1. Pattern Match (blob detection)
If there is a print there and it’s of a similar pattern to a reference sample. Though only the overall pattern is being matched, not each letter, nor the 2D barcode.
2. 2D barcode and OCV system
The camera takes an image and reads the information that it finds. It does this using a 2D datamatrix tool for the barcode and an “OCR” tool for the text. It can then compare the information read to reference information entered by the operator (which can be done via a “teach” facility using a reference sample) and decides if it matches (this is the ‘OCV’ bit – verification).
3. 2D barcode and OCV system with online grading
As 2. above, but the system also tells you how good a quality the print is – it ‘grades’ it – though this only applies to the barcode.
There is a key point to note on this: The ISO/IEC 15415 standard for the verification of datamatrix barcodes requires that a number of images are taken with the lighting coming from different angles each time. Clearly this is not possible on-line, so any system fitted to one of our feeders can only offer an “indicative” grade. Therefore the use of a bench top verifier that gives a grading to this standard and then compares the two results is also preferable.
The online system would normally err on the side of caution so a grade B on-line, may be an A under the verifier. This means that so long as the on-line system is passing grade Cs and above, they must be good.
Terminology is somewhat key here, when referencing to a “good quality code”, it would be better to simply say a “good code” i.e. the camera can confirm that the correct information is printed. Quality takes us into the realms of verification.