronic means a model for automatically inspecting the print quality on deformable objects. The model is firstly produced by capturing with an electronic camera (CCD for example) the images of a set of sheets whose print quality is regarded as acceptable; the images are stored so as to produce a first reference image, together with the relevant densitometric tolerance limits. This reference image is thereafter divided into a multitude of sub-images by superimposing a grid with very small mesh cells. During inspection, the distances between the nodes of the grid are measured on the image to be inspected: this therefore produces an elastic modification of the model, which is such as to make the distances between the nodes the same as in the image to be inspected. The image to be inspected is thus verified with respect to the modified reference (model) by using any of the standard inspection techniques.
A process for automatically judging the print quality of images printed on a deformable carrier by using an optoelectronic image capture device and an image processing system which measures the deformation of the carrier by superimposing a suitable grid on an image to be inspected, and thereafter by measuring the displacement of positions of characteristic structures of the grid with respect to their position in an image regarded as an undeformed reference image, which, before comparing them with the thresholds, deforms the images to be inspected so that their respective characteristic structures have the same position as those of the reference image.
A process for automatically judging the print quality of images printed on a deformable carrier by using an optoelectronic image capture device and an image processing system which measures the deformation of the carrier by superimposing a suitable grid on an image to be inspected, and thereafter by measuring the displacement of positions of characteristic structures of the grid with respect to their position in an image regarded as an undeformed reference image, which, before comparing them with the thresholds, deforms the images to be inspected so that their respective characteristic structures have the same position as those of the reference image, in which the characteristic structures are positioned automatically at a maximum over each mesh cell of the quantity defined by the following equation:
A process for automatically judging the print quality of images printed on a deformable carrier by using an optoelectronic image capture device and an image processing system which measures the deformation of the carrier by superimposing a suitable grid on an image to be inspected, and thereafter by measuring the displacement of positions of characteristic structures of the grid with respect to their position in an image regarded as an undeformed reference image, which, before comparing the characteristic structures with the thresholds, deforms the model so as to obtain the same positions of the characteristic structures as in the image to be inspected.
A process for automatically judging the print quality of images printed on a deformable carrier by using an optoelectronic image capture device and an image processing system which measures the deformation of the carrier by superimposing a suitable grid on an image to be inspected, and thereafter by measuring the displacement of positions of characteristic structures of the grid with respect to their position in an image regarded as an undeformed reference image, which, before comparing the characteristic structures with the thresholds, deforms the reference image so as to obtain the same positions of the characteristic structures as in the image to be inspected.
Dependencies are inferred from the claim text.