Adimec Camera Link OPAL Series, Operating And Users Manual

Page: 47 / 86

OPERATING AND USER MANUAL OPAL FAMILY
47
IMAGE AND DATA FORMATTING
Image and Data Formatting 8.
Introduction 8.1
Although the CCD in the camera has a fixed format there are several possibilities to change the way
the CCD is read-out. It is possible to limit the amount of lines read from the CCD (discussed in par
8.2); it is also possible to change the readout-direction (discussed in par. 8.7).
The video-processing, which converts the analog CCD-signal to the digital Camera Link output can
also be changed. It is possible to choose the number of bits on the output (discussed in par. 8.6, it is
possible to program a digital gain (discussed in par. 8.8) and there is a possibility to change the output
offset. For color camera models it is possible to program additional gains for the R- G- and B-pixels in
color camera models.
All cameras have a factory set defect pixel correction. Enabling / disabling this correction can be
selected by the user. The user is able to add defect pixels to and remove defect pixels from the defect
pixel table. A defect pixel mask can be made visible to the user.
Binning 8.2
Settings 8.2.1.
In certain circumstances it might be preferable to sum 2 or more pixels. In CCD terms this process
is called binning. If two or more pixels are binned the combination of those pixels can be regarded
as one larger “bin-pixel”. In which circumstances this is preferable can be determined if the
consequenses of binning are known.
A typical CCD implementation of this mechanism is to bin 2 pixels vertically. This is referred to as
vertical binning and can be done on the CCD chip. This is the only binning feature that is available
on a standard OPAL camera. Theoretically more pixels vertically can be binned and even horizontal
binning is theoretically possible, the latter is discussed later.
One important property of on-chip binning is that it takes less time to read all the data out of the chip.
As a consequence the maximum framespeed rises, this is regarded as the most important advantage.
Another consequence is that there is less data on the CameraLink output to process.
Another consequense is that at N times binning the sensitivity of the camera increases with a factor of
N at the cost of a decrease in resolution by a factor of N.
At the camera output Full Scale will always correspond with a Qmax of 18kel. Note that at 2x binning
this corresponds with 18 kel in the “bin-pixel” or 9 kel per normal pixel.
OPTIONAL: Optionally 4 and 8 times vertical binning and horizontal binning is available. The following
only refers to cameras with these non-standard options in place.
For 4x and 8x vertical binning goes that sensitivity increases with a factor of 4 and 8. The maximum
possible framespeed also increases
Horizontal binning cannot be done on the CCD. This type of binning is done electronically, referred to
as off-chip. This enables the possibility to correct for the increasing sensitivity. In the OPAL camera
this is done automatically and can not be switched off. So when changing from no horizontal binning
to 2x horizontal binning image brightness will not alter.
Horizontal binning gives no speed advantage; it does give the advantage of having less data on the
CameraLink interface.