Fig. 1. Chromaticity diagrams of 1600 Munsell color blocks obtained by CIE D65 and CIE 1931 standard observers. (a) L^*-a^* chromaticity diagram; (b) L^*-b^* chromaticity diagram; (c) a^*-b^* chromaticity diagram

Fig. 2. Spectral error distributions obtained by different dimension reduction methods. (a) Dimension reduction by LabPQR method; (b) dimension reduction by LabKMN method

Fig. 3. Spectral reconstruction RMSE curves obtained by different dimension reduction methods. (a) Dimension reduction by LabPQR method; (b) dimension reduction by LabKMN method

Fig. 4. Fitted curves of reconstructed spectra for different samples. (a) Sample with good fitted effect; (b) sample with general fitted effect; (c) sample with poor fitted effect