1、 FORD LABORATORY TEST METHOD BI 109-03 Date Action Revisions 2001 03 14 Revised Editorial no technical change A. Cockman 1996 10 24 Printed copies are uncontrolled Page 1 of 8 Copyright 2001, Ford Global Technologies, Inc. COLOR DIFFERENCE EVALUATION OF TEXTILE MATERIALS Application This procedure d
2、escribes a method for determining the quantitative color difference between any two textile materials which meet the measurability requirements. Apparatus Required Spectrophotometer Macbeth MS2000, MS2020 or Micromatch spectrophotometer system. Source: Instrumental Color Systems Ltd. Kennetside, Ken
3、netside Park Industrial Estate Newbury, Berkshire RTG14 5TE Equivalent spectrophotometers may also be used provided they have been given prior approval by Ford Motor Company. In cases of dispute, the above system as used by Ford Materials Engineering will be used as referee. Optical Geometry Sample
4、shall be diffusely illuminated by means of a diffusing sphere. The angle of vi ewing shall not exceed 10. The converse geometry of illumination 0.008856 but L* = 903.3(Y/Yn) if Y/Yn 0.008856 but f(X/Xn) = 7.787(X/Xn) + 16/116 if X/Xn 0.00856 but f(Z/Zn) = 7.87(Z/Zn)1/3 + 16/116 if Z/Zn or = 1.0 desc
5、ribes an ellipsoid volume with axes in the direction of lightness, chroma and hue centered about a standard. Ellipsoid semi-axes lengths of 1SL, cSC and SH calculated for a given standard describe a unit volume of acceptance within which all samples are less than 1.0 DEcmc unit from the standard. Th
6、is volume and the size and the ratio of its semi-axes becomes the basis for the establishment of an appropriately sized volume of acceptability for a given commercial situation by the application of commercial factor (cf) to all dimensions. The volume of acceptance is defined by DEcmc = cf Note: The
7、 size and the orientation of the ellipsoid varies considerably depending on location of standard in color space. Interpretation of Results The color difference between two specimens can be partitioned into components of lightness, chroma and hue. Lightness Component The lightness component is calcul
8、ated for use in the equation for DE and L*/1SL , and is the difference in lightness between the test specimen and the reference specimen; it is designated DL. The nature of any lightness difference can be derived from the following equation: L = LT* - LR* If * is positive the test specimen is lighte
9、r than the reference specimen. If * is negative, the test specimen is darker than the reference specimen. If L* is zero, there is no difference in lightness. Chroma Component The chroma component is calculated for use in the equation for DE and Cab and is the difference in chroma between the test sp
10、ecimen and the reference specimen; it is designated DC. The nature of any chroma difference can be derived from the following equation. Cab, T* = Cab, T* - Cab, R* If Cab* is positive, the test specimen is of more chroma than the reference specimen. If Cab* is negative, the test specimen is of less
11、chroma than the reference specimen. If Cab* is zero, i.e. the test specimen lies on the isochrome line passing the position of the reference specimen, there is no difference in chromatic strength. FORD LABORATORY TEST METHOD BI 109-03 Page 8 of 8 Copyright 2001, Ford Global Technologies, Inc. Hue Co
12、mponent The hue component is calculated for use in the equation for DE and Hab* /Sh and is the difference in hue between the test specimen and the reference specimen; it is designated DH. The nature of any hue difference can be derived in the following way: Rotate the chroma axis passing through the
13、 a*b* coordinates of the reference specimen so that it passes through the a*b* coordinates of the test specimen; minimizing angular displacement. The hue associated with the first major axis to be crossed during the rotation, continuing if necessary, will describe the nature of the hue difference un
14、less the test specimen is of the same hue; to describe a test specimen as being redder than a reference specimen which is red, for example, is meaningless. To overcome this limitation the rotation of the chroma axis is continued until the next major axis is crossed. The hue associated with this axis
15、 is quoted, expressed in brackets. One of the two hue difference terms will be valid, the other meaningless. If desired the value of DH may be designated + if the chroma axis rotation is anticlockwise and - if clockwise. Color Difference of White, Grey and Black (Achromatic) Specimens Although the t
16、otal color difference is CMC (1:c) units is valid for achromatic specimens the method of partitioning this difference is valid for lightness differences only when Cab = 4.0 since the chroma and hue difference components often do not correspond with visual assessments. Test Report The total color dif
17、ference and the component color differences shall be described as being in CMC (1:c) units and the values of 1 and c shall be stated. If any combination of illuminant and color matching functions other than D 65/10 have been used in the calculations it shall be stated. In the case of achromatic specimens which are defined as having Cab* = 4.0 only the total color difference DE and the lightness difference shall be reported.
