GB/T 24288-2009 "Determination of Principal Wavelength and Excitation Purity of Paper and Cardboard D65/10 ° Diffuse reflection method" specifies the standard method for determining the principal wavelength and excitation purity of paper and Cardboard. The standard is tested by D65/10 ° diffuse reflection method, which is suitable for Color evaluation of paper and Cardboard. During the test, the Color characteristics and color purity of paper are determined by Diffuse Reflection spectrum analysis using D65 Light source and 10 ° viewing angle. The standard describes in detail the configuration of test equipment, sample preparation and test conditions to ensure the accuracy and conformity of the measurement results. This method is essential for quality control and color management of paper products.