Time-resolved microscopy in a variety of configurations is used for three-dimensional imaging of laser photothermal materials used in offset lithographic computer-to-plate printing applications. Materials having an ink-repelling silicone layer and either a metallic absorbing layer or an energetic absorbing layer are studied. The energetic layers result in lower exposure thresholds when 10 microsecond and 2 microsecond duration near-IR laser pulses are used. The images explain the mechanism of threshold lowering, as a result of hot gas from the energetic layer causing the silicone layer to balloon. The expanding balloon results in less laser energy needed to produce an exposed spot.