Color difference

Abstract: In this study the effect of high temperature on mechanical properties, dimensional stability and color of spruce was investigated. Wood specimens conditioned at different relative humidities (50, 65, 80 and 95 %) were subjected to heat treatment at 200 degreesC for 2, 4, 8, 10 and 24 h and at 100, 150 and 200degreesC for 24 h. Color changes were measured in the Minolta Croma-Meter CR-300 color system. Bending strength and modulus of elasticity were determined according to DIN 52186. The results show that heat treatment mainly resulted in a darkening of wood tissues, improvement of the dimensional stability of wood and reduction of its mechanical properties. The darkening accelerated generally when treatment temperature exceeded approximately 200degreesC. Most of the darkening occurred within the first 4 h of exposure. For the specimens heated to high temperatures, the average decrease in bending strength was about 44-50 %, while modulus of elasticity was reduced by only 4-9 %. We found that treatment time and temperature were more important than relative humidity regarding the color responses. Strong correlations between total color difference and both modulus of elasticity and bending strength were found. Thus, the color parameters can be estimated quantitatively and used as a prediction of wood strength.

Abstract: Preface. Contributors and Referees. Part I: Historic Retrospection. 1. Translation of CIE 1931 Resolutions on Colorimetry (Translated by P. Bodrogi). 2. Professor Wright's Paper from the Golden Jubilee Book: The Historical and Experimental Background to the 1931 CIE System of Colorimetry (W. D. Wright). 3. CIE Colorimetry (Janos Schanda). 4. CIE Color Difference Metrics (Klaus Witt). 5. Spectral Color Measurement (Yoshi Ohno). 6. Tristimulus Color Measurement of Self-Luminous Sources (Janos Schanda, George Eppeldauer, and Georg Sauter). 7. Color Management (Jan Morovic and Johan Lammens). 8. Color Rendering of Light Sources (Janos Schanda). Part III: Advances in Colorimetry. 9. Color-Matching Functions: Physiological Basis (Francoise Vienot and Pieter Walraven). 10. Open Problems on the Validity of Grassmann's Laws (Michael H. Brill and Alan R. Robertson). 11. CIE Color Appearance Models and Associated Color Spaces (M. Ronnier Luo and Changjun Li). 12. Image Appearance Modeling (Garrett M. Johnson and Mark D. Fairchild). 13. Spatial and Temporal Problems of Colorimetry (Eugenio Martinez-Uriegas). 14. The Future of Colorimetry in the CIE (Robert W.G. Hunt). Appendix 1: Measurement Uncertainty (Georg Sauter). Appendix 2: Uncertainties in Spectral Color Measurement (James L. Gardner). Appendix 3: Use of CIE Colorimetry in the Pulp, Paper, and Textile Industries (Robert Hirschler and Joanne Zwinkels). Appendix 4: List of CIE Publications. Glossary. Index.

Abstract: The International Commission on Illumination (CIE) has recommended the use of two approximately uniform color spaces and associated color-difference formulae chosen from among several of similar merit to promote uniformity of practice. In this paper, the various features of the two formulae are discussed and compared. It is shown that the two are approximately equal in their degree of agreement with visual judgements of color difference. Choice of which formula to use in a particular situation will often depend not so much on scientific merit as on other factors such as familiarity and conformance to common practice in a particular industry or group.