PrintQual (Print Quality Inspection), part of the Common Vision Blox hardware-independent imaging toolkit from Stemmer Imaging, is an ActiveX control which can be used to inspect a wide range of print substrates, such as paper, cardboard and labels as well as overprints.
The software features a sophisticated facility allowing a monochrome or colour test image to be compared quantitatively against a specified reference image. Even highly complex work pieces such as lead frames and printed circuit boards can be inspected for errors. Work with PrintQual is divided into a learning or training phase and the subsequent automatic inspection of the items.
Acceptance thresholds can easily be determined by one or more acceptable test images. The thresholds can be adjusted for the images to be accepted. The test image is position and distortion corrected and a comparison is made in terms of small, medium and large scale structures within the image. All images producing a quality score below the determined acceptance thresholds will be rejected.
Unlike conventional correlation methods, PrintQual makes it possible to distinguish between a large number of small errors and a single large error. The algorithm is so sensitive that errors of only a few pixels in size can be identified.