Imaging and Machine
Vision Systems
Imaging
and Machine Vision Systems can be described as the integration
of image acquisition devices, computers, and imaging software.
The automated manufacturing also requires application-specific
material handling,
Motion Controllers,
Part-tracking Controllers and sensors, and control software. Today's
high-speed, complex manufacturing systems require a machine
vision system that can efficiently collect data, use historical
information to provide context, and generate process knowledge
for automatic characterization and control of product quality
and the manufacturing process. The System
consist of:
Image Acquisition Devices
- Lighting
to illuminate the object,
Optics/Lens
to couple the image to a camera sensor,
a
Camera
to convert optical image to an analog signal, and for
automated manufacturing a Trigger Sensor to initiate the image acquisition. Computer
– Typically a PC with a CPU (decision-making and control), an
Operator Console (the operator interface), and
Imaging
Hardware (typically an analog to digital converter and
image processing). The automated manufacturing also requires an addition
of I/O Interface, Material Handling and communications
to customer process information and control system. Software
– Operating System Software (e.g. Windows NT/2000/XP) and
Imaging Software
(the user interface, image acquisition and processing, image analysis
and decision-making, historical data collection and analysis). Image Acquisition Devices Acquiring an
image in machine vision is similar to photography – it requires
proper lighting and a lens to capture a picture of the object
and focus it onto a light sensitive camera sensor.
The quality
and placement of the lighting and the quality of the optics (lens)
affects the quality of the image and are key factors in creating
the contrast required for the inspection system to distinguish
features in the object under inspection. The solid-state
(semiconductor) image sensor consists of a finite number of equi-spaced
discrete light-sensing elements arranged in a line (line-scan
camera) or in a rectangular array (matrix camera). Each discrete
element produces a portion of the total picture or a pixel. The
camera image sensor dictates the smallest detail that the system
can discriminate. A typical machine vision camera has a sensor
with approximately 500 x 500 pixels. The smallest detail that
the system can discriminate also depends, like in photography,
on the lens field of view. If the field of view is 1", one pixel
represents 0.002" and if the field of view is 10", one pixel represents
0.02". When an object
is illuminated, all of its points are simultaneously imaged on
the imaging plane of the sensor by light-sensing elements - which
are then read out, point by point, in a programmed sequence. The
image sensor outputs a sequential electrical signal corresponding
to the intensity of the light at the individual image points.
The intensity of the light is a function of the intensity of a
light source, the reflectivity of the object, the light and object
position, and the sensitivity of the camera sensor. For a computer
to operate on the image, the electrical signal (analog image)
is digitized in dedicated hardware (analog to digital converter)
and stored into dedicated memory (frame store). Typically, the
brightness is represented by a value between 0 and 255 and is
referred to as a level (shade) of gray.
For more information, please contact
High-Tech Digital Technical Support.
310-265-8203
support@high-techdigital.com.
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