This paper attempts to estimate the coefficients of the RGB-> XYZ-> LAB color calibration model based on calibration model relating to the relationship of the RGB values of the X-rite standard color checker and its Lab values by adopting nonlinear polynomial regression analysis, then build the color assessment and measurement system based on the digital images. Numerical results indicate that the value predicted by the multi-factor model show a significant correlation with the value measured by the spectroradiometer, and lay the basis of applied research for the future digital image method for color measurement.