Stranica 65 [65]
OCR
Rexrite T re A NSCCPPCCOSO? sza xrite TETTETETT TTTTTTTETI TETTETETT TETTETETT TETTETETT Het Figure 2-17. X-Rite ColorChecker Passport which has replaced the X-Rite ColorChecker Mini.”° The targets themselves come in a range of sizes and formats, from the full-size ColorChecker Classic (20.9 x 27.9 cm), preferable for large works, to the now discontinued ColorChecker Mini (5.7 x 8.2 cm), which has been integrated into the ColorChecker Passport” (Figure 2-17) and is used for close-up shots or smaller works. Note that the frame of this new version exhibits luminescence, and should be masked off for use in the acquisition of luminescence images. The manufacturer suggests that the typical lifespan of a ColorChecker target is two years. However, it is important to note that prolonged exposure of these targets to radiation, particularly UV radiation, will fade the ColorChecker patches and alter the Lab values, thus affecting the colour calibration procedure. — Spectralon diffuse reflectance standards The Spectralon diffuse reflectance standards referred to in Chapter 1 carry out several functions, including luminance calibration of reflected images, and detection of the presence of ambient stray radiation in luminescence images. These standards are recommended due to their durability, chemically inertness and their certified spectral flatness over the UV-VISNIR spectrum (Figure 2-18). Version No. 1.0 57 Date : 14/10/2013
