The numerical computional method for color image rendering,which aims to calculate the tristimulus values of vision responses from the surface reflecting spectral power distribution in the scene,is presented.The linear model is exploited to approximate the reflecting continuous spectrum of the object surface and the numerical computation is conducted via Gaussian quadrature (GQ) and Riemannian summation (RS).The tristimulus values are converted to chromatic coordinates which match the images captured by CCD camera.