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A procedure for creating efficient reflectance spectra from CIE tristimulus colour values is described using a modified linear model. By fixing certain criteria based on colour difference values, the proposed technique preliminarily selects a series of suitable samples from a main data set containing the reflectance values of a large number of different coloured samples, based on the colour specifications of a given sample. In this way, a series of different databases containing the reflectance values of confirmed samples relating to the particular samples are formed. Then, a well‐known principal components linear model is applied using three basis functions. This operation yields higher cumulative variances in comparison with the original database, having the same number of basis vectors. The performance of the proposed method is evaluated using a different collection of samples and the resulting spectra show considerable improvements in terms of root mean square error as well as colour difference values under different illuminants.

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The surface of a LDPE was modified by Ar, O 2 , N 2 , CO 2 gaseous plasma. The changes in surface morphology and surface wettability were investigated using AFM and SEM. The surface chemical changes of LDPE were also characterized by FTIR-ATR. The SEM and AFM results demonstrated variable changes in surface roughness for different types of plasma gas used, the changes being more for the Ar and N 2 plasma treatments. Considering the nature of the LDPE film, XRD studies were carried out to determine changes in the percentage crystalinity. The results showed that all low pressure O 2 , Ar, N 2 , CO 2 gas plasmas improved the wettability of LDPE films. Contact angles decreased significantly depending on the discharge powers and exposure times. Surface morphology was also found to vary with plasma discharge powers, exposure times, and the type of gas being used. Ar and N 2 gas plasmas in general produced more superior results.

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