The present disclosure relates to an apparatus and method for improving image quality by combining an unbiased image and a biased image using a James-Stein combiner. An apparatus for improving image quality using a James-Stein combiner according to the present disclosure includes an unbiased image buffer configured to output an unbiased image block, a biased image buffer configured to output a biased image block, a sample variance buffer configured to output a sample variance of the unbiased image, an artificial neural network model configured to derive a variance weight per pixel, a variance estimator configured to output a variance estimate of the unbiased image block, and a James-Stein combiner configured to locally combine the biased image block, the unbiased image block, and the variance estimate of the unbiased image block by applying a James-Stein combination equation.