High-pressure fluorescence study using a polarity-sensitive probe Prodan on phosphatidylcholine (PC) bilayers is reviewed. The author has constructed a three-dimensional image plot based on the second-derivative of the Prodan fluorescence spectra that change depending on the phase state of the PC bilayers, which enables us to examine the packing state of the bilayer. The effects of (1) acyl chain length, (2) vesicle size, and (3) chain asymmetry on the PC bilayers are discussed by using the technique of bilayer imaging. Further the formation of the lamellar crystal phase of the PC bilayer is also revealed by the technique.