The bleaching rate of the emulsion made with the selected complexes SP1 for yellow, SP3 for magenta and SP4 for cyan is shown in Fig. 9. A comparison with Fig. 7 illustrates the amplification. This is particularly apparent for the cyan complex where the optical density dropped from 1.5 to 0.25 in less than 20 s. The examination of these curves shows that the amplification is closely related to the structure of the spiropyran complexes. To provide a more uniform amplification