Camera Control and Performing a Scan
15
Instruction Manual
SK1024U3HU
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Instruction Manual SK1024U3HU © 2019-07 E
Shading Correction
Shading correction compensates for non-uniform illumination, lens vignetting as well as any differences in pixel
sensitivity. The signal of a white homogeneous background is used as a reference. For correction, each pixel of
the sensor is scaled to the intensity maximum with an individual factor (255 at 8 bit resolution and 4095 at 12 bit).
The reference signal is stored in the camera's Shading Correction Memory (SCM). Subsequent scans are norma-
lized with the scaling factors of this white reference.
•
Open the "Shading Correction" dialog (Alt+s).
Shading Correction dialog
• Use a homogeneous white object to capture the
reference data, e.g. a white sheet of paper.
• Either take a 2-dimesional scan ("Area Scan
Function" [F3] ) or
use a single line signal that was averaged over a
number of single line scans.
• To suppress influences of the surface structure,
move the displayed object during image acqui-
sition.
• Input the scale range:
Minimum in %: intensity values lower than
“Minimum” will not be changed.
A typical appropriate value is 10% of the full
intensity range, i.e. 26 (= 10% · 255) for an 8-bit
intensity scale.
Maximum in %: target value for scaling
A typical appropriate value is 90% of the full
intensity range. The result will be a homogeneous
line at 230 (= 90% · 255) for an 8-bit intensity scale.
• Click on button New Reference
• Click on Save SCM to Flash to save the SCM
reference signal in the flash memory of the camera
Once the reference signal is copied from the shading
correction memory (SCM) to the camera flash
memory it will persist even after a power down.
On a re-start, this data will be restored from the flash
memory back to the SCM.
The current shading correction status - active or not
active - is also retained after power down.
ON Activate shading correction with the reference
signal stored in the SCM.
OFF Switch off Shading Correction. The shading
correction data will not be loaded from the flash
memory into the SCM the next time the camera
is started - even if the SCM data was previously
stored in the flash memory.
Load File to SCM
A stored reference signal
is loaded into the SCM of the camera. Shading
correction is then active.
After shading correction, the line scan signal has a homogeneous intensity
at 255 (8 bit, Maximum 100%)
Shading Correction dialog
