Factors to consider for
high-speed character reading
Developers should consider factors such as print quality and line speed when
specifying hardware and software components for optical character recognition.
Chris Walker
Optical character recognition (OCR) vision
systems help manufacturers improve brand
reputation, achieve traceability and package
compliance, as well as minimize the risk of
recalls. Many product labels have common
issues that can be prevented with an automated machine vision system, such as: wrinkles, typographical errors, incorrect date
codes, misprints and general flaws.
An experienced vision system engineer
will integrate the correctly specified camera,
optics, lighting and processor into an automated machine vision system that minimizes or eliminates failed quality checks
and product returns. OCR vision systems are
used on high speed packaging lines across
a variety of products and industries, including medical, pharmaceutical, automotive
and consumer packaged goods.
Depending on the
product being inspected,
manufacturers com-
monly depoly or use this
type of inspection appli-
cation for one or more of
the following purposes:
ensuring product quality; reducing repeti-
tive labor tasks; eliminating or reducing risk;
FDA compliance with Title 21 (i.e. phar-
maceuticals); and finally, complying with
export/import regulations.
Vision Systems utilizing OCR algorithms
read and verify label date
and expiration codes on
packaging. A traditional
OCR vision system scans
alphanumeric characters
on a package and com-
pares it to a trained data-
base of characters to
determine if it recog-
nizes the characters
in view. If the char-
acters are recognized
and verified, it passes
inspection; if it is not recognized, then the
product is sent to a reject bin.
Processing time
OCR inspection is typically a three-step pro-
cess. First, the vision system finds the alphanu-
meric code and determines its orientation, char-
acter-to-character spacing, size and scale based
on pre-defined limits and then parses each
character, including spaces, from the code.
Next, each character is compared to a
trained set of characters and the highest
match is returned. Lastly, the highest match
Chris Walker, Senior Project
Manager for Vision Systems, EPIC
Systems, Inc. St. Louis, MO, USA
( www.epicvisionsystems.com)
Figure 1: At high-speeds of 600-1000
parts per minute,
OCR solutions often
require other hardware features such as
high-speed strobed
lighting to reduce
image blur.
