1. A method for displaying an image on a target display comprising: receiving image data at the target display, the image data comprising a predetermined image value of the image data corresponding to a predetermined mid-tone value displayed on a reference display; and mapping the image data to the target display so that the mid-tone value when viewed on the target display matches the predetermined mid-tone value when viewed on the reference display, wherein a dynamic range of the target display differs from a dynamic range of the reference display, wherein the mapping sets a slope of a mid-tone region of a response function when viewed on the target display to match a corresponding mid-tone region of a response function of the reference display, and wherein the mapping comprises a mapping function given by: L OUT = c 1 + c 2 ⁢ L IN n 1 + c 3 ⁢ L IN n where L OUT is an output of the mapping, L IN is an input of the mapping, and c1, c2,c3 and n are numeric parameters.