Print quality inspection
This works by comparing a master image or 'golden template' with a captured image of the printed material. The identification of reference points on the captured image enables the correction of position, scale and rotation.
Once the images have been accurately aligned with the template, any differences can be analysed. It is possible to set-up different tolerances that allow the system to be configured in such a way as to highlight particular types of faults or the severity of errors.
Some printing jobs may contain areas where the print varies intentionally, such as serial numbers or batch codes. This is commonplace in the food and pharmaceutical sectors. Normally these would be identified as errors; however, using masks, certain areas of the image can be ignored, allowing these types of applications to be handled satisfactorily.
To simplify print inspection, the use of image learning techniques are now being incorporated into print inspection tools to learn the level of acceptable variation by example.