In order to fully exploit the energy-time degree of freedom for photonic quantum information processing, it is necessary to develop techniques to manipulate single-photon waveforms on the sub-picosecond time scale. One possible method is to combine dispersive pulse shaping and sum-frequency generation to customize a photon's spectral and temporal profiles. In this talk, I will explain how this process can be used to image a single photon in the time domain, in direct analogy to a lens being used to image an object in space. I will then discuss our experimental demonstrations which show the versatility of this method, from customizing energy-time entanglement in downconversion sources to measuring coherent superpositions of picosecond-separated time bins with slow detectors.