Right now there are at least three publicly known ranking systems for cell phones (CPIQ [IEEE P1858, in preparation, DxOmark, VCX) that try to tell us which camera phone provides the best image quality. Now that IEEE is about to publish the P1858 standard with currently only 6 Image quality parameters the question arises how many parameters are needed to characterize a camera in a current cell phone and how important is each factor for the perceived quality. For testing the importance of a factor the IEEE cellphone image quality group (CPIQ) has created psychophysical studies for all 6 image quality factors that are described in the first version of IEEE P1858. That way a connection between the physical measurement of the image quality aspect and the perceived quality can be made.