1. Test overview.
This test is used to adjust the Voffset of the 135 Film carrier so that the scanned image does not have dark edge at the top or at the bottom.For this, the scanner will scan a B&W film and will determine the centre of the film, which will correspond to Voffset.
Note : 135 Film is made of 2624 pixels from top into High resolution, and the CCD of 6000 pixels, you must decide on which part of the 6000 pixels of the CCD is to be measured. It is on this part that the calibration will be made.
If Voffset is incorrectly adjusted the customer may complain about black edges on scanned images.
2. Test Conditions.
This test relates to the 135 Film carrier inserted in the scanner.The 135 Film carrier must be inserted in the scanner to carry out this test.
A short B&W film must be used for this test (ref 070 100 422A) :
The value of Voffset is saved in the file im1500data.ini, in chapter FILM_CARRIER_135, line CENTREING_VERTICAL_OFFSET.
3. Pre-requirements.
- 135 Sharpness-CoeffG Test is accepted to ensure that the image is sufficiently sharp and the CoefG is correct.
4. Test realisation.
Click on RUNcarry out the test. A message will be displayed requiring the insertion of short B&W film. When the film is inserted (caution : watch for the direction of film), click on OK.A incorrect Voffset value will be used in order to see the high edge of film. The scanner will scan the first exposure of film then will go on to automatically detect the high edge of film (that can be carried out doing several try). A first value of Voffset for the film in this direction is found.
A message will be displayed requiring the insertion of the short B&W film in the other direction. When the film is inserted (caution : watch for the direction of film), click on OK.
A incorrect Voffset value will be used in order to see the low edge of film. The scanner will scan the first exposure of film then will go on to automatically detect the low edge of film (that can be be carried out in doing several scans. One second Voffset value for the film in this direction is found.
The final Voffset value is in fact the average of the 2 values found. At the end, the final value is displayed on the screen. This value will be saved. Note : This test uses the B&W film because this film moves less vertically in the film carrier (it is slightly larger than the colour film). Moreover, the adjustment is made with film in one direction then in the other direction because the image on the B&W film can be out of frame more in one direction that in the other.
5. Test acceptance.
No acceptance criteria for this test: the value found is the saved value.The value computed in this test replaces automatically the value computed during the V-Offset pre-adjustement (135 cal Pre-V-Offset on Edges).
The Voffset value can be positive or negative.