Oldal 138 [138]
OCR
cn A B 7 18) A matrix of values is created by subdividing the image of the standards by the number entered and determining the average X, Y and Z values for each of these. Double leftclicking on the "sample" thumbnail (Figure 3-30 and Figure 3-31) opens a window (Bl.sample), which aids in the visualisation of the areas being sampled to create this matrix of values. A slider is provided to adjust this area. Thus in Figure 3-30, 50% of the area of each target is sampled. In Figure 3-31 this has been adjusted to 40%, to ensure the area sampled is within the targets (as these are further apart and vary in shape). Adjust as necessary for the available Spectralon diffuse reflectance standards. Generating the colour calibration matrix 19) Click on the “viscalib” tab to the right. Column D on the left carries out the analysis and generates the calibration matrix from the Macbeth chart (Figure 3-32). The image at D1 is automatically carried over from the “markup” tab. input linear | markup | viscalb | uvicalib align | specden falsecolour uvistray | uvikm | vilstray ! vilkm results + V H- calibrate visible reflectance image a i 2 m0 label | visible reflectance | v v targets_label | visible reflectance with calibration targets, colour-calibrated S targets ! object label | visible reflectance of object, colour-calibrated macbeth | Pick a Macbeth data file: macbeth_lab_d65.mat Ő D8.sample - 50% = = =| Elle view Help mode input LUT: [linear input, set brightness from chart © > Shane wes 08 75 By Kt ci linearising_lut Image, unsigned gli ( 514, 16) — 110 109 146 Magnification 1:2 a ts sans, 256 pots, range [0,25], vrange (0, 0.996076] is M |0.290469 (0.674184 (0.0158778 v 0.543422 (1.51308 | 0.0303436 ~0.180834 0.143996 | 1.04073 scale | 1.325384 ava_dE76 | 4.892412 worst patch | Blue (patch 13, 13.174 de) input.Find_calib_item.action D1 ( fs] 6B 6) B+\ os) ae] wolfe Eel] Seach desir [GPO GB wx Figure 3-32 20) Double left-clicking on the “sample” thumbnail (Figure 3-32) opens a window (D8.sample), which aids in the visualisation of the areas being sampled to create the calibration matrix. A slider is provided to adjust this area if necessary. 21) Check that the file “macbeth_lab_d65.mat” has been selected in the “Pick a Macbeth data file” option (this should be loaded automatically on loading the workspace), (Figure 3-32). 22) Check that the “Linear output, set brightness from chart” option has been selected from the “Input LUT” menu in D8, (Figure 3-32). This sets the brightness or luminance of the image from the grey scale on the Macbeth chart. Version No. 1.0 130 Date : 14/10/2013
