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Quickpack is the Euresys line
of products providing the most appropriate image
acquisition and a set of hardware accelerated
processing functions. This line of products offers,
in a quick way, the right solution to a dedicated
application. Grablink Quickpack Colorscan acquires
high-resolution images from Camera Link RGB line-scan
cameras. It provides on its FPGA the image pre-processing
functions necessary for color scanning applications.
These functions are executed with a much higher
speed than on a PC sparing the processing power
of the computer. Color document scanning or PCB
inspections are then considerably eased and accelerated
providing on the fly enhanced images ready for
further processing. ColorScan offers scan-delay
compensation, shading correction, look-up table
transformation and white balance functions.
- Acquisition from one RGB line-scan Camera
Link camera
- Base configuration up to 60 MHz
Maximum processing rate:
50 MPixel/s (150 MB/s)
- Image pre-processing functions accelerated
by the FPGA
Scan-delay compensation
Shading correction
Look-up table transformation
White balance
- Output formats: RGB 24- and 32-bit packed,
RGB 24-bit planar
- Form factor: 64-bit 66 MHz Desktop PCI
- System connector: isolated inputs for line
and page triggers
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| Color line-scan
acquisition
Grablink Quickpack Colorscan acquires images from one
RGB line-scan Camera Link camera. Two kinds of RGB imagers
are supported: trilinear and 3-CCD. ColorScan is used
with a single Camera Link?compliant camera in a 24-bit
RGB Base configuration. The maximum Camera Link clock
rate is 60 MHz. The Grablink Quickpack Colorscan processes
the data at a maximum rate of 50 MPixel/s (150 MB/s).
Raw acquired image |
Image pre-processing functions
accelerated by the FPGA |
Scan-delay compensated image |
Scan-delay compensation
A trilinear color camera captures the luminance
information at three light wavelength ranges from
three distinct locations. A gap between these lines
analyzed in red, green and blue is resulting due
to the sensor geometry and the optical arrangement.
The scan-delay compensation offered in Quickpack
ColorScan gathers the color information coming from
three different locations in order to reconstruct
consistent RGB information.
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Scan-delay compensated and shading corrected image
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Shading correction
During an acquisition, shading correction is required
to compensate for lighting spatial nonuniformity,
lens defects and sensor response defects. This process
is carried out through the acquisition of two reference
profiles, a white reference profile and a black
reference profile, during a calibration phase. Quickpack
ColorScan includes a shading correction applied
on the fly on each of the three color components.
After the calibration phase, the six profiles are
compiled into the frame grabber hardware to correct
the distortions. This correction is handled applying
a multiplicative ?ain?and an additive ?ffset- correction
to each pixel issued in the scanned signal. This
processing drastically improves the quality of the
acquired images facilitating the application processing.
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Look-up table transformer
A look-up table (LUT) transformer allows a dynamic
transformation of a digital signal according to
a pre-defined law. Quickpack ColorScan includes
three LUT transformers, modifying each RGB color
component after shading correction. The LUT process
involves the creation of a mapping table assigning
to each input value a programmable output value.
The LUT device offers a great flexibility leaving
the user free to define its own table contents or
providing means to automatically generate LUT contents.
The LUT capability included within Grablink Quickpack
Colorscan offers the following setup methods: exhaustive
definition of the transformation law, parametric
shaping of the transformation law through a few
intuitive controls, white balance by RGB gain correction
implemented as special transformation laws.
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Scan-delay compensated, shading corrected and white
balanced image |
White balance
Grablink Quickpack Colorscan is able to manage white
balance correcting for RGB channel imbalance mainly
due to differences in sensitivity of sensors, to
the illumination system and due to the optical filter.
After calibration, a correcting gain is then individually
applied to each color channel to compensate for
unbalanced R, G and B components.
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Shutterless cameras
Most high-resolution color line-scan cameras have no
electronic shutter capability. Consequently, they have
to be operated at a constant cycling rate in order to
maintain a constant sensitivity. QuickPack ColorScan
implements a unique downweb resampling feature(1) yielding
a defined aspect ratio irrespective of web speed variations.
A built-in rate converter accomodates an off-the-shelf
motion encoder to control the line acquisition process,
enabling any programmable aspect ratio, including perfect
square pixels.
(1) Patent pending
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