tailieunhanh - COLOR MANAGEMENT- P7

COLOR MANAGEMENT- P7: ICC White Papers are one of the formal deliverables of the International Color Consortium, the other being the ICC specification itself – ISO 15076: Image technology color management – Architecture, profile format, and data structure. The White Papers undergo an exhaustive internal development process, followed by a formal technical review by the membership and a ballot for approval by the ICC Steering Committee. | 164 Measurement and Viewing Conditions The ICC recommends that when making measurements for the purpose of generating profiles polarization filters should be removed and instruments with polarization that cannot be removed should not be used. Instruments with polarization may still be appropriate for in-plant process control purposes to monitor the deviation between dry proof and wet print. Furthermore time should where possible be allowed to ensure that the print is properly dry before making measurements. In some cases the drying time required to stabilize color measurements is longer than might be expected from just observing the surface gloss or tackiness. Measurement and Calculation Procedures for Transmitting Media The recommendations of ISO 13655 should be followed when measuring transmitting media with the exception of the source of illumination which is generally less critical because transmitting substrates with fluorescence are extremely uncommon. ISO 13655 specifies that the measurement geometry for transmitting media should be either 0 diffuse or diffuse 0. If an opal glass diffuser is used it should conform to that defined in ISO 5-2. The procedure for the calculation of tristimulus values should be the same as for reflecting media by using the CIE 1931 Standard Colorimetric Observer 2 with the CIE illuminant D50. The ISO 13655 spectral weighting functions derived from this observer and illuminant should be used when the measurement is made with a spectrophotometer or spectroradiometer in which the spectral sampling interval is coarser than that specified by CIE - that is less than or equal to 5 nm. Of the different ISO 13655 measurement conditions ICC recommends an M2 condition typically achieved with a tungsten source conforming to that in ISO 5-2 with any UV excluded when making measurements for characterization data intended for the creation of ICC profiles. The recommendations as to averaging a number of measurements should be consistent .