1. A method for converting input image data into output image data comprising the act of: splitting the input image data into at least two signals, a first signal comprising regional contrast data and a second signal comprising detail data; stretching a dynamic range of the first signal to provide a stretched first signal; stretching a dynamic range of the second signal to provide a stretched second signal, wherein the dynamic range of the first signal is stretched to a higher degree than the dynamic range of the second signal; combining the stretched first and second signals to from a combined signal: analyzing the input image signal to identify groups of pixels forming highlights in the image, wherein the dynamic range of an output signal is bound by an upper value, converting pixel data for said identified groups of pixels are converted into a third signal such that the third signal covers a dynamic range extending upwards above the said upper value to an upper maximum pixel value; and combining the third signal with the combined signal to form the output signal; and outputting the output signal.