Planmeca Viso Technical Manual page 78

5 Adjustments and calibrations
72 Planmeca Viso
2. Protect yourself from radiation and press the exposure button to take the
exposure. The Geometry calibration esposure results will appear in the
window.
3. Perform all the Flat field calibrations: 1x1 3pF, 2x2 1pF, 3x3 0,5pF, 1x1
0,5pF and 2x2 0,5pF.
In case bad map image is unsuccessful
In case bad map image is unsuccessful adjust the blemish threshold for
linear value. The blemish threshold defines which pixel is defined as blemish
(bad). If pixels value in flat field image differs more than [blemish threshold]
% from the flat field images average value, the pixel is marked as blemish.
Too many blemishes may also be due to saturating sensor. It may also be
due to collimator adjustment.
1. Select Settings from the File menu in the Device Tool main page.
2. Enter value to the Blemish Threshold for Linear Flat Field (%) field. The
value can be adjusted between 3 and 7%. The default value is 5.
3. Click OK.
If you see plenty of bad columns on the right, left, top and/or bottom side
of the image, primary collimator can be incorrectly calibrated.
It is acceptable to have 1 or 2 columns marked bad on the left and right
edges of the image.
Technical manual