1、 FORD LABORATORY TEST METHOD EU-BI 009-03 Date Action Revisions 2001 03 13 Revised Editorial no technical change A. Cockman 1994 02 28 Printed copies are uncontrolled Page 1 of 5 Copyright 2001, Ford Global Technologies, Inc. COLOUR DIFFERENCE EVALUATION Application This procedure describes a method
2、 for determining the quantitative colour difference between any two visually similar materials. Equipment Required Trilac Recording Spectrophotometer Source: Kollmorgen (UK) Ltd. or Kollmorgen Colour Systems 219 Kings Road 3 that is, the spectrophotometric properties are essentially similar. Conditi
3、oning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/- 2 C and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Procedure 1. Viewing conditi
4、ons of the instruments are to be i, (diffuse) where i is angle at which light is incident on the samples, not to be greater than 10, and that light viewed by the instrument is diffusely reflected from the sample; or alternately, (v, diffuse) where illumination of the sample is diffused and v is an a
5、ngle of viewing not greater than 10. 2. The specular component is to be included in all measurements. 3. Calibration of the instruments must be followed according to the written instructions of the manufacturers. 4. Sample and standard must be presented to the measuring port in the same direction ac
6、cording to grain, machine direction or mould grating. 5. A measurement is to be made for the standard with each evaluation of a new sample. FORD LABORATORY TEST METHOD EU-BI 009-03 Page 3 of 5 Copyright 2001, Ford Global Technologies, Inc. 6. In the case of the Trilac spectrophotometer or equivalent
7、 the spectrophotometric curves of standard and sample are to be drawn in accordance with the recommended operating instructions. 7. Computation of colour difference is to be by the FMC-2 method (see Appendix). Preferred method of computation is with a digital computer. 8. Total colour difference is
8、 to be reported as Delta E. Reporting of accompanying data is optional (see Appendix). Reference For more detailed information and discussion of equipment, samples and procedure, see the following: “A Catalogue of Colour Measuring Instruments and A Guide to Their Selection“, Inter-Society Colour Cou
9、ncil, April 1970. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD EU-BI 009-03 Page 4 of 5 Copyright 2001, Ford Global Technologi
10、es, Inc. COLOUR DIFFERENCE EVALUATION Appendix - Computation of E by FMC-2 Given a pair of samples, for which the CIE tristimulus values are known, to compute the colour difference E by the method known as FMC-2. Let the tristimulus values of the standard be designated by X, Y and Z, and the tristim
11、ulus values of the sample being compared with it by X, Y, and Z. The FMC-2 colour difference E is then given by E = ( C)2 + ( L)2 0.5 Where C is the total chromaticity difference between sample and standard, and L is the lightness difference. C may be considered as consisting of a red-green differen
12、ce (rg), and a yellow-blue difference (yb), according to C = ( (rg) 2 + (yb) 2 ) 0.5 (The algebraic meaning of signs in the definition of these chromaticity differences is such that the sample is redder than standard if (rg) is positive, greener if negative. The sample is yellower than standard if (
13、yb) is positive, bluer if negative.) These quantities may be computed as follows: Let P = 0.724X + 0.382Y - 0.098Z Q = -0.48X + 1.37Y + 0.1276Z S = 0.686Z a2 = 17.3 x 10-6 (P2 + Q2) / 1 + 2.73P2Q2 / (P4 + Q4) b2 = 3.098 x 10-4 (S2 + 0.2015Y2) and P = P1 -P Q = Q1 -Q S = S1 S FORD LABORATORY TEST MET
14、HOD EU-BI 009-03 Page 5 of 5 Copyright 2001, Ford Global Technologies, Inc. then (rg) = K 1 Q P - P Q a (P2 + Q2) 0.5 (yb) = K 1 (S L 1 - S) b (P2 + Q2) 0.5 L = 0.279 K 2 L 1 a Where: K1 = 0.55669 + 0.049434Y - 0.82575.10-3Y2 + 0.79172 x 10-5Y3 - 0.30087 x 10-7Y4 K2 = 0.17548 + 0.027556Y - 0.57262 x
15、 10-3Y2 + 0.63893 x 10-5Y3 - 0.26731 x 10-7Y4 L = P P + Q Q (P2 + Q2 )0.5 Reference: Wyszecki, JOSA 58, 292, 1968 McLaren, Colour Engineering 7, 38, 1969 Chickering, JOSA 61, 118, 1971 FMC-2 Formula Fortran IV November - December, 1967, Colour Engineering Title “Optimized Equations for MacAdam Colour Differences“ by F.W. Billmyer, Jr., and Roger Smith
