In this article, the authors present a method for assessing image quality in stereoscopic images: QUALITAS. The proposed method is inspired by some features of the human visual system, such as contrast sensitivity, response to visual disparity and perception of distance. Individual qualities of the stereo-pair are not simply averaged. QUALITAS introduces Contrast Band-Pass Filtering on a wavelet domain in both views; in this way it weights left and right images perceptually depending on viewing conditions. The authors have tested the method on the LIVE 3D stereoscopic image database and compared the results with a wide set of image quality metrics from current research.