Release 4.6 of AxioVision FRET (Fluorescence Resonance Energy Transfer) microscopy software facilitates fast, comprehensive evaluation of FRET measurements. It combines all current methods of FRET measurement by using different correction techniques or acceptor bleaches. This makes it possible to also determine the FRET portion in FRET-coded color images. The evaluation can already be performed online during the capture of time series images. The FRET method allows the determination of the energy transfer portion between two closely adjacent protein molecules or the measurement of the distance between two closely adjacent protein molecules below the microscope resolution. It is used to determine quantitative temporal and spatial information about the bonding and interaction between proteins, lipids, enzymes, DNS and RNS.