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Applying the camera colour calibration and white-point adjustment to the UVL images.
7) Click on the “uvicalib” tab. Column A calculates the colour temperature adjustment
required to compensate for the difference in colour temperature between D65 (the
colour temperature at which the colour calibration is carried out for the VIS images - see
workflow for the correction of VIS images) and the colour temperature at which the
VIS images are acquired. This is described in more detail in Chapter 1.
8) Move the slider at Al (Figure 3-65) to select the VIS illuminant colour temperature, from
a source with known colour temperature (e.g. for a D50 flash, choose the 5000K) or as
measured with a colour temperature meter. A9 shows the resultant white-point
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Figure 3-65
9) Scroll right to column B, which applies the colour calibration for the VIS image
(automatically carried over to B1 from the “viscalib” tab) to the UVL images to be
calibrated (automatically carried over to B2 from the “linear” tab).
10) The colour calibrated images can be seen at B3 (Figure 3-65). Note that the calibration
is applied to the images at both the “target” and “object” thumbnails, which can be the
same image (as in Figure 3-65) or another image taken with the same camera and
under the same lighting conditions (Figure 3-66).
11) The adjustment is applied to the images at B3 to give the colour-calibrated and white
point adjusted images at B6 (Figure 3-65 and Figure 3-66).
12) Figure 3-67 shows a comparison of one of the image sets discussed above before
(right) and after calibration (left).
Version No. 1.0 156 Date : 14/10/2013