This study deals with a two-step modification of the linear gray scales for the display of calculated T1 and T2 images. The first step, isoprecision display, links up the gray scales for T1 and T2 images and the estimated precisions of these parameters. For arbitrary experimental setups isoprecision gray scales can be calculated and implemented using table-lookup techniques. In the special case of a minimal dataset ratio images turn out to provide good approximations for isoprecision gray scales. The second step adapts the gray scales to the response of the human visual system by applying Weber's law.