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Bc BR 7 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 T 65346. antonine lady.ws (F:\Technical Imaging\WP10.3b_c meeting\Materials\Test Images) - uvicalib - nip2 Eile Edit View Toolkits Help [input linear marta [iscatb [vet Jaen specden falsecolour uvistray uvkm_ vilstray vilkm | results + Y A- visible illuminant colour temperature x \ve- apply camera calibration and white-point adjustment x >| At |macbeth illuminant colour temperature: {5000 | === | >| B1 | viscalib.D8 label | UV-induced visible luminescence targets_label | UV-induced visible luminescence with calibration targets, colour-calibrated object label | UV-induced visible luminescence of object, colour-calibrated J) to convert to: | xvz >] Colour_convert_item.X¥Z_item.action A2 A S object | A4 | target colour temperature — nip2 neutral is DES AS viscalib.Apply. calib B1 B2 >| 86 label | UV-induced visible luminescence A > targets > <> | space [colour space: | Lab a) v a Colour_new_item.Widget_colour_item.action S) object ‘a6 | Apply_ct A9 B3 iA a S| to |Convert to: | xvz s] Colour. convert, item. XYZ. item. action AS colour | Colour value: (50, 0, 0] <> [a7 2.71464 | 48 | calculated white-point adjustment to get to D65 wo | c CR ID] A stant] 628 (D)inbox...| (w] cheap... | Gp Pecs | > Test 1... | HB unsav...|[H 6534. (P)Fig3_...| (W] chapt...[ { Seaich Deskior O80 8 GB 11:47 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
