The slanted-edge method is commonly used for measuring the spatial frequency response (SFR) of digital imaging systems. To investigate the intrinsic capability of the slanted-edge method, this study formulated a procedure for calculating the SFR and proposed a numerical method for evaluating the accuracy of the estimated SFR relative to the theoretical value. It is shown that the slanted-edge method yields an accurate value of the SFR under ideal conditions and is a rational and consistent tool for determining the true resolution characteristics. However, under practical conditions, this includes some estimation errors. Based on this analysis, it is possible to identify the parameter that influences the estimation accuracy in the SFR computation.